Disposable laryngeal mask airway device

ES 2 371 013 T3

DESCRIPTION

Disposable Laryngeal Airway Mask Device.

Background of the invention

The present invention relates to a laryngeal airway mask (LMA) device. More specifically, the present invention relates to low cost laryngeal masks, improved geometric configurations for laryngeal masks, and inexpensive manufacturing methods for such masks.

The Laryngeal Airway Mask (LMA) device is a well-known device that is useful for establishing airways in unconscious patients. LMAs have been in use for approximately twelve years and offer an alternative to the older, even better known endotracheal tubes. For at least seventy years, endotracheal tubes comprising a long thin tube with an inflatable balloon disposed at the distal end of the tube have been used to establish airways in unconscious patients. In operation, the distal end of the endotracheal tube is inserted through the patient's mouth, past the patient's laryngeal inlet (or glottic opening), and into the patient's trachea. Once so positioned, the balloon is inflated to form a seal with the inner lining of the trachea. After this seal is established, positive pressure can be applied to the proximal end of the tube to ventilate the patient's lungs. Also, the seal between the balloon and the inner lining of the trachea protects the lungs from aspiration (for example, the seal prevents regurgitated material from the stomach from being aspirated into the patient's lungs).

Although they have been enormously successful, endotracheal tubes suffer from some major disadvantages. The main disadvantage of the endotracheal tube is related to the difficulty of inserting the tube correctly. Inserting an endotracheal tube into a patient is a highly skilled procedure. Also, even for experienced practitioners, insertion of an endotracheal tube is sometimes difficult or impossible. In many cases, the difficulty of inserting endotracheal tubes has tragically led to the death of a patient as it was not possible to establish an airway in the patient quickly enough.

In addition to this main disadvantage, there are also other disadvantages associated with endotracheal tubes. For example, intubation with an endotracheal tube often causes patients to suffer from severe “sore throats”. The "sore throat" is mainly caused by friction between the tube and the notch between the patient's arytenoid cartilages. Another disadvantage is that patients cannot cough effectively while intubated with an endotracheal tube. Still another problem with endotracheal tubes relates to the way they are inserted. Typically the insertion of an endotracheal tube requires manipulations of the patient's head and neck and further requires that the patient's jaw be forcefully and widely opened. These necessary manipulations make it difficult, or undesirable, to insert an endotracheal tube into a patient who may be suffering from a neck injury. Still another disadvantage is that these endotracheal tubes provide an airway that is relatively small or narrow. The size of the airway must be relatively narrow because the distal end of the tube must be small enough to fit into the trachea.

In contrast to the endotracheal tube, it is relatively easy to insert an LMA into a patient and thereby establish an airway. Also, the LMA is a "compassionate" device in that even when inserted improperly, it still tends to establish an airway. Consequently, the LMA is often thought of as a "lifesaving" device. Also, the LMA can be inserted with only relatively minor manipulations of the patient's head, neck, and jaw. In addition, LMA maintains ventilation of the patient's lungs without requiring contact with the sensitive inner lining of the trachea, and the size of the airway established with an LMA is typically and significantly larger than the size of the airway established with a tube. endotracheal. Also, LMA does not interfere with coughing to the same extent as endotracheal tubes. Due in large part to these advantages, MLA has enjoyed increasing popularity over the past twelve years.

Figure 1 shows a perspective view of a prior art LMA 100 and Figure 2 illustrates an LMA 100 that has been inserted into a patient. MLAs such as MLA 100 are described for example in US Patent No. 4,509,514. The MLA 100 includes a flexible cylindrical tube 110 and a portion of the mask 130. The tube 110 extends from a proximal end 112 to a distal end 114 and a portion of the mask 130 couples to the distal end of the tube 114. The mask portion 130 includes a proximal end 132 and a generally elliptical inflatable cuff 134. The mask portion 130 also defines a central passageway that extends from the proximal end 132 to an open end 136 of the cuff 134. The distal end 114 of the tube 110 telescopes into the proximal end 132 of the mask portion 130, and the LMA 100 provides a continuous, sealed airway that extends from the proximal end 112 of the tube 110 to the open end. 136 of cuff 134. The MLA 100 also includes an inflation tube 138 to selectively inflate or deflate cuff 134.

In operation, cuff 134 is deflated, and then the mask portion is inserted through the patient's mouth into the patient's pharynx. The mask portion is preferably positioned so that a distal end 140 of cuff 134 rests against the patient's normally closed esophagus and so that the open end 136 of cuff 134 is aligned with the entry port of the patient's trachea (i.e. , the glottic opening of the patient). After the mask portion is positioned, the cuff is inflated to form a seal around the opening.

ES 2 371 013 T3 glottic tube of the patient and this establishes a sealed entry pathway extending from the proximal end 112 of tube 110 into the trachea of ​​the patient.

For convenience of discussion, the term "fully inserted configuration" will be used herein to refer to an LMA that has been inserted into a patient and has the following characteristics: (1) The mask portion is disposed around the glottic opening of the patient; (2) the cuff is inflated to form a seal around the glottic opening of the patient; and (3) the airway tube extends from a proximal end located outside the patient's mouth to a distal end that engages the mask portion, the tube extending through the patient's mouth and the airway. patient's natural upper airway for the LMA to provide a sealed airway extending from the proximal end of the tube into the patient's lungs. Figure 2 shows an LMA in the fully inserted configuration.

When the MLA 100 is in the fully inserted configuration, the MLA 100 advantageously does not contact the inner lining of the trachea. Rather, the seal is established by contact between the tissues surrounding the patient's laryngeal inlet and the inflatable cuff 134. Contrary to the delicate inner lining of the trachea, the tissues at the laryngeal inlet are used to contacting foreign matter. For example, during the act of swallowing food, food normally squeezes against these tissues on its way up the esophagus. These fabrics are therefore less sensitive and less susceptible to being damaged by contact with the inflatable cuff.

Figure 3 shows a side sectional view of the mask portion 230 of another prior art LMA. The portion of the illustrated mask 230 that is more fully described in US Patent No. 5,355,879 includes an inflatable cuff 234 and a back plate 250. The back plate 250 defines a proximal end 232 for receiving, or engaging, a via tube. cylindrical aerial (not shown). Mask portion 230 defines a sealed passageway, or airway, that extends from proximal end 232 through open end 236 of cuff 234. This portion of mask 230 also includes an inflatable back cushion which, when inflated , extends to the outline illustrated by the dotted line 252. As shown in Figure 3, the cross sections of the prior art cuffs are generally circular. The thickness T1 of the material used to form the cuff (ie the wall thickness of the cuff) is typically about 0.7-0.8 millimeters.

US Patent No. 5,303,697 describes an example of another type of prior art MLA that is commonly known as an "MLA intubation". MLA intubation is helpful to facilitate the insertion of an endotracheal tube. After an LMA intubation has been placed in the fully inserted configuration, the LMA can act as a guide for a subsequently inserted endotracheal tube. The use of the LMA in this way facilitates what is commonly known as "blind insertion" of the endotracheal tube. Only minor movements of the patient's head, neck, and jaw are required to insert the MLA intubation, and once the MLA intubation has been placed in the fully inserted configuration, the endotracheal tube can be inserted with virtually no additional patient movement. . This resists in contrast to the relatively large movements of the patient's head, neck, and jaw that would be required if the endotracheal tube were inserted without the aid of MLA intubation.

US Patent No. 5,632,271 describes yet another example of another type of prior art MLA. In addition to providing an airway tube to ventilate a patient's lungs, this LMA also provides a second tube, a drainage tube, used to drain or remove regurgitated material. The distal end of the drainage tube is disposed proximate the normally closed entrance to the patient's esophagus. In addition to providing drainage, the drainage tube can also be used to guide the insertion of a gastric tube.

In general, prior art MLAs have been manufactured by molding elastomeric materials, such as silicone, into desired shapes. An advantage of these materials is that they are durable enough to allow the LAMs to be autoclaved and reused. For example, MLAs sold by MLA International SA of Henley, England, are guaranteed to survive forty sterilizations, and in practice these devices can generally be sterilized (and reused) more than forty times before becoming too deteriorated to be reused. However, a disadvantage of these materials is that they are relatively expensive. Therefore, it would be advantageous to develop a low cost MLA.

Various efforts have been made in the prior art to provide low cost MLAs. For example, US Patent No. 6,012,452 discloses a LMA in which the mask portion is formed by adhering a foam material to both sides of a back plate. The foam forms an inflatable cuff that attaches to both sides of the plate. US Patent No. 5,983,897 discloses another LMA in which the mask portion is formed by adhering the cuff members to the top and bottom of a back plate. The cuff members can be formed of flexible, elastic plastic material, such as PVC. A disadvantage of the MLAs disclosed in the '897 and' 452 patents is that the assembly of the disclosed mask portions necessarily involves two steps: a first step of manufacturing the back plate and then a second step of adhering the back plate. fist to the top and bottom of the plate. It would therefore be advantageous to develop a process to simultaneously form all parts of the mask portion of an MLA.

In addition to cost, another disadvantage of the prior art LMAs relates to the quality of the seal established between the patient and the LMA. The MLA shown in Figure 1 generally maintains a seal of approximately eight inches H₂O. That is, when the MLA is in the fully inserted configuration, the seal between the MLA and

ES 2 371 013 T3 the patient will be maintained as long as the pressure applied to the proximal end of the airway tube is less than approximately twenty cm from H₂O. However, if higher pressures are applied to the proximal end of the airway tube, the seal tends to be lost causing the loss of some fraction of the delivered gas volume, so positive pressure ventilation may be less effective. This is in contrast to the endotracheal tube which can normally maintain a seal at fifty cm from H₂O. Accordingly, it would be advantageous to provide an MLA that provides improved seals.

Yet another disadvantage of prior art LMAs relates to the profile, or geometric configuration, of the deflated LMA. When the cuff of an LMA is deflated, the LMA would ideally and automatically assume a shape that was optimized for ease of insertion. However, prior art LMAs do not tend to automatically form such shapes when the cuff is deflated. Accordingly, various "shaping tools" have been provided to affect the shape of the deflated LMA. US Patent No. 5,711,293 discloses such a forming tool. However, it would be advantageous to provide an LMA that automatically assumes a profile that facilitates insertion when the cuff is deflated.

Still another disadvantage of prior art LMAs relates to the way they are inserted into the patient. Anesthetists or other practitioners insert many types of LMA by pushing one of their fingers against the proximal end of the cuff. Unfortunately this procedure requires the practitioner to insert their fingers into the patient's mouth and guide the LMA past their throat. Since many practitioners prefer not to insert their fingers into patients' mouths, many tools have been developed to facilitate the insertion of various LMAs. However, it would be advantageous to provide an LMA that can be inserted without any tools and without requiring the insertion of a finger into the patient's mouth.

According to the invention there is provided an airway laryngeal mask device that includes a mask portion and an airway tube, the mask portion including a generally elliptical plate and a cuff, the elliptical plate defining a laryngeal side, a side pharyngeal, and a central opening, an inner perimeter of the cuff being attached to the laryngeal side next to the plate at a perimeter of the opening, an outer perimeter of the cuff being adhered to the laryngeal side of the plate next to an outer perimeter of the plate, the airway tube extending from a proximal end to a distal end, the distal end of the airway tube being adhered to the pharyngeal side of the plate, the cuff defining a laryngeal side when inflated, characterized by an angle (α) between the pharyngeal side of the plate and the laryngeal side of the cuff that is equal to ten degrees plus or minus one degree, as defined in claim 1. Preferred embodiments are defined in claims 2-4. A method of forming such a device is defined in claim 5.

Brief description of the figures

For a more complete understanding of the nature and purposes of the present invention, reference should be made to the following detailed description taken in connection with the accompanying drawings in which the same reference numerals are used to indicate the same or similar parts in which:

Figure 1 shows a perspective view of a prior art LMA.

Figure 2 shows a prior art LMA inserted into a patient in the fully inserted configuration.

Figure 3 shows a cross-sectional view of another prior art LMA.

Figure 4A shows a side view of an LMA, the mask portion of the LMA being in an inflated condition.

Figures 4B and 4C show two perspective views of the LMA shown in Figure 4A.

Figure 5A shows a side view of the inflated mask portion of the LMA shown in Figures 4A, 4B and 4C.

Figures 5B and 5C show two perspective views of the anterior portion of the mask portion shown in Figure 5A.

Figure 5D shows a perspective view of the rear portion of the portion of the mask shown in Figure 5A.

Figure 5E shows a rear view of the portion of the mask shown in Figure 5A.

Figure 6 shows a cross-sectional view of the portion of the mask taken in the direction of line 6-6 as shown in Figure 5A.

Figure 7A shows a side view of the portion of the mask shown in Figure 5A when the portion of the mask is deflated.

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Figure 7B shows an anterior view of the portion of the deflated mask shown in Figure 7A.

Figure 8A shows a top view of a mold that can be used to make the portion of the mask shown in Figure 5-7.

Figure 8B shows a cross-sectional view of the mold taken in the direction of line 8B-8B as shown in Figure 8A.

Figures 8C and 8D show perspective views of the mold shown in Figure 8A.

Figure 9A shows a side view of the LMA airway tube shown in Figures 4A, 4B and 4C.

Figure 9B shows a perspective view of the proximal section of the airway tube shown in Figure 9A.

Figures 9C and 9D show proximal section views taken in the direction of lines 9C-9C and 9D-9D, respectively, as shown in Figure 9B.

Figure 9E shows a side view of the integral tube and the section of the back plate of the airway tube shown in Figure 9A.

Figures 9F and 9G show two perspective views of the integral tube and backplate section shown in Figure 9E.

Figure 10A shows a cross-sectional view of the proximal section inserted into the integral tube and the section of the posterior plate taken in the direction of line 10A-10A as shown in Figure 9A.

Figure 10B shows a cross-sectional view of the curved portion of the integral tube and the backplate section taken in the direction of line 10B-10B as shown in Figure 9A.

Figure 10C shows a cross-sectional view of the same component illustrated in Figure 10B when that component is subjected to external compressive forces.

Figure 10D shows a side view of one embodiment of an LMA tubing and an endotracheal tube extending through the LMA.

Figure 10E shows a cross-sectional view of an LMA tubing taken along line 10E-10E as shown in Figure 10D.

Figure 10F shows a side view of another embodiment of an LMA.

Figure 10G shows a perspective view of the embodiment shown in Figure 10F.

Figure 11 shows a perspective view of a tube that has formed a kink in response to bending the tube.

Figure 12 shows a perspective view of an LMA in which the inflation tube has been attached to the airway tube so that the inflation tube extends into one of the slots in the airway tube.

Figure 13 illustrates how the airway tube shown in Figure 9A deviates from its preformed configuration when the LMA is located in the fully inserted configuration.

Figure 14 shows a perspective view of the laryngeal side of the mask portion of an LMA and illustrates the regions of the mask portion that seals with the different portions of the human anatomy when the LMA is located in the fully configured configuration. inserted.

Figure 15A shows a sectional view of a prior art LMA that has been placed in the fully inserted configuration.

Figure 15B shows a sectional view of an LMA constructed in accordance with the invention that has been placed in the fully inserted configuration.

Figure 16A shows a side view of the LMA shown in Figure 4A when the mask portion is deflated.

Figures 16B and 16C show perspective views of the LMA, with the portion of the mask deflated, shown in Figure 16A.

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Figure 17 shows an LMA that is partially inserted into a patient.

Figure 18A shows a side view of another LMA.

Figures 18B and 18C show perspective views of the LMA shown in Figure 18A.

Figure 18D shows a cross-sectional view of the airway tube taken in the direction of line 18D-18D as shown in Figure 18A.

Figure 19A illustrates how the LMA airway tube shown in Figures 18A-18D can be used to guide a subsequently inserted endotracheal tube.

Figure 19B shows an alternative embodiment of the LMA shown in Figures 18A-18C in which the proximal end of the plate is not attached to the proximal end of the posterior portion of the plate of the airway tube.

Figure 20 shows an alternative embodiment of a portion of the mask.

Figure 21 is a simplified perspective view for another LMA device according to the invention, as seen in three-quarter perspective and viewing the back side of the mask structure, in an inflated condition to the distal end of an airway tube. .

Figure 22 is a similar view of the structure of Figure 21, as a front side view (or facing the trachea) of the device of Figure 21, but in the evacuated state in which the thin film material of the Inflation has collapsed and has become entangled against the structure of the structural base of the device.

Figure 23 is a view similar to Figure 21, for an LMA device having a gastric drainage feature.

Figure 24 is a view similar to Figure 22, for the device of Figure 23.

Figure 25 is a cross-sectional view taken generally in the longitudinal sagittal plane of the device of Figure 23, certain parts have been omitted, for clarity.

Figure 26 is a rear side plan view of the device of Figure 23, certain parts omitted for clarity.

Figure 27 is a plan view as in Figure 26 but with samples added, to include the omitted structure of Figure 26.

Figure 28 is a sectional view, taken at 28-28 in Figure 27.

Figure 29 is a similar sectional view, but taken at 29-29 in Figure 27.

Figure 30 is a longitudinal section as in Figure 25, for a modified embodiment.

Figure 31 is another similar longitudinal section, taken only to show an integrally formed feature that is a major component of the embodiment of Figure 30.

Figure 31A is a view similar to Figure 31 to show a modification.

Figure 32 is a rear side plan view of the component of Figure 31.

Figure 33 is a view of a slightly modified version of the component of Figure 31.

Detailed description of the preferred embodiments

Figure 4A shows a side view of one embodiment of an MLA 400. Figures 4B and 4C show two perspective views of the MLA 400. The MLA 400 is preferably constructed of two separate pieces that are bonded, or bonded, together. The first piece is an airway tube 410 and the second piece is a mask portion 430. In Figures 4a, 4B and 4C, the mask portion 430 is shown in an inflated condition. As will be discussed in greater detail below, the mask portion 430 can advantageously be formed by a process called rotational molding. Airway tube 410 can also be produced by rotational molding, or alternatively, it could be produced using injection or other types of molding.

Figure 5A shows a side view of the mask portion 430 when inflated. Figures 5B and 5C show two perspective views of the anterior side of the mask portion 430 when inflated. Figure 5D shows a perspective view of the rear side of the mask portion 430 when inflated, and Figure 5E shows a view of the rear side of the mask portion 430 when inflated. The terms before

ES 2 371 013 T3 front and rear as used above in connection with Figures 5B-5E refer to the fully inserted configuration. That is, when the MLA 400 is in the fully inserted configuration, the portion of the mask portion 430 shown in Figures 5B and 5C will be located in front of, or anterior to, the portion shown in Figures 5D and 5E. Also, when the LMA 400 is in the fully inserted configuration, the portion of the mask portion 430 shown in Figures 5D and 5E will be disposed proximal to the pharyngeal wall of the patient, posterior to the portions shown in Figures 5B and 5C. . Figure 6 shows a cross-sectional view of the mask portion 430 taken in the direction of line 6-6 as shown in Figure 5A. Figures 7A and 7B show side and front views, respectively, of the mask portion 430 when deflated.

The mask portion 430 includes a plate 440, an inflatable cuff 460, and an inflation tube 490. The mask portion 430 also defines a proximal end 432 and a distal end 434 (shown for example in Figure 5D). Plate 440 is characterized by a generally elliptical shape and defines a central opening or through hole 442 (best shown in Figure 5E). For convenience in discussion, the shape of plate 440 may be referred to as an elliptical ring. A classical ring has circular symmetry, however, the elliptical ring on plate 442 follows the elliptical profile illustrated in Figure 5E. Also plate 440 defines a pharyngeal side 444 and a laryngeal side 446 (shown for example in Figure 5A). The pharyngeal side 444 of the plate 440 is so named because, as will be discussed below, the pharyngeal side 444 is disposed proximal to the pharyngeal wall of a patient when the LMA 400 is in the fully inserted configuration. The central opening 442 of plate 440 extends through the entire plate from the pharyngeal side 444 to the laryngeal side 446. The distance between the pharyngeal side 444 and the laryngeal side 446 of the plate 440, or the thickness of the plate, will be named T2, as shown in Figure 6. In some embodiments, the plate is substantially flat since the thickness T2 is substantially uniform across the plate. A preferred value for the thickness T2 of the substantially flat plate 440 is about two millimeters plus or minus one millimeter . Even more preferably, the thickness T2 of the substantially flat plate 440 is two millimeters plus or minus 0.5 millimeters. Even more preferably, the thickness T2 of the substantially flat plate 440 is substantially equal to two millimeters. In other embodiments, it may be advantageous for the plate to have a reduced thickness so that the plate is thicker at the proximal end than at the distal end. For example, the thickness of plate T2 can be about two millimeters at the proximal end and can be slightly reduced to about one and a half millimeters at the distal end.

The inflatable cuff 460 is formed of a very thin, flexible sheet of material that is attached to the laryngeal side 446 of the plate 440. As best shown in Figure 6, the cross section of the cuff 460, when inflated, generally It is U-shaped (or shaped like an inverted “U”). The generally elliptical inner periphery 460-I of the cuff 460 is sealed, or attached, to the plate 440 proximate the generally elliptical periphery of the opening 442, and the generally elliptical outer periphery 460-O of the cuff 460 is sealed, or attached, to plate 440 proximate the generally elliptical outer periphery of plate 440. The thickness of the cuff (ie, the cuff wall), as shown in Figure 6, will be named T3. A preferred value for the cuff thickness T3 is about 0.04 to 0.24 millimeters. More preferably, the thickness T3 is in the range of 0.08 to 0.20 millimeters (or 0.14 plus or minus 0.06 millimeters). Even more preferred, the thickness T3 of the cuff is 0.14 plus or minus 0.03 millimeters.

For convenience of discussion, the shape of the inflated cuff 460 will be called "generally toroidal." The fist shape is not strictly a bull for a number of reasons. For example, the cuff cross section is U-shaped rather than circular (as shown in Figure 6). Also, a classical torus is shaped like a ring, or donut (and is formed by rotating a circle about an axis in the plane of the circle that does not intercept the circle), while the fist 460 follows the generally elliptical shape of the plate. 440. Also, the thickness of the inflated cuff is not constant from the proximal end to the distal end (as shown for example in Figure 5A by angle alpha). However, despite these variations of the classical torus, the inflated cuff can be described as having a generally toroidal configuration (as it is formed essentially by sweeping the U-shaped cross section of the inflated cuff along the elliptical contour defined by the plate 440).

Plate 440 and cuff 460 of mask portion 430 help define a generally toroidal interior volume. Inflation tube 490 extends from the pharyngeal side 444 of plate 440 through the plate and into the interior volume to allow for selective inflation and deflation of cuff 460.

Like plate 440, mask portion 430 defines a pharyngeal side and a laryngeal side. The pharyngeal side of the mask portion 430 is coincident with the pharyngeal side 444 of the plate 440. The laryngeal side 448 of the mask portion 430 is defined by the inflatable cuff 460. As best shown in Figures 5A and 6, when the cuff 460 is inflated, the laryngeal side 448 of the mask portion 430 is defined by the outer surface of the cuff 460 at the cuff portion 460 that is disposed opposite the cuff. plate 440, or further from plate 440. When the LMA 400 is in the fully inserted configuration, the laryngeal side 448 of the mask portion 430 is in physical contact with the tissues surrounding the patient's laryngeal inlet. As best shown in Figures 5D and 5E, when cuff 460 is inflated, opening 442 extends completely through the mask portion so that the mask portion 430 defines a passageway 442 that extends from the laryngeal side. to the pharyngeal side.

For convenience of discussion, three directions will be defined with respect to the mask portion 430. The PtD arrow shown in Figure 5A extends in a proximal to distal direction. Mask portion 430 extends in a proximal to distal direction from proximal end 432 to distal end 434. It will be appreciated that a distal to proximal direction extends opposite to, or rotated 180 degrees from, the proximal direction.

ES 2 371 013 T3 a distal. The LtP arrow shown in Figure 5A extends in a direction from larynx to pharynx. Mask portion 430 extends in a laryngeal-to-pharyngeal direction from laryngeal side 448 to pharyngeal side 444. It will be appreciated that a pharyngeal-to-laryngeal direction extends opposite to, or rotated 180 degrees from, the direction of larynx to pharynx (The direction from larynx to pharynx could also be called the “anteroposterior direction”). The arrow LtR shown in Figure 5E extends in the direction from left to right. It will be appreciated that a right-to-left direction extends opposite to, or rotated 180 degrees from, the left-to-right direction. These directions are so named because when the MLA 400 is inserted into a patient, the MLA will extend from a left side to a right side within the patient. These right-to-left and left-to-right directions could also be called "side" directions. The directions from proximal to distal, from larynx to pharynx, and from left to right are mutually orthogonal and maintain a convenient reference coordinate system for describing LMA.

As shown in Figure 5A, the thickness of the mask portion inflated to the distal end 434 (i.e., the distance between the pharyngeal side 444 and the laryngeal side 448 of the mask portion 430 as measured in the direction of larynx to pharynx) will be called T4, and the thickness of the inflated portion of the mask at the proximal end 432, as measured in the direction from larynx to pharynx, will be called T5. The preferred values ​​for T4 and T5 in adult female sizes are approximately 12.7 and 25.4 millimeters, respectively. (It will be appreciated that external dimensions such as T4 and T5 would be approximately thirteen percent larger in an MLA adult male size. Unless otherwise specified, the dimensions discussed here will be for the female adult size). The profile of the cuff 460 is preferably slightly reduced as shown in Figure 5A so that the thickness of the mask portion 430 decreases slightly from the proximal end 432 to the distal end 434. This reduction is described in terms of the angle alpha between the pharyngeal side 444 and the laryngeal side 448 of the mask portion 430, as shown in Figure 5A. The alpha angle is equal to ten degrees plus or minus one degree. More preferably, the angle alpha is ten degrees plus or minus half a degree. More preferably, the angle alpha is substantially equal to ten degrees. As will be discussed below, this alpha angle is selected to match the human anatomy to allow all portions of the inflated cuff to contact the tissues surrounding the laryngeal inlet and thereby provide improved seals.

Plate 440 shown in Figure 5A is characterized by a substantially constant thickness. That is, the thickness T2 (as shown in Figure 6) of plate 440 is substantially constant from the proximal end of the mask portion to the distal end of the mask portion and the variation in thickness of the portion of the mask is fully provided by the cuff 460. However, as mentioned above, in some embodiments it may be advantageous to provide plate 440 with reduced thickness so that the distal end of the plate is thinner than the proximal end.

As shown in Figure 5E, the length of plate 440, or the distance between proximal end 432 and distal end 434 as measured in the proximal to distal direction, will be called L1, and the length of opening 442 as measured in the proximal to distal direction will be called L2. The width of plate 440, as measured in the left-to-right direction will be called W1, and the width of aperture 442 as measured in the left-to-right direction will be called W2. In MLA 400 adult sizes, the preferred values ​​for L1, L2, W1, and W2 are 90, 59, 47, and 26 millimeters, respectively.

As stated above, the mask portion 430 can be formed by a process called rotational molding. Figure 8A shows a plan view of a mold 800 that can be used to produce the mask portion 430 by rotational molding. Figure 8B shows a cross-sectional view of mold 800 taken along line 8B-8B as indicated in Figure 8A. Figures 8C and 8D show perspective views of the mold 800. As shown in Figure 8A, the mold 800 is symmetrical about an axis 802. As best shown in Figures 8C and 8D, the mold 800 includes an upper part 810 and a lower part 812. When the upper part 810 and the bottom piece 812 are bolted or clamped together, define a hollow interior volume 820 as shown in Figure 8B. The interior walls 830 of the mold 800 define the limits of the hollow interior volume 820.

A portion 822 of inner volume 820 has a generally toroidal shape that corresponds to the generally toroidal shape of inflated cuff 460. Another portion 824 of inner volume 820 has a generally elliptical shape that corresponds to the shape of plate 440. That is, the Portion 824 defines a hollow volume, the shape of which is substantially identical to the flat, elliptical shape of plate 440. Similarly, portion 822 defines a hollow volume, the shape of which is substantially identical to the shape of inflated cuff 460.

In operation, the mask portion 430 can be formed by adding or injecting a liquid plastic material (eg, polyvinyl chloride or "PVC") into the inner volume 820 of the mold 800 and then rotating or otherwise moving the mold 800 to cover the inner wall 830 with the liquid plastic material. Preferably, mold 800 is simultaneously rotated about two axes that are ninety degrees from each other (eg, axis 802 and another axis that is perpendicular to axis 802). While the mold 800 is rotating, centrifugal forces cause the liquid plastic material to coat all portions of the inner wall 830 of the mold 800. After all portions of the inner wall 830 have been so covered, the mold is then preferably held stationary in the position illustrated in Figure 8B. That is, the mold 800 is preferably oriented so that the portion 824 of the hollow interior 820 is at the bottom of the mold (that is, such that the portion 824 is parallel to the ground and is closer to the ground, or more lower than any other portion of the hollow interior 820) while the mold 800 is held stationary. While the mold 800 is held in this stationary position, it drains most of the

ES 2 371 013 T3 liquid plastic materials, or flows, downward along the inner wall 830 in portion 824. However, and not all of the liquid plastic material flows into portion 824. Rather, the surface tension u other forces cause a thin layer of the liquid plastic material to remain in contact with the inner wall 830 that defines the portion

822. The mold 800 is preferably held stationary long enough for the plastic material to vulcanize and solidify before the mold is opened to separate the upper and lower parts 810, 812.

The material that fills the portion 824 forms the plate 440 of the mask portion 430. The thin layer of plastic material that lined the inner wall 830 of the portion 822 forms a cuff 460 that integrally adheres to the plate 440. Entrapped air within inner volume 820, while mask portion 430 is being formed, it is trapped within cuff 460. Thus, when mask portion 430 is removed from mold 800, cuff 460 is partially inflated. Cuff 460 is only partially inflated (rather than fully inflated) when mask portion 430 is removed from mold 800 because, as the mold cools, the trapped air decreases in volume and consequently only partially fills the interior volume defined by fist 460.

It will be appreciated that a variety of materials can be introduced into mold 800 and used to form mask portion 430. The term "liquid plastic material" is used herein to refer to any material that is capable of vulcanizing from a liquid or fluid state to a solid, flexible, or plastic state. Due to its flexibility, resistance to stretching, and ability to define complex shapes such as inflated cuff 460, polyvinyl chloride is a preferred material for use as the liquid plastic material that forms the mask portion 430. However, It will be appreciated that other materials could also be used.

Once the mold 800 has been opened and the vulcanized plastic plate and cuff have been removed, the fabrication of the mask portion 430 can be completed by adding the inflation tube 490. It will be appreciated that adding the inflation tube 490 is a relatively simple step and is accomplished by forming an opening in the plate 440 that extends from the pharyngeal side 444 through the plate and into the interior volume defined by the cuff 460, and then fixing the inflation tube 490 to that opening. Alternatively, as will be discussed below, it may sometimes be advantageous to provide a mask portion 430 that does not include an inflation tube. In these cases, fabrication of the mask portion is complete as soon as the integrally formed vulcanizates, plate 440 and cuff 460 have been removed from mold 800.

The vulcanized mask portion is preferably relatively soft and flexible. In a preferred embodiment, the durometer of the vulcanized mask portion 430 is fifty-four, plus or minus ten on the Shore A Scale of hardness. More preferably, the durometer of the cured mask portion 430 is fifty four plus or minus five on the Shore A Scale of hardness. More preferably, the durometer of the vulcanized mask portion 430 is substantially equal to fifty four on the Shore A Scale of hardness.

Figure 9A shows a side view of the airway tube 410 including a connector section 411 and an integral tube and rear plate section 416. Figure 9B shows a perspective view of the connector section 411. Figures 9C and 9D shows views of connector section 411 taken in the directions indicated by lines 9C-9C and 9D-9D, respectively, as shown in Figure 9B. Figure 9E shows a side view of the integral tube and backplate section 416. Figures 9F and 9G show two perspective views of the integral tube and backplate section 416.

Referring to Figures 9B, 9C, and 9D, the connector section 411 includes a proximal portion 412 and a distal portion 413. The proximal portion 412 is preferably cylindrical and is configured to engage standard anesthetic or ventilatory medical devices. The distal portion 413 is preferably oblong as best shown in the perspective view of Figure 9B. The connecting section 411 further includes a plate-shaped disc, or flange 414 that extends around the junction of the proximal portion 412 and the distal portion 413. The connecting section 411 also defines a sealed inner airway passage 415 that is extends completely through proximal portion 412 and distal portion 413. In the proximal portion 412, the cross section of the passage 415 is circular, and in the distal portion 413, the cross section of the passage 415 is oblong.

Referring to Figures 9E, 9F, and 9G, the complete airway tube and rear plate section 416 includes a proximal portion 417, a central or curved portion 418, and a rear plate portion 419. A shaped plate disc, or flange, 420 are integrally attached to the proximal end of proximal portion 417. Section 416 defines a hollow interior passage 421 that extends completely through the proximal, curved, and rear plate portions 417,418,419.

The airway tube 410 is assembled by coupling the connector section 411 and the entire airway tube and backplate section 416 together. As shown in Figure 9A, when the parts are thus coupled, the flange 414 of the section Connector 411 abuts flange 420 of section 416. Also, distal portion 413 of connector section 411 telescopes into the interior portion of passage 421 that is defined by proximal portion 417 of section 416. Also, interior passage 415 of connector section 411 communicates with interior passage 421 of section 416 such that airway tube 410 defines a continuous sealed interior passage 424 (shown for example in Figures 10A and 10B) that extends from the proximal end of the tube to the distal end of the tube. Airway tube 410 also defines a left side 410-l, a right side 410-r (shown for example in Figure 9F), an inner side 410-i, and an outer side 410-o (shown for example in Figure 9E). Note that the left and right sides are defined with respect to a person (for example, a doctor) who is

ES 2 371 013 T3 inserting the LMA into a patient and that the left side 410-1 of the tube will actually lie on the right side of the patient's natural airway when the LMA is in the fully inserted configuration.

The rear plate portion 419 defines a laryngeal side 422 and a pharyngeal side 423. When the LMA 400 is assembled, the laryngeal side 422 of the rear plate portion 419 adheres or is attached to the pharyngeal side 444 of the rear plate portion. mask 430. Also, when the assembled LMA 400 is in the fully inserted configuration, the pharyngeal side 423 of the backplate portion 419 contacts the pharyngeal wall of the patient. When the LMA 400 is assembled, the inner passage 424 of the tube 410 communicates with the passage defined by the mask portion 430 and the LMA 400 defines a sealed airway passage that extends from the proximal end of the tube 410 to the central opening 442 of mask portion 430.

The airway tube 410 is dimensioned so that when the LMA is in the fully inserted configuration, the proximal portion 417 of the airway tube is disposed between the upper and lower teeth of the patient. Figure 10A shows a cross-sectional view of proximal portion 417 into which connector section 411 has been inserted taken along line 10A-10A as shown in Figure 9A. Airway tube 410 is also dimensioned so that when the LMA is in the fully inserted configuration, central portion 418 extends through the patient's natural upper airway between the laryngeal inlet and the patient's teeth. Figure 10B shows a cross-sectional view of central portion 418 taken along line 10B-10B as shown in Figure 9A. As shown in Figure 10B (as well as Figures 9A and 9E), the airway tube 410 defines the longitudinal folds 423 that extend along the left and right sides of the center and rear plate portions. 418, 419.

The connector section 411 and the integral tube and the rear plate section 416 of the airway tube 410 are preferably formed using molding techniques such as injection or rotational molding. In a preferred embodiment, connector section 411 is formed of polycarbonate and the material of section 411 is characterized by a Shore A durometer of 95. The integral tube and backplate section 416 is preferably formed of a flexible plastic material (eg, PVC) and is characterized by a Shore A durometer of 70 or so.

fifteen. More preferably, the integral tube material and backplate section 416 is characterized by a Shore A durometer of 70 plus or minus 7 (or plus or minus ten percent). Even more preferably, the integral tube material and backplate section 416 is characterized by a Shore A durometer of 70 plus or minus 3.5 (or plus or minus 5 percent). More preferably, the integral tube material and backplate section 416 are characterized by a Shore A durometer that is substantially equal to 70.

The connecting section 411 is preferably relatively hard so that (1) it is easy to reliably adhere the proximal section 412 of the section 411 to the standard breathing apparatus and (2) the patient can bite into the distal portion 413 without causing collapse or shrinkage of the interior airway passage provided by section 411. Note that when the LMA is in the fully inserted configuration, the patient's teeth will contact the proximal portion 417 of the integral tube and the rear plate section instead of the section 411, as the distal portion of the section 411 extends in proximal portion 417 as illustrated in Figure 9A. However, pressure applied by the patient's teeth will transfer to section 411, and section 411 is preferably hard enough to withstand this pressure without allowing interior passage 415 to collapse. Section 416 is preferably softer than section 411 to facilitate bending of section 416 as necessary to insert the LMA into a patient and to allow expeditious flexion and extension of the patient's neck while the LMA 400 is in the fully inserted configuration. However, as will be discussed below, section 416 is preferably rigid enough, at least at room temperature, so that V-MLAs constructed in accordance with the invention can be inserted by applying pressure to section 416 without requiring insertion of a finger into the patient's mouth.

Returning to Figures 4A-4C, it can be seen that the LMA 400 can be formed by securing or adhering the airway tube 410 to the portion of the mask 430. More specifically, the laryngeal side of the back plate portion of the tube The airway will adhere to the pharyngeal side of the mask portion so that the outer perimeter of the laryngeal side 422 of the rear plate portion surrounds the central opening 442 of the plate 440. The airway tube 410 can be adhered to the mask portion 430 by heat sealing, gluing, or otherwise by joining or fixing the two components together.

As shown for example in Figure 9F, the backplate portion 419 defines a "dome-shaped" or "bowl-shaped" interior volume. When the backplate portion 419 adheres to the mask portion 430, the backplate portion 419 and the mask portion 430 cooperatively define a hollow bowl-shaped interior volume as shown for example in FIG. 4C. As will be discussed below, portions of the larynx extend into this bowl-shaped volume when the LMA is in the fully inserted configuration.

An advantage of the MLA 400 is that it is relatively simple and cheap to produce. As discussed above, both the mask portion 430 and the airway tube 410 can be produced using a rotary molding process. Airway tube 410 can alternatively be produced using injection molding. Each of these steps (ie, producing the mask portion 430 and producing the airway tube 410) is relatively simple and inexpensive. Fabrication of the MLA 400 can be completed by adding an inflation tube to the mask portion 430 (in embodiments using inflation tubes) and adhering the airway tube 410 to the mask portion 430. Accordingly, the MLA 400 can be manufactured at very low cost. This low manufacturing cost

ES 2 371 013 T3 allows MLAs constructed according to the invention to be used as disposable devices. That is, the low manufacturing cost of the MLAs according to the invention, such as the MLA 400, allows them to be used once and then discarded.

Various structural advantages of MLAs constructed according to the invention will now be discussed. As shown for example in Figures 4A-4C and 9A, the backplate portion 419 essentially forms a backplate of the MLA 400. In older art MLA constructions (for example, as shown in Figure 3), the portion of the mask includes a back plate and defines a cylindrical opening for receiving, or connecting with, a cylindrical airway tube. Forming the mask portion with an added back plate disadvantageously increases (1) the mechanical complexity of the mask portion and (2) the cost of manufacturing the mask portion. Also, the junction, which is found in prior art LMAs, of a cylindrical airway tube and a cylindrical opening in a back plate tends to form a relatively rigid construction. For example, in the LMA illustrated in Figure 3, it is relatively difficult to compress the junction of the cylindrical airway tube and the backplate in the direction indicated by arrows 260. Accordingly, this portion of the LMA constructs of the art The anterior disadvantageously forms a relatively thick, non-compressible structure, which must be pushed between the upper and lower teeth of the patient and pass the throat of the patient to insert the LMA. In contrast to those prior art constructions, the mask portions of the MLAs constructed in accordance with the invention are formed without backplates (e.g., as shown in the mask portion 430 in Figures 5A-5D) and the The back plate of the LMA is provided by the airway tube. It is less complex, and less expensive, to provide the back plate as part of the airway tube. Also, by eliminating the telescopic attachment of two cylindrical components that characterized prior art fabrication, LMAs constructed according to the invention are more compressible and easier to insert into patients. For example, referring to Figure 4A, the back plate of the MLA 400 compresses in the direction indicated by arrows 260 more easily than prior art MLAs. This facilitates pushing the MLAs constructed according to the invention between the upper and lower teeth of the patient and past the throat of the patient.

In addition to providing a back plate, the general shape of the airway tube 410 distinguishes the MLA 400 from prior art MLAs. In more prior art MLAs (eg, as shown in Figures 1 and 3), the airway tube is cylindrical. While cylindrical airway tubes have worked well for many years in many different models of MLAs, the cylindrical configuration has some disadvantages. A critical feature for an airway tube of any LMA is the size of the inner airway passage. This passage must be large enough to provide adequate ventilation of the patient's lungs. That is, moderate pressure differentials (for example, a pressure drop of one to two cm H2O) between the proximal and distal ends of the airway tube should be sufficient to move a volume of air through the tube that is large enough to ventilate the patient's lungs adequately. With a cylindrical airway tube it is easy to calculate the volume of air that can move through the tube for any given pressure differential, and the volume can be adjusted simply by adjusting (i.e. increasing or decreasing) the radius of the airway passage. internal airway.

However, one restriction that must be considered in the design of airway tubes is that these tubes will extend through the patient's mouth, between the patient's upper and lower teeth, as long as the LMA remains in the fully configured configuration. inserted. Thus, while an LMA is inserted into a patient, the patient's mouth must remain open wide enough to create an interdental opening (ie, a space between the upper and lower teeth) that is large enough to accommodate the airway tube. Holding the mouth open for long periods of time to create a large interdental opening can cause discomfort to the post-operative patient. More importantly, some patients cannot open their mouth wide enough to allow easy insertion of cylindrical tubes of the appropriate sizes. Consequently, a disadvantage of cylindrical airway tubes is that they require a larger interdental opening than a tube having a flatter, or more oblong, cross-section would have.

Another restriction that must be considered in the design of airway tubes is that these tubes will extend through the patient's natural upper airway as long as the LMA remains in the fully inserted configuration. This natural, or anatomical, upper airway, which is made up of various anatomical structures including the pharyngeal wall, hard and soft palates, and the tongue, is not itself cylindrical. Consequently, a cylindrical airway tube does not form a “good fit” with the anatomic upper airway. For example, when a cylindrical tube is extended through the anatomic upper airway, the tube tends to only contact isolated portions of the anatomical structures that define the anatomic upper airway. Consequently, more pressure is applied to those structures, and those structures undergo more trauma, which would be the case if the shape of the tube is better matched to the shape of the anatomical upper airway.

As shown in Figures 9A, 9E, 9F, and 9G, the proximal and central portions 417,418 of the airway tube 410 are oblong or flattened rather than cylindrical. As will be discussed in greater detail below, this advantageously (1) maximizes the size of the inner airway passage of the tube; (2) minimizes the interdental opening required to accommodate the airway tube; and (3) allows the tube to fit well within, or couple to, the patient's natural airway.

As noted above, the airway tube 410 is sized so that the proximal section 417 is disposed between the upper and lower teeth of the patient when the LMA is in the fully inserted configuration. As shown in Figure 10A, the interdental opening G required to accommodate proximal section 417 is narrower than would be required if proximal section 417 were cylindrical. Instead of a cross section

ES 2 371 013 T3 circular, the cross section of the inner airway passage 424 is oblong. In a preferred embodiment, the thickness G of proximal section 417 is approximately 13.0 millimeters. The cross-sectional area of ​​the interior passageway defined by the airway tube 410 is preferably at least as large as that of a cylindrical tube with a passageway that is nine millimeter inside diameter. As shown in Figure 10A, the width of the inner passage 424 can be called W3 and the thickness of the inner passage 424 can be called T6. In a preferred embodiment, W3, and T6 are 20.0 and 6.7 millimeters, respectively.

As also noted above, the airway tube 410 is dimensioned so that the central portion 418 extends through the anatomical upper airway of the patient while the LMA is in the fully inserted configuration. As shown in Figure 10B, the cross section of the central portion 418 is oblong rather than cylindrical. Consequently, the central portion 418 provides a "better fit" to the anatomic airway than cylindrical tubes. As shown in Figure 10B, the width of the central portion of the airway tube can be called W4 and the thickness of the central portion of the airway tube can be called T7. A preferred value for W4 is 23.7 millimeters plus or minus 10 percent (or plus or minus 2.37 millimeters) and a preferred value for T7 is 103 millimeters plus or minus 10 percent (or plus or minus 1, 03 millimeters). More preferably, W4 and T7 are equal to 23.7 millimeters plus or minus 5 percent and 10.3 millimeters plus or minus 5 percent, respectively. Even more preferred, W4 and T7 are substantially equal to 23.7 millimeters and 10.3 millimeters, respectively. Also, the width W4 of the central portion of the airway tube is preferably equal to the thickness T7 multiplied by a factor of two, plus or minus ten percent (ie, W4 = (2 ± 0.2) x T7). More preferably, the width W4 is equal to the thickness T7 multiplied by a factor of two, plus or minus five percent (ie, W4 = (2 ± 0.1) x T7).

As shown in Figure 2, the airway tube of any LMA should follow a curve (on an axis extending in a left-to-right direction) from the point where it engages the mask portion to the point where the teeth contact the tube. This curve allows the tube to extend through the patient's natural upper airway from the teeth to the laryngeal inlet. An important design consideration for an airway tube of any LMA is that the airway tube must be designed so that it does not “kink” when twisted, or bent, as a requirement for inserting the LMA into a patient.

Figure 11 shows an example of a tube that has formed a kink 1102 as a result of bending the tube to an extreme amount. As is well known, the size of the inner passageway defined by any tube decreases dramatically in any of these kinks 1102. The effects of kinks in tubes are normally experienced in a similar way to garden hoses. For example, the formation of a single kink in a garden hose can dramatically decrease the amount of water that can pass through the hose and be distributed by a sprinkler. The effects of sprains are similar in LMAs. Any kink that forms in the airway tube of an LMA essentially closes the airway passage of the tube and dramatically decreases the volume of air that can pass through the tube. Consequently, it is very important to design the airway tube so that kinks in the tube do not form when the tube is inserted into a patient.

An advantage of cylindrical airway tubes over tubes with flatter, or more oblong cross sections, is that for any given amount of bend, the cylindrical tube is less prone to kink. To reduce the risk of the airway tube 410 forming any kinks, the tube 410 is preferably provided with two longitudinal turns 425 that extend along the left and right sides of the central tube and the central portions 418,419. As shown in Figure 10B, the cross section of the longitudinal turn 425 that extends along the left side of the airway tube defines a niche, or channel 425-g that extends from the left of the outer edge of the airway. airway tube towards the center of the tube in the direction from left to right. Similarly, the cross-section of the turn 425 that extends along the right side of the airway tube defines a niche that extends from the right outer edge of the airway tube toward the center of the tube in the right-hand direction. left. Each of the recesses defines an upper outer surface 425-u and a lower outer surface 425-1. The thickness of the longitudinal turns 425 (that is, the thickness as measured in a direction extending from the inner 410-i side to the 410-o outer side of the airway tube) can be called T12 and the thickness of the Longitudinal turns 425 as measured in the direction from left to right can be called T13. In a preferred embodiment, the thicknesses T12 and T13 are approximately three millimeters and 2.7 millimeters, respectively.

As indicated in Figure 10B and the curvature of tube 410 (on an axis extending in the direction from left to right) caused by inserting the LMA through the anatomical airway of the patient generates compressive forces in the directions indicated by arrows 260. Longitudinal turns 425 tend to prevent localized collapse of interior passage 424 as a result of twisting the tube. If the tube 410 is subjected to compressive forces in the direction of the arrows 260 large enough to deform the tube, the tube can deform in the manner illustrated in Figure 10C. As shown, the deformation of the tube in the region of the longitudinal turns 425 can resemble the movement of an accordion or concertina. The size of the interior passage 424 decreases as the tube is compressed from the profile shown in Figure 10B to the profile shown in Figure 10C. However, once the airway tube has reached the configuration shown in Figure 10C, the longitudinal turns 425 resist further decreases in the size of the passage 424, even in response to further compression of the tube. Thus, the airway tube 410 advantageously (1) reduces the size of the interdental opening required to accommodate the tube; (2) provides a large airway passage; (3) reduces the likelihood that the tube will kink when the LMA is inserted into a patient; (4) reduces the likelihood of the tube kinking

ES 2 371 013 T3 in response to bending the patient's neck above the likely range of head movement; and (5) fits well within the patient's anatomical airway.

Another advantage of the longitudinal turns 425 is that they maintain a convenient slot 425-g to place the inflation tube 490. Figure 12 shows a perspective view of an MLA 400 constructed according to the invention in which the inflation tube 490 has been glued into the 425-g slot that runs along the right side of the airway tube.

Another important feature of the airway tube 410 is the degree of curvature through which the central portion 418 extends. As discussed in US Patent Application Serial No. 08 / 901,055, there is an optimal degree of curvature for the airway tube of an LMA that will allow the patient to remain in a "neutral position" while the LMA is in the LMA. fully inserted configuration. The neutral position is a position in which the patient is lying on his back and in which the patient's head is positioned, for example with a pillow, so that the geometric relationship of the head to the rest of the body is the same as when the patient He is upright, standing and looking forward. The MLA disclosed in the '055 application used a rigid airway tube, and as discussed in that application, for rigid airway tubes the optimum degree of curvature is between 125 and 135 degrees. This degree of curvature allows the patient to remain in the neutral position while the LMA is being inserted and after the LMA has been brought into the fully inserted configuration.

For convenience in discussion, the shape assumed by the airway tube 410 when the tube is not subjected to any external forces will be called a "preformed configuration". As will be discussed below, since the airway tube 410 is somewhat flexible, it can deviate from the configuration made when the LMA is in use. Figure 9E shows the integral tube and section 416 in their preformed configuration. As shown, the airway tube 410 is preferably manufactured so that when not subjected to any external force, the central portion 418 follows a circular curve about an axis C (the axis C extending in the direction from left to right and being perpendicular to the plane of the page in Figure 9E) from a proximal limit of curvature 426 to a distal limit of curvature 427. In a preferred embodiment, the angle theta between two rays extending from the C axis to the proximal and distal limits 426, 427 for the preformed configuration is 105 degrees plus or minus ten degrees. More preferably, the angle theta for the preformed configuration is 105 degrees plus or minus five degrees. Even more preferred, the angle theta is substantially equal to 105 degrees. In a preferred embodiment of a female adult size, the distance, or radius Ri, between the C axis and the inner surface 410-i of the airway tube 410 for the preformed configuration is substantially equal to forty millimeters plus or minus about three millimeters, and the distance, or radius R₂, between the axis C and the outer surface 410-o of the airway tube 410 for the preformed configuration is substantially equal to fifty millimeters plus or minus approximately three millimeters.

The preferred degree of curvature for the preformed configuration of the MLA 400 is different than for the rigid tube MLA disclosed in the earlier referenced '055 application. This difference in curvature facilitates insertion of the LMA 400. When an LMA is inserted into a patient, proper insertion begins by placing the mask portion in the patient's mouth so that the pharyngeal side of the mask is in contact with the patient's mouth. hard palate of the patient. At this point, in LMAs designed according to the '055 application, the bend in the rigid airway tube forces the proximal end of the airway tube against the patient's chest. Positioning the end of the tube against the patient's chest makes insertion of the LMA somewhat more difficult than if the proximal end could be positioned in a position that is detached from the patient's body. However, the requirements of a rigid airway tube (which facilitates the posterior insertion of an endotracheal tube) and allows the patient to remain in a neutral position before, during, and after insertion, make it necessary to position the proximal end of the tube. airway tube against the patient's chest at the start of insertion.

Like the MLA of the '055 application, the MLA 400 allows the patient to remain in a neutral position before, during, and after insertion. However, unlike the LMA of the '055 application, the proximal end of the airway tube of the LMA 400 does not need to be positioned against the patient's body at any time during insertion. If the airway tube 410 of the LMA 400 were rigid and formed in the preformed configuration discussed above, then the patient might not remain in a neutral position while the LMA was in the fully inserted configuration. Rather, the patient's head would have to be tilted back to allow the airway tube to fit into the patient's anatomical airway. However, since the airway tube 410 is not rigid, the tube can flex, or bend, slightly out of the preformed configuration when it is being inserted allowing the tube to fit into the anatomical airway of a patient who is in the position. neutral. The curve of the preformed configuration of the central portion 418 of the airway tube preferably does not deviate away from the 125-135 degree anatomical curve so that the tube does not need to bend greatly to fit the anatomical airway. However, the curve of the preformed configuration of central portion 418 preferably deviates somewhat from the anatomical curve of 125 to 135 degrees to eliminate the need to press the proximal end of the tube against the patient's chest during insertion.

Figure 13 shows in solid lines a side view of the integral tube and backplate section 416 in the preformed configuration. Also Figure 13 shows in dotted lines the shape that the integral tube and backplate section 416 assumes after the MLA 400 has been placed in the fully inserted configuration within a patient who is lying in the neutral position. As shown, the airway tube 410 bends about an axis extending in the direction from left to right when the LMA is inserted into a patient. When the LMA is inserted into a patient, the center or curvature, or the axis about which the tube is bent, changes from C

ES 2 371 013 T3 to C ', and the angle through which the tube bends changes from the 105 degrees (plus or minus five or ten degrees) of the preformed configuration to the 125 to 135 degrees required to fit inside the track anatomical view of a patient lying in the neutral position.

As discussed above, in a preferred embodiment, the entire airway tube and backplate section 416 are formed of polyvinyl chloride. This material is relatively rigid at room temperature but becomes much more flexible at body temperature. In this way, the airway tube is relatively rigid when the MLA 400 is being inserted into the patient. However, after the MLA 400 has been placed in the fully inserted configuration for some time (for example, three to five minutes), the airway tube softens and becomes more flexible so that its shape easily accommodates. the shape of the patient's anatomical airway without exerting undue force against the anatomical structures that define the anatomical airway. Also, since the material is relatively stiff at room temperature, the airway tube is generally stiff enough to act as an insertion tool. That is, the MLA 400 can be completely controlled during insertion by simply manipulating the portions of the airway tube 410 that extend outside the patient's mouth. This eliminates the need to insert a finger into the patient's mouth while inserting the LMA and further eliminates the need for additional insertion tools.

Another important advantage of the MLA 400 relates to the quality of the seal provided with the laryngeal inlet. As shown in Figure 4A, there is a relatively large void S behind the mask portion 430. The void behind the mask portion 430 is substantially greater than that provided by prior art MLAs and, as discussed below, it advantageously allows the MLA 400 to provide improved seals.

As shown in Figure 4A, the space S is defined by the distance T9 between the laryngeal side of the proximal end of the inflated cuff and the airway tube 410 as measured in the direction from larynx to pharynx. A preferred value for distance T9, when the airway tube is in the preformed configuration, is 32 millimeters plus or minus 3 millimeters. More preferably, the distance T9, when the airway tube is in the preformed configuration, is 32 millimeters plus or minus 2 millimeters. Even more preferred, the distance T9, when the airway tube is in the preformed configuration, is substantially equal to 32 millimeters.

When the MLA 400 is in the fully inserted configuration, the posterior portion of the patient's tongue rests in the S-space. As will be discussed below, expanding the S-space in which the tongue rests improves the quality of the seal between the proximal end of the tongue. inflated cuff and laryngeal inlet of the patient.

Figure 14 shows a view of an inflated cuff of an LMA, and the illustrated cuff has been divided into three different regions. When the LMA is located in the fully inserted configuration, each region of the cuff contacts a different portion of the patient's anatomy. Region 1, at the proximal end of the cuff, engages the patient's vales (ie, the space behind the underside of the tongue). Region 2 which is arranged between the proximal and distal ends of the cuff, contacts the patient's piriform fossae which are symmetrically arranged on either side of the patient's glottic opening. Region 3, which is arranged at the distal end of the cuff, contacts the cricoid cartilage of the patient. Consequently, when the LMA is inserted into a patient, a continuously extending seal around the glottic opening of the patient is formed by contact between the inflated cuff and the patient's vallecules, pyriform fossae, and cricoid cartilage.

Figure 15A shows a prior art MLA 1500 that has been placed in the fully inserted configuration. As shown, the inflated cuff 1502 has formed a seal around the glottic opening of the patient thereby coupling the passageway of the airway tube 1504 to the trachea 1506 of the patient. The laryngeal side of the proximal cuff engages the patient's vales 1508, and the laryngeal side of the distal cuff contacts the patient's cricoid cartilage 1510. The patient's tongue 1512 is generally disposed along the inner, or anterior, side of the airway tube between the patient's teeth and the proximal end of the inflated cuff. The posterior portion 1514 of the patient's tongue 1512 is disposed in space S (between the proximal end of the inflated cuff and the inner, or anterior, side of the airway tube). The dashed line 1516 illustrating the contour of the tongue 1512 would follow if the MLA 1500 were not inserted into the patient. As shown, the insertion of the LMA displaces the tongue 1512 in the pharyngeal-to-laryngeal direction away from the natural position indicated by the dashed line 1516. Pushing the tongue in this direction also pushes or pries portions of the larynx in the pharynx-to-larynx direction and thereby tends to prevent the fist from fitting tightly around the larynx. This weakens the seal provided by the LMA by decreasing the pressure between the cuff and anatomical structures such as the piriform fossae.

Figure 15B shows the MLA 400 in the fully inserted configuration. The dashed line 1602 represents the contour assumed by the tongue when the MLA 1500 is in the fully inserted configuration. As shown, the enlarged void S provided by the MLA 400 allows the tongue to assume a more natural position than the prior art MLA 1500. In particular, the enlarged void S of the MLA 400 allows the tongue to be moved in the direction from larynx to pharynx where the tongue would be if the MLA 1500 were in the fully inserted configuration. Allowing the tongue to assume a more natural position allows the other anatomical structures to assume a more natural position (i.e. to be displaced in the direction from larynx to pharynx where they would be if the MLA 1500 were in the fully inserted configuration) and thus improves the seal provided by the MLA 400.

ES 2 371 013 T3

As is well known, portions of the larynx (eg, aryepiglottic folds) can extend into the bowl-shaped space bounded by the inflated cuff when an LMA is in the fully inserted configuration. Figure 15B suggests this by showing the structures 1530 extending into the bowl-shaped volume defined by the cuff and backplate of the MLA 400. Expanding the space S also has the beneficial effect of increasing the size of the bowl-shaped volume defined by the MLA 400 (i.e., increasing the void space that is limited by the back plate portion and inflated cuff of the MLA 400). This also improves the quality of the seal provided by the MLA 400 by allowing the larynx to extend further in the bowl-shaped volume that was possible with the prior art MLAs. Allowing the larynx to extend further into this space allows the larynx to assume a more natural position (i.e., a position similar to the position the larynx would occupy if the LMAs were not inserted) and improves the seal provided by the LMA.

Several features of the MLA 400 cooperate to provide the enlarged void S. First, as shown in Figure 5A, the thickness T5 of the proximal portion of the mask portion is substantially thicker than the thickness T4 of the distal portion of the mask portion. Another feature that cooperates to define the enlarged void space S is the angle between the central portion 418 and the rear plate portion 419 of the airway tube. As shown in Figure 4A, at the junction of the central portion 418 and the rear plate portion 419, the central portion 418 extends at an angle alpha relative to the plate 440. In a preferred embodiment, the angle alpha it is equal to ten degrees plus or minus two degrees. More preferably, the angle alpha is equal to ten degrees plus or minus one degree. Even more preferred, the angle alpha is substantially equal to ten degrees. This angle provides additional clearance between the proximal end of the plate and the inner side of the airway tube as measured in the direction from larynx to pharynx. Still another feature that helps define void space is an absence of an inflation tube in space. In most prior art LMAs, as shown for example in Figure 3, the inflation tube extends from the proximal end of the cuff in the distal to proximal direction in space. However, in the MLA 400, as shown for example in Figure 12, the inflation tube does not extend from the proximal end of the cuff and instead extends from the pharyngeal side of the plate to one of the notches 425 without enter space S.

As previously discussed, and as illustrated in Figures 5A-5C and 15B, a feature that helps define the enlarged void S is the increased thickness of the proximal end of the inflated cuff: When the MLA 400 is in the fully inserted configuration, The inflatable cuff is preferably inflated to a pressure of about 60 cm H₂O. The pressure in the cuff tends to increase during surgical procedures because normally used anesthesia gases (eg, nitrous oxide) tend to diffuse through the semi-permeable wall of the cuff. An advantage of forming the mask portion 430 of PVC is that a cuff formed from this material can maintain the profile illustrated in Figures 5A-5C and 15B when the pressure within the cuff rises due to this diffusion. In contrast, if the cuff were formed of a more elastic material, such as the silicone material used to form most of the prior art LMA cuffs, the cuff would not tend to maintain this profile and would instead deform, or "It would puff up like a balloon" when the pressure inside the fist rises due to this diffusion.

Still another advantage of the MLA 400 relates to the ease with which it can be inserted into a patient. Figure 16A shows a side view of the MLA 400 when the cuff 460 is deflated. Figures 16B and 16c show perspective views of the MLA 400 when the cuff 460 is deflated. Cuff thickness T3 (as shown in Figure 6) is thin enough that when cuff 460 deflates, the profile of the distal portion of the LMA is almost completely determined by plate 440 of the mask portion and the rear plate portion 419 of the airway tube. As shown in Figure 16A, the thickness T10 of the distal end, as measured in the direction from larynx to pharynx, is determined virtually and entirely by the thickness of plate 440. The thickness of the deflated LMA, as measured in the larynx-to-pharynx direction, gradually increases with increases in the distal-to-proximal direction until the thickest point, at the proximal end of the mask portion, is reached. which has a thickness T11, as measured in the direction from larynx to pharynx. The rate of increase in thickness is determined by the angle theta between plate 440 and the pharyngeal side of the rear plate portion 418. In a preferred embodiment, the angle theta is approximately eleven degrees and the thickness T10 is approximately two millimeters (ie, the deflated cuff adds virtually no thickness beyond the thickness of the T2 plate). The thickness T11 is preferred and about seventeen millimeters plus or minus two millimeters. More preferably, the thickness T11 is about seventeen millimeters plus or minus one millimeter. Even more preferred, the thickness T11 is substantially equal to seventeen millimeters. The thickness T11 which is the thickest part of the deflated MLA 400 as measured in the direction from larynx to pharynx, is relatively thin compared to prior art MLAs which are usually about 26 millimeters thick in sizes. comparable.

Figure 16C illustrates the size of the deflated MLA 400 as measured in the left to right direction. The width of the distal tip of the LMA is relatively narrow and the width of the LMA gradually increases with increases in the direction from distal to proximal. The width of the widest part of the deflated LMA, as measured in the left-to-right direction, W1, is equal to the width of the widest part of the plate (as shown in Figure 5E).

The overall profile of the deflated LMA 400, as measured in the larynx-to-pharyngeal direction, as well as in the left-to-right direction, is small compared to deflated prior art LMAs. Having such a small profile greatly increases the ease with which the deflated MLA 400 can be inserted into a patient. In particular, the slim profile, as measured in the larynx to pharynx direction, makes it very easy to push the deflated mask portion and the back plate between the upper and lower teeth of a patient.

ES 2 371 013 T3 and pass the patient's throat. The slim profile also increases the likelihood that the deflated portion of the mask will fit between the pharyngeal wall and the epiglottis without disturbing or otherwise pushing into the epiglottis when the distal tip of the mask portion is pushing past the epiglottis. towards the esophageal sphincter.

Figure 17 shows a deflated MLA 400 that has been partially inserted into a patient who is lying in the neutral position. As shown, the distal tip 434 of the deflated LMA has engaged between the pharyngeal wall 1078 and the epiglottis 1710 of the patient. When an unconscious patient lies on their back, muscle relaxation tends to allow the back of the tongue and the epiglottis to descend toward the pharyngeal wall, thus reducing or minimizing the space between the epiglottis and the pharyngeal wall. Consequently, the thinner the deflated LMA, the more likely the LMA will fit into the space between the pharyngeal wall and the epiglottis without pushing, or otherwise moving, the epiglottis. The slim profile of the deflated MLA 400 thus facilitates proper insertion of the LMA.

One problem with prior art LMAs is that they are often improperly inserted. As discussed above, the LMA is a "compassionate" device and tends to establish an airway even when the device is improperly inserted. Ideally, however, the LMA should be inserted properly so that the epiglottis is not disturbed and so that the distal tip of the LMA is positioned adjacent to the esophageal sphincter. A problem that contributes to the difficulty of inserting the LAMs of the prior art relates to the profile assumed by the deflated cuff. In prior art LMAs, the deflated cuff forms a "structural component" of the LMA in which (1) a significant portion of the profile of a deflated prior art LMA is determined by the cuff and (2) the shape of the Deflated fist significantly affects the path taken by the LMA through the body when inserted into a patient. Consequently, proper insertion of a prior art LMA generally requires properly molding or shaping the cuff when deflated. US Patent No. 5,711,293 discloses an example of a prior art tool for molding or forming an LMA into an ideal shape for insertion when the cuff is deflating.

In the MLA 400, the deflated cuff contributes only negligibly to the profile of the deflated LMA. Rather, the profile of the deflated device is almost completely determined by the plate 440 of the mask portion 430 and the back plate portion 419 of the airway tube 410. As shown in Figure 16A-C, these components define a slim profile that facilitates proper insertion of the LMA.

Another advantage of the MLA 400 relates to the profile of the device when deflated compared to the profile of the device when inflated. As discussed above, when the MLA 400 is deflated it exhibits a thin, thin, or small profile compared to prior art MLAs. However, when the MLA 400 is inflated, the cuff is extended considerably and, as discussed above, this allows the MLA to provide an improved seal with the tissues surrounding the glottic opening of the patient. The relatively large difference between the thickness (as measured in the larynx to pharynx direction) of the deflated device compared to the thickness of the inflated device distinguishes the MLA 400 from prior art MLAs. As discussed above, the thickest part of the deflated LMA, T11, is approximately seventeen millimeters. The thickest part of the inflated LMA, T5, is approx 25.4 millimeters. Consequently, the thickest part of the inflated MLA 400 is approximately 1.5 times larger than the thickest part of the deflated MLA 400. Although 1.5 is a preferred factor for differentiating the thickest parts of the inflated and deflated LMA, it may be preferable for the thickest part of the inflated LMA to be 1.5, plus or minus 0.15, times greater than the thickest part of deflated LMA (i.e., T5 = (1.5 ± 0.15) x T11).

As shown in Figure 17, any LMA will bend or flex when the LMA is being inserted into a patient. More specifically, when the distal tip of the LMA contacts the patient's palatopharyngeal arch, the distal tip curves toward the larynx (or curves about an axis extending in the left-to-right direction). When the LMA is inserted further into the patient, the portions of the LMA that are close to the palatopharyngeal arch will curve around the arch and the portions of the LMA that have already passed through the palatopharyngeal arch will align. In this manner, the point of curvature or flexure begins at the distal tip of the LMA and moves back in the distal to proximal direction as the LMA continues to be inserted into the patient.

As shown for example in Figure 16B, the rear plate portion 419 of the MLA 400 is "lance-shaped" or tapered in that its width decreases with increases in the proximal to distal direction. The very narrow width of the distal tip of the back plate makes the distal tip of the LMA relatively flexible so that the distal tip easily curves or flexes toward the larynx when the LMA 400 is inserted into the patient. As the LMA is further inserted, the resistance of the LMA to bending increases in a linear fashion due to the gradual dilation of the "lance-shaped" portion of the back plate. This linear increase in resistance to bending about an axis extending in the left-right direction is an advantageous feature of the MLA 400. If the increase in resistance is not linear and instead increases suddenly or dramatically (in a non-linear fashion) at one or more points when the LMA is being inserted, the LMA will tend to twist, or form a localized fold, rather than easily bend around the palatopharyngeal arch. Such a twist as a deformation would be more stimulating to the patient and increases the probability of a bad position and / or trauma during insertion. Some prior art LMAs are capable of offering a substantially linear increase in resistance to bending when the LMA is inserted into a patient as long as the cuff has been properly deflated and formed into an appropriate configuration. However, since the cuff of these prior art LMAs forms a structural component of the LMA, they do not offer a linear increase in resistance to bending, and they tend to kink while in place.

ES 2 371 013 T3 being inserted, when the cuff deflates without the proper use of a shaping tool. An advantage of the MLA

400 is that the LMA will provide the desired substantially linear increase in resistance to bending regardless of the manner in which the cuff deflates. This is so since the deflated cuff does not contribute significantly to the LMA structure and the LMA's resistance to bending is determined virtually and entirely by the geometry of the backplate portion 419.

Still another advantage of the MLA 400 relates to the size of the inflated cuff. As shown for example in Figures 5A and 15A, the thickness T5, as measured in the direction from pharynx to larynx, the proximal end of the inflated cuff is relatively large compared to prior art LMAs. The relatively large thickness T5 of the proximal end of the inflated cuff advantageously increases the clearance between the epiglottis and the opening 442 of plate 440 and thereby decreases the likelihood that the epiglottis can block the airway provided by the MLA 400. The MLAs of The prior art often includes "bars" or "slits" arranged in the mask portion to prevent the epiglottis from blocking the LMA airway. Such bars are disclosed for example in US Patent No. 5,297,547 (see Figure 8 of the '547 patent). Although MLAs constructed in accordance with the invention could include such "bars", the MLA 400 advantageously eliminates the need for such bars and consequently can be manufactured less expensively.

Returning to Figure 17, as shown the distal tip of the LMA 400 has passed through the opening between the epiglottis and the pharyngeal wall. Sometimes the distal tip of the LMA will reach the epiglottis when the LMA is inserting and will push the epiglottis into a "folded down" condition. In such a "down-folded" condition, the epiglottis can block the trachea or airway provided by an LMA. Another advantage of the MLA 400 is that the cuff 460 can lift an epiglottis in a "folded down", or posterior, front, or anterior position, thereby keeping the airway clear. Figure 7B illustrates a preferred folded configuration for the deflated cuff. As shown, when cuff 460 is deflated, extra or detached cuff material can be folded toward the center of the mask portion so that the deflated cuff covers all or nearly all of the central opening 442 of the cuff. plate 440. If the cuff is folded into this position to cover all or nearly all of the central opening 442, then cuff 460 will advantageously lift the epiglottis anteriorly and thereby open the airway when the cuff is inflated.

A disadvantage of reusable prior art MLAs is that after each sterilization, the cuff must be deflated and the LMA must be configured for insertion into a patient. Unfortunately, most clinicians using MLAs lack the skill or dedication required to prepare the MLA in the optimal configuration to facilitate insertion. Another advantage of the MLA 400 is that when used as a disposable device, the MLA can be packaged and sold in a configuration that is optimal to facilitate insertion of the device into a patient. As discussed above, the MLA 400 is advantageous in that (1) the deflated cuff only adds a small amount of thickness to the mask portion and (2) the deflated cuff can be configured to lift an epiglottis lying down or posteriorly folded. off the road. Preferably, the MLA 400 is placed in this optimal configuration (i.e. with the cuff deflated and folded as discussed above in connection with Figures 7A and 7B) prior to sale and then packaged in a sterile pouch or package (e.g. , a sterile plastic bag). Thus, when a physician wishes to insert an LMA into a patient, the physician can simply remove an LMA from its sterile packaging and can insert it into the patient without first having to deflate or reposition the cuff.

As discussed above, in some embodiments of the MLA 400 an inflation tube 490 need not be provided. Thus, in embodiments that do not include an inflation tube, fabrication of the LMA is completed by attaching the airway tube to the partially inflated portion of the mask after the portion of the mask is removed from the mold. When the mask portion 430 is formed by rotational molding, the cuff is partially inflated when the mask portion is removed from the mold. The amount of air that is trapped in the cuff during manufacturing is similar to the amount of air that is normally injected into the cuff via the inflation tube after the portion of the mask has been inserted into a patient to achieve Desired pressure within the cuff of 60 cm H2O. Consequently, such a partially inflated cuff is capable of forming an effective seal around the laryngeal inlet of a patient.

These masks have a major disadvantage compared to the MLA 400 embodiments that include an inflation tube. The profile of the partially inflated cuff is thicker, as measured in the proximal to distal direction, which is achievable on the MLA 400 when the cuff is fully deflated via the inflation tube, and this can make insertion the LMA more difficult. However, LMAs that do not include an inflation tube have one main advantage. Namely, they can be easier and faster to use in emergency situations since the practitioner does not need to bother with deflating or inflating the cuff and the airway is established as soon as the mask portion is inserted into the patient's pharynx. . The thicker profile can complicate the insertion of such an LMA. However, two factors make insertion easier than might otherwise be the case. First, in unconscious patients, the muscles of the body become very relaxed which can make it easier to push a thick profile device through the upper and lower teeth and down into the throat. Second, since the cuff is only partially inflated, and since the cuff is very thin and flexible, a very small amount of pressure applied to a portion of the cuff will reduce, or shrink, the size of that portion, and force trapped air into the cuff into other portions of the cuff thereby inflating or expanding those other portions. For example, the proximal end of the cuff will extend if the distal end is absolutely depressed, and only very little pressure is required to fully depress the distal end. When an MLA 400 with a partially inflated cuff is inserted into a patient,

ES 2 371 013 T3 some parts of the cuff can be extended while other parts are reduced by anatomical structures. However, the ability to shrink in some places while expanding in others makes it relatively easy to push the partially inflated fist into the patient's pharynx.

Accordingly, one method of manufacturing an LMA in accordance with the invention is to (1) produce a mask portion 430 using the rotational molding process described in relation to Figures 8A-8D; (2) removing the mask portion 430 from the mold 800; and (3) attaching an airway tube to the mask portion. The rotary molding process produces a partially inflated portion of the mask that is inflated to a desirable degree. Once the airway tube is attached to the mask portion, the fabrication of the LMA is complete. An inflation tube does not need to be added. The completed MLA can be packaged for sale in a sterile bag. Such MLAs can be very useful for emergency situations, for example for use by emergency workers in ambulances or in emergency areas.

Figure 18A shows a side view of another embodiment of an MLA 1800 constructed in accordance with the invention. Figures 18B and 18C show two perspective views of the MLA 1800. As shown, the MLA 1800 is very similar to the MLA 400. Both the MLA 1800 and MLA 400 include identical 430 mask portions. Also, the plates backs of both MLA 1800 and 400 are very similar. The main difference between the two MLAs is in the airway tube.

The MLA 1800 airway tube 1810 is a double barreled tube. Figure 18D shows a cross-sectional view of the airway tube 1810 taken in the direction indicated by line 18D-18D as shown in Figure 18A. Airway tube 1810 includes a left tube 1812 and a right tube 1814. The tubes are attached, glued, or extruded together at a central joint 1816 that extends from the proximal ends to the distal ends of the two tubes. Airway tube 1810 also defines an inner side 1810-i and an outer side 1810-o.

As with airway tube 410, tube 1810 has an oblong or flattened overall cross section. Consequently, tube 1810 (like tube 410), fits relatively well within the anatomic airway of the patient and minimizes the interdental opening required to accommodate the tube. Also as with tube 410, airway tube 1810 includes a proximal portion 1820, a central portion 1822, and a rear plate portion 1824. The backplate portion 1824 is nearly identical to the backplate portion 419. The only major difference between the two backplate portions is how they engage their respective central portions of the airway tube.

As shown in Figure 18D, the joining of the two cylindrical tubes 1812 and 1814 at the joint 1816 formed grooves, or niches, 1830, 1832 in the airway tube. The groove 1830 extends along the inner side 1810-i of the airway tube and the groove 1832 extends along the outer side 1810-o of the tube. An advantage of tube 1810 is that slot 1830 can serve as a guide to guide subsequently inserted tubes, such as an endotracheal tube. That is, after the MLA 1800 has been positioned in the fully inserted configuration, the slot 1830 can be used to guide a subsequently inserted device. Figure 19A shows a perspective view of an endotracheal tube being guided through slot 1830 when the endotracheal tube is inserted into the patient's body (not shown).

Embodiments of the MLA 1800 that are used to guide a subsequently inserted endotracheal tube (or some other type of tube), preferably define a "gap", or opening, between the mask portion and the rear plate portion at the end. proximal portion of the mask. When the distal tip of the endotracheal tube reaches the proximal end of the mask portion, continued insertion of the endotracheal tube will push the distal end of the endotracheal tube through the opening between the mask portion and the back plate of the LMA and allows the distal end of the endotracheal tube to proceed through the opening 442 of the mask portion and into the trachea of ​​the patient.

Figure 19B shows an embodiment of the MLA 1800 defining such an opening 1910. Both the MLA 400 and MLA 1800 are constructed by joining or joining the outer perimeter of the laryngeal side of the rear plate portion of the airway tube to the pharyngeal side of the plate 440 of the mask portion 430. In the case of the MLA 400, the entire outer perimeter of the back plate portion is thus attached to plate 440. However, in the case of the MLA 1800, a portion of the outer perimeter of the rear plate (to the proximal end of the rear plate) is not attached to the plate 440 and the remainder of the outer perimeter of the rear plate is attached to the plate 440. Since the proximal ends of the back plate and plate 440 are not joined together, pressure on plate 440 can push plate 440 from the mask portion out of the back plate and create gap 1910. In the absence of downward pressure on plate 440, the portions of the back plate and plate 440 that are joined together also tend to hold the disjointed portions together. The effect is to create an LMA that has a "reed valve." Under normal conditions, the 440 plate and the back plate of the MLA 1800 remain in contact as in the case of the MLA 400. Also, when the MLA 1800 is in the fully inserted configuration, the pressure exerted by the pharyngeal and laryngeal walls of the patient tends to push the plate 440 and the rear plate toward each other, or together. However, in the MLA 1800, pressure at the proximal end of the mask portion (generated for example by subsequent insertion of an endotracheal tube that is guided through slot 1830) can push plate 440 out of the plate. rearward to generate gap 1910. Subsequently inserted endotracheal tubes may extend through gap 1910 and then through opening 442 and into the patient's trachea.

ES 2 371 013 T3

Figure 20 shows a perspective view of an alternative embodiment of a mask portion 430 'that can be used in the LMA constructed in accordance with the invention. Mask portion 430 'is similar to mask portion 430, however, the pharyngeal side of plate 440' of mask portion 430 'is not flat and instead defines a passage, or slot, 2010, which is extends around the elliptical central opening of the mask portion. It will be appreciated that slot 2010 can be used to properly position the rear plate of the airway tube when the portion of the rear plate is attached to the mask portion. Preferably, the laryngeal side of the rear plate portion is attached or fixed to the bottom of the slot 2010. When the rear plate portion is attached to the bottom of slot 2010, a small portion 2012 to the distal end of plate 440 'separates the distal end of the rear plate portion from the distal tip of the LMA. This can be advantageous as the airway tube is generally tougher and stiffer than the mask portion. Thus, when the LMA is inserted into a patient, and the distal tip of the LMA contacts anatomical structures within the patient's natural airway, the contact is between the patient and the relatively soft portion of the mask rather than between the patient and the hardest portion of the back plate. The mask portion 430 'therefore advantageously provides a simple mechanism to properly position the back plate when the LMA is being assembled and also protects the patient from potential traumatic contact with the relatively hard distal end of the back plate portion when the LMA is being assembled. is inserting. It will be appreciated that the mask portion 430 'may be used in place of the mask portion 430 in the MLA 400, MLA 1800, or any other MLA constructed in accordance with the invention.

As discussed above in connection with Figures 10B and 10C, the longitudinal pleats in the airway tube allow the tube to compress somewhat in an accordion or concertina fashion. Another advantage of longitudinal pleats is that they can allow the airway tube to stretch in response to forces applied to the interior of the tube. This expansion may advantageously allow the airway tube to accommodate a subsequently inserted endotracheal tube and thereby allow the MLA 400 to function as an MLA intubation. Figure 10D shows a side view of one embodiment of the MLA 400 into which an endotracheal tube 1010 has been inserted. To achieve the configuration illustrated in Figure 10D, the distal end 1012 of the endotracheal tube 1010 was inserted into the proximal end of the integral tube and the rear plate section 416 and advanced through the section 416 to the emerged distal end 1012. through the opening in the mask portion 430 as shown. As endotracheal tube 1010 advances through integral tube and backplate section 416, longitudinal folds in section 416 allow section 416 to extend and thereby accommodate the endotracheal tube.

It will be appreciated that when the MLA 400 is used as a tubing LMA, it may be desirable to use alternate embodiments of the airway tube 410 or the integral tube and backplate section 416. For example, the integral tube and the tube section. Backplate 416 shown in Figure 10D includes two longitudinal pleats that extend below the left and right sides of the tube in place of the single pleat provided in section 416 illustrated in Figures 10B and 10C. Figure 10E shows a cross section of section 416 taken in the direction of line 10E-10E as shown in Figure 10D. Figure 10E shows the two longitudinal folds extending under the left and right sides of the integral tube and the back plate section. Figure 10E shows the integral tube and backplate section in an expanded condition. That is, the longitudinal folds have expanded in a concertina fashion to accommodate the subsequently inserted endotracheal tube. It will be appreciated that airway tubes constructed in accordance with the invention can be provided with one, two, or more longitudinal folds that extend below the left and right sides of the tube.

In addition to including extra longitudinal pleats, it will be appreciated that it may be advantageous for the airway tube, or the integral tube and backplate section, of the tubing LAMs constructed in accordance with the invention to include a modified proximal end that is cylindrical or otherwise wide enough to accommodate insertion of an endotracheal tube as shown in Figure 10D.

Figure 10F shows a side view of another embodiment of the MLA 400 constructed in accordance with the invention, and Figure 10G shows a perspective view of the embodiment shown in Figure 10F. In the illustrated embodiment, the airway tube includes a flange 1020. Flange 1020 extends in the proximal to distal direction from a point near the middle of the rear plate portion 419 to a point on the curved portion 418 that is proximal to a junction of the rear plate portion 419 and the portion 418 curved. The flange 1020 also extends from the outer side 410-o of the tube into the passageway defined by the tube. In this embodiment, the walls of the tube near the junction of the curved portion 418 and the rear plate portion 419 are also preferably weaker than the walls at other portions of the tube. For example, the wall of the tube can be made thinner in this region to weaken this portion of the tube.

The embodiment illustrated in Figures 10F and 10G facilitates turning of the patient's head while the LMA is in the fully inserted configuration. For example, the LMA can be placed in the fully inserted configuration while the patient is lying in the neutral position (i.e. the patient will be lying on their back and the patient's nose will be the part of the patient's head that is furthest from the Earth). Once the LMA is positioned in this way, it may be desirable to turn the patient's head. For example, if the patient's ear is being operated on, it may be desirable to rotate the patient's head approximately ninety degrees so that instead of the patient's nose, the patient's ear is now the part of the patient's head that is farthest from the patient. the earth. It will be appreciated that this exposes the ear and makes it easier to operate on the ear. Ideally, rotating the patient's head in this manner while the LMA is placed in the fully inserted configuration (1) will not disturb the seal between the inflated cuff and the tissues surrounding the patient's glottic opening and (2) will not cause collapse of the interior passage provided by the airway tube. Weaken the walls of the airway tube near the junction of the backplate portion 419 and the

ES 2 371 013 T3 curved portion 418 allows the distal portion of the LMA (i.e., the mask portion and the back plate portion) to rotate relative to the rest of the airway tube without exerting undue force on the cuff inflated, and this tends to preserve the seal between the cuff and the tissues surrounding the glottic opening when the patient's head is thus rotated. The flange 1020 tends to prevent the interior passage provided by the airway tube from collapsing when the patient's head is thus rotated and the airway tube is correspondingly twisted.

Figures 21 and 22 show another embodiment of an LMA constructed according to the invention. In this embodiment, an air inlet tube 10 will be designed to provide a service of air (or other gas) to the lungs of a patient via the mask structure 11 and the patient's trachea. As best seen in Figure 22, the base structure of the mask 11 comprises a relatively rigidly flexible structural base 12 of generally elliptical configuration, a portion of this base being directly visible through a drawing, opening its way through a collapsed inflatable thin cover 13 which will be understood to be inflatable by external supply of inflation air via a flexible inflation line 15; Line 15 shall be understood to include a conventional two-way check valve (not shown) for the purposes of maintaining an inflated condition of the tire 13 (as in Figure 21) or to maintain a deflated condition of the tire (as in Figure 22). The cover 13 is merely a one-piece, integrally formed inflatable portion with full closure served by the inflation / deflation line 15 and is the product of a so-called rotational molding process, in which a single plastic material in a liquid state originates to build a thin layer or film of vulcanized plastic material progressively against and along the inner surface area of ​​a given annular mold cavity, Gravitationally drained debris from the liquid phase plastic is allowed to vulcanize in situ as the relatively rigid annular member of the LAM structure, at the bottom of the mold. The cured product of such molding not only provides the indicated function of the structural base but also, between the inner and outer peripheries of the frame rings, the additional function of completing, as a frame ring, provides the inflatable and peripherally accessible cover closure provided by molded film. For the case of the component formed as a whole described (12/13) when it is formed from suitable plastic such as polyvinyl chloride, the thin film at 13 is typically of a thickness in the order of 0.1 to 0.3 mm, while the base 12 of the structure may typically be 10 to 20 times the molded thickness of film 13. Such film will be designed to collapse and flatten or will stretch randomly in response to deflation action via line 15. It will be understood that while it is possible to form the base 12 of the structure as flat and of relatively uniform thickness, it is also possible to use the molding process described to develop a thickness of the structural base which varies as a function of longitudinal progression, from a relatively thick proximal location (eg 2-3mm thick) at a much smaller distal end thickness (eg 1mm), hence in accordance with the desired flexibility of a distal end which may usefully serve the process of installing the LMA in the patient. Such variation in thickness from proximal to distal is then indicated in Figure 25 (at 12 ') as a feature of the device of Figures 23 and 24.

To complete a description of the LMA device of Figures 21 and 22, the airway tube 10 is shown to be supported on and by overlapping the posterior surface of the proximal region of the structural base ring 12, the end distally open 16 of the airway tube preferably having an angularly truncated configuration within the generally elliptical lumen 17 of the structural base 12. Finally, the closure of the posterior side of the mask structure is effected by a tent-like roof 18 of flexible plastic sheet material, in which the superimposed distal end of the airway tube is analogous to a flanged post, so that the sheet tent roof is tilted out of its central support longitudinally by the distal end of the airway tube, to its peripherally sealed link to the margin of the structural base, as seen in Figure 21, it is understood that sheet 18 also adequately overlaps and seals in its proximal end closure around airway tube 10.

Figures 23 and 24 are recognizable by their resemblance to Figures 21 and 22, except for the additional provision of a gastric drainage tube 20, in a side-by-side bonded relationship to an airway tube 21, which may be in all aspects as described for an airway tube 10 of Figures 21 and 22, except for the fact that tubes 20/21 are symmetrically and oppositely offset from the longitudinal sagittal plane of the generally elliptical configuration of mask structure 22. This symmetrical relationship is seen to continue until the distally open end 23 of the airway of the airway tube 21 is positioned to curve over the lumen 24 of the generally elliptical annular structural base 25 of the mask frame. As with the LMA of Figures 21 and 22, the structural base member 25 may be a product of the rotary molding operation in which a thin film inflatable / deflatable tire 26 is integrally formed therewith, with provision for selective inflation / deflation action via flexible line 15, as also in Figures 21 and 22.

For gastric drainage purposes, and as best seen in Figures 25 to 29, the tube 20 drainage is viewed in Figure 26 to undergo a smooth change of zigzag course, from lateral displacement adjacent to the airway tube 21 to its alignment of the distal end of symmetry with respect to the sagittal plane of the mask. Within the distal half of the structural base 25, and the distal end of the drainage tube 20 passes through the base 25 and slightly projects its angularly truncated open end 27 beyond the distal end of the base 25.

As previously noted, the longitudinal progression of reducing the thickness of the structural base 25 in the distal direction allows a more flexible action to be inherently imparted to the distal half of the mask. Also Figure 25 illustrates that the inflated sectional area of ​​the inflated thin film cover 26 is similarly and progressively tapered in the distal direction, such that the tubes 20, 21 can be oriented to the proximal outlet of the mask.

ES 2 371 013 T3 to incorporate a preferred angle α in the range of 20 ° to 30 °, at the beginning of its next course over the tongue, for air (gas) and gastric service connections (not shown), as is necessary out of the patient's mouth.

As with the LMA of Figures 21 and 22, the structure of Figures 23 and 24 can be completed with a tent closure 28 on the back side of the mask. Again, such closure is performed by a flexible sheet material which is seen in Figure 28 to obtain a "flange post" bearing from the tube 20, centered on the distal half of the structural base 25. In Figure 29, the section shows the tent closure 28 being supported on the adjacent tubes 20, 21, to the passage over the lumen 24 of the mask, with the skirt of the tent peripherally secured to the structural base 25, it is understood again that at its proximal end, the tent sheet is also shaped and sealed to both tubes 20, 21 to complete the closure of the posterior side of the mask.

In Figure 28, a phantom contour protrusion profile 30 on the anterior side of the mask will be understood to suggest inflation of the film cover away from the anterior surface of the structural base 25, and an additional inflation profile 31 on the phantom outline on the back surface of the mask shall be understood to suggest an inflatable cuff 31 on the periphery of the base 25, to provide cushioned reference of the mask to the rear wall of the patient's pharynx. As shown, the rear cushioning material is shown for further connection to tent 28 along the sagittal plane intersected with tent 28.

It is desirable to facilitate the installation of the mask on a patient, that the deflated condition can offer a minimum thickness dimension. This will be clarified in Figures 28 and 29 where the respective minimum dimensions, D1, and D2 will be compared with the maximum available inflation dimensions D3, D4 without the rear shock 31, and D5, D6 with rear shock 31.

In the embodiment of Figures 30 to 32, the simplest difference to note is that the structural base 40 is flat and its integrally formed thin film of the inflatable cover portion 41 is otherwise described for the inflatable film 26 of the Figure 25. Also, the distal portion 42 of the drainage tube 43 is locally curved for straight but inclined passage through a similarly inclined orientation opening 44 in the region of the distal end of the base 40. In remaining overlap with the proximal end region of the base 40, the drainage tube 43 is laterally displaced to the extent that it can mate symmetrically with the airway tube 44, and both tubes 43, 44 can be attached to the flat surface. base support rear 40. The tent-like sheet material described for the closure of the back side of the mask can be as described for Figures 25 to 29, it should be noted that in section aa of Figure 30, the local section bears an almost identical appearance similar to the one sketched in Figure 28 for the mask in Figure 27.

According to a manufacturing technique of the unitary base 40 with an integrally molded thin film covering portion 41, this single component is outlined in the longitudinal section of Figure 21 and in the plan view of Figure 22, it being understood that such passages as in 43 '(for the passage of the drain tube as in 43', for the orientation of the drain tube), in 45 (for the air inflation access), and at 46 (for lumen definition) they are the product of the known center pin and another mold feature that define the mold structures as a whole. The preassembly of tubes 43, 44 side-by-side adjacency, together with the pre-bent and truncated open distal end of drain tube 43 is then assembled for adhesively or otherwise sealed passage of the distal end of drain tube 43 and for perforated film and the peripherally sealed passage of the truncated distal end of tube 43 in the relationship outlined in Figure 30.

In an alternative mode of structural assembly, outlined in Figure 31A, a suitably curved and preformed distal end fitting 50, for subsequent assembly to the remainder of the drainage tube (not shown) is a part of the insert in which in the Rotational molding process becomes part of Figure 31A to be then assembled to the parts of the mask which becomes an LMA with the gastric drainage feature. To this end, the drainage of the preassembly and airway tubes 43, 44 will be understood to terminate over lumen 46 and that the end projecting distally of the drainage tube portion (43) of these preassembled tubes (43, 44) can be properly fitted to the opening of the proximal mounting end 50, to establish continuity of the full function of the drain tube. Such continuity may be provided by known telescopic adjustment techniques, as in the magnitude denoted by dotted line 51 in Figure 31A, or by a short heat reduction plastic sheath (not shown) which overlaps the ends. equal diameter splice tubes of the tubular ends, namely the proximal end of the assembly 50 to the distal end of the preassembly of the two tubes (43, 44).

The structural base plan view 40 'of Figure 33 will be recognized as identical to that of Figure 32, except that two elongated and spaced parallel bars 55, 56 are symmetrically seated in the longitudinal sagittal plane of the mask (not shown) at which this component can be integrated. The purpose that the bars 55, 56 serve is to provide a measure of support for the drainage tube 43 as it passes over the lumen and when it alters the course for the symmetrical orientation of the distal end with respect to the sagittal plane.