Laryngeal mask airway device

The present invention relates to a Laringel mask airway management device. More specifically, the present invention relates to an improved airway tube used with the above instruments.

The Laringel mask airway management device is a well-known device useful for establishing the airway of an unconscious patient. Such instruments have been in use for about 13 years and have provided an alternative to older and well-known endotracheal tubes. For at least 70 years, endotracheal tubes, including elongated tubes with inflatable balloons located at the ends of the tubes, have been used to secure the airways of unconscious patients. In actual use, the end of the endotracheal tube is inserted from the patient's mouth through the laryngeal opening (or vocal cord opening) to the trachea. Once in position, the balloon inflates to seal the inner surface of the trachea. Once this seal is established, pressure is applied to the end near the base of the tube to arouse the patient's lungs. Also, the seal between the balloon and the inner surface of the trachea protects the lungs from aspiration (eg, the seal prevents substances retrograde from the stomach from being aspirated by the lungs).

Although endotracheal tubes have been very successful, they have some major drawbacks. The main drawback of endotracheal tubes is that they are difficult to insert properly. Inserting an endotracheal tube into a patient is a highly technical procedure. It may also be difficult or impossible for even a skilled practitioner to insert an endotracheal tube. In many cases, the endotracheal tube insertion can tragically lead to death of the patient because the patient's airway management was not prompt enough.

In addition to the main drawbacks mentioned above, there are other drawbacks related to endotracheal tubes. For example, intubation of an endotracheal tube often causes patients to suffer from severe "rough throat". The "rough throat" is mainly caused by friction between the tube and the notch between the patient's ruptured cartilage. Another drawback is that the patient is virtually unable to cough while the endotracheal tube is intubated. Yet another problem with endotracheal tubes concerns how to insert the endotracheal tubes. Insertion of an endotracheal tube usually requires skillful handling of the patient's head and neck and forcing the patient's jaw to open wide. The need to handle the head and neck in this way makes it difficult or undesirable to insert an endotracheal tube into a patient who may have a neck injury. Yet another drawback is that the airways provided in the endotracheal tube are relatively small and narrow. The size of the airway must be relatively narrow because the end of the tube must be small enough to fit the trachea.

In contrast to the endotracheal tube, it is relatively easy to insert a Laringel mask airway management device into the patient and thereby open the airway. Also, the Laringel mask airway management device, if inserted improperly, is a device that "allows" it and tends to be able to open the airway. Therefore, the Laringel mask airway management device is often considered a "lifesaving" device. In addition, the Laringel mask airway management device can be inserted with relatively small manipulations on the patient's head, neck, and chin. In addition, the Laringelmask airway management device can ventilate the patient's lungs without the need to touch the inner surface of the sensitive trachea, and the size of the airway secured is generally significantly larger than that provided by the endotracheal tube. Also, the Laringel mask airway management device does not interfere with coughing as much as an endotracheal tube. Primarily due to these advantages, the Lalingel mask airway management device has enjoyed increasing popularity over the last 13 years.

1A and 1B are perspective side views showing a conventional Laringel mask airway management device 100. FIG. 2 illustrates an instrument 100 inserted into a patient. A Laringel mask airway management device, such as device 100, is described, for example, in US Pat. No. 4,509,514. The Laringel Mask Company of It has been marketed for many years as "Classic" by Cyprus). Instrument 100 includes a bendable cylindrical airway tube 110 and a mask portion 130. The tube 110 extends from the end 112 near the base to the end 114, and the mask portion 130 is connected to the end 114 of the tube. The mask portion 130 includes an end 132 near the base and a substantially elliptical inflatable cuff 134. The mask portion 130 defines a central passage extending from the end 132 near the base to the open end 136 of the cuff 134. The end 114 of the tube 110 fits into the end 132 near the cylindrical base of the mask 130, and the instrument 100 is continuously sealed extending from the end 112 near the base of the tube 110 to the open end 136 of the cuff 134. It has an airway that has been removed. Instrument 100 also includes a pressure tube 138 for inflating and contracting the cuff 134.

In actual use, the cuff 134 contracts and the mask is inserted into the pharynx through the patient's mouth. The mask is placed so that the end 140 of the cuff 134 rests on the patient's normally closed esophagus and the open end 136 of the cuff 134 is aligned with the entrance of the patient's trachea (ie, the patient's vocal cord opening). It is preferable to be squeezed. When the mask is placed in such a position, the cuff inflates to seal around the patient's vocal cord opening, which ensures a closed airway extending from the end 112 near the base of the tube 110 to the patient's trachea. Will be done.

For convenience of explanation, the term "complete insertion arrangement" is used herein to refer to a Laringel mask airway management device that is inserted into a patient and has the following characteristics: (1) The mask is located around the patient's vocal cord opening, (2) the cuff swells to seal around the patient's vocal cord opening, and (3) the airway tube is on the outside of the patient's mouth. The tube extends over the patient's mouth and patient so that it extends from the end near the base where it is located to the end connected to the mask and the instrument has a closed airway that extends from the end near the base of the tube to the patient's lungs. It extends through the airways. Figure 2 shows a Laringel mask airway management device in a fully inserted position.

When the instrument 100 is in the fully inserted position, the instrument 100 has the effect of not touching the inner surface of the trachea. More preferably, the tissue surrounding the patient's laryngeal opening is in contact with the inflatable cuff 134 to provide a seal. Unlike the inner surface of the sensitive trachea, the tissue of the laryngeal opening adapts to foreign bodies. For example, while swallowing food, on the way to the esophagus, food is usually crushed by these tissues. Therefore, these tissues are less sensitive and less susceptible to damage from contact with inflatable cuffs.

U.S. Pat. No. 5,303,697 describes another type of prior art device that would be referred to as the "intubated Laringel mask airway management device." The intubation device is useful for facilitating the insertion of the endotracheal tube. After the intubated Laringel mask airway management device is in full insertion position, the device serves to guide the endotracheal tube to be subsequently inserted. The use of the Laringel mask airway management device in this way facilitates what is commonly known as "blind intubation" of endotracheal tubes. Intubation Laringel Mask To insert an airway management device, the patient's head, neck and jaw need only be moved slightly. Once the device is in full insertion position, the endotracheal tube can be inserted by simply inserting the endotracheal tube into the airway tube of the intubation Laringel mask airway management device without moving the patient further. become. This is in contrast to the relatively large movements of the patient's head, neck and jaw required when inserting an endotracheal tube without the help of an intubated Laringel mask airway management device.

As seen in FIG. 2, when the instrument 100 is in the fully inserted position, the airway tube 110 is defined by the patient's upper respiratory tract (ie, the hard palate, soft palate, and anatomical tissue such as the pharynx, mouth and vocal cords. It takes the shape of a curve defined by the shape of the patient's airway), which allows air to pass freely between it and the opening. For convenience of explanation, the term "insertion shape" is used here to refer to the shape that the airway tube takes when the Laringel mask airway management device is in the full insertion position, and "natural placement" and "natural placement". "Shape" is used to refer to the shape that an airway tube takes when no external force is exerted on the tube (for example, when the device is not inserted into the patient or simply not in use). To.

In the intubated Laringel mask, the airway tube is made of a rigid body or a material similar to a rigid body, and the natural shape of the tube is the same as or almost the same as the insertion shape of the tube. However, it is not always desirable for the airway tube to be made of a rigid material. For example, the use of rigid materials such as metal can increase the cost of the instrument and complicate the insertion of the instrument.

In other Laringel mask airway management devices such as the device 100, an elastic air web tube is used, in which the natural shape is different from the insertion shape and is more linear than the insertion shape. However, the airway tube is also required to flex or bend upon insertion and to maintain a bent or pressured position while the device is in the patient's body. In the instrument 100, the amount of bending of the airway tube during insertion (or the difference between the natural shape and the insertion shape) is reduced by manufacturing a tube whose natural shape is slightly bent rather than straight. FIG. 1B shows the natural shape of the airway tube 110 of instrument 100.

Several factors influence the design of airway tubes for elastic tubing appliances such as Instrument 100. The airway tube 110 must be elastic enough to allow the tube to easily bend or bend from its natural shape to its insert shape. However, the airway tube 110 should also be stiff enough or strong enough to withstand the formation of twists when bent into its shape as it is inside the body. FIG. 3 shows an example of a tube having a twist of 180 as a result of the tube bending due to an extreme amount. As is well known, in any tube, the size of the inner passage defined by the tube is drastically reduced at twist 180. The effect of twisting on tubes is usually experienced with garden hoses. For example, a single twist in a garden hose will drastically reduce the amount of water distributed by the sprinkler through the hose. The effect of the twist is similar in the Laringel mask airway management device. Any twist formed on the airway tube of the Laringel mask airway management device essentially closes the airway of the tube and drastically reduces the amount of air passing through the tube. Therefore, it is important to design the airway tube so that no twist is formed when the tube is bent into the shape it is in the body. The airway tube should be flexible enough to allow easy transition between the natural shape and the insertion shape, but not bendable enough to twist when bent into the shape it is in the body. ..

Instrument 100 achieved this compromise with a nearly cylindrical airway tube 110. If the airway tube is not pre-bent (see Figure 1B) so that the central axis of the tube is bent rather than straight when the tube is in the rest position, the tube is perfectly cylindrical. FIG. 4 shows a cross section of the airway tube 110 taken along line 4-4 as seen in FIG. 1B. As can be seen in FIG. 4, the outer circumference 110-o of the airway tube 110 is circular. The inner circumference 110-i of the airway tube 110, which defines the airway inside the tube, is also circular. The outer and inner circumferences, 110-i and 110-o are centered on the common point C. The airway tube 110 can be made of polyvinyl chloride (PVC) or silicone characterized by about 50-80 durometas on the ShoreA scale. In adult male size, air wake The inner radius Ri (that is, the distance from the center C to the inner circumference 110-i) is equal to about 5 mm and the outer radius Ro (that is, the outer circumference 110 from the center C) so that the wall thickness T of the tube 110 is approximately equal to 2.5 mm. The distance to -o) is approximately equal to 7.5mm.

The airway tube 110 of the instrument 100 is flexible enough to be easily inserted into the patient (and has a natural shape that deforms relatively easily between its natural shape and its shape when inside the body) and has an insertable shape. Although we have achieved the desired compromise of being stiff enough not to twist when bent, the airway tube 110 is always under pressure when in the insert shape. This pressure reflects the tendency of elastic airway tubes to automatically return to their natural shape. As a result of this pressure, a force F acts on the patient's anatomical tissue whenever the instrument 100 is in the fully inserted position, as shown in FIG.

An improved airway tube is needed for use with the Laringel Mask airway management device.

Such a purpose is given to the Laringel mask airway management device characterized by an improved airway tube. According to the present invention, an airway tube for a Laringel mask airway management device is provided, the Laringel mask airway management device comprises an inflatable cuff, which defines a central opening at least during inflatation and is intended for the patient. It can be inserted through the mouth to the insertion position in the patient's body, surrounds the patient's vocal cord opening at the insertion position when inflated, the airway tube has an elastic wall, and the elastic wall. Includes at least one reduced thickness region in the region that undergoes compression or expansion when the airway tube is in the inserted shape.

In one aspect, the invention provides tubes used in Lalingel mask airway management devices, including inflatable cuffs and airway tubes. The inflatable cuff defines a central opening at least when inflated. The cuff can be inserted through the patient's mouth to the insertion position inside the patient. When inflated and in the insertion position, the cuff surrounds the patient's vocal cord opening. The airway tube extends from the end near the base to the end. The airway tube defines an internal passage, front, rear, left, and right. When the cuff is in the inflated and inserted position, the airway extends from the end near the base of the tube through the internal passage to the vocal cord opening. The front is characterized by a thinner wall than the left and right. The rear is characterized by a thinner wall than the left and right.

The outer circumference of the airway tube defines a flat portion, which extends from near the end of the tube to near the end near the base. The inner circumference of the airway tube is characterized by being oval.

The shape of the tube has the effect of reducing the pressure exerted by the device on the patient when the device is inserted into the patient. Further, the shape of the tube has the effect of increasing the size of the airway provided in the tube. Also, the shape of the tube makes it possible to facilitate insertion of the device into the patient.

<figref num="1A">FIG. 5 is a perspective view and a side view showing a conventional Laringel mask airway management device.</figref><figref num="1B">FIG. 5 is a perspective view and a side view showing a conventional Laringel mask airway management device.</figref><figref num="2">The conventional instruments shown in FIGS. 1A and 1B in a fully inserted position are shown.</figref><figref num="3">Indicates a tube that is bent enough to form a kink.</figref><figref num="4">It is a cross-sectional view showing the airway tube of the instrument shown in FIG. 1A and FIG. 1B, and is the cross-sectional view taken along the straight line 4-4 shown in FIG. 1B.</figref><figref num="5A">It is a perspective view which shows the Laringel mask airway management apparatus constructed by this invention.</figref><figref num="5B">FIG. 5A is a side view showing the instrument shown in FIG. 5A, showing the natural shape of the tube.</figref><figref num="5C">It is a side view which shows the instrument shown in FIG. 5A, and shows the insertion shape of the said tube.</figref><figref num="5D">The instruments shown in Figures 5A-C, disassembled into components, are shown.</figref><figref num="6A">It is sectional drawing which shows the airway tube taken along the straight line 6A-6A shown in FIG. 5B.</figref><figref num="6B">It is sectional drawing which shows the airway tube taken along the straight line 6B-6B shown in FIG. 5C.</figref><figref num="7">It is sectional drawing which shows the cross section of the airway tube and the mask part of the instrument shown in FIG. 5A taken along the straight line 7-7 shown in FIG. 5A.</figref>

[Detailed explanation] Other objects and effects of the present invention will be readily apparent to those skilled in the art from the following detailed description and drawings in which some embodiments are shown and described solely for the purpose of explaining the present invention. The drawings and descriptions should be considered as examples and should not be considered in the sense of limiting or limiting the scope of the claims set forth in the claims.

To fully understand the nature and purpose of the invention, the following detailed description given with respect to the given drawings, in which the same reference numbers are used to indicate the same or similar parts, should be referred to. is there.

With reference to the drawings, FIGS. 5A and 5B are a perspective view and a side view showing the Laringel mask airway management device 500 configured according to the present invention when no external force is applied to the device, respectively. Is. FIG. 5C is a side view showing the shape of the instrument 500 in the fully inserted position. That is, FIGS. 5A and 5B show the natural shape of the airway tube of the instrument, and FIG. 5C shows the insertion shape of the airway tube of the instrument. As shown, the instrument 500 shares many features with the conventional instrument 100. However, instrument 500 includes an improved airway tube 510 instead of the airway tube 110. FIG. 6A is a cross-sectional view showing a cross section of the airway tube 510 taken along the straight line 6A-6A shown in FIG. 5B. FIG. 6B is a cross-sectional view showing a cross section of the tube 510 taken along the straight line 6B-6B shown in FIG. 5C. That is, FIGS. 6A and 6B are cross-sectional views showing a cross section of the airway tube 510 in its natural and inserted shape, respectively.

As discussed in more detail below, the airway tube 510 differs from the conventional airway tube 110 in two main respects. First, the improved tube 510 defines a flat portion 510-f (see, eg, Figure 5A). Second, at least when the tube is in its natural shape, the inner circumference of the improved tube 510 is characterized by an oval shape rather than a circular shape, or an elliptical shape, as shown in FIG. 6A. Further, as discussed below, the above configuration of the airway tube 510 has the effect of reducing the force exerted by the airway tube on the patient's delicate anatomical tissue when the instrument 500 is in a fully inserted position. .. Also, the configuration of the airway tube 510 alleviates the tendency of the tube 510 to collapse or twist when the tube is bent into an insert shape, maximizing the capacity of the internal airway defined by the tube 510. This has the effect of reducing the resistance of the flow. Other advantages of the instrument 500 will be described later.

Figure 5D shows the instrument 500 disassembled into its components. As shown, the airway tube 510 includes a connection portion 550 and a pipe portion 560. The connection portion 550 is preferably the same as that used in the prior art apparatus. The connection 550 is generally stiffer than the tubing 560, the end near the base is designed to fit into a standard ventilator, and the end fits into the end near the tubing 560. The end of the tube 560 near the base receives the end of the connection 550, and the end 514 of the tube 560 is in a columnar opening defined by the end 132 near the base of the mask 130. It extends in a detachable state. As shown in FIGS. 5A-D, the flat portion 510-f preferably extends from the end 514 of the pipe portion 560 to a location 562 near the end of the base of the pipe portion 560.

As best shown in FIGS. 5A, 5B, and 6B, the outer circumference 510-o of the airway tube 510 is not circular. More appropriately, the outer circumference 510-o is defined by two portions, a curved segment 510-c and a linear segment 510-l. The curved segment 510-c is an arc that forms most of the circle defined by the center of curvature C and the radius Ro, and extends clockwise from point A to point B. The straight line segment 510-l is a de facto straight line defined as the minimum distance between points A and B. The presence of a linear segment 510-l on the outer circumference of the airway tube 510 gives the tube a "flat" appearance. As shown in FIGS. 5A-D, the tube 510 defines a flat portion 510-f extending approximately from the end 514 to location 562.

It is considered that the airway tube 510 defines the front part, the rear part, the right part, and the left part. Comparing FIGS. 6A, 5C, and 2, especially the portion of FIG. 2 showing a portion of the airway tube near the mask, the flat portion 510-f defines the front portion of the airway tube 510 and also. , It can be seen that the posterior 510-p faces the flat (ie, when the instrument 500 is in full insertion and full insertion, the posterior 510-p is adjacent to the patient's pharyngeal wall and flat 510- f is near the mask section 130 and is "front" or anterior to the rear 510-p). The right and left parts of the airway tube, 510-left and 510-right, respectively, are shown in FIG. 6A, respectively. It will be appreciated that the front, rear, right, and left names are all given to the instrument 500 in the full insertion position and the full insertion position.

The airway tube 510 defines an internal airway 520, which extends between the ends near the base of the tube. In the pipe 560, the boundary of the airway is defined by the inner circumference 510-i of the pipe 560. As noted above, the inner circumference 510-i of the tube portion 560 is oval, at least when the tube 510 is in its natural shape. The egg-shaped inner circumference 510-i is characterized by a short axis 521 and a long axis 522 (the short axis 521 and the long axis 522 are indicated by a chain line in FIG. 6A). The short axis 521 extends between the left side and the right side of the pipe portion 560. The long axis 522 extends between the front 510-l and the rear 510-p. As the name suggests, the major axis 522 is longer than the minor axis 521, at least when the tube 510 is in its natural shape.

The egg-shaped inner circumference 510-i is not centered on the center of curvature C of the curved segment 510-c. In FIG. 6A, the dashed horizontal line 521 divides the airway 520 into two equal-sized upper and lower halves. As shown in the figure, the dichotomy line 521 is deviated from the center of curvature C and is located between the center of curvature C and the front surface 510-p.

As shown in FIG. 6A, the thickness of the front wall of the pipe 560 is T1, the thickness of the back wall of the pipe 560 is T2, and the thickness of the wall on the left side of the pipe 560 is T3. The thickness of the wall on the right side of the pipe portion 560 is T1. As a result of the flattened rear part of the tube and the deviation of the oval internal path, the front and back wall thicknesses (T1 and T2, respectively) are the left side view and the right side wall thickness (T1 and T2, respectively). It is thinner than T3 and T4), respectively. Preferably, the front thickness T1 is substantially equal to the back thickness T2. Further, preferably, the thickness T3 of the left side surface portion is equal to the thickness T4 of the right side surface portion. In one preferred embodiment of adult male size, the thicknesses T1, T2, T3, and T4 of the tube section 560 are approximately equal to 1.7 mm, 1.7 mm, 3.3 mm, and 3.3 mm, and of the curved segment 510-c. The radius Ro is approximately equal to 7.5 mm. In the preferred embodiment, the tube portion 560 of the airway tube 510 is formed of a PVC material characterized by a durometer in the range 50-90 on the ShoreA scale.

As outlined in Figures 5A-C and 2, when a resilient, flexible airway tube is bent into an insert shape, the tube tends to naturally return to its natural shape. .. Due to this tendency, the device in the fully inserted position exerts a force F on the delicate anatomical tissue. When the duration of insertion is relatively short (eg, minutes), such forces do not raise significant concerns. However, in some situations it may be desirable to leave the Laringel mask airway management device fully inserted for extended periods of several hours. Under these conditions, the force F acting on the patient (shown in FIGS. 2 and 5C) is important and should be minimized.

When the elastic airway tube is bent from the natural shape to the insertion shape, each part of the tube wall is deformed as a result. In particular, at least a portion of the anterior portion of the tube is compressed and at least a portion of the posterior portion of the tube is elastically stretched or placed under tension. A force F is generated in response to compression in one part of the airway tube and extension in another part. In general, the force generated by the compression and expansion of an elastic member increases with the thickness of the member. When the airway tube 510 is bent into an insert shape, maximum compression and decompression occur at the front 510-f and rear 510-p of the tube 560, respectively. The wall thickness of these parts of the airway tube 510 (ie, the wall thickness at the front 510-f and the rear 510-p) is designed to be reduced to a minimum. By reducing the wall thickness in the area of the tube 510 that undergoes compression and decompression, it is possible to effectively reduce the force generated by the tube and acting on the patient when the device is in a fully inserted position. Become.

In addition to reducing the patient's trauma, reducing force F has the effect of increasing the stability of the Laringel Mask Airway Management Device 500. Ideally, when the Laringel mask airway management device is in a fully inserted position, no force should act on the device to move the device relative to the patient. However, the force F causes the device to move within the patient. If the force F is large enough, or combined with other forces resulting from the movement of the patient or the movement of the airway tube outside the patient's body, the resulting force will force the device inside the patient. Will move with. By reducing the force F to a minimum, the instrument 500 has the effect of reducing the likelihood that the instrument will move relative to the patient in a fully inserted position.

As discussed above, reducing the wall thickness between the anterior 510-f and the posterior 510-p of the airway tube has the effect of reducing the force F acting on the patient when the instrument 500 is in full insertion position. .. Also, reducing these wall thicknesses has little effect on the tube's ability to prevent the tube 510 from forming a twist when bent into an insert shape. This is because the ability to prevent twisting from forming when a tube is bent is in principle determined by the thickness of the walls on the right and left sides of the tube (because when twisting is possible). Because these right and left walls collapse). In tube 510, the right and left walls of the airway tube are thick enough to inhibit the formation of twists, and the front and back walls of the airway tube exert a force acting on the patient. It is thin enough to reduce it.

Another effective feature of the tubing 560 is to support the thinnest part of the tubing 560 (ie, front 510-F and rear 510-p) and prevent the formation of twists. Referring to FIG. 6A, the portion of the tube above chain line 521 is characterized by an "arch shape". The tube wall at the base of the arch (near chain line 521) is thicker than the tube wall near the top of the arch (near 510-p at the rear). This "arch shape" is due to the oval or elliptical, inner circumference 510-i, and in particular the long axis 522 of the ellipse oriented to extend from the anterior to the posterior of the tube. It is a consequence. The "arch shape" is convenient for supporting the relatively thin rear 510-p and prevents the formation of twists. Similarly, the lower portion of the dashed line 521 in the tube is also characterized by an "arch shape", which supports the thin anterior part and prevents the formation of twists.

In addition, FIG. 6B shows another advantage of the airway tube 510. Bending the tube 510 into the insert shape creates a pressure Fс that pushes the front and back of the tube. As mentioned above, the tube 510 is configured to resist such pressure and prevent the tube from being crushed or twisted. However, the pressure Fс affects the shape of the tube 510. In particular, such pressure tends to tighten the tube and make the inner circumference 510-i more circular. That is, when the tube 510 has a natural shape, the inner circumference 510-i is oval. However, when the tube 510 is forcibly made into an insertion shape, the naturally oval inner circumference 510-i is deformed into a shape closer to a circle.

When the tube 510 has a natural shape, the inner circumference 510-i is oval, and the semimajor axis 522 of the inner circumference (see Figure 6A) extends between the front and back of the tube. It is characterized by its characteristics. The long axis 522 on the inner circumference coincides with the direction of the pressure generated by bending the tube into the insertion shape. (Alternatively, regardless of whether the tube 510 has a natural shape or an insertion shape, both the long axis 522 and the central axis of the airway tube 510 are placed on a common surface.) The long axis 522 is the direction of these pressures. By matching with, when the tube is bent into the insertion shape, the inner circumference is contracted in the long axis direction, and the inner circumference is deformed into a shape closer to a circle. The outer circumference 510-o is substantially circular (excluding the flat portion 510-l) when the tube 510 has a natural shape, but is similarly deformed into a shape closer to an ellipse. When a conventional cylindrical tube was bent into an insert shape, both the outer and inner circumferences, which were naturally circular, were deformed into an elliptical shape. Therefore, when the conventional airway tube is forced into an insertion shape, the inner airway becomes narrow or elliptical, which makes subsequent insertion of the catheter or endotracheal tube more difficult, and further. Increased resistance to gas flow through the airway. However, when the tube 510 bends into an insertion shape, the airway inside it deforms into a more circular shape, thus facilitating the insertion of the catheter or endotracheal tube and maintaining good flow.

In addition to the above advantages, the above configuration of the airway tube 510 has the effect of providing an airway with a larger cross-sectional area as compared to conventional tubes of similar size. With reference to FIGS. 4 and 6A, dimension D is the distance between the outer front and outer rear of the airway tube. For the conventional tube 110 seen in FIG. 4, the distance D is simply the outer diameter of the tube. For the tube 510 seen in FIG. 6A, the distance D is not the "diameter" because the outer cross section of the tube is not circular. However, in both tube 110 and tube 510, distance D is the space between the teeth needed to insert the tube (ie, the space between the upper and lower teeth needed to accommodate the airway tube). Or the amount by which the patient must open the jaw to accommodate the tube). For an arbitrarily given distance D, the cross-sectional area of the airway 520 is greater than the cross-sectional area of the airway obtained by the prior art tube 110. That is, in a conventional cylindrical tube characterized by an outer diameter D, only a smaller size airway can be obtained compared to the airway obtained by the tube 510 characterized by the same dimension D. This is because the wall thickness required by the conventional cylindrical tube to prevent the formation of kinks makes the cross section of the airway smaller than that of the airway 520.

In general, it is desirable to minimize the outer dimension D of the airway tube (and the gap between the corresponding teeth) while simultaneously maximizing the airway portion of the tube. The large airway facilitates ventilation of the patient's lungs and facilitates the use of the Laringel mask airway management device as an intubation device to guide the subsequently inserted endotracheal tube.

Compared to the cylindrical tube of the prior art, the airway tube 510 comprises a wider airway 520 for an arbitrarily given outer dimension D. Therefore, the airway tube 510 can be configured to have an airway having a cross-sectional area equal to that of the conventional tube while having an outer dimension D smaller than that of the conventional tube. A Laringel mask airway management device constructed using such an airway tube has the same ventilation capacity as the corresponding conventional device, but can be inserted more easily at the same time. Alternatively, the airway tube 510 may be configured to have an outer dimension D equivalent to that of the prior art cylindrical tube, while at the same time providing an airway with a wider cross-sectional area. A Laringel mask airway management device constructed using such an airway tube has a larger ventilation capacity and a larger diameter endotracheal tube without difficulty in insertion compared to the corresponding conventional device. It has the effect of enabling insertion.

Another advantage of the Airway Tube 510 is that the flat section 510-f facilitates the insertion of the instrument 500. The practitioner usually places the index finger on the device, near the joint between the airway tube and the mask, and presses the device with the finger to insert the Laringel mask airway management device, thereby placing the mask in the patient's mouth and throat. Push it into. Conventional cylindrical tubes make this type of insertion somewhat difficult, as the practitioner's fingers can easily slip off the airway tube during insertion. The flat portion 510-f of the airway tube 510 comprises a stable operating platform on which the practitioner places his finger and applies pressure during insertion of the instrument.

Another advantage of the Instrument 500 is with respect to the use of insertion jigs that coordinate the insertion of the instrument into the patient. A well-known alternative to the use of fingers to adjust insertion is the use of "insertion jigs". Such insertion jigs generally have an end attached to the Laringel mask airway management device near the joint between the airway tube and the mask portion. Such insertion jigs also generally have a near-base end that is gripped by the practitioner during insertion and is out of the patient's mouth throughout the insertion procedure.

FIG. 7 shows a view of the instrument 500 taken along the straight line 7-7 shown in FIG. 5A, especially the instrument near the junction between the airway tube 510 and the mask portion 130. As shown, the end of the airway tube 510 fits into the end 132 of the mask portion 130 near the cylindrical base. As shown, the gap 710 is defined as the gap between the flat portion 510-f of the tube 510 and the end of the mask portion 130 near the base. The gap 710 provides a useful place to place the end of the insertion jig while inserting the instrument 500.

As noted above, FIG. 6A shows the cross section of the tube section 560 when the tube is in its natural shape. The outer circumference 510-o has been described as being bounded by a curved segment 510-c and a linear segment 510-l. In a preferred embodiment, the curved segment 510-c is the larger arc of the circle centered on the point C and the linear segment 510-o extends between the two endpoints of the larger arc 510-c. It is the string of the above circle. However, it should be recognized that the airway tube according to the present invention does not necessarily require this exact cross section, and that the airway tube defining the flat portion 510-f is generally included in the present invention. For example, instead of the larger arc of the circle, the curved segment 510-C can be obtained from an ellipse or a non-circular curve. Further, the curved segment 510-c does not necessarily have to be centered on the point C. Similarly, the linear segment 510-l does not necessarily have to be linear. More properly, it can be obtained from curved or arched paths. However, it is preferable that the radius of curvature of the linear segment 510-l is sufficiently larger than the radius of curvature of the curved segment 510-c. In other words, the linear segment 510-l is preferably more linear than the curved segment 510-c. Also, the cross section taken at any point along the substantial length of the airway tube is preferably characterized by the merger of the curved segment 510-c and the linear segment 510-l. The presence of linear segments 510-l in a cross section taken at any point along the length of the tube results in a tube with the desired flat portion 510F.

Similarly, although the preferred inner circumference 510-i is elliptical, the airway tubes according to the invention may be characterized by an inner circumference having a different type of curved shape. Preferably, the inner circumference of the tube is not circular in the stationary state, and the distance between the right side and the left side of the inner circumference is smaller than the distance between the front side and the rear side of the inner circumference.