Breathing assistance apparatus

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DESCRIPTION

Apparatus for assisted breathing.

Invention field

This invention relates to nasal cannulas, and more particularly, but not exclusively, to nasal cannulas for delivering continuous positive airway pressure (CPAP) to neonates. A device according to the preamble of claim 1 is described in US-A-4 782 832.

Background

Certain patients require a respiratory supplement such as air, oxygen, or other gases. These gases are supplied either freely or are supplied at controlled pressures. Said gases are also delivered through the patient's mouth or through the patient's nose. Nasal feeding systems provide an advantage in that they are generally more convenient and less intrusive than mouth-based or mouth-covering devices. Despite their convenience, nose-based devices are considered cumbersome as a result of the fixation strips that must be placed across the face and / or around the head and used to secure the device to the respiratory cavity. of a patient. Furthermore, conventional cannulas do not provide a tight seal around the nostrils to inhibit apnea and provide a high flow system that stimulates patient respiration. Hence, even with such fastening strips, these nasal devices often slip out of the respiratory cavity. This is of particular concern to infants, children, or older people who do not understand the importance of keeping the nasal breathing device in place, be it a nasal CPAP or nasal cannula.

It is known that it is beneficial and therapeutic to deliver a sufficient amount of air pressure to the airway to the patient in order to maintain a minimum level of air volume in the lungs. If the air volume falls below this minimum level, the lungs could be crushed, which can be extremely dangerous or even fatal to the patient. Also, back pressure can increase oxygen levels and lower carbon dioxide levels in the lungs. This will also improve the pH by removing carbon dioxide, which is an acid, from the blood. Hence it has been found that the application of such sufficient pressure, called continuous positive airway pressure (CPAP), is advantageous in maintaining a minimum volume of air or pressure in the lungs when a patient is breathing spontaneously. CPAP can be delivered through nasal fixation devices such as a nasal cannula, or through mouth-based devices or endotracheal devices.

A number of CPAP devices are known including endotracheal tubes, head chambers, masks, nasal goggles, and nasal cannulas. Although each type of device has its advantages and disadvantages, the nasal cannula provides a comfortable alternative to assist with CPAP or airflow. Nasal cannulas of the prior art have been described in many embodiments with various methods of attaching the device to the nostrils. In US Pat. No. 3,513,844 discloses one such cannula assembly that uses an adjustable band that surrounds the patient's head. A similar device is described in US Patent No. 4,106,605 in which the feeding tubes to the cannula are hooked above the ears and around the head of the patient. For its part, US Pat. No. 5,477,852 describes an even more cumbersome device with a headband for holding and positioning the nasal inserts and corresponding feeding tubes. Still another system in US Pat. No. 5,271,391 discloses a cannula that is secured by applying a strip of pressure-sensitive adhesive tape to the feeding tubes emerging from each side of the cannula, thereby securing the feeding tubes to the cheeks of the patient. a patient with the cannula placed between them.

Devices of the "cap" type are also used to hold CPAP nasal cannulas in place. However, this method generally applies pressure to the patient's nose and upper lip, causing pressure necrosis in the center of the nose. A particularly sensitive patient is a young person, a child or a baby. The hat is also not able to adequately hold the nostrils in place, particularly in the case of babies who are moving or rolling around in their crib. In a hospital or medical facility, it is not uncommon for a caretaker to discover that the CPAP device has become disconnected from a patient's nose, which can lead to apnea, desaturations, bradycardia, or hypoxia resulting in levels of dangerously low oxygen in the blood. In practice, the tube for these cap-type CPAPs is draped around both sides of the patient's cheek, which means that the most comfortable position to lie down is on the patient's back (face up). Pressure on the patient's cheeks caused by the clamping device can make other positions uncomfortable.

Other prior art fixation systems include adhesive devices that are attached directly to the nose. US Patent No. 4,823,789 describes a nose tube anchor strap having an adhesive coated sheet shaped to fit over a patient's nose and an appendage to secure a nasal gastric tube. A similar system has been found in US Pat. No. 5,156,641 having an anchor cord adhesively attached to a patient's nose at one end and attached to secure a naso-gastric catheter at the other end. US Patent No. 5,513,635 provides a clamping device with a body engaging portion that is attached through a patient's nose with downwardly extending cannula engaging portions.

ES 2 318 062 T3 from it. Similarly, US Patent No. 5,682,881 describes the use of an adhesive foam pad attached to the upper lip for positioning of the cannula.

In US Patent No. 3,643,660 a unified nasal cannula comprises a hollow tubular body having a flat or smooth upper surface and a pair of spaced, curved, elongated tubular extensions, having outer holes to direct a flow. gas with extensions that protrude upward at an angle with the surface. With reference to Figures 2 and 3, it can be seen that since the intake 400 is from the side, the tips 402, 404 could appreciate slightly different pressures. There is also the possibility that expired CO2 from upstream tip 402 is breathed in through tip 404.

In US Patent No. 5,975,077 a cannula is described that includes a gas that is injected into an airway in communication for fluid passage with the nasal windows of a patient and aerodynamically designed passageways for the passage of fluid. ambient air and injected gas in order to optimize the characteristics of fluid circulation during inhalation and exhalation of the patient.

A cannula attached to an elongated flexible tube is disclosed in US Patent No. 4,774,946. The nasal tips include bulbous parts that seat and seal the nasal tubes in the nostrils.

US Patent No. 5,193,532 describes a device for generating by ejector action a continuous positive airway pressure (hereinafter CPAP), which comprises a breathing channel that opens at one end to atmosphere and at the other end is adapted to be provided with a fixation device to the nose and / or mouth of the patient as seen in Figure 1. The inlet is located between a channel open to the atmosphere and open to the tips in such a way that the fresh gas stream is directed mainly in a coaxial direction into the channel, producing an ejector action.

However, while these prior art systems do provide CPAP, they suffer from a variety of drawbacks including: insufficient grip on the patient's head, potential for pressure imbalances at each tip, and the ability to re-breathe CO.₂ expired.

Summary of the invention

An object of the present invention is to provide a nasal cannula which will somewhat alleviate the aforementioned drawbacks or which will at least offer the public a useful choice.

Accordingly, in a first aspect, the present invention consists of a nasal gas cannula for discharging respiratory gases to a patient, comprising:

- a gas inlet configured to be coupled to an inspiratory conduit;

- a gas discharge configured to be coupled to a separate expiratory conduit;

- a pair of nasal tips, each of which tips substantially equidistant from - and is in fluid passage communication with - said gas inlet and substantially equidistant from - and is in fluid passage communication with - said gas discharge,

- a low resistance path between said gas inlet and said gas outlet,

- whose nasal cannula is characterized by

- said gas inlet, said gas outlet and said tips are configured in such a way as to limit the dead space of said nasal cannula substantially to the volume of said extremities.

Many changes in construction and widely different embodiments and applications of the invention will suggest themselves to those skilled in the art to which the invention is concerned without departing from the scope of the invention as defined in the appended claims. The descriptions and explanations herein are purely illustrative and not limiting.

The invention consists of the foregoing, and also contemplates constructions of which the text that follows gives examples.

Brief description of the drawings

A preferred form of the present invention is described below with reference to the accompanying drawings, in which:

Figure 1 is a side view of a prior art cannula placed in an infant.

Figure 2 is a perspective view of a prior art cannula placed in an infant.

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Figure 3 is a cross section of a prior art cannula.

Figure 4 is a top perspective view of the present invention.

Figure 5 is a sectional view of the present invention.

Figure 6 is a perspective view of the present invention.

Figure 7 is a side view of the present invention.

Figure 8 is a bottom view of the present invention.

Figure 9 is a top view of the present invention.

Figure 10 is an illustration of the present invention in use in a neonate.

Figure 11 is a block diagram of a CPAP system, in use with the present invention.

Figure 12 is a side view of a cap, used to hold the cannula of the present invention in place.

Figure 13 is an illustration of the cap of Figure 13 in use on a neonate.

Detailed description of the preferred embodiments

Referring now to Figure 11, in which a typical application has been drawn, a humidified continuous positive airway pressure (CPAP) system is shown, in which a patient 19 is receiving pressurized and humidified gases through of a nasal cannula 100 connected to an inhalation conduit 21. However, it should be understood that the present invention is not limited to CPAP gas delivery, but is also applicable to other types of gas delivery systems. The inhalation conduit 21 is connected to the outlet 12 of a humidification chamber 10 containing a volume of water 15. Inspiratory conduit 21 could contain heating means or heating wires 20 that heat the conduit walls to ensure a constant humidity profile along the conduit and thereby reduce condensation of humid gases within the conduit. When the volume of water 15 contained in the humidification chamber 10 is heated, the water vapor begins to fill the volume of the chamber above the surface of the water and exits the discharge 12 of the humidification chamber 10 with the flow of gases (for example air) provided from a gas supply means or drive fan 18 that enters the chamber 10 through the intake 16.

With reference to Figures 5 and 11, the humidified gases pass through the inhalation conduit 21 to the cannula 100, which is in communication with the nose of a patient 19 through tips 116, 118. The expired gases pass through from tips 116, 118 to outlet manifold 130. Excess gases then circulate through exhalation conduit 230. It is preferred that exhalation conduit 230 is connected to a pressure regulator 234.

In the preferred embodiment of the present invention, the flow of the exhalation gases is discharged into a chamber 204 containing a column of water 238, as seen in Figure 11. The gases circulating through the exhalation passage 230 they are discharged into the body of water 238 from a short conduit 236 that extends from the expiration conduit into the container 204. This results in a bubbling effect, whereby gases eventually exit container 204 through discharge port 252, which can also be used to fill chamber 204 with water. Discharge port 252 includes a shield to prevent it from the liquid aerosols created by the vigorous bubbling on the surface of the water are expelled. Note that the short conduit 236 could also be integrated into the end of the expiratory conduit 230. Note also that by adjusting the level of which the short conduit 236 is submerged, the average pressure of the gases delivered through the cannula 100 can be controlled.

Nasal cannula

Referring now to Figures 4 to 10, the nasal cannula 100 is seen in more detail. The intake manifold 110 is connected to an intake port 112. This intake port 112 accepts the flow of gas that comes from the humidifier and the air / oxygen mixer or from any other device that is a source of flow that is appropriate. . The diameter of the intake manifold 110 is as large as possible to ensure a minimum pressure drop in the gases prior to administration to the patient. In communication for fluid passage with the intake manifold are two nasal tips 116, 118. The gases are then able to flow from the intake manifold 110 upward through the nasal tips to the corresponding nostrils of the patient. The tips 116,118 themselves are cylindrical with a progressive taper at the top. The diameter is carefully chosen so that a substantial seal is effected against the interior of the nostril, without imparting any substantial pressure thereon. Along with a seal, they also provide some degree of grip and hold cannula 100 in position.

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An important feature of the present invention is shown in Figure 4. The two nostrils 116, 118 are separated by a distance optimized for the spacing between the nares of a neonatal infant. However, the present invention would be equally applicable for patients of all sizes, and the design is easily scalable. It will be appreciated that, while the nasal structure of each baby will be somewhat different, the septum will almost inevitably be lower than the fleshy parts on the side of the nose. As mentioned in the prior art discussion, this could result in irritation and pressure necrosis on the septum. To avoid this, there is a notch or slit 126 between the two nose tips 116, 118 as shown in Figure 4 and Figure 6. The slit 126 is designed such that there is no contact with the septum.

Reference is now made to Figure 5, which presents a sectional view of the cannula 100. The intake manifold 110 is separated from the discharge manifold 130 by a bulkhead 132 running horizontally between the intake 110 and the outlet 130. The bulkhead 132 ends near the base 134 of tips 116, 118. Thus, there will always be at least some flow flowing directly from the intake manifold to the discharge manifold 130 as shown by arrow 170. Since the diameter of the intake manifold 110 is as large as possible and the inlet / outlet of the intake and discharge manifolds 110, 130 are located on either side of the bulkhead 132, there is a path from the intake manifold 110 to discharge manifold 130 which is a low resistance path as shown by arrow 170. This ensures that dead space or periodic flow volume is limited to the volume of tips 116, 118. This configuration results in minimal accumulation of expired CO2 and also reduces any possibility for condensation in cannula 100.

Tips 116,118 are formed as part of a molded rubber or silicon insert 136 that seals from the hard plastic body 138 of the cannula 100 by means of a hard or compression fit, the hard plastic body 138 of the cannula cannula 100. Tips 116,118 can be used as a disposable component, or alternatively can be easily interchanged for a different sized nasal mask, mouthpiece, or other interface, as desired. The intake port 112 is formed as part of the body 138, with the inlet 110 at the base of the intake port 112. The intake port 112 could be adapted to fit any typical connection configuration for commercially available conduits. Similarly, discharge port 142 is in fluid communication with discharge manifold 130. An additional sensing port 144 may be provided to measure any parameters of the delivered gases, eg, pressure, temperature, or humidity. As shown in Figure 7, an inlet / outlet connector 154 can be connected to act as an interface between the nasal cannula 100 and the inhalation passage 21 and the exhalation passage 230. Connector 154 can be formed of extruded PVC or silicon or any other suitable material. Detection port 144 can also be connected to metering tube 156 that can be formed as part of connector 154.

Head restraint

As can be seen in Figures 10 to 12, the cannula 100 is attached to the head of a patient 19 by a head cover means 330. A preferred embodiment of head cover means 330 is a baby cap which preferably fits formed from a stretchable or elastic material that has thermal insulation properties. An example of a suitable material is a cotton or synthetic knitted fabric. The head cover means 330 is in the form of an open ended tube in the baby cap embodiment. When the material used for the cap provides more elongation along a major axis, then that major axis is preferably aligned transverse to the longitudinal axis of the tube.

As shown in Figure 12, in the cap embodiment, the head cover means 330 has an open end 332. A zone 331 adjacent this open end 332 is stiffer than the surrounding region. Zone 331 could comprise, for example, a modified knitted shape region, a sleeve formed from an alternative material or material configuration, or a multi-layer tube hem.

A band is provided on the outer surface of the cap shape of the head covering means 330 to support a breathing tube or other conduits or wires for medical use.

The fastening means are constituted by a band 333 that is sewn onto the cap. The band has a Velcro ™ adhesive attached to one end. As shown in Figure 10, a foam block 334 with a triangular outer shape fits over the connector 154. The foam block 334 is positioned over the band 333. The band 333 is then closed around the foam block, and fastens with Velcro ™. The foam block 334 is used to firmly retain the connector 154 in position in the cap shape of the head cover means 330 to prevent displacement of the nasal tips of the nostrils. Alternatively, as shown in Figure 13, if an inlet / outlet connector 154 is not used, hoses 321 can be attached directly to the head cover 330.

The second open end 347 of the cap of the head cover means 330 is preferably formed with a simple hem. The open end 347 may preferably be retained or closed in a closed position by a closure means 340. The closure means 340 could comprise an additional loop or ligature of similar configuration to the fastening means 333. The loop or ligature 340 has two arms 342, 344. These arms 342, 344 preferably link together or pass through a lever.

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In use, the end 347 of the cap of the head covering means 330 is brought together as an end bundle 341. The loop of the loop or ligature 340 is passed over the bundle 341. The bundle 341 is held firmly in a closed configuration within of the tight loop of the tie or ligature 340.

Thus, the closure means 340 provides easy operations for opening or closing the baby's cap, should the need arise to access the upper part of the baby's head. This access, for example, would be required for the placement of cranial electrodes or ultrasound elements. When access is needed, the closure means 340 could be released and the end beam portion 347 opened to provide the necessary access. This access is available without disturbing the other end 332 of the cap of the head cover means 330 nor the fastening means 333 that hold medical tubes or wires in place. It will be understood that any suitable head covering means may be used to hold the cannula 100.

Cannula clamping

Ideally, patient 19 should not breathe through his mouth. Both inhalation and exhalation should be done through the cannula. In the preferred embodiment, the patient's jaw 19 is kept closed to eliminate leakage from the mouth. These leaks or losses of air through the mouth are not convenient, because they cause a reduction in pressure, thus lowering the level of CPAP.

Referring now more particularly to Figures 8 to 10, it is seen that the base of the cannula 100 is secured to the head of the patient 19 using the band 150. In the preferred embodiment, the band 150 passes around the back of the neck of the patient. patient 19 and is attached to cannula 100 by means of a slide bar 152. Bar 152 is secured to body 138 by jaws or clamp 160 as shown in Figure 8. This arrangement allows rod 152 to effect substantial lateral and rotational relative movement with respect to cannula 100 as patient 19 twists their head, and exerts forces on band 160. Adequate restraining force is provided directly on cannula 100 without completely twist cannula 100. Rod 152 may be of a plastic material, for example acetal material, which engages jaw or clamp 160 on the underside of body 138. The tension in the band 150 can be adjusted to a level comfortable for the patient 19. Alternatively, the free ends of the band 150 could be attached to the head cover means 330, and not completely surround the neck of the patient 19. Description above is a nasal capsule refined for use with a CPAP respirator. The improvement reduces the possibility of irritation or pressure necrosis that would normally be associated with the use of one of these devices. The refinement ensures a balanced feed to the two ends, a small dead space, with a high flow through the collector, thus minimizing the rebreathing of expired CO2.