WO1997045153A1

WO1997045153A1 - Laryngeal cap

Info

Publication number: WO1997045153A1
Application number: PCT/CA1997/000365
Authority: WO
Inventors: Arnold Zidulka; Robert E. Mitchell
Original assignee: Mcgill University
Priority date: 1996-05-28
Filing date: 1997-05-27
Publication date: 1997-12-04
Also published as: AU2883297A

Abstract

A laryngeal cap (20, 120, 220) including an elongated tube having a diameter greater than an endotracheal tube (22) and adapted to pass thereover. The cap (20, 120, 220) has a distal end merging with an enlarged bell shaped skirt (26, 126, 226) adapted to cover the tracheal inlet and the epiglottis (14) in a patient's throat, thereby reducing aspiration of material within the trachea.

Description

LARYNGEAL CAP

Technical Field

The present invention relates to artificial airway devices to facilitate lung ventilation and more particularly to a laryngeal cap to be used in conjunc¬ tion with an endotracheal tube in order to seal the laryngeal inlet against aspirated material entering the trachea.

Background Art For intubated and mechanically ventilated patients the risk of nosocomial pneumonia has been estimated to increase 7 to 21 fold over the general hospital population and ranges from 9 to 67%.

The risk after endotracheal intubation was highest when the tube had been in place for 4 to 8 days. A Langer, T; Mosconi, P.; Cigada, M; Mandelli, M. ; Intensive Care Unit Group of Infection Control; Long-term respiratory support and the risk of pneumonia in critically ill patients. Am Rev Respir Dis 1987; 140:305-5) involving 23 Italian intubated patients the incidence of pneumonia rose from 5% in patients receiv¬ ing one day of respiratory assistance to 69% in patients mechanically ventilated for more than 30 days. The potential causes of nosocomial pneumonia in mechanically ventilated patients are numerous. In an article by Cross, AS; Roup, B.; Role of respiratory assistance devices in endemic nosocomial pneumonia. Am J Med 1981; 70:681-5, some causes are summarized, including a breakdown in the sterilization technique of the tubing and ventilator apparatus; introduction of infection from the outside by disconnection of the ven- tilatory circuit; aspiration of naso-oro-pharyngeal or gastric contents; reduction of host defenses (e.g. immunocompromised patients), septicemia, bacterial translocation from breakdown in the gastrointestinal barrier, and the development of organisms resistant to antibiotics. The relative importance of these potential causes has been difficult to estimate.

When an endotracheal tube passes through the larynx into the trachea, above the inflatable cuff of existing devices, there is a space around the tube within the trachea which could fill up with aspirated material. The presence of an endotracheal tube does not allow the normal swallowing mechanism to occur and the anterior epiglottis is blocked by the tube from bending backward and downward to occlude the laryngeal inlet.

As a result, material from the naso-oro-pharynx and from gastric reflux can easily enter the glottis and remain above the blown up cuff of the endotracheal tube. It has been demonstrated that this aspirated material can easily leak distally around the blown up cuff. This is presumably a result of traction on the cuff with respiration as well as by the patient's head movement. In addition there may be the occasional deflation and reinflation of the cuff which would cause the material above the cuff to descend into the lower airways.

Evidence that aspiration of material around the cuff of the endotracheal tube is indeed a potent cause of nosocomial pneumonia is well documented.

Patients with chronic obstructive pulmonary disease in exacerbation and requiring ICU (Intensive Care Unit) care were selected at random to receive either conventional medical treatment or non invasive nasal ventilation in addition to conventional medical treatment (Brochard L. Presentation to the American Thoracic Society Meetings, Boston, May 1994)). In those receiving the non invasive ventilation, the frequency of endotracheal intubation was 26% whereas with con- ventional treatment only it was 74%. The mortality rate between the two groups was 9% and 28% respectively. Although not conclusive, this would tend to support the proposition there is a danger, during intubation and mechanical ventilation, of the leakage of aspirated material around the cuff.

Currently no good method exists for clearing out these secretions within the trachea and glottis above the cuff. It would therefore seem prudent to attempt to prevent the secretions from arriving there in the first place. I am therefore proposing, soon after endotracheal intubation has occurred, to slide a bell shaped cap over the endotracheal tube to cover the epiglottis and glottis. This would prevent aspirated material from entering the glottis and trachea around the endotracheal tube.

It is possible to transiently seal the laryn- geal inlet demonstrated by the development of the laryngeal mask. Such masks are known from Canadian Patent 1,324,551 Brain 1993; U.S. Patent 4,995,388 Brain 1991; and U.S. Patent 5,249,571 Brain 1993. This mask is at the end of a tube similar to an endotracheal tube and covers the upper edge of the glottic inlet. This mask is placed in a blind fashion and is used for light anesthesia when endotracheal intubation is not desired. It can slide over an endotracheal tube but was not designed for this purpose.

Disclosure of the Invention

It is an aim of the present invention to pro¬ vide a laryngeal mask wherein the so formed cap extends anterior the epiglottis and glottis in order to ensure an adequate seal of the anterior glottic inlet. It is a further aim of the present invention that the bell shaped cap drapes around the sides of the glottis and epiglottis so that secretions and gastric substances would not be able to enter the glottic inlet. A construction in accordance with the present invention comprises a laryngeal cap for use with an endotracheal tube, the laryngeal cap including an enlarged bell shaped skirt having a first opening defined by a collar having a diameter sufficient to fit over the endotracheal tube, the skirt extending away from the collar and defining a second opening delimited by a hem having a diameter greater than the diameter of the first opening and a circumference greater than the typical glottic inlet and the epiglottis whereby the skirt completely covers the tracheal inlet and the epiglottis in a patient's throat when the laryngeal cap is positioned to pass over the endotracheal tube within the patient's throat, thereby reducing aspiration of material into the trachea.

Brief Description Of The Drawings Having thus generally described the nature of the invention, reference will now be made to the accom¬ panying drawings, showing by way of illustration, pre¬ ferred embodiments thereof, and in which:

Fig. 1 is a side elevation showing the laryn- geal cap of the present invention;

Fig 2 is a front elevation also referred to as a coronal view showing the laryngeal cap of the pre¬ sent invention in comparison with the prior art;

Fig. 3 is a cross-sectional view showing the laryngeal cap of the present invention;

Fig. 4 is a perspective view of another embodiment of the present invention; and

Fig. 5 is a perspective view of another embodiment of the present invention. Mode For Carrying Out The Invention

In the present invention, as shown in

Figs. 1, 2 and 3, the laryngeal cap 20 can be used over a conventional endotracheal tube 22. The laryngeal cap 20 has a tube portion 24 and en enlarged bell shaped skirt 26. The skirt 26 is flared and cut at an oblique angle with the leading edge 28 and a shorter trailing edge 30.

The cap 20 can be made of an elastic material such as latex or silicon. It may also have annular ribs 32 in order to provide sufficient rigidity to the skirt portion 26 to prevent the cap 20 from deforming when it is being inserted in the mouth. The wall thick¬ ness and different materials can also be used to pro¬ vide sufficient compliance of the skirt 26 to drape around and over the glottic inlet and the epiglot¬ tis 14. The caudad edges will be smooth and rounded so as to minimize trauma to the tissues. There is consid¬ erable advantage to making the bell shaped skirt 26 large enough to overlie the epiglottis 14. Thus, rather than being tightly sealed around the tracheal inlet, it can also drape over the inlet to cover the endotracheal tube 22.

The laryngeal cap 20 will be especially use¬ ful for patients who are intubated for more than 24 hours. The typical patient would be one with acute lung injury. Other patients needing a prolonged intubation might be those with drug overdose, pneumonia, heart failure, and neuromuscular disease with respiratory muscle weakness. The bell shaped skirt 26 as shown in Fig. 1 may be seen as a hoop skirt with thicker annular ribs 32 connected by thin membranes which will maintain the integrity of the skirt but allow it to collapse like an accordion. Other embodiments have also been contemplated with respect of the laryngeal cap. For instance as shown in Fig. 4 the Laryngeal cap 120 is in the form of a cone having an open top and open bottom. The skirt 126 of the cone is flared and the hem is cut at an oblique angle with a leading edge 128 and a shorter trailing edge 130. The skirt 126 is split at 127. A push rod 129 may be provided at the top of the cap 120. In operation, the cap 120 would be inserted over the endotracheal tube in the patient's mouth and could be pushed down along the endotracheal tube by means of the push rod 129. It is also contemplated to have fasteners such as an adhesive tape 131 to close the skirt 126 over the endotracheal tube once it has been placed on the tube.

Another embodiment has been contemplated which includes a skirt 226 formed as a membrane with inflatable tubular ribs 236 extending from the top to the bottom in the same manner as an umbrella. Annular inflatable tubular ribs 238 could also intersect with the longitudinal ribs 236 and be in communication therewith. The tubular ribs can be inflated by an exte- rior air source so as to fully deploy the bell shaped cap 210 when it is inserted into the patent's mouth and then the cap 210 may be deflated once in position so that the skirt will collapse on the epiglottis and the at least the tracheal inlet to prevent aspiration of material into the trachea.

Claims

CLAIMS :

1. A laryngeal cap for use with an endotracheal tube, the laryngeal cap including an enlarged bell shaped skirt having a first opening defined by a collar having a diameter sufficient to fit over the endotra¬ cheal tube, the skirt extending away from the collar and defining a second opening delimited by a hem having a diameter greater than the diameter of the first open¬ ing and a circumference greater than the typical glot- tic inlet and the epiglottis whereby the skirt com¬ pletely covers the tracheal inlet and the epiglottis in a patient's throat when the laryngeal cap is positioned to pass over the endotracheal tube within the patient's throat, thereby reducing aspiration of material into the trachea.

2. A laryngeal cap as defined in claim 1 wherein the collar is integral with an elongated tube having a diameter greater than the endotracheal tube whereby the tube and skirt of the cap pass over the endotracheal tube to be placed so that the skirt overlaps the tra¬ cheal inlet and the epiglottis.

3. A laryngeal cap as defined in claims 1 and 2 wherein the skirt is flared and the hem is cut at an oblique angle with the hem having a leading edge and a shorter trailing edge with the trailing edge adapted to fit behind the epiglottis.

4. A laryngeal cap as defined in claim 1, 2 or 3 wherein the skirt is made of an elastic material with annular ribs provided for sufficient rigidity to the skirt portion.

5. A laryngeal cap as defined in any of claim 1 wherein the bell shaped cap includes a collar and a push rod connected to the collar for moving the cap into the throat of the patient passing over the endotracheal tube.,

6. A laryngeal cap as defined in claim 5 wherein the skirt of the cap is slit longitudinally from the collar to the hem so as to open the cap and pass it over the endotracheal tube and fastening means are pro¬ vided for closing the skirt over the tube.

7. A laryngeal cap as defined in claims 1 to 6 wherein the skirt is made of a thin flexible material and is provided with longitudinal inflatable ribs whereby the skirt is expanded when air is supplied under pressure into the inflatable ribs and the skirt can collapse when the air is released from the ribs.

8. A laryngeal cap as defined in claim 7 wherein there are both longitudinal inflatable ribs and annular inflatable ribs.