Endotracheal Tube With Liquid Fillable Cuff

Abstract

Endotracheal and tracheotomy tubes having liquid-fillable sealing cuffs formed of material permeable to air and substantially non-permeable to the liquid at sealing pressure. Preferably the cuff material is a hydrophobic cellular plastic, preferably of expanded polytetrafluoroethylene. The cuff may be inflated directly by a pre-packaged, pre-filled syringe or by a collapsible bag filled with the liquid.

Parent Case Text

This application is a continuation-in-part of my copending application Ser. No. 191,708, filed Oct. 22, 1971, now U.S. Pat. No. 3,766,927, issued Oct. 23, 1973, entitled "Hydraulic Cuff Tracheal Tube."

Description

This invention relates to endotracheal (including trachetomy) tubes of the low-pressure type in which liquid within the cuff produces a minimal cuff pressure against the tracheal tissue to provide a seal for control of breathing with anesthesia or respirator machines. The main object of the invention is to provide an endotracheal tube of this type which is improved with regard to ease of administration.

The invention features an endotracheal tube in which the cuff material is permeable to air but is non-permeable to the filling liquid at the desired sealing pressure. Preferably the cuff material is hydrophobic, preferably cellular plastic, preferably expanded polytetrafluoroethylene heat-sealed to the tube and preferably the endotracheal tube is packaged with a liquid-filled syringe in a ready-to-use assembly. Another embodiment features a pre-filled collapsible container as of flaccid material connected to fill the cuff as the container collapses and as air is expelled through the cuff wall. These and other objects and features will be understood from the description of the preferred embodiment taken in conjunction with the drawings wherein:

FIG. 1 is a diagrammatic cross-sectional view showing the inflation of the cuff of the endotracheal tube by means of a syringe;

FIG. 2 is a cross-sectional view taken at line 2--2 of FIG. 1;

FIG. 3 depicts a ready-to-use endotracheal tube assembly; and

FIG. 4 is a view similar to FIG. 1 of an endotracheal tube device combined with a collapsible filling container according to the invention.

Referring to FIG. 1, the endotracheal tube 10 has a connector 12 and the usual curved configuration terminating in a slanted distal end 14. Cuff 16 inflated by liquid through lumen 18 is disposed circumferentially about the tube proper to seal against the tracheal tissue 20. The cuff, in the form of a tube of diameter considerably greater than tube 10, is heat-sealed at its ends to tube 10. The lumen 18 extends to a proximal filling connector 22 provided for receiving a syringe 24 filled with the hydraulic fluid. The material defining the cuff 16 in this preferred embodiment is comprised of heat-sealable expanded polytetrafluoroethylene (DuPont's teflon) which is of thin, pliable sheet, expanded form, available under the trade designation Gore-tex from W. L. Gore and Associates Inc. of Newark, Del. This material has microscopic open cells, is highly permeable to air, and is nonpermeable to water or other hydraulic fluid up to a prespecified breakthrough pressure. In this preferred embodiment the breakthrough pressure is selected to be in excess of 20 cm H.sub.2 O head, dimension H in FIG. 1. The technique for administering the endotracheal tube comprises first inserting the endotracheal tube through the mouth into the patient's trachea according to the usual procedure and then connecting the syringe 24 filled with the hydraulic fluid to filling connector 22. Thereupon the plunger of the syringe is depressed in the direction of the arrow forcing liquid through the syringe and through the lumen 18 into the cuff 16.

Referring to FIG. 2, the liquid, e.g., water, 26 proceeding in the filling direction through lumen 18 applies pressure to the air in volume 17 of the cuff 16 and because of the air-permeability of the cuff material 16, this air is expelled to the trachea, see arrows A. As the liquid fills the cuff, as indicated in the dotted lines, this expulsion of air continues. When resistence is felt on the plunger, the cuff is filled with liquid, no air remaining. Upon detachment of the syringe 24 from the filling connector 22, the liquid is allowed to restore to ambient pressure with the release of a few drops of liquid from the filling point, thus establishing the pressure of the liquid within the cuff as the height H between the filling point 22 and the cuff 16. Thereupon the lumen is sealed with pinch clamp 23.

Thus it is seen that a liquid-filled cuff is provided which through the weight of the water establishes a desired low pressure in the manner previously taught by me (prior art) with the attendant advantages of ensuring adequate blood circulation in the contacted tissue and avoiding tissue damage. According to the present invention, because of the self-purging of air, the cuff is readily fillable with no special procedures required as might detract from the acceptability of the liquid-filled system. Air pockets are avoided in the hydraulic cuff and at the same time special procedures such as evacuating the lumen prior to filling are avoided.

In an alternative embodiment the breakthrough pressure of the cuff material may be predetermined at such a level as to provide a safety relief--that is, should the cuff be inflated with the syringe above its predetermined breakthrough pressure, it will automatically relieve itself down to the breakthrough pressure. Thus by predetermining the breakthrough pressure below the probable damage pressure for tracheal tissue, i.e., below 30 cm H.sub.2 O, a safety feature can be provided against excessive inflation pressure even if the preferred gravity head technique just outlined is not followed. The particular breakthrough pressure must be specified in relation to the ambient chemical constituents. Thus the presence of conventional pre-applied lubricant to the cuff with a water filling will cause water-breakthrough the cuff at a lower pressure than will a system without the lubricant.

In another embodiment the liquid may be supplied to the cuff through the filling device as shownn in my copending patent application Ser. No. 191,708, incorporated by reference herein.

Referring to FIG. 4, the filling lumen is flexible and has its proximal end connected to a collapsible, non-pressure applying filling container 24a. The container, lumen, and cuff comprise a closed liquid system, the lumen and container extending a predetermined distance from the cuff enabling the container to be vertically spaced a distance equal substantially to the predetermined gravity head pressure to be exerted on the tracheal wall by the cuff when there is no air pressure differential across the trachea. (It will be understood that when the respirator applies pressure to the patient, that pressure will be transmitted to liquid in the cuff and transmitted thereby against the tracheal tissue, this occurring periodically with the periodic operation of the respirator.)

For filling, when the container is raised above the cuff, the system is capable of permitting free flow of liquid from the container into the cuff under influence substantially only of the gravity head with attendant non-pressure applying partial collapse of the container. The air-permeable cuff material may exhaust any resident air as the liquid flows downwardly to insure that the cuff is fully filled with liquid.

In another embodiment, according to the invention, the hydraulic fluid which fills the cuff incorporates liquid surface effective anesthetic. Normally the fluid pressure in the cuff is below break-through pressure. Periodically, however, perhaps every 2 or 4 hours, the system is designed to permit the attendant to temporarily over-pressure the cuff above break-through pressure, thus causing some of the liquid and anesthetic to pass through the cuff wall, anesthetizing the tissue and enabling the patient to more easily tolerate the presence of the tube. In the case of the embodiment of FIG. 1 this is accomplished by temporarily releasing pinch clamp 23 and applying the syringe. In the case of the embodiment of FIG. 4 this is accomplished by similarly releasing clamp 23 and squeezing the still partially filled bag or container.

For use in the foregoing embodiments a specific example of cuff material is Gore-tex of 0.4 density (expanded, comprising in volume 40 percent polytetrafluorethylene and 60 percent air) in sheet form of 0.004 inch thickness backed with a thin perforated polyethylene film, and having by itself a break-through pressure of 10-12 p.s.i. The effective break-through pressure is lowered by the presence of usual amounts of endotracheal tube lubricant containing polyethylene and propylene glycols to a level of about 1.0 p.s.i.

Other air-permeable materials may be used including films made air-permeable by nuclear bombardment, and other variations will be understood to be within the spirit and scope of the following claims.

Claims

What is claimed is:

1. A tracheal tube device comprising a tube sized for introduction of air through the trachea into the lungs of a living being, a cuff member surrounding and secured to said tube and adapted to be filled with liquid to cause extension of said cuff into sealing contact with tracheal tissue about said cuff to create a seal between said tube and the trachea and a filling lumen extending proximally from said cuff for communication with a source of filling liquid, the improvement wherein said cuff comprises a material which in the presence of said liquid is permeable to air and substantially nonpermeable to said liquid at the normal pressure said liquid exerts upon the interior of said cuff while creating said seal.

2. the tracheal device of claim 1 wherein said cuff material is a hydrophobic cellular plastic.

3. The tracheal device of claim 2 wherein said cuff material comprises expanded polytetrafluoroethylene having an open cell construction.

4. The tracheal tube device of claim 2 wherein said plastic cuff-forming material is heat-sealed to said tube at the proximal and distal regions of said cuff.

5. A ready-to-use tracheal assembly comprising a tracheal tube in accordance with claim 1 in combination with a syringe filled with water, joined together in a common package.

6. The tracheal device of claim 1 wherein said cuff material has a predetermined breakthrough pressure to said liquid (i.e., the pressure above which said liquid can substantially pass through the material of said cuff) less than the probable tissue-damaging pressure.

7. The tracheal tube device according to claim 1 in combination with a filling means which includes a collapsible, non-pressure applying filling container connected to the proximal end of said filling lumen, to communicate therethrough with said cuff, said container, lumen and cuff comprising a closed liquid system, said lumen and container extending a predetermined distance from said cuff enabling the container to be vertically spaced a distance equal substantially to the predetermined gravity head pressure to be exerted on the tracheal wall by said cuff when there is no air pressure differential across the trachea, said system, when said container is raised above said cuff capable of permitting free flow of liquid from said container into said cuff under influence substantially only of the gravity head, with attendant non-pressure applying partial collapse of said container.

8. The assembly of claim 7 wherein said collapsible container comprises a collapsible bag formed of flaccid material.

9. The assembly of claim 8 wherein said bag is defined by flexible plastic sheet.

10. The assembly of claim 7 wherein said container extends less than 25 cm from said cuff and said closed liquid system is adapted to contain water.

11. The device of claim 1 wherein said liquid includes surface-effective anesthetic, the normal operating pressure within said cuff being below the effective break-through pressure at which said anesthetic can pass through said material (i.e., the pressure above which said liquid including said anesthetic can substantially pass through the material of said cuff), and the material of the cuff selected so that elevating the pressure within said cuff above said break-through pressure is effective to apply said anesthetic to said tracheal tissue.