US 3731692 A
An inflatable cuff for use in combination with a ventilation tube inserted into the trachea of a patient, a major portion of the outer surface of the inflated cuff sealingly engages the trachea gently enough to avoid distortion of, or trauma to the sensitive trachea wall. The cuff is of flexible material having thickness between 0.005 and 0.01 inch and, when inflated outside the trachea, the cuff takes the shape of a right cylinder having essentially flat end walls with curved transition portions between the end walls and the straight cylindrical walls.
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United States Patent 1 Goodyear 1 May 8, 1973  TRACHEOTOMY OR ENDOTRACHEAL TUBE CUFF  Inventor: Chalmers M. Goodyear, Coopersburg, Pa.
 Assignee: The Foregger Smithtown, NY.
 Filed: Mar. 19, 1971  App1.No.: 126,207
 US. Cl. ..l28/351, 128/349 B  Int. Cl. ..A6lm 25/00  Field of Search ..l28/351, 348, 349 B,
 References Cited UNITED STATES PATIENTS 3,659,612 5/1972 Shiley eta] ..l28/35l 3,565,079 2/1971 Jackson 3,504,676 4/1970 Lomholt.. 2,792,837 5/1957 Kardos ..l28/35l OTHER PUBLICATIONS Cooper et al., Surgery, Gyne, Obstet. Dec. 1969, V01. 129, pp. 1235-1241 J.A.M.A. Feb. 2, 1970, Vol. 211, No.5, p. 759
Primary ExaminerDalton L. Truluck Attorney-Ronald B. Sherer, James C. Simmons and B. Max Klevit  ABSTRACT An inflatable cuff for use in combination with a ventilation tube inserted into the trachea of a patient, a major portion of the outer surface of the inflated cuff sealingly engages the trachea gently enough to avoid distortion of, or trauma to the sensitive trachea wall. The cuff is of flexible material having thickness between 0.005 and 0.01 inch and, when inflated outside the trachea, the cuff takes the shape of a right cylinder having essentially flat end walls with curved transition portions between the end walls and the straight cylindrical walls.
8 Claims, 6 Drawing Figures PATENTEUHAY 8l975 SHEET 1 OF 2 IN VENT (11-h Cfio/mens M Gooojear BY Z / ATTORNEX PATENTEDNAY' 81975 7 3,781,692
SHEET 2 OF 2 PRIOR ART ATTORNEY TRACHEOTOMY OR ENDOTRACHEAL TUBE CUFF BACKGROUND OF THE INVENTION The invention related to endotracheal and tracheotomy tube cuffs, and more particularly to a novel cuff which, when inflated, gently yet sealingly conforms to the trachea without inflicting trauma.
Modern endotracheal and tracheotomy tubes inserted into the trachea of a patient whose breathing is to be assisted are conventionally provided with an in flatable cuff for closing off the tracheal passage around the tube to avoid leakage of air from lungs around the ventilation tube. Such cuffed tubes are in wide use. Recently, however, some serious disadvantages and dangers resulting from the use of conventional cuffs have been discovered and investigated.
Numerous cases have occurred where patients who have undergone respiratory assistance and treatment for respiratory failure with the use of conventional cuffed ventilating tubes have subsequently suffered various serious lesions of the trachea including tracheal stenosis, tracheomalacia and localized tracheal erosion. There have even been cases of rupture of the trachea. The fact that lesions have occurred in the area engaged by the cuff leads to the conclusion that pressure of the cuff against the trachea wall has been responsible for the damage by inflicting localized trauma on the tracheal wall. The pressure used to inflate conventional tube cuffs is of the order of 200 to 300 mm of mercury. The high pressure is required just to inflate these cuffs to their expanded contour which in longitudinal cross-section is an elipse. The trachea deforms quite easily, so it is understood such inflation of the cuff will distend the tracheal wall.
In many cases cuffed tubes are kept in place in the trachea for extended periods, sometimes as long as several months. But lesions have occurred even when a cuffed tube had been used for only several days. lnjury has occurred even though great care has been taken to avoid over-inflation of the cuff and the cuff has been periodically deflated.
The damage has been very serious in many cases, and sometimes fatal. Within a period ranging from several weeks to some months after respiratory assistance through intubation has ceased, the lesions have interfered with breathing by obstructing the tracheal passage. Resection of the trachea has been successfully performed in cases of severe obstruction, but many cases have probably been undiscovered until after death or never discovered, since death might have been attributed to heart failure or other causes rather than to the real cause. This problem of tracheal injury is summarized in an article appearing in Annals of Surgery, Vol. 169, No. 3, Mar. 1969 entitled The Evolution of Tracheal lnjury Due to Ventilatory Assistance Through Cuffed Tubesz" A Pathologic Study by Doctors Joel D. Cooper and Hermes C. Grillo.
The fact that cuffed endotracheal and tracheotomy tubes are in such general use makes this problem a very serious one. Although attempts have been made to solve the problem of localized injury to the trachea caused by the use of cuffed tubes, no satisfactory solution has been found in the prior art.
US. Pat. No. 3,481,339 discloses a double-chambered cuff intended to solve the problem of pressureinduced trauma on the tracheal wall by periodically exerting higher and lower pressures. This double-chambered cuff did not provide sufficient improvement over the prior art to gain acceptance.
An approach to solving tracheal damage is described by Doctors Joel D. Cooper and Hermes C. Grillo in an article in Surgery, Gynecology & Obstetrics, Vol. 129, pp. 1235-1241, Dec. 1969, entitled Experimental Production and Prevention of Injury Due to Cuffed Tracheal Tubes. In this article the authors show and describe a low pressure cuff of very thin latex material. This cuff is operated at low pressures; however, because the walls of the cuff were extremely thin, it was possible to have the cuff wall hemiate below the endotracheal tube when inserted into the patients trachea and then when inflated, block the lower end of the endotracheal tube.
SUMMARY OF THE INVENTION In order to avoid the problems inherent in prior art cuffs for endotracheal or tracheotomy tubes it has been found that the wall of the cufi in contact with the surface of the trachea should be of a flexible material having a thickness of between 0.005 and 0.01 inches, and when inflated outside of the trachea, should be in the shape of a right cylinder having substantially flat parallel top and bottom walls with a curved-transition surface between the end walls and the straight, axial wall of the cylinder. In longitudinal cross-section the cylinder would appear as a rectangle with pronounced rounded comers.
Observing the above teachings will result in a cuff that creates the desired sealing engagement with the trachea of a patient' at inflation pressures of between 10 and mm of mercury, as opposed to the prior art cuffs requiring 200 to 300 mm of mercury to expand them into sealing engagement. At these pressures the cuff will form a surface of contact with the trachea for an area of the tracheal wall substantially equal to the length of the cuff. Unlike the conventional cuff, which inflates to a normal contour substantially in the shape of a football under high pressure, the cuff of the invention inflates under low pressure to the substantially rounded end cylinder. The pressures used in inflating the cuff of the present invention need be only slightly greater than that normally present upon the trachea wall during assisted respiration; and, therefore, the trachea is not distended. Thus, the pressure inflates the cuff, but does not expand it beyond its normal shape.
Cuffs may be provided according to the invention either in the form of a single-walled, unitary inflatable sleeve for sealed attachment directly to the ventilating tube at both of sleeve ends or in a double-walled form, with an inner, cylindrical wall secured to the tube and an outer flexible and inflatable wall. In either embodiment, the outer cuff wall is of flexible, material having a thickness in the range of from about 0.005 to 0.01 inch. While the material may be elastomeric such as latex, it need not be, since the cuff is only inflated, not expanded.
The cuff is inflated after the cuffed tube has been inserted into the trachea by means of a smaller tube, or inflation hose, leading from the cuff to a source of air under the proper low pressure. A pilot balloon is provided in communication with the smaller hose to show that the cuff is inflated.
Clinical tests have shown that when cuffs according to the invention have been used, satisfactory ventilation can be accomplished with minimal trauma to the trachea.
It is accordingly the primary object of the invention to provide an improved cuff for use in combination with an endotracheal or tracheotomy tube to avoid injury to the trachea.
A further object is to provide an inflatable cuff which will inflate under low inflation pressure to sealingly conform to the trachea wall without distending the trachea.
It is another object of the invention to provide in combination with a ventilating tube for a patient a cuff of thin flexible material, whereby, the cuff will gently engage substantially all of the trachea wall for a length substantially equal to the length of the cuff under a constant low pressure only slightly above that in the trachea.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an overall view in perspective of an-endotracheal tube provided with a cuff according to the invention.
FIG. 2 is a view in longitudinal cross-section of the cuff of FIG. 1, with the cuffinflated.
FIG. 3 is a view in cross-section of the cuff in place on a tube with the cuff in its deflated state.
FIG. 4a is a cross-sectional schematic diagram of the tracheal portion of the human anatomy.
FIG. 4b is the trachea of FIG. 4a with an inflated prior art cuffin place.
FIG. 4c is the trachea of FIG. 4a with an inflated cuff of FIG. 1 in place.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, in which like parts are indicated by like reference characters throughout, a cuff generally designated and constructed according to the invention is shown secured in place on a conventional endotracheal tube generally designated 1 1.
FIG. 1 shows the cuff 10 in its inflated state. A flexible inflation hose 12 of much smaller diameter than the tube 11 from a source of air under pressure (not shown) leads to the cuff 10, for supplying air to inflate the cuff after the tube has been placed in position in the trachea.
The inflation hose 12 is equipped with a pilot balloon l3, and terminates in a widened end portion at 14 for connection to a suitable nipple or the like at the source of air under pressure. The inflation hose 12 is shown with sections cut away, and it will be understood that the hose 12 is ofa suitable length to accommodate tube 11 in its operative position.
The tube 11 and the hose 12 may be of suitable plastic material of one of the types known in the art, and may be transparent or opaquev These elements possess sufficient rigidity to retain their general cylindrical shape though they are flexible enough to be bent as needed for use, as shown by the way the hose I2 bends as it diverges from the tube II at point 15.
Referring to FIG. 2, the tube II will be seen to have a generally cylindrical passage 16 for the delivery of air, oxygen, or other ventilating gases to the patient, and inflation hose 12 has a generally cylindrical passage 17 for admitting air or othergases to the cuff 10. The passages 16 and 17 must, of course, remain unobstructed and substantially undiminished in cross-sectional area throughout their length to assure uninterrupted flow therethrough.
The cuff 10, as shown in FIGS. 1 and 2, has an elongated axially extending wall portion 20 which is cylindrical in shape when the cuff is inflated outside the trachea. The cylindrical wall portion terminates in flat, parallel end walls 19, 21 with rounded corners 26, 28. This outer contour of the cuff 10 is formed by the cuff wall 20, which has a thickness in the range of from 0.005 to 0.01 inches. For best results clinical tests have shown that the thickness of the wall 20 should be between 0.006 and 0.009 inches. The cuff wall may be formed of latex rubber or of some other soft flexible material such as a plastisol. Because of its thinness the cuff wall 20 will inflate to conform to the trachea under a very low pressure in the range of from 10-90 mm of mercury. The normal operating pressure is from 40-50 mm Hg. However, the material will withstand greater pressure without rupture if accidentally subjected to such greater pressure, or if in some very special case higher inflation pressure is deemed desirable. The normal range of pressures (4050 mm Hg) applied to inflate, the cuff I0 is substantially equivalent to that normally present on the trachea wall, so no damage to the trachea or distortion of the trachea will result from the pressure of the cuff 10 against the trachea wall.
The thickness of the cuff wall 20 is critical. The wall 21 can be neither too thin nor too thick if the desired results are to be obtained. If the cuff wall 20 were thicker than 0.01 inches the pressure required to inflate the cuff would exceed that which is safe if damage to the trachea is to be avoided as has been the case with prior art high pressure cuffs. On the other hand, a cuff having an outer wall 20 thinner than 0.005 inches would be flimsy and subject to rupture; also, since a cuff is normally positioned quite near the open end of a tracheotomy or endotracheal tube through which gases are delivered to a patient, a cuff which was too thin (under 0.005 inches) would be likely to be pushed downwardly over the open delivery end of the ventilating tube and interfere with the passage of gases to the patient.
As best shown in FIG. 2 the outer wall 20 terminates in reduced diameter collar portions 22 and 23 at opposite ends of the middle, inflatable portion 20. These collar portions 22 and 23 generally conform to the size of the ventilating tube 11.
In the embodiment of the cuff 10 shown in FIGS. 1 and 2 there is shown a cylindrical inner endotracheal tube and adaptor sleeve 24, which may be, and preferably is, thicker than the cuff wall 20. The wall 20 is sealingly secured to the adaptor 24 at the end portions 22 and 23 to prevent leakage of air. The cylindrical adaptor sleeve 24$ may suitably be of rubber or a plastic material, and is of such a diameter to fit snugly around the outside of the tube 11, to which it may be secured, as by adhesive, if desired.
The cuff 10 may alternatively be formed as a unitary member, having only the outer wall 20, the collars 22 and 23 of which are sealing secured to a tube 1 1. In this alternate embodiment the cuff would also have a cylindrical wall 20 and flat end walls 19, 21 as illustrated.
The inflation hose 12 enters the cuff at the position 25 at the upstream end portion 22 of cuff wall 20. Here the cuff wall is formed into an outwardly extended portion for admitting the hose 12. The cuff wall 20 and adaptor sleeve 24 are sealed to the hose 12 at the position 25 to prevent air leakage. Where the cuff 10 has only a single wall 20, the wall 20 is similarly formed at its end 22 to admit the hose 12 between the wall 20 and the outer surface of the tube 11 and the place of entry is similarly suitably sealed against air leakage, with the hose 12 lying directly against the tube 1 1.
As shown in FIG. 2 the end 27 of the inflation hose 12 is preferably mitered so that no sharp outer edge is presented at the hose end 27. This also provides a larger opening for entry of air into the interior of the cuff 10.
The collapsed state of the cuff 10 is shown in FIG. 3 wherein it will be noted that the cuff has folds and convolutions. Thus, the deflated cuff is easily insertable into the trachea with the tube 11. Even if the cuff 10 is located near the open delivery end of the tube 11 it is thick enough so that it will not be subject to stretching dangerously downward to cover the end of the tube 10 in which position it could interfere with the supply of gases to the patient.
In clinical use the folded, convoluted cuff is inserted and inflated to normal shape of FIGS. 1 and 2, but not expanded. Flat end walls 19, 21 do not block tube 11, and the full axial length of cylindrical wall 20 gently engages trachea.
The pilot balloon 13, as shown in FIGS. 1 and 2, must be responsive to the low inflation pressure used to inflate the cuff 10 since its purpose is to indicate that the cuff 10 is properly inflated when the cuff is out of sight within the trachea. The pilot balloon 13 is preferably diamond shaped in longitudinal cross-section but may be of some other suitable shape as desired. At its ends the pilot balloon 13 tapers down to cylindrical sleeve portions 30 and 31 which are of suitable diameter to snugly engage the inflation tube 12, to which the end portions 30 and 31 are preferably adhesively secured.
As shown in FIG. 4c the cuff of the present invention inflates to sealingly engage the tracheal wall without changing the shape of the tracheal wall. This sealing engagement is assured by having the inflatable wall 20 of cuff 10 constructed so as to form the cylindrical shape I of FIG. 1 when inflated outside the trachea. As shown in FIG. 4b prior art cuffs were expanded to distort the trachea and thereby form the required air seal.
The inflation hose 12 may pass through the pilot balloon l3 and if constructed this way is formed with one or more small apertures 32 through its wall. Preferably a pair of such apertures 32 allow communication between the internal passage 17 of the hose 12 and the interior of the pilot balloon 13 whereby the pressure existing within the hose 12 (and hence within the cuff 10) is also experienced by the pilot balloon, which inflates in response to the pressure to indicate that the cuff 10 is in its inflated condition.
It may be preferred that the delivery tube 12 not pass through the pilot balloon 13. In that case the portion of tube 12 between sleeves 30 and 31 is eliminated.
Various modifications and substitutions within the sco e of the invention will sug est themselves to those skil ed in the art, and the inven 1on is not limited to the preferred embodiment illustrated and described. For example, a cuff according to the invention could be formed with a fluted outer wall, or with a shape otherwise differing from that illustrated without departing from the spirit and scope of the invention. Also a portion of the inflation hose 12 might be replaced by a passage formed within the wall of the tube 1 itself.
Although illustrated in combination with a tracheotomy tube, the combination of the cuff and manner of use of the cuff of the invention with an endotracheal tube will be obvious to those skilled in the art.
1. In a ventilating tube for insertion into the trachea of a patient said tube having an inflatable cuff for sealingly engaging the trachea when inflated the im provement which comprises:
said cuff being of a flexible imperforate material the major portions of which have a wall thickness of between 0.005 and 0.01 inches;
said cuff including means for inflating said cuff to a constant pressure of between 10 and millimeters of mercury thereby engaging said trachea without distorting the trachea;
said inflated cuff having a longitudinal cross-section in the shape of a rectangle with pronounced rounded comers; whereby said cuff engages the trachea along a substantial portion of its outer surface.
2. A cuffed ventilating tube according to claim 1 wherein the cuff is separable from the ventilating tube.
3. A cuffed ventilating tube according to claim 1 wherein the cuff is an elastomeric material.
4. A cuffed ventilating tube according to claim 1 wherein said cuff achieves optimum shape and sealing characteristics at pressure of between 30 and 50 mm of mercury.
5. An inflatable tracheotomy cuff for use in combination with a ventilating tube for insertion into the trachea of a patient comprising an elongated imper forate generally cylindrical ventilating tube adaptor of flexible material, overlying said adaptor and having a thickness of between 0.005 and 0.01 inches, a flexible cuff wall means securing and sealing the ends of said cuff wall to said adaptor, means for inflating said cuff, said outer cuff wall being adapted upon inflation thereof to a constant pressure of about 10 to 90 mm of mercury to assume the shape of a cylinder with top and bottom ends generally perpendicular to the longitudinal axis of said cylinder with an arcuate transition zone between the walls and the ends of said cylinder whereby said cuff sealingly conforms to the trachea along a substantial length of the trachea without distorting the trachea.
6. An inflatable tracheotomy cuff as in claim 5, said cuff wall being formed of expandable material.
7. The inflatable cuff of claim 5, wherein the material of said cuff wall and said adaptor is an elastomeric material.
8. The inflatable cuff of claim 5 wherein the means for inflating the cuff comprises a tube with an indicating device to show when the cuff is inflated.
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