US 3815606 A
An endotracheal catheter especially useful for the application of mechanical respiration or the administration of anesthetic gases to newborn infants. A pliable hollow outer tube is formed with a main body portion of constant diameter having a reduced diameter relatively short end section at one end. When inserted into the trachea, the shoulder at juncture of the main body and end section of the outer tube is seated at the upper end of the trachea. A second tube, of a diameter approximately equal to that of the reduced diameter end section of the first tube is passed through the side wall of the main body of the first tube at a location spaced longitudinally of the first tube from the shoulder. The second tube exends through the main body portion of the first tube and terminates at an open end located within the main body closely adjacent the shoulder so that a space of only relatively small volume exists within the first tube between the open ends of the two tubes. One-way check valves employing a light easily actuated valve member may be mounted at the opposite ends of the respective tubes.
Description (OCR text may contain errors)
United States Patent [191 Mazal ENDOTRACHEAL CATHETER  Inventor: Charles N. Mazal, Roma 19, Mexico 6, DR, Mexico  Filed: Sept. 21, 1972  Appl. No.: 290,964
3,175,557 3/1965 Hammond. 128/351 3,730,179 5/1973 Williams 128/145 5 FOREIGN PATENTS OR APPLICATIONS 1,113,065 8/1961 Germany 128/147 OTHER PUBLICATIONS Beattie et al., Resuscitation of the Asphyxiated Newborn Infant, in Jour. Amer. Med. Assoc. 152: 21 221. 1953.
Mann, Method and Machine for Resuscitation of the Newborn, in Jour. Amer. Med. Assoc. 152": 1333 1335. 1953.
[ June 11, 1974 Primary Examiner-Charming L. Pace Attorney, Agent, or Firm-Burton, Crandell, Polumbus & Harris [5 7] ABSTRACT An endotracheal catheter especially useful for the application of mechanical respiration or the administration of anesthetic gases to newborn infants. A pliable hollow outer tube is formed with a main body portion of constant diameter having a reduced diameter relatively short end section at one end. When inserted into the trachea, the shoulder at juncture of the main body and end section of the outer tube is seated at the upper end of the trachea. A second tube, of a diameter approximately equal to that of the reduced diameter end section of the first tube is passed through the side wall of the main body of the first tube at a location spaced longitudinally of the first tube from the shoulder. The second tube exends through the main body portion of the first tube and terminates at an open end located within the main body 'closely adjacent the shoulder so that a space of only relatively small volume exists within the first tube between the open ends of the two tubes. One-way check valves employing a light easily actuated valve member may be mounted at the opposite ends of the respective tubes.
. 4 Claims, 2 Drawing Figures ENDOTRACI'IEAL CATHETER BACKGROUND OF THE INVENTION The application of mechanical respiration or the administration of anaesthetic gases presents special problems in newborn infants, particularly those which are premature or are of very low corporal weight. A term described as dead space is a determining factor in these cases and what this term refers to is the space between the actual lungs and supply of fresh air, or oxygen. The physiological dead space is, of course, the entire tract comprising the nasal or mouth cavity, the trachea and the bronchial tubes. With the mouth closed, the dead space of a premature infant weighing two kilograms is approximately 3.5 cubic centimeters. When it is considered that the total respiratory volume of a child of this weight is between and cubic centimeters and that each normal breath would renew 8-l2 cubic centimeters of air in the lungs, then it is an important consideration not to increase the physiological dead space while attempting to administrate gases to the infant. Until now, it has been extremely difficult and in some cases, impossible, to apply mechanical respiration to a premature infant undergoing chest surgery. The dead space of the tubes and valves or facemask has been considerably higher than eight cubic centimeters and, if added to the physiological dead space of the infant, it is apparent that the infant would be inhaling very much the same gases that he had just exhaled which in short time would lead to suffocation. The most used method in these cases is to perform a tracheotomy-an incision in the trachea-- through which a small tube is passed directly to the traa chea, thereby bypassing the physiological dead space" of the patient in the upper trachea, larynx, pharynx, mouth or nasal cavity. The placement of a tracheotomy tube does help to reduce the dead space but, even so, the cumbersome method used to pass fresh air through that tube and to retrieve the spent air through the same orifice has necessitated the use of connectors and valves, the dead space of which borders on the limits of a full-term infant and usually exceeds the limits of a premature infant.
The present invention is directed to the provision of an endotracheal. catheter system having a dead space which is less than the physiological dead space of most premature or full-term infants and which is compatible with present methods of mechanical respiration and administration of anaesthetic gases to infants.
SUMMARYOF THE INVENTION In essence, the present invention contemplates the employment of two telescoped tubes, the outermost of which is formed with a shoulder from which projects a relatively short reduced diameter end section. The end of the inner of the two tubes terminates within the outer tube closely adjacent the aforementioned shoulder. In the administration, forexample, of an anaesthetic gas, the gas is fed through the inner tube and discharged from the end section of the outer tube which is inserted into the trachea of the patient. Exhalation by the patient passes into the end section of the outer tube and is conducted through the space between the outer and inner tubes to the discharge end of the outer tube. 7
Flow of exhaled gases into the inner or supply tube is prevented by a one-way check valve in this latter tube which seats immediately upon the sensing of reversed flow in this tube. By this arrangement, the inner or gas supply tube is kept filled with gas at all times, while the interior of the outer tube is free to accept the flow of exhaled gases. The dead space of this system is represented only by that relatively small volume, mainly the interior of the end section of the outer tube, which exists between the end of the outer tube and the adjacent end of the inner tube.
Other objects and features of the invention will become apparent by reference to the following specification and to the drawings.
IN THE DRAWINGS FIG. 1 is a cross sectional view of an endrotracheal catheter embodying the present invention; and
FIG. 2 is a cross sectional view showing the catheter of FIG. I inserted into the trachea of a patient.
Referring to the drawings, a catheter embodying the present invention includes a main or outer tube designated generally 10 which is preferably formed from a pliable, nontoxic or chemically inert material such as polyethlene or polyvinyl chloride. Main tube 10 includes a main body portion 12 of constant diameter and wall thickness which is formed at its operative or distal end (right-hand end as viewed-in FIG. 1) with a relatively short reduced diameter end section 14 which merges with main body portion 12 at shoulder 16. The open end of end section 14 is beveled as at 18 to facilitate the insertion of end section 14 into the trachea, shoulder 16 providing a seat engagable with the upper end of the trachea, see FIG. 2, to indicate that end section 14 is inserted into the trachea, thus avoiding-inadvertent gas discharge into the esophagus.
For some application of the catheter, a schematically illustrated one-way check valve 20 is mounted in the end of main tube 10 remote fromend section 14 to permit the flow of gas only outwardly from this remote end of the tube. Where such a one-way check valve is employed, it is essential that the valve have an extremely low actuating pressure, particularly where the catheter is to be used on a newborn infant. One form of valve suitable for this purpose is schematically illustrated at 20 as having a centrally located inlet passage 22 at one end and two or more outlet passages 24 which are offset from inlet passage 22. A lightweight disc 26 is loosely received within a chamber 28 commonly communicating with both inlet passage 22 and outlet passages 24. When the pressure within main tube 10 exceeds that in outlet passages 24, the disc shifts to the left as viewed in FIG. I and gaseous flow occurs around the edges of the disc from inlet passage 22 into outlet passages 24. When the pressure in outlet passages 24 exceeds that within inlet passage 22, the disc shifts to the right as viewed in FIG. 1 to overlie and seal the lefthand end of inlet passage 22. By using a very lightweight and loosely fitting disc 26, seating or unseating of disc 26 can be accomplished by an extremely small differential pressure.
A second tube 30 has a leading end portion 30a of an external diameter less than the internal diameter of main body portion 12 and the leading end portion 300 of the tube'30 is passed through the side wall of main body 12 at a location 32 longitudinally spaced from shoulder 16 by a fairly substantial distance. This longitudinal spacing is selected to provide maximum c0nvenience in inserting the catheter. The second tube 30 has a trailing end portion 30b received on the external end of the leading end portion 30a, and the outer walls of the trailing end portion 30b and the main tube are hermetically sealed to each other at the approximate location where tube 30 passes through the wall of tube 10. Preferably,the trailing end portion 30b of tube 30 is bonded to tube 10 as at 34 for at least a short distance along the exterior of tube 10 to minimize strain on the seal. The trailing end portion 30b of tube 30 which is disposed at the exterior of main body 12 is of a larger diameter than the leading end portion 300 of tube 30 inside main body 10 to minimize resistance to the flow of gases.
Tube 30 extends freely through main body portion 12 and terminates at an open end 36 located within main body 12 closely adjacent shoulder 16.
Tube 30 is employed as the source or inlet of gases to be supplied to the tube and, in most applications, is fitted with a one-way check valve 38 at its external or inlet end. Check valve 38 is of construction similar to that of check valve 20, except that valve 38 is oriented to permit flow into but not out of, tube 30.
ln'use, the catheter is insertedinto the patients trachea as shown in FIG. 2, and a source S of gas which is to be inhaled is connected to the external end of tube 30, In some applications, the gas to be inhaled is supplied underpressure, while in other cases the inhalations of the patient are relied upon to aspirate gas through tube 30. The gas to be inhaled is supplied from source 8 (FIG. 2), passes through tube 30, is discharged at discharge end 36 and then passes through end section 14 of main tube 10 into the trachea. When the patient exhales, the exhaled gas passesinto end section- 18 and thence through main body portion l2of main tube 10 to be discharged through one-way check valve 20 or in those cases where no valve 20 is employed, directly to atmosphere. In some applications it may be desirable to employ a light spring in check valve 20 biasing this valve to its closed position to assure that the path of least resistance to flow from tube is toward opening 18. Exhaled gas does not pass into end 36 of tube 30 to any substantial extent, because the pressure of the exhaled gas promptly seats or closes check valve 38. Thus, at the commencement of a subsequent inhalation, the only exhaled gas which is returned to the patient is that relatively small volume of gas indicated by dotsin FIG. 2 which occupies the interior of end section 14 and that relatively small portion of main portion 12 which is between end 36 of tube 30 and the end section 14. This volume is relatively small as compared to the physiological dead space of the patient.
While one embodiment of the invention has been described in detail, it will be apparent to those skilled in the art that the disclosed embodiment may be modified. Therefore, the foregoing description is to be considered exemplary rather than limiting, and the true scope of the invention is that defined in the following claims.
1. An endotracheal catheter comprising a first pliable hollow tube having a main body portion of a first diameter extending the major portion of the length of said tube, an integral relatively short reduced diameter end portion on said first tube extending coaxially from one end of said main body to one end of said first tube and defining an annular seating shoulder at the juncture of said main body and end portion, a second hollow tube having one end located externally of said first tube, said second tube projecting through the side wall of said first tube into the interior of said main body portion at a location spaced longitudinally of said main body portion from said shoulder and extending longitudinally through the interior of said main body portion to terminate at an open end located within said body portion closely adjacent said shoulder, the external diameter of that portion of said second tube within said main body portion being less than the internal diameter of said main body portion to establish an annular flow passage through said main body portion externally of said second tube.
2. An endotracheal catheter as defined in claim 1 further comprising a first one-way check valve means at the end of said main body portion remote from said end portion accommodating fluid flow out of said main body portion through said remote end, and second oneway check valve means at the end of said second tube opposite said one end thereof accommodating flow into the last-mentioned end of saidsecond tube.
3. The invention defined in claim 2 wherein said oneway check valves each comprise a housing having an internal chamber with a first passage at one end and a second passage offset from said first passage at its other end, and a thin lightweight valve disc floating in said chamber adapted to seat upon and overlie the first passage upon flow of fluid from the second passage toward the first passage.
4. An endotracheal catheter comprising hollow first and second tubes, said second tube having a first portion extending longitudinally within said first tube, said first tube having a main body portion with an internal diameter greater than the external diameter of said second tube, a radially inwardly extending shoulder at one end of said main body portion of said first tube, a relatively short end section integrally joined by said shoulder to the main body portion of said first tube and projecting coaxially therefrom to terminate at a beveled outer end, said second tube terminating at one end in a discharge opening located within said main body portion closely adjacent said shoulder.
. UNITED STATES PATENT. OFFICE- (IERTIFTLCATE (3F CQRRE CTEGN Patent No. 3,815,606 Dated un 11, 1974 %nventor(vs) Charles' N. Mazal J It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Abstract, line l4, "eXends" should read eXtends-.
Column 2, line 5 "dead space" should read --"dead space".
Column 3, line 51 and 52 "dead space" should read --"dead space"--.
Column 4 line'l9 after "said" insert main.
Signed and sealed this 18th day of February 1975.
c. MARSHALL DANN f RUTH c MASON Commissioner of Patents Attesting Officer and Trademarks