US3481339A - Endotracheal tube - Google Patents

Description

Dec. 2, 1969 J. A. MILLET PUIG 3,481,339

ENDQTRACHEAL TUBE Filed March 28, 1968 F/Zz/ BY M P w,

ATTORNEY;

United States Patent 3,481,339 ENDOTRACHEAL TUBE Jorge Alberto Millet Puig, 2336 Sarmiento St., Castelar, Buenos Aires, Argentina Filed Mar. 28, 1968, Ser. No. 716,752 Claims priority, applicaztgzn Argentina, Apr. 10, 1967,

Int. 01. A61m 25/02, /00

U.S. Cl. 128-351 4 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Field of the invention The present invention refers to an endotracheal tube for the ventilation of the lungs, to be used in operations and also for prolonged treatments.

Description of the prior art To facilitate the ventilation of the lungs, in certain circumstances, and to carry out a number of operational steps, it is necessary to place a tube or cannula into the trachea. This requirement is more demanding in all those cases where there is breathing trouble or paralysis; for example in certain diseases (poliomyelitis), traumatisms (specially of the cranium or thorax) or during operations.

There are two different procedures, tracheotomy and endotracheal intubation, for inserting the tube or cannula, the selection of which depends on the particular case. The first requires, in itself, an operation, the purpose of which is to directly communicate the endotracheal space with the outside, to which end an incision is made at the base of the throat and extending into the inner cartilage wall portion of the trachea to insert therethrough the tube. The insertion could be temporary or permanent. Once this operation has been carried out, the air or gases at the entrance or exit of the lungs need no longer circulate through the so-called upper airways (upper portion of the trachea, larynx and mouth or nose).

The endotracheal intubation, on the other hand, is bloodless, and is carried out by using one of several known techniques and different auxiliary devices (laryngoscope or bronchoscope). Here, the tube is introduced through the upper airways (mouth or nose, larynx and trachea) without the need for an incision. In this case the aforementioned tube is used.

Although sometimes a distinction is made between canula and tube for the purpose of this invention, these expressions are considered to be synonymous. Some experts also use the term catheter.

In the two above mentioned cases (tracheotomy and endotracheal intubation) it may be necessary to form a seal between the endotracheal tube or cannula and the inside of the tracheal wall so as to obtain two results. On the one hand, the isolation of the respiratory organs from the feeding tract, such as in the case of dysphagia, to avoid the aspiration of secretions, regurgitations, etc. On the other hand, in the case where artificial respiration,

either by intermittent positive pressure or alternate positive-negative pressure, is required.

To obtain this seal, endotracheal canules or tubes are universally used with a cuff placed close to the lower end, inflatable once in place.

Even though the use of these known cuffed tubes provides advantages, there are a number of drawbacks which can have very serious or even mortal consequences for the patient. As regards this, J. Mck Watts states the following, in his paper Tracheotomy in Modern Practice (The British Journal of Surgery 50; 954-975; (1963) for which he received in England in 1962, the Moynihan prize.

The major problem in the use of an inflated cuff in the trachea is its liability to produce pressure necrosis of the mucous membrane (page 969).

To avoid this serious complication, amongst other expedients, he proposes a minimum possible distention of the cuff, allowing it to collapse during several minutes every hour.

In another chapter of his paper, when reviewing the possible complications arising in a tracheotomy, he emphasizes:

The complications of tracheotomy; 5 Pressure effects of tracheotomy tubes: (c) Pressure on the tracheal wall by an inflated cuff in the lumen.

It is of vital importance, in the use of inflated cuffs in the trachea to attempt to prevent pressure necrosis of the tracheal mucosa. The methods used have been described. Beaver (1961) reports the absence of pressure complications following the use of inflated cuffs, but our experience has not been so fortunate in following the use of the James tube. This tube was used on 19 occasions between 1953 and 196.0 but in only 4 patients was the trachea examined following the removal of the tube. Of the four trachea examined, two had extensive anterior and posterior tracheal wall ulceration at the site of the cuff. In another, a severe tracheal stenosis developed at the site of the cuff, and this patient now has a permanent tracheotomy and requires repeated tracheal dilatation.

Two further tracheas have recently been examined at autopsy following the use of the James tube. Posterior wall ulceration was present in one; in the other a circumferential tracheal stenosis was present at the site of the cuff.

From what can be seen from the above, the known tubes including an inflatable cuff, required the distention of said cuff, once the tube had been inserted in the trachea, so as to immobilize the tube, and produce an isolation between the upper and lower portions of the trachea.

This distention was produced by directly inflating the cuff through an air injecting tube connected to the cuff. The distended cuff produced the lesions previously analyzed.

The cult must be inflated in such a way that the pressure in it is larger than the maximum endotracheal pressure that the patient is capable of generating and which corresponds to the maximum pressure level. If these steps are now followed with the known devices, the maximum endotracheal pressure would compress and collapse the inflated cuff and this would destroy the seal-tight anchorage of the tube in the trachea. The pressure which has to be generated in the cuff necessarily reaches such a high level as to interrupt the blood circulation through the trachea tissues, pressurized by the cult, thereby producing the lesions already analyzed.

Taking into account the tubes and canulas already known prior to the present invention, with a view to overcome in every possible way all the drawbacks just mentioned, it has been proposed that the pressure in the cuff be diminished now and then at regular intervals, to 'momentaneously permit circulation of the blood through the tissues surrounding the cuff. If these decompressions are to be carried out during an operation, a highly expert person is required to perform this task, since, if the decompression is excessive, the tube is apt to be moved out of position and could even produce the drainage of certain accumulated substances from one or other side of the cuff, that would create difficulties in the patients breathing.

It is obvious that before each decompression the foreign matter accumulated on the cuff should be suctioned out.

It has also been suggested that tubes With successive cuffs be used, so that successive compression can be carried out in different parts or portions corresponding to each cuff. In this case also the assistance of an expert i required and in practice, these tubes with two cuffs have not shown good results, since in many cases, the length of the tube that is surrounded by the two cuffs can produce bronchial occlusion and further consequences. Also, the accumulation of secretions that are produced between both cuffs are diffcult and sometimes impossible to be suctioned out, producing the same difficulties as in the case previously analyzed.

SUMMARY OF THE INVENTION The idea on which the present inventon is based, is that a tube should be provided having a cuff for maintaining the tube in its proper position, but which also guarantees that the blood circulation through the tissues surrounding the cuff is not interrupted for a longer period of time than it takes to change from inspiration to expiration during each breathing cycle. In this way, normal conditions are maintained in the tissues, exempting them from the formation of ulcerations or any other type of the aforementioned deterioration. To achieve this objective, it has been thought to make use of the variations in pressure provided by the patient himself during breathing, using as a point of reference the moment of minimum endotracheal pressure to additionally create a minimum necessary pressure in the particular cuff of this invention, so as to immobilize the tube lodged in the trachea. Also, the inspiration step is used to increase the pressure in the cuff, as shall be explained later on. In this way, a certain massage is carried out on these tissues and a perfect isolation is gained between the two tracheal zones separated by the cuff.

More particularly, the invention refers to an endotracheal tube for the pulmonary ventilation, applicable during surgical operations as well as for prolonged treatments. The endotracheal tube is of the type including a main tubular member open at both ends, a cuff surrounding an intermediate portion of said main tubular I member adjacent to one of its end portions, the edges of said cuff being sealed to spaced-apart zones. of said intermediate portion of said main tubular member, and said cuff defining with said intermediate portion of said main tubular member a chamber. An additional tubular air injecting member is connected to said cuff. The invention is characterized in that at least one part of said intermediate portion of said main tubular member is surrounded by an inflatable bag, which sealingly divides said chamber into an external subchamber and an internal sub-chamber, and said intermediate portion of said main tubular member having at least one opening facing said internal sub-chamber.

In one of its preferred embodiments, the endotracheal tube of the present invention, may have more than one opening that faces said internal sub-chamber and said openings should preferably be elongated to avoid obstruction, facilitating at the same time, the cleaning of the device.

The edges of the bag are preferably linked in the same zone as the edges of the cuff to the intermediate portion of said main tubular member.

As regards the air injecting tube, this can be externally disposed to the main tubular member, or could also be arranged within this main tubular member. The remote end portion of the injecting tube is preferably provided with a globe known as pilot through which the surgeon or his assistant can easily detect if there is pressure in the external sub-chamber.

BRIEF DESCRIPTION OF THE DRAWINGS So as to facilitate the understanding of the present invention, reference will now be made to a specific embodiment by way of example, in relation to the accompanying drawings, wherein:

FIG. 1 is a schematic representation, partially in section, of an endotracheal tube in accordance with the present invention, and which is shown as inserted in a trachea.

FIG. 2 is a diagram of cuff pressures for an endotracheal tube of the known type, that does not include the bag that forms part of the present invention.

FIG. 3 is a diagram of cuff pressures for an endotracheal tube in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, reference numeral 1, identifies a schematically illustrate-d human trachea. The lower end of the trachea 1 is likewise shown, as dividing into branches 2 and 3 leading to the left and right lungs respectively. Upon having to carry out an operation as is already known by those skilled in the art, an endotracheal tube is inserted in the trachea of the patient so that the lower end of said tube remains close to the bifurcating branches 2 and 3. In the embodiment shown of the endotracheal tube of the present invention, the former comprises a main tubular member 4 having a lower end 4' arranged adjacent the bifurcating branches 2 and 3. The upper end of the main tubular member 4 is not shown, as being of no interest to the present invention, bearing in mind that the upper end is also open, although it may be connected to any additional device.

An intermediate portion of the main tubular member 4, adjacent the lower end portion 4', which intermediate portion is identified by reference numeral 5, is surrounded by a cuff 6 having an upper edge 7 and a lower edge 8, both usually of the reinforce-d type and sealed to spaced-apart zones of said intermediate portion 5 of said tubular member 4. It can now be appreciated that the cuff 6 defines with the external face of the intermediate portion 5 a chamber which, as will later be seen, is actually divided into two sub-chambers.

In the most current known structures of endotracheal tubes, the arrangement so far described is provided with a cuff, where the inside of the intermediate portion 5, forming part of the conduit defined by the main tubular member, is not connected to the chamber defined by the cuff 6. This cuff 6 is connected to an additional tubular injecting member 9, the outer end of which can for example be connected to the already cited pilot globe 10. A structure of this type, without taking into consideration the other means to be described further on, and which would be then a known structure, requires, to immobilize the endotracheal tube, that a quantity of air is injected through the additional injecting member 9 until the cuff sufficiently anchors the endotracheal tube in the trachea, even though outstanding momentary overpressures are generated, such as when the patient coughs. As is already known, the volume of air to be inflated in such a case is so large that the cuff 6 oppresses the trachea 1, whereby blood circulation to the tissues is obstructed in the oppressed zone.

In accordance with the present invention, the intermediate portion 5 of said main tubular member 4 has at least one opening in the embodiment shown, such as the two elongated openings 11.

Furthermore, the zone in which these openings 11 are located, is surrounded and hermetically enclosed in an inflatable bag 12 that divides the already cited chamber into an external sub-chamber 13'and an internal subchamber 14, which are sealed from each other.

In fact, in the embodiment shown, the edges of the bag 12 are also sealed to the edges 7 and 8.

Obviously, the bag could also have its 'own edges, spaced-apart from the edges 7 and 8, and be placed closer to the openings 11. t

It should still be pointed out that the edges 7 and 8 in the embodiment illustrated, could rigidly be linked to the intermediate portion 5 or could be resiliently gripped thereto so that each edge defines a sealed collar. The resiliently gripping collars are preferred since they facilitate the cleaning of the instrument, i.e. the cuff and bag assembly 6, 12, can be easily removed from the main tubular member 4.

Before analyzing the operational behaviour of the endotracheal tube in accordance with the present invention, it is convenient that some comments are made with regard to the respiratory cycle.

The entrance and exit of gases in the respiratory al velous or cavities of the lung, depend on-the variations in internal lung pressure in relation to the room pressure.

During natural or spontaneous respiration, the entrance of gases (inspiration) into the lungs is produced due to the reduction of internal lung pressure produced by the increase of thoracic volume formed by the contraction of the respiratory muscles. The loosening of these muscles causes a decrease in the volume of the thorax, with pulmonary compression and an increase of the endotracheal pressure that stresses and expels the internal lung gases (expiration) If for any reason (save obstruction of the superior airways) there is an alteration in the normal cycle of inspiration and expiration, an emergency is produced, which becomes the more outstanding as the respiration decreases.

In cases of paralysis of the respiratory system, it is considered that after 3 minutes having passed, signs of irreversible cerebral deficiences start to show, producing death within more or less short periods, but always within minutes.

To counteract such emergencies, taking into account the causes and the elements at hand, apparatus are used that modify the room pressures (e.g. pulmotor or iron lungs) or endotracheal tubes (mechanical respirators) which act by air or other gas injections.

Depending on the device used, variations of the intertracheal pressure are similar (pulmotor and iron lungs) or reverse (mechanical respirators) to the spontaneous respiration.

If known type of endotracheal tube is used, similar to the present invention, but without the bag 12, and the openings 11, the cuff corresponding to cuff 6 is inflated, through the additional tubular injecting member 9 until expanding the cuff sufficiently to generate radial pressure on the surrounding tissues with a view to obtain at all times, the sealing off of the respiratory cycle, including those cases in which there is accidental over-pressure (cough). If FIG. 2 is analyzed where the ordinate axis Y indicates pressures and the abcissa axisX indicates time, the curve R represents the respiratory cycles of the patient. More particularly, the ascendant curved portion R indicates the inspiration which reaches its maximum at peak M to diminish thereafter as shown by curve R corresponding to expiration which obviously reaches, in the final portion of the cycle, beneath the atmospheric pressure. For anchoring the cuff of the known devices, in the trachea, it is necessary to inflate the edit with air until generating a constant pressure larger than peak M, which pressure is shown by the horizontal line P.

On the other hand, by using the present invention, as

shown in FIG. 3, where the ordinate Y, the abscissa X and the curve R correspond to the same concepts as those shown in FIG. 2, curve R which could also be defined as representing the variations of intertracheal pressure. These pressures are freely transmitted to the internal subcharnber 14 (FIG. 1) through the openings 11, thereby increasing and decreasing the size of the bag 12, in accordance with the variation of the cycle of the curve R. To anchor the tube in the trachea, it is necessary to inflate air into the external sub-chamber 13 through the additional tubular injecting member 9, until a final pressure is achieved, which is the sum of the proper pressure in the external sub-chamber 13 plus the pressure that is generated in the internal sub-chamber 14, during the expiration stage, which is sufficient to anchor the tube and provide the necessary sealing. This pressure is defined by the height A shown in the FIG. 3. As the pressure in the thorax increases and thereby the endotracheal pressure during the inspiration step, the pressure of line P also increases and which in FIG. 3 is not constant, as in FIG. 2, Thus, the resulting pressure in the cult is always the same or only slightly greater than the pressure reigning in the trachea.

Thus it can be appreciated that a slight over-pressure in the external sub-chamber 13 is enough to assure a seal with low pressure on the tracheal wall during the major part of the respiratory cycle, which pressure automatically increases any time the pressure increases in the trachea, which results in maintaining the seal.

Giving a practical example, it could be said that normally the pressure produced by the respiratory cycle varies between +20 and 4 cm. of water column. The previously known endotracheal tubes have only one cuff, must therefore be inflated until reaching a pressure that will assure the seal at a pressure of at least +20 cm. of Water column.

On the other hand, by using the endotracheal tube of the present invention, air is inflated into the external subchamber 13 until a pressure is reached which is suflicient to maintain the seal between the internal face of the trachea and the external face of the cuff, upon reaching a minimum pressure of 4 cm. of water column in the respiratory cycle.

As the endotracheal pressure increases, which tends to collapse the cuff 6 since there would not be sufficient pressure inside it, this pressure is automatically increased due to the additional pressure supplied by the patient himself inflating the internal sub-chamber 14.

Therefore, the pressure exerted on the trachea through the cuff 6 is only substantially increased, upon the respiratory cycle reaching its peaks.

It is obvious that within the spirit and scope of the present invention, several changes and modifications may be suggested. Thus, to avoid that the tubular member 4 in the portion above the cuff 6 enters into frictional contact with the trachea tissues, it may prove advisable in certain cases to enlarge the length of the cuff 6 and eventually of the inflated bag 12 to cover substantially the entire length of the portion of the tubular member which is to be inserted in the trachea. An alternative suggestion along these items of avoiding frictional engagement, would be to provide two arrangements of the combined type of cuff and bag, which arrangements are to be located, one adjacent the branches 2 and 3 and the other spaced-apart from the first one adjacent the other open end of the tubular member.

This last arrangement has not yet been tested so that certain drawbacks of the type already described in connection with the evacuation of secretions may arise.

What is claimed is:

1. In an endotracheal tube for the ventilation of the lungs, applicable during operations as well as for prolonged treatments, of the type comprising a main tubular member having an intermediate portion and two ends, said main tubular member being open at both ends, said intermediate portion having two spaced apart zones, a cutf surrounding said intermediate portion of said main tubular member, said cufi having a pair of spaced apart edges, said edges of said cuif being each sealed to one of said spaced-apart zones of said intermediate portion of said main tubular member, said cufi defining with said intermediate portion of said main tubular member a chamber, an air injecting tube connected to said cuff, at least one part of said intermediate portion of the main tubular member being surrounded by an inflatable bag that divides said chamber into an external sub-chamber and an internal sub-chamber isolated from each other, and said intermediate portion of said main tubular member having at least one opening facing said internal sub-chamber.

2. An endotracheal tube in accordance with claim 1, wherein said cuff surrounds said main tubular member close to one of its ends.

3. An endotracheal tube in accordance with claim 1, wherein said bag has two opposite edges joined to said spaced apart edges of said cuff, thereby forming reinforced edges sealed to the intermediate portion of said main tubular member.

4. An endotracheal tube in accordance with claim 2, wherein said intermediate portion of the main tubular member has two elongated openings.

References Cited UNITED STATES PATENTS OTHER REFERENCES Martinez, Jour. Thoracic & Card. Surg., vol. 47 #3, March 1964, pp. 404-405.

DALTON L. TRULUCK, Primary Examiner US. Cl. X.R. 128--208

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