US2073192A - Method and apparatus for the administration of gases - Google Patents

Description

March 9, 1937. K. CONNELL 2,073,192.

METHOD AND APPARATUS FOR THE ADMINISTRATION OF GASES Filed Oct. 21, 1931 I VENTOR 4-24, Z/ BY ATTORNEY @etentet] Q, 337

UNHTEL) Z WBAQZ ()FFHQE acrea e METHQD AND APPARATUS EG'Fs 'LJHIE ADMIINKSTRATHUN (F GASES 28 Claims.

This invention relates to a method and means for administering gases and more particularly to a method of gas delivery for anaesthesia and other therapeutic purposes. I

In general, it is an object of this invention to provide a safe economical method of gas delivery and apparatus for use in connection therewith, which is simple of construction and inexpensive to manufacture, which can be expeditiously and conveniently manipulated, and which will efficiently perform the purposes for which it is intended.

Another object is to provide apparatus which will effectively utilize substantially all of the fresh gas delivered.

Another object is to provide apparatus which will give controlled extrusion of used gases and products of metabolism.

Another object is to provide apparatus adapted to prevent explosion of combustible vapors used in gaseous therapeusis.

Another object is to provide apparatus adapted to deliver fresh gas to the patient at the beginning of the breathing cycle and redeliver exhaled gas thereafter, whereby the fresh gas is carried to the alveolar passages.

Another object is to provide apparatus which receives a constant input of fresh gas and which feeds a substantial portion of said gas still fresh to the patient, and which also at some period of the breathing cycle feeds the patient gas previously exhaled.

Another object is to provide apparatus adapted to guide fresh gas during a portion of the breathing cycle directly to the respiratory tracts.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation and order of one or more of such steps with respect to each of the others, and the apparatus embodying features of construction, combinations of elements and arrangement of parts which are adapted to effect such steps, all as exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drawing, in

(Cl. 128-2il3) Fig. 2 is a detailed view in elevation and partly in section of the pressure control means shown in Fig. 1;

Fig. 3 is a detailed view in elevation and partly in section of the water supply means shown in Fig. 1;

Fig. 4 is a view in elevation of a modification of a portion of the apparatus shown in Fig. 1;

Fig. 5 is a, view similar to Fig. 4 showing the valve in position for affording communication between the mask and the air and showing the valve handle; and

Fig. 6 is a view similar to a portion of Fig. 1 showing a slightly modified construction.

The average human adult breathes ineach cycle a certain normal volume of air which is known as tidal air. At rest the tidal air is about 200 c. c. The normal rate of breathing is from 12 to 18 cycles per minute and the normal total exchange of air is from 4,000 to 6,000 c. 0. per 0 minute. Under the excitation of an anaesthesia and the stimulation of retained carbon dioxide, the rate may rise to or more per minute and the tidal volume to 300 c. c., or, on occasional unusual effort, to 1200 c. c. 25

In anaesthetic practice where the patient is caused to rebreathe exhaled air it is necessary to add a certain quantity of fresh gas200 c. c. of oxygen per minute to replace oxygen actually consumed and needed to supply the vital needs, 400 c. e. per minute to maintain sufficient pressure to cause the diffusion of the gases to the far alveolar lung passages, and a proper quantity of anaesthetic gases and vapors to maintain the required anaesthetic pressure in the blood. Furthermore, there must be an excess for washing out of the breathing system the products of metabolism so that the vapor pressure of the carbon dioxide in the alveolar air may be but about mm. of mercury. An amount of gas may constantly be spilled, i. e., discarded, equivalent to the added fresh gas. It is economically of importance that the spilled gas should be the used exhaled gas and that it should contain substantially none of the fresh gas. It is also of importance both economically and physiologically that the fresh gas enter directly into the deflated lung and substantially unmixed with gas previously exhaled. The more proximal to the patient the delivery of fresh gas is into the apparatus, the less intermlngling there will be with the expired gas and the more effective the operation of the device. Under special conditions it may be necessary to deliver the fresh gas directly by intubation into the bifurcation of the trachea and thus avoid using the fresh gas to fill the 140 c. c. of dead air space in the upper respiratory tract. It usually suffices, however, to deliver the fresh gas I into a mask adjacent to the nares.

This invention contemplates a tube for fresh gas leading into such a mask and a conduit for expired gas leading away from the mask. The

conduit may have suflioient capaeity to contain not only a normal, but also an excessive, tidal volume. It is possible to lead the tube directly into the conduit proximal to the patient and to insert the conduit into the respiratory tract. A construction of this type is shown in Fig. 6 wherein the tube lit for fresh gas leads directly to the conduit 9 do. for expired gas and the conduit is introduced into the mouth of the patient. The breathing cycle is normally carried out in three periods-the inspiration, the expiration and a quiet period. During the quiet period the fresh gas pushes the expired gas out of the mask and to some extent distally from. the patient along the conduit. The excess, much rebreathed gas in the distal, i. e., far, end of conduit thereby is spilled from the conduit. Upon inspiration the fresh gas passes deep into the lungs and penetrates the alveolar passages, where it is immediately available to the blood stream. The previously-expired gas is drawn in next in succession, having a slight intermixture of the continuouslysupplied fresh gas, and fills the remaining portions of the respiratory passages. During expiration some of the fresh gas mixes with the expired gas as it passes out of the mask and into the conduit. Only a relatively small fraction of this fresh gas is lost going into that portion of the expired gas which does not return to'the patient. On a three-liter flow of fresh gas to a patient breathing nine liters per minute in such a closed breath- 40 ing system, this total loss is but one-ninth of the fresh gas on the average.

It may be observed in this connection that it is desirable to change the character of the fresh gas introduced from time to time during the anaesthetic treatment.

The cross-section of the conduit should not be too small to permit easy breathing by the patient. If, however, the cross-section is too large, the rear end of the expired gas which is being 59 pushed along the conduit by the fresh gas during the quiet period presents a large area to that fresh gas with the result that the latter is contaminated by the former, due not only to simple difi'usion but also to the eddying set up.

Under certain conditions apositive pressure may be advantageous and a distensible reservoir, preferably a bag, may be attached to the distal end of the conduit, in which case the conduit need not be as long as would otherwise be desirfi able to prevent outside air from being breathed by the patient under extraordinary conditions.

The actual spill device may control the ingress of atmospheric air.

Preferably'the conduit itself provides a sum- 85 cient capacity to take care of the usual tidal Volumes.

In accordance with the invention, conduits having a capacity of from 100 c. c. to 2,000 c. c.

70 may be provided, thereby providing for the reception of fresh gas during the time between exhalation and inhalation and for the inhalation of used gas during the latter part of the inhalation period, but a minimum volume of from 200 to 300 c. c. is preferable.

In apparatus using anaesthetizing and other gases through rubber tubing, there is a small, but in many cases, almost prohibitive danger of explosion of the gasdue to heat conditions or to the sparking as a result of the electric charges induced by friction of the gas or by small particles of solid matter carried thereby against the dielectric walls of the tube, or due to differences in potential of metallic parts at difierent portions of the dielectric conduit. There is also a danger in a wide variety of operation of combustion or explosion of combustible or explosive gases due to various causes including the proximity of electric charges, of hot metal, or of flame. Gaseous anaesthesia employs nitrous oxide, ethylene, and other gases and vapors together with oxygen. Certain of these combinations, especially mixtures of ethylene and acetylene in oxygen are highly explosive. Mixtures of from 5 to 45% of gaseous hydrocarbons in oxygen are particularly sensitive to small ignition sources such as minute static sparks, and are combustible from 3.1% to 79.9% on sufilcient heat of ignition. The spill in the present invention is situated at a distance from the patient, preferably more than 150 centimeters at a point preferably a meter above the floor and central to a standard which may support, beside the tube conduit, other mechanisms such as gages, humidifiers, etc. It has been found that such an arrangement is favorable to diffusion and dilution by the surrounding air to a concentration less than the explosive limit of 3% of gaseous hydrocarbon. It has also been found that a spark must come to within"7.5 centimeters of the spillway so placed or a candle flame to within 15 centimeters to cause a combustion train in gases of specific gravity equal or less than air when spilling 66 c. c. a second. If the gas is a heavy sensitive anaesthetic mixture, e. g., 10% ether in oxygen flowing at 133 c. c. a second, the ignition origin must be within 10 centimeters above, or within centimeters below, to cause ignition. Gases spilling at a distance from the patient recited above are at a safe distance from the electrostatically-charged attendants who may be grouped with their operating devices about the patient.

The mask which may be of electrically-nonconducting material such as rubber, may be provided with a conducting surface over a portion of the outer face to enable the apparatus to be electrically coupled with the patient.

The distensible nonconducting reservoir in its action may give rise to frictional electric charges, particularly on its inner surface. A wick leading from a water source and into said reservoir may deposit drops of water therein which will give a moist equipotential surface and minimize the danger from sparking. The standard and patient may also be grounded. The fresh gas may be prehumidifled.

In the embodiment of the invention shown in the drawing the stand it is adapted to support various control members including decompression valve units 3, flow gages i, and a pressure control valve unit ll, dials, gas humidifier unit 5, tanks 7, etc., shown generally at l l, and it may support the means for supplying a regulated flow of fresh gas preferably a flexible tube if to the mask exemplified conventionally, in the present instance, at E3. The other end of the tube communicates through piping 82a and the humidifier unit 6 to the flow gages which in turn are connected by means of tubes l2b extending through a hollow upright lZc to certain of the decompressionvalves within the tube are one or more balls all of less 3. As will be readily apparent by the regulation of the decompression valves in accordance with the showing of the fiow'gages, the proper gases in suitable admixture may be admitted in regulated amounts from pressure tanks l to the tube i2 in the usual manner. The stand iii may also support the distal end of the conduit it, which is adapted to contain the tidal air. The other end of the conduit may open into the mask it with which it may be integral. The volume may desirably range from 200 to 1200 c. c., and preferably in a number of cases is about 600 c. c. The conduit may be connected by conducting means such as piping iii to a flexible reservoir 80, which,

7 with the conduit, will give a volume of 1200 c. c.,

the tidal volume of an excessive respiratory ef-' fort. The piping it may form a part of the stand iii. If the volume of the conduit is more than 1200 c. c. it may open directly into the atmosphere. The cross-section of the conduit may be from 2.8 to 12 square centimeters.

The piping it may discharge downward into and support the reservoir iii, which may be a cylindrical elastic bag, certain horizontal portions preferably tending to have a smaller cross-section than others in the manner of a Japanese lantern. A- bag of this type gives relatively little friction between the parts as it changes volume. The end ita of the bag fits over the distal end it?) of the piping l5 and is supported thereby.

Leading out of the piping l5, near the reservoir. and radially central with respect to the stand 80, is a spillway and valve unit ll, which may include a pressure control which may be in the form of a tube leading into the atmosphere through openings 08b. The spillway may be at a height of at least a meter above the floor. The tube i l, piping i) and bag it have no other communication with the atmosphere. The passage in said tube is restricted at the point'iii between which point and the outer end of the tube and be multiple and divergent for more effective ditfusion of the spillage. The tube may be rotatable about a horizontal axis and may be associated therewith a scale it graduated to read the pressure which the balls will set up in the system corresponding to the various angles said tube makes with the horizontal. The greater such an angle the greater is the pressure set up. Reference may be had in this connection to my copending application. Serial No. 441860 filed May 1, 1930. As will be apparent, the valvehnit H exerts a greater or less restraining pressure to counterbalance the pressure in the expansibie bag it dependent upon the inclination of the unit ll as indicated on the scale 2@. The bag it thus serves as a supplemental tidal chamber and because of its expansible nature will contract as the patient breathes in and will expand to a certain extent as the patient exhales, this expansion being controlled by the adjustment of the valve unit.

Associated with the piping i5 is a tank 2i from which means such as the wick 22 may convey water into the reservoir it. As shown, the wick passes into the piping thence into the reservoir. The tank, piping and stand may be grounded by conductor 23.

The mask i3 is adapted to admit the fresh gas entering the mask to the respiratory tract of the patient and also to admit gas from the conduit II. The outer surface of the mask may be provided with a conducting metallic layer 2%. The conductor 28 may couple the layer to the patient or to earth.

Valve means of any suitable type may be provided for controlling the rate of flow of fresh gas delivered through tube i2.

Fig. 4 shows a modification of that portion of the apparatus where the tube it, the conduit i l and the mask come together. The housing 20. which may be metallic, has tubular projections 30 onto which the tube, the conduit and an entrance to the mask fit. The housing may be provided with valve means 3i for connecting the interior of the housing with the atmosphere. means may comprise a bronze shoe 32 and a spring 33. As will be seen the shoe 32 is adapted to close the gas inlet conduit when swung in a clockwise direction as by a handle M.

The above described method and apparatus is adapted to give high eiilciency through the almost complete utilization of the fresh gas, and the exact dosage possible. It is adaptable for the administration of any gas or succession or combination of gases and may be used for anaesthesia, insufflation, super-oxygenation, resuscitation, narcotic poisoning, carbon monoxide poisoning, respiratory collapse. asphyxia, hiccough and pneumonia therapy and the like.

Since certain changes in carrying out the above process and in the constructions set forth which embody the invention may be made without departing from its scope, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described my invention. what I claim as new and desire to secure by Letters Patent, is: i. In apparatus of the character described, means for delivering, after said apparatus has begun to operate, fresh gas to a patient, means for removing gas exhaled by said patient and for re-delivering a portion oi said exhaled gas to said patient at the end of a breath, and means for building up a supply of gas in the removing means between an exhalation and an inhalation.

2. In apparatus of the character described. means for receiving from and re-delivering exhaled gas to a patient. means for delivering fresh gas to said patient. the first-mentioned means comprising a long narrow conduit. and means to deliver a substantial amount of said fresh gas being delivered to said patient substantially unmixed with said exhaled gas before said exhaled gas is re-delivered.

3. In apparatus of the character described.

-means for receiving from and re-delivering exhaled gas to a patient, and means for delivering fresh gas to said patient, a connection between said delivery and receiving means, said receiving means comprising a long. narrow conduit whereby a substantial amount of said fresh gas is delivered to said patient substantially unmixed with said exhaled gas before said exhaled gas is re-delivered. said first mentioned means providing a volume equal to the tidal flow of 'a patient under the conditions described and having a cross section large enough to accommodate said flow without undue difference in pressure,

These til) but not large enough to permit said fresh gas to mix substantially with said exhaled gas.

4. In apparatus of the character described, means for receiving from and re-delivering exhaled gas to a patient, and means for delivering fresh gasto the said patient, the delivering means for the fresh gas, being adapted to deliver a substantial amount of the fresh gas to the patient substantially unmixed with the exhaled gas before the exhaled gas is re-delivered, the means for receiving and re-delivering exhaled gas comprising a conduit having a cross-section greater than 2.9 square centimeters and less than 12 square centimeters, and having a capacity greater than 200 cubic centimeters.

5. In apparatus of the character described, means for receiving from and re-delivering ex= haled gas to a patient, and means for delivering fresh gas to the said patient, the means for delivering fresh gas being adapted to deliver to the said patient a substantial amount of the fresh gas substantially unmixed with the exhaled gas before the said exhaled gas is re-delivered, the means for receiving and re-delivering exhaled gas comprising a conduit having a cross-section greater than 2.9 square centimeters and less than 12 square centimeters, and having a length of substantially not less than 150 centimeters.

6. In apparatus of the character described, a respiratory system comprising means for re= ceiving' from and re-delivering exhaled gas to a patient, and means for delivering fresh gas to the patient, the means for delivering fresh gas being adapted to deliver to the said patient a substantial amount of the fresh gas substantially unmixed with the exhaled gas before the said exhaled gas is re-delivered, the said means for receiving and re-delivering exhaled gas comprising instrumentalities for spilling a portion of the 40 exhaled gas from the system and a distensible reservoir connected to the said means at a point removed from the patient for providing tidal volume of an excessive respiratory efiort.

7. In apparatus of the character described, a

conduit adapted for receiving from and re-delivering to a patient expired gas, the distal end of said conduit forming an inverted U, a breathing bag opening into said end, a container on top of said inverted U.-shaped end, a liquid adapted to conduct electricity, and means for supplying said liquid from said reservoir to the interior of said bag.

8. In apparatus of the character described,

a conduit adapted for receiving from and re= delivering to a patient expired gas, a distensible breathing bag opening into said conduit, said bag being accordion-shaped, and means for maintaining the electric potential of various inner surfaces of said bag equal.

9. In a system for the administration of gases wherein fresh gas is delivered to a patient and gas exhaled by said patient is removed,'and a portion of the exhaled gas is'redelivered from a breathing reservoir to said patient, the combi-- nation with a reservoir of electric-potential equalizing means comprising a water tank and a wick extending from said tank to said reservoir.

10. In a system for the administration of gases wherein fresh gas is delivered to a patient and gas exhaled by said patient is removed, the pres sure of the gas which is being removed being maintained at a predetermined pressure by spilling means, and wherein a portion of the exhaled gas is redelivered from a breathing reservoir to said patient, the combination with a resenvoir of electric-potential equalizing means coin= .prising a water tank and a wick extending from said tank to said reservoir.

11. A stand adapted for supporting a source of fresh gas, means for delivering fresh gas to a, patient and means for removing gas exhaled by said patient and for redelivering a portion of said exhaled gas to said patient, said removing means having a length of substantially not less than 150 centimeters and having an end spilling at a point radially central to said stand and at a point substantially not less than centimeters above the hour.

12. A stand adapted for supporting a source of fresh gas, means for delivering fresh gas to a patient and means for removing gas exhaled by said patient and for redelivering a, portion of said exhaled gas to said patient, said removing means having a length of substantially not less than centimeters and having an end spilling at a point radially central to said stand and at apoint substantially not less than 100 centimeters above the floor, a, breathing reservoir, means for equalizing the electric potential of various parts of said reservoir, a face mask associated with said delivering and removing means and provided with metallic coating, electrical means adapted for coupling said coating and said pa= tient, and means for grounding said stand, said coating and said mechanism.

13. A stand adapted for supporting gas control mechanism, means for delivering fresh gas to a patient and means for removing gas exhaled by said patient and for redelivering a portion of said exhaled gas to said patient, "said removing means having a length of substantially not less than 150 centimeters and having an end spilling at a point radially central to said stand and'at a point substantially not less than 100 centimeters above the floor, a breathing reservoir, means for equalizing the electric potential of various parts of said reservoir, a. face mask associated with said delivering and removing means and provided with metallic coating, electrical means adapted for coupling said coating and said patient, and means for grounding said stand, said coating and said mechanism.

14. In apparatus of the character described, means adapted for removing a tidal volume of expired gas, means adapted for adding fresh gas to said volume at a point adjacent the patient, means adapted for maintaining said fresh and said expired gases substantially undiifused in said resultant volume, and means for delivering said fresh gas and then a portion of said expired gas to the patient.

15. In apparatus of the character described, means adapted for receiving a tidal volume of expired gas and means adapted for supplying fresh gas to that portion of saidilrst mentioned means adjacent the patient, said first mentioned means adapted for spilling an amount of expired gas substantially equal to the amount of fresh gas supplied, for maintaining said expired gas and said fresh gas substantially unmixed, and for delivering said fresh gas and then 'a portion of said expired gas to the patient.

16. In apparatus of the character described, means for receiving fromand re-delivering exhaled gas to a patient, and means for delivering fresh gas to said patient, a substantial amount of said fresh gas being delivered to said patient substantially unmixed with said exhaled gas before said exhaled gas is re-delivered, said first mentioned means comprising a conduit having a cross section greater than 2.9 square centimeters and less than 12 square centimeters and having a capacity greaterthan 600 cubic centimeters.

1'7. The method of administering gas, comprising removing and re-delivering exhaled gas, delivering fresh gas to the patient at the beginning of the inspiration period of the breathing cycle before said re-delivery.

18. The method of administering gas, comprising removing the tidal volume of exhaled gas, adding to said volume a quantity of fresh gas, spilling from said volume an equal amount of expired gas, maintaining the fresh and expired gases substantially undifiused in the resultant volume, and delivering said resultant volume to the patient in such a manner that the fresh gas is inspired first.

19. The method of administering gas, comprising removing exhaled gas, adding fresh gas to said expired gas at a point proximal to the patient, spilling part of the expired gas distally from the patient, maintaining said gases substantially unmixed, and delivering said gases to the patient, the fresh gas being delivered first.

20. The method of administering an anaesthetic gas to a patient, comprising allowing exhaled gas to be expired into a container, using fresh gas to replace a certain amount of the exhaled gas during the quiet portion of the breathing cycle, and delivering to the patient first fresh gas and then the non-replaced exhaled gas, the fresh gas and the said exhaled gas being delivered substantially unmixed from the container to the patient.

21. The method of administering gas, comprising storingthe gas of an exhalation, interposing fresh gas in a conduit between the exhaled gas and the patient, and delivering to the patient the fresh gas followed by a portion of the stored gas of the preceding exhalation.

22. Apparatus of the character described,

comprising an enclosure formed with means adapted to fit over the face of the patient, means to deliver a-controlled supply of gas to said enclosure, and a conduit leading away from said enclosure, means including said conduit providing a reservoir for exhaled gas, means providing an outlet at a distal point in said reservoir, said reservoir having a greater capacity than a single breath of the patient, and said conduit having a sufficiently small cross-sectional area to prevent the ready mixing of gases therein.

23. Apparatus of the character described, comprising an enclosure formed with means adapted to fit over the face of the patient, means to deliver a controlled supply of gas to said enclosure, and a conduit leading away from said enclosure, means including said conduit providing a reservoir for exhaled gas, means providing an outlet at a distal point in said reservoir, said reservoir having a greater capacity than a single breath of the patient, said conduit having a suflilcient capacity to receivethe inflow of gas during the quiet period in the patients breath and having insuflicient cross-sectional area to permit any substantial intermingling of said introduced gas with the exhaled gas.

KARL CONNELL.

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