US3757783A - Suction drainage apparatus - Google Patents

Abstract

Suction drainage apparatus for use in conjunction with vacuum sources of the type that may fail in either an ''''open'''' or a ''''closed'''' state. The system includes a trap chamber having an inlet adapted to be connected to a catheter for receipt in a body cavity and an outlet connected to a pressure regulation device which, in turn, is connected to the vacuum source. To preclude pressure buildup within the body cavity of the patient in the event of vacuum failure in the ''''closed'''' state, a pressure release path from the trap chamber is provided. To prevent backflow of ambient air into the body cavity of the patient in the event the vacuum source fails in an ''''open'''' state, a backflow precluding device in the vacuum flow path is provided.

Description

United States Patent [1 1 Alley 1 Sept. 11 1973 SUCTION DRAINAGE APPARATUS [75] Inventor: RalphD. Alley, Loudonville,N.Y.

[73] Assignee: Sherwood Medical Industries, Inc., St. Louis, Mo.

22 Filed: Sept. 24, 1971 21 Appl. No.: 183,332

OTHER PUBLICATIONS Surgery, Vol. 61, No. 2 pp. l96-199 Feb. 1967.

Primary Examiner-Charles F. Rosenbaum Att0rneyStanley Garber [57] ABSTRACT Suction drainage apparatus for use in conjunction with vacuum sources of the type that may fail in either an open or a closed" state. The system includes a trap chamber having an inlet adapted to be connected to a catheter for receipt in a body cavity and an outlet connected to a pressure regulation device which, in turn, is connected to the vacuum source. To preclude pressure buildup within the body cavity of the patient in the event of vacuum failure in the closed state, a pressure release path from the trap chamber is provided. To prevent backflow of ambient air into the body cavity of the patient in the event the vacuum source fails in an open state, a backflow precluding device in the vacuum flow path is provided.

16 Claims, 5 Drawing Figures CATHETER PATENTEDSEPI 1 ma 757, 783

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-10 U 1 PUMP PRIOR ART CATHETER SUCTION DRAINAGE APPARATUS BACKGROUND OF THE INVENTION This invention relates to suction drainage apparatus of the type used to drain gases and body fluids from a body cavity as, for example, the pleural cavity.

Injuries to the lungs and/or various surgical procedures will often result in the accumulation of air and/or fluid between the lung and the chest wall, in the pleural space, which will interfere with respiratory mechanics. Such interference may be fatal and often invites other complications. Thus, in such instances, the need for chest drainage has long been recognized and practiced by the medical profession.

Initial chest drainage techniques employed drainage apparatus comprised of a single-seal bottle and a chest drainage catheter. The catheter was connected to a glass tube which led through a stopper in the bottle to a point beneath the surface of water in the bottom of the bottle. A second opening in the bottle stopper permitted escape to the atmosphere of air evacuated from the chest cavity during the respiratory process. The water in the bottle served to preclude backflow of ambient air into the chest cavity of the patient. The principal drawback of the single-bottle drainage system was that the same could not be used for evacuation of body fluids from the chest cavity. If so used, the ultimate result would be a fluid level rise in the bottle which, correspondingly, increased the depth to which the glass tube was submerged, thereby increasing the head of back pressure which resulted in a progressive elevation in resistance to drainage.

Accordingly, the prior art interposed a trap bottle in the system between the patients chest cavity and the seal bottle creating a two-bottle system. This system operated satisfactorily so long as there was no need to operate the same by forces greater than that of gravity and the patients respiratory mechanics.

Thereafter, the medical profession determined that in many instances, evacuation of air and fluid from the chest cavity is enhanced and could be effected safely by the addition of negative pressure from an external source with the result that the three-bottle suction drainage system evolved. In one form or another, the three-bottle system is almost universally employed today where suction is required, is desirable, and/or is available.

In all forms, the three-bottle system consists of a trap bottle, a seal bottle and a pressure-regulating or suction control bottle. The suction control bottle can be linked to the seal bottle or to the trap bottle with the result that two schoolsof practice evolved. Each arrangement has its respective advantages, and, under certain operating conditions, hazards.

The most common arrangement of the three-bottle system may be termed a series arrangement wherein the pressure-regulating bottle is linked to the seal bottle, which, in turn, is linked to the trap bottle. This arrangement may also be practiced with but two chambers by appropriately locating the sealing elements and pressure-regulating elements in a single chamber. The advantage of a series system is that the seal bottle acts as a backflow-preventing valve when the pressureregulating bottle is not connected to a vacuum source, as, for example, during transport of a patient from the operating room to the recovery room or when a vacuum source fails in an open state. An additional advantage of the series system is that an air leak from the lung will be displayed by air bubbling through the seal bottle, and its magnitude and variation can be visually assessed.

The hazard of the arrangement emerges when the suction port of the pressure-regulating bottle becomes obstructed (as when a vacuum source fails in a closed state) for then the system becomes closed and lethal intrapleural pressures may be generated. When such occurs, the only possible escape for the patient hinges on his ability to withstand the pressures necessary to drive the water in the pressure-regulating bottle through the conventional submerged tube therein and out of the bottle.

An alternate commonly used system to the series arrangement of the bottles may be termed the in parallel" system, wherein both the pressure-regulating bottle and the seal bottle are separately connected to the trap bottle. The advantage of this system is that the seal bottle functions as an escape valve even when the suction port of the pressure-regulating bottle is obstructed. The disadvantage is that when the system is not connected to suction, as in the transport of the patient or when a vacuum source fails in an open state, a connection between the trap bottle and pressure-regulating bottle must be occluded to prevent ambient air from backflowing through the open suction port to the patients chest cavity causing respiratory embarassment due to collapse of the lung. Moreover, with this system, the seal does not provide an indicator of air leakage from the lung.

Thus, there is a need for a suction drainage apparatus that not only precludes possible lethal pressure buildup from an air leak from the lung, but prevents the possibility of backflow of ambient air into the patients pleural cavity as well, and provides suitable visual indications of air leaks from the lung.

SUMMARY OF THE INVENTION It is the principal object of the invention to provide a new and improved suction drainage apparatus. More specifically, it is an object of the invention to provide a suction drainage apparatus that prevents lethal pressure buildup in a patients chest cavity from a pulmonary air leak and precludes collapse of the lung from backflow of ambient air through the drainage system, and which further can provide visual indications of air leakage from the lung.

The exemplary embodiment of 1 the invention achieves the foregoing objects by means of a construction employing four chambers. A first one of the chambers serves as a trap chamber for collection of drainage and has an inlet connected to a catheter which is located in the patients body cavity to be drained. A secand chamber has an inlet which is submerged below liquid in said chamber and is connected to the trap chamber. Said second chamber also has an outlet connected to atmosphere. A third chamber also includes an inlet which is submerged below liquid and is connected to the trap chamber. The third chamber has an outlet which is connected to an inlet of the fourth chamber above a desired liquid level therein. An outlet is provided in the fourth chamber for connection to a source of vacuum. A second inlet in the fourth chamberleads from the atmosphere to a variable depth below the level of the liquid in the fourth chamber.

As mentioned previously, the second chamber provides a pressure-release path to dissipate pressures as when the outlet of the fourth chamber is closed while the third chamber serves to preclude backflow of ambient air into the patients chest when the outlet of the fourth chamber is open.

It is contemplated that the chambers may be defined by separate bottles or, preferably, in a single, integral disposable unit.

The invention further contemplates the provision of a selectively operable liquid communication path between the second and third chambers which may be open when liquid is introduced into the same so that the user of the device need not fill both chambers separately.

As will be seen, the invention does away with the disadvantages of prior systems in that there is no need to concern oneself with the opening or closing of ports during patient transportation nor need there be concern for vacuum source failure which could result in either a closed-system condition or an open-system condition.

Other objects and advantages will become apparent from the following specification taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration of the one-bottle system of the prior art;

FIG. 2 is a schematic illustration of the two-bottle system of the prior art;

FIG. 3 is a schematic illustration of the series threebottle system of theprior art;

FIG. 4 is a schematic illustration of the parallel threebottle system of the prior art; and

FIG. 5 is a schematic illustration of a suction drainage system made according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT An early form of drainage apparatus for body cavities is illustrated in FIG. 1 and is seen to include a single container having a stopper l2 and containing aliquid 14 such as water. Atube 16 extends through thestopper 12 to vent the space above the liquid level to the atmosphere while asecond tube 18 extends through thestopper 12 to a point just below the liquid level. The upper end of thetube 18 is connected via a conduit 20 to a catheter located in a body cavity as, for example, the pleural cavity. This system may be used successfully to vent air from the pleural cavity and operates as a result of respiratory mechanics of the patient. Air existing in the pleural cavity, between the lining of the chest and the lung, upon exhalation by the patient, is compressed and forced through the conduit 20, thetube 18, the liquid 14, thecontainer 10 and out thevent 16 to atmosphere. The liquid 14 covering the lower end of thetube 18 serves as a seal to preclude backflow of ambient air into the pleural cavity when the patient inhales.

The single-bottle system is not suitable for drainage when both air and body fluids must be drained from the cavity. More particularly, if body fluids are passed into the conduit 20, gradually, the level of the liquid 14 within the container will build up. As a result, there will be a back pressure-head generated corresponding to the height of the liquid level above the lower end of thetube 18. The resistance of the pressure-head to the escape of air from the pleural cavity can become sufficiently great as to seriously interfere with the patients breathing mechanics.

In order to accommodate both body fluid and air drainage, the prior art resorted to the configuration illustrated in FIG. 2. The same includes abottle 10 which is identical to thebottle 10 illustrated in FIG. 1 and will hereinafter be referred to as a seal bottle" by reason of the fact that the same serves to prevent backflow. In addition, the system illustrated in FIG. 2 includes asecond container 32 to serve as a trap forbody fluids 34. Thetrap container 32 includes astopper 36 through whichtubes 38 and 40 extend to terminate well above the contemplated level of thebody fluids 34 within thecontainer 32. Thetube 40 is connected via aconduit 42 to thelong tube 18 which has its one end submerged below the level of the liquid 14 in theseal bottle 10 while thetube 38 is connected via aconduit 44 to a catheter in the pleural cavity of the patient. Thetube 16 vents the seal bottle to atmosphere. As a result, when the two-bottle system illustrated in FIG. 2 is employed, drainedbody fluids 34 are isolated from theseal bottle 10 so that they can be drained without any accompanying back pressure buildup that could be detrimental to the patient.

It is self-evident that the function of the foregoing two-bottle system is dependent upon gravity and the forces of the patients respiratory mechanics.

The next step in the evolution of a chest drainage apparatus was to add an external source of controlled negative pressure to enhance drainage. This was achieved by the development of three-bottle drainage systems, and, more particularly, two types of threebottle systems, hereinafter termed the in series system and the in parallel system.

FIG. 3 illustrates the three-bottle in series system which is the most common in use today. The same consists of atrap bottle 32 in all respects identical to that shown in FIG. 1; aseal bottle 10 identical to that illustrated in FIG. 1 and a pressure-regulatingbottle 50. The pressure-regulatingbottle 50 includes astopper 52 through whichtubes 54, 56 and 58 extend. The pressure-regulatingbottle 50 is further adapted to receive a liquid 60 such as water. Thetube 54 is connected via aconduit 62 to thevent tube 16 of theseal bottle 10 while aconduit 64 connects thetube 58 to a source of vacuum such as apump 66. Both of thetubes 54 and 58 terminate well above the level of the liquid 60 within thepressure regulating bottle 50.

Thetube 56 is in communication with the atmosphere externally of thebottle 50 and has its lower end located below the level of the liquid 60 within thebottle 50 to some predetermined distance. The same operates as follows. The height of the level of the liquid 60 above the lower end of thetube 56 determines essentially the negative pressure differential from atmospheric pressure to be ultimately applied to the pleural cavity for draining the same. Should the pump 66 attempt to draw a greater vacuum, than that needed or desired for drainage, atmospheric air will flow in through thetube 56 into thebottle 50 to maintain the negative pressure at the desired level.

This system works well for its intended purpose as long as there is no failure of thepump 66. As is well known, vacuum pumps typically alternate between conditions wherein their vacuum port is in communication with the atmosphere or is cut off from communication with the atmosphere. Hereinafter, such conditions will be termed open and closed" states, respectively. Should the pump 66 fail in an open state, the system illustrated in FIG. 3 is perfectly adequate in that it may then function much the same way as the two-bottle system illustrated in FIG. 2 with a proper seal against backflow being maintained by theseal bottle 10. However, should the pump 66 fail in the closed state, as air and body fluids are forced into the system at thetrap bottle 32, the resulting increase in pressure will ultimately be conveyed to the pressure-regulatingbottle 50 from which it cannot escape except through thetube 56. As mentioned previously, the liquid level within thebottle 50 to accomplish the pressureregulating function, must be well above the lower end of thetube 56 so that there can be no relief of the pressure buildup except by forcing the liquid 60 up the entire height of the column defined by thetube 56 until such time as the liquid level has been decreased by evacuation to the lower end of thetube 56. Thus, the three-bottle system illustrated in FIG. 3 can be extremely dangerous should the pump 66 fail in the closed condition. It is also obvious in view of the foregoing that this hazard is not always dependent on total pump failure. For, the same circumstance will occur if the volume of air leaked from the lung exceeds the cap city of the suction source.

While not shown herein, there is a variation of the series three-bottle system illustrated in FIG. 3 which only requires two separate vessels. According to this variation, the pressure-regulatingbottle 50 also serves as the seal bottle and the arrangement is constructed by substituting thetube 18 of theseal bottle 10 for thetube 54 of the pressure-regulatingbottle 50. Of course, in so doing, it is necessary that the lower end of thetube 18 be just below the liquid level of the liquid 60 in thebottle 50. It is to be understood that reference herein to a three-bottle system is expressly intended to include this variation thereof, for the principle is the same.

Another type of three-bottle system, the in parallel" system, is illustrated in FIG. 4 and is seen to include atrap bottle 32 in all respects identical to that illustrated in FIG. 2 with the exception that its stopper is provided with anadditional outlet tube 70 well above the contemplated level ofbody fluids 34 therein. Theseal bottle 10 has astopper 12 through whichtube 18 extends to a point below the surface level of the liquid 14 therein. Thetube 18 is connected intotrap bottle 32 by means oftubes 42 and 40.Seal bottle 10 is vented to the atmosphere by means oftube 16 extending through thestopper 12. Pressure-regulatingbottle 50 has astopper 52 withtubes 54, 56, and 58 passing therethrough.Tube 56 extends from atmosphere to a point below the surface level ofliquid 60 in the bottle.Vacuum pump 66 is connected intobottle 50 by means oftube 64 connecting totube 58 which tube terminates in the bottle above the liquid level. Tube 54is connected bytube 72 to theoutlet tube 70 in thetrap bottle 32.

Malfunction of the in paralled three-bottle system may occur if failure of thepump 66 occurs. When thepump 66 fails in the closed mode, though external suction is lost, pressure buildup is prevented through theseal bottle 10 which is vented bytube 16 to atmosphere. However, should the pump 66 fail in the open state, it will be appreciated that a path of direct communication from the atmosphere to the pleural cavity of the patient exists which will result in backflow of ambient air causing collapse of the lung.

Thus, the suction drainage systems heretofore known are subject to disadvantages under certain operating circumstances and certain conditions of suction system failure.

The invention overcomes all of "the foregoing disadvantages. An exemplary embodiment of a suction drainage apparatus made according to the invention is illustrated in FIG. 5. And while the same is illustrated as being comprised of a plurality of separate containers interconnected by conduits or tubing, it is to be understood that the following description is but an exemplification of the principles and it is contemplated that the invention may be implemented by the use of separate vessels and connectors as illustrated or by a unitized construction of a disposable nature according to techniques well known in the art.

The exemplary embodiment of the invention includes atrap bottle 32 having astopper 36 through whichtubes 38, 7t) and 40 extend. All of thetubes 38, 70, 40 have their lower ends well above any contemplated level ofbody fluid drainage 34 within thetrap bottle 32.

Thetube 38 is connected via aconduit 44 to any suitable form of catheter 94 which is positioned in a body cavity for drainage while thetube 40 is connected via aconduit 42 to atube 18 extending through thestopper 12 of afirst seal bottle 10. Thetube 18 has its lower end just below the level of a liquid 14, such as water, therein. Thefirst seal bottle 10 is closed by astopper 12 having ashort tube 16 extending therethrough to establish communication between the atmosphere and the interior of thebottle 10 above the liquid 14. Thetube 70 in thetrap bottle 32 passes throughstopper 36 and is connected into asecond seal bottle 102 viaconduit 72 andtube 98..Tube 98 in thesecond seal bottle 102 is similar to thetube 18 in thefirst seal bottle 10. Again, the lower end of thetube 98 is located just below the level of a liquid MM within the seal bottle 1 .02.

Returning to thesecond seal bottle 102, the same also includes a short tube 118 similar to thetube 16 extending through itsstopper 100. However, the tube 118. is connected via a conduit 120 to atube 54 extending throughstopper 52 in the pressure-regulatingbottle 50 which may be identical to the pressure-regulatingbottles 50 of FIGS. 3 and 5.Tube 56 extends from atmosphere throughstopper 52 to a point below the liquid level inbottle 60. Avacuum pump 66 is also connected to the pressure-regulatingbottle 50 by means of aconduit 64 andtube 58 as illustrated.

In normal operation, thetube 18 in thefirst seal bottle 10 serves as a manometer reflecting the negative pressure in the drainage system. However, should the pump 66 fail in a closed state, it will be recognized that pressure release will obtain via thefirst seal bottle 10 without a detrimental buildup of pressure by reason of the fact that thetube 16 establishes communication of the interior of thebottle 10 to the atmosphere while the lower end of thetube 18, in communication with thetrap bottle 32 is just below the level ofliquid 14 inbot tle 10.

On the other hand, should the pump 66 fail in the open state, it will be appreciated that the location of the lower end of thetube 98 of thesecond seal bottle 102 just below the level of the liquid 104 therein will preclude any backflow of air into the pleural cavity of the patient. Thus, the system is adaptable for use with suction and eliminates any possibility of harm to the patient due to pump failure. Moreover, it will be appreciated that the same can be employed without suction in the same way as the two-bottle system illustrated in .FIG. 2. And, as with the in series three-bottle system,

air leaks in the lungs may be visually assessed by observation of the bubbling in thesecond seal bottle 102.

The invention also contemplates the provision of a liquid flow path between the first andsecond seal bottles 10 and 102, respectively. As illustrated, aconduit 128 extends therebetween and includes a manuallyoperable valve 130. The purpose of this construction is simplification of filling of theseal bottles 10 and 102 with a liquid such as water, particularly when the invention is embodied in a unitized structure. When such is the case, only one of the bottles need be filled with thevalve 130 open to result in the other of the bottles being filled to the same level. After filling, thevalve 130 may be closed, the entire operation not requiring separate filling of each bottle.

It will also be appreciated that the invention does not require four distinct chambers to practice. For example, the structure of theseal bottle 102 may be incorporated in the pressure-regulatingbottle 50 as described above in conjunction with the description of the variation of the in series three-bottle system of FIG. 3.

Finally, it should be recognized that vacuum source failure referred to herein is not limited to failure of a vacuum pump itself. Source failure of the open type can occur due to large-scale leaks in a vacuum line while closed state failure may result from the closing of a valve in a vacuum line.

I claim:

1. Suction drainage apparatus comprising: first means defining a trap chamber having an inlet adapted to be connected to a catheter to be received in a body cavity to drain fluids therefrom, and an outlet, said chamber being adapted to serve as a trap for body fluids drained from the body cavity; second means defining at least one additional chamber for receiving liquid and having a first inlet connected to said first chamber outlet, a second inlet, and an outlet adapted to be con nected to a vacuum source; said additional chamber first inlet extending thereinto a distance sufficient to be just immersed in a liquid received in said additional chamber; said second inlet establishing communication from the interior of said additional chamber to the exterior thereof and extending thereinto to be immersed in a liquid received in said additional chamber a distance sufficient to establish a desired negative pressure; and means in said apparatus for preventing reverse flow through said first chamber inlet while precluding pressure buildup in said first chamber.

2. The suction drainage system of claim 1 wherein said additional chamber is comprised of two components each adapted to receive a liquid, a first of said compartments including said first inlet and the second of said compartments including said second inlet and said outlet, and means establishing a path of gas flow between said compartments.

3. The suction drainage apparatus of claim 2 wherein said preventing means comprises a third chamber adapted to receive a liquid, said third chamber including an outlet to the exterior of the third chamber above a desired liquid level therein and an inlet just slightly below the desired liquid level; and means establishing a gas flow path between said third chamber inlet and one of said first chamber and said first and second compartments.

4. The suction drainage apparatus of claim 3 further including means establishing a liquid flow path between said third chamber and said first compartment.

5. The suction drainage apparatus of claim 4 wherein said liquid flow path includes selectively operable valve means.

6. The suction drainage apparatus of claim 3 wherein said gas flow path is established to said first chamber.

7. The suction drainage apparatus of claim 1 wherein said preventing means comprises a third chamber adapted to receive a liquid, said third chamber including an outlet to the exterior of the third chamber above a desired liquid level therein and an inlet just slightly below the desired liquid level; and means establishing a gas flow path between said third chamber inlet and one of said first and second chambers.

8. The suction drainage apparatus of claim 7 wherein said gas flow path is established to said first chamber.

9. Suction drainage apparatus comprising: a chamber defining a body fluid drainage trap, said chamber including an inlet and an outlet; a catheter in fluid communication with said inlet; a vacuum source of the type that may fail in open or closed states; vacuumregulating means; means establishing a gas flow path from said outlet to said vacuum source via said vacuum-regulating means; means in said gas flow path for precluding the flow of gas therein from said vacuum source to said cathether should the vacuum source fail in an open state; and means in fluid communication with said chamber for establishing a pressure relief path should the vacuum source fail in a closed state.

10. Suction drainage apparatus comprising: means defining a trap chamber having an inlet adapted to be connected to a catheter, and an outlet; means defining a pair of seal chambers, each adapted to receive liquid to a predetermined level, and each having an inlet at least just below said predetermined level and an outlet above said predetermined level; means defining a pres sure regulating chamber adapted to receive liquid to a predetermined level and having a first inlet and an outlet thereabove and a second inlet therebelow, said outlet being adapted to be connected to a vacuum source; means establishing a first gas flow path from said trap chamber outlet to at least one of said seal chamber inlets; means establishing a second gas flow path from said one seal chamber outlet to said pressure regulating chamber first inlet; ane means establishing a third gas flow path from the other seal chamber inlet to one of said trap chamber, said one seal chamber and said pressure-regulating chamber; said other seal chamber outlet and said pressure-regulating chamber second inlet I being open to the atmosphere.

9 10 13. The suction drainage apparatus ofclaim 12 further including selectively operable valve means in said ther including selectively operable valve means in said liquid flow path. liquid flow path. 16. The suction drainage apparatus ofclaim 10 fur- 14. The suction drainage apparatus ofclaim 10 further including a catheter connected to said trap chamther including means establishing a liquid flow path be- 5 ber inlet and a vacuum pump connected to said prestween said seal chambers. sure regulating chamber outlet.

15. The suction drainage apparatus ofclaim 14 fur-

Claims (16)

1. Suction drainage apparatus comprising: first means defining a trap chamber having an inlet adapted to be connected to a catheter to be received in a body cavity to drain fluids therefrom, and an outlet, said chamber being adapted to serve as a trap foR body fluids drained from the body cavity; second means defining at least one additional chamber for receiving liquid and having a first inlet connected to said first chamber outlet, a second inlet, and an outlet adapted to be connected to a vacuum source; said additional chamber first inlet extending thereinto a distance sufficient to be just immersed in a liquid received in said additional chamber; said second inlet establishing communication from the interior of said additional chamber to the exterior thereof and extending thereinto to be immersed in a liquid received in said additional chamber a distance sufficient to establish a desired negative pressure; and means in said apparatus for preventing reverse flow through said first chamber inlet while precluding pressure buildup in said first chamber.

2. The suction drainage system of claim 1 wherein said additional chamber is comprised of two components each adapted to receive a liquid, a first of said compartments including said first inlet and the second of said compartments including said second inlet and said outlet, and means establishing a path of gas flow between said compartments.

3. The suction drainage apparatus of claim 2 wherein said preventing means comprises a third chamber adapted to receive a liquid, said third chamber including an outlet to the exterior of the third chamber above a desired liquid level therein and an inlet just slightly below the desired liquid level; and means establishing a gas flow path between said third chamber inlet and one of said first chamber and said first and second compartments.

4. The suction drainage apparatus of claim 3 further including means establishing a liquid flow path between said third chamber and said first compartment.

5. The suction drainage apparatus of claim 4 wherein said liquid flow path includes selectively operable valve means.

6. The suction drainage apparatus of claim 3 wherein said gas flow path is established to said first chamber.

7. The suction drainage apparatus of claim 1 wherein said preventing means comprises a third chamber adapted to receive a liquid, said third chamber including an outlet to the exterior of the third chamber above a desired liquid level therein and an inlet just slightly below the desired liquid level; and means establishing a gas flow path between said third chamber inlet and one of said first and second chambers.

8. The suction drainage apparatus of claim 7 wherein said gas flow path is established to said first chamber.

9. Suction drainage apparatus comprising: a chamber defining a body fluid drainage trap, said chamber including an inlet and an outlet; a catheter in fluid communication with said inlet; a vacuum source of the type that may fail in open or closed states; vacuum-regulating means; means establishing a gas flow path from said outlet to said vacuum source via said vacuum-regulating means; means in said gas flow path for precluding the flow of gas therein from said vacuum source to said cathether should the vacuum source fail in an open state; and means in fluid communication with said chamber for establishing a pressure relief path should the vacuum source fail in a closed state.

10. Suction drainage apparatus comprising: means defining a trap chamber having an inlet adapted to be connected to a catheter, and an outlet; means defining a pair of seal chambers, each adapted to receive liquid to a predetermined level, and each having an inlet at least just below said predetermined level and an outlet above said predetermined level; means defining a pressure regulating chamber adapted to receive liquid to a predetermined level and having a first inlet and an outlet thereabove and a second inlet therebelow, said outlet being adapted to be connected to a vacuum source; means establishing a first gas flow path from said trap chamber outlet to at least one of said seal chamber inlets; means establishing a second gas flow path from said one seal chamber outlet to said pressure regulating chamber first inlet; ane means establishing a third gas flow path from the other seal chamber inlet to one of said trap chamber, said one seal chamber and said pressure-regulating chamber; said other seal chamber outlet and said pressure-regulating chamber second inlet being open to the atmosphere.

11. The suction drainage apparatus of claim 10 wherein said third gas flow path is established between said other seal chamber inlet and said trap chamber outlet.

12. The suction drainage apparatus of claim 11 further including means establishing a liquid flow path between said seal chambers.

13. The suction drainage apparatus of claim 12 further including selectively operable valve means in said liquid flow path.

14. The suction drainage apparatus of claim 10 further including means establishing a liquid flow path between said seal chambers.

15. The suction drainage apparatus of claim 14 further including selectively operable valve means in said liquid flow path.

16. The suction drainage apparatus of claim 10 further including a catheter connected to said trap chamber inlet and a vacuum pump connected to said pressure regulating chamber outlet.

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