WO1996012511A1

WO1996012511A1 - Apparatus and method for continuous aspiration and reinfusion of blood during or after surgery

Info

Publication number: WO1996012511A1
Application number: PCT/US1995/013549
Authority: WO
Inventors: James W. Jones; William H. Marshall; Robert E. Williams
Original assignee: Haemonetics Corporation
Priority date: 1994-10-19
Filing date: 1995-10-16
Publication date: 1996-05-02
Also published as: AU4005995A

Abstract

A system for continuous withdrawal of blood and other fluids from a chest cavity and continuous reinfusion of such blood and other fluids into the patient, includes a withdrawal member for insertion into the chest or other wound cavity, the withdrawal member including a blood removal chamber which extends into the chest cavity of the patient. Flow of blood and other fluids from the chest cavity into the withdrawal member is controlled by a one-way valve, such as a Heimlich valve. The withdrawal or pump-tube member includes a central tubular member which extends outwardly of the pump-tube member with an annular chamber being formed between the central withdrawal tubular member and the outer wall of the pump-tube apparatus. A supply of ambient air and one or more maintenance fluids are delivered into the annular area of the pump-tube apparatus for convergence in a blood removal chamber portion such that blood which has passed through the Heimlich valve is aspirated and flowed into the withdrawal tube. The withdrawal tube is connected to a collection chamber which itself is under vacuum to cooperate in the removal of the blood and any maintenance fluids from the pump-tube apparatus for collection in the collection chamber. A reinfusion line is connected to the collection chamber for attachment to the patient such that blood is continually withdrawn from the patient's chest area during and after surgery and continuously re-infused into the patient with a minimum amount of exposure to foreign substances.

Description

APPARATUS AND METHOD FOR CONTINUOUS ASPIRATION AND REINFUSION OF BLOOD DURING OR AFTER SURGERY

FIELD OF THE INVENTION

This invention relates to the continuous withdrawal of blood from the pleural or mediastinal cavity during and after surgery. BACKGROUND OF THE INVENTION

While it has previously been recognized that it is desirable to return blood drawn from a patient during surgery to the patient, concern over the safety of blood transfusions from donors has created an even greater need for reinfusion of a patient with his or her own blood during and/or after surgery. For example, during cardiac surgery, it is not unusual for a patient to lose 500 cc or more of blood in the first 8 hours after the surgery. Typically, this blood is allowed to flow by gravity into a plastic sump where it collects and is measured. If the quantity collected is small, it may be discarded. If the quantity of blood collected is large, it may be reinfused into the patient. Typically, this reinfusion is accomplished as a batch process. Every hour a nurse monitors the amount of blood lost. If reinfusion is indicated, the nurse will hang the plastic sump on an IV pole to allow the blood to flow back by gravity into the patient. However, this procedure may cause damage to the blood. Simply by pooling, and further because of contact of the blood with the foreign substance, the wall of the plastic sump, blood undergoes a number of adverse reactions, including clotting, that make it potentially unsuitable for reinfusion. It is desirable to reinfuse the blood into the patient as soon as it is collected from the wound site. A truly continuous collection and reinfusion method would require the blood to remain in contact with foreign substances for a minimal time rather than a few hours as is typically done.

This batch process of withdrawal of blood from the chest cavity is also inefficient because the flow of blood from the chest cavity is accomplished by gravity. For example, it is known that a nurse may have to even squeeze the chest drainage tubes in order to empty blood which has been drained out of the chest.

U.S. Patent No. 4,382,442, naming James W. Jones as inventor, and entitled "Thoracostomy Pump-Tube Apparatus," is directed to solution of part of the problem just described. The thoracostomy tube disclosed in the '442 patent provides a pumping arrangement associated with a tube for removing blood and other body fluids which enter the tube from the chest cavity. The pump-tube is an elongated tube and is partially insertable into the thoracic cavity of a patient during a thoracostomy. A one-way valve, such as for example a Heimlich or duck-bill valve, is mounted within a passageway in the tube to allow blood and other chest fluids to flow into the tube under the urging of only the pressure normally experienced within the lung cavity. However, once the fluids pass from the lung cavity into the tube through the Heimlich valve, they are removed by a vacuum which is created at the outlet portion of the valve. The vacuum is created by attaching a suitable vacuum means or suction to the proximal end portion of the tube. It is taught in the •442 patent that the vacuum may be provided by any suitable vacuum source such as vacuum sources provided in hospitals, medical offices, clinics and similar institutions. Additionally, a pair of air conveying conduits are provided within the inner bore of the tube. Each of the conduits is provided with an air intake open to atmospheric pressure and an air discharge. The normal flow of air during operation of the tube will be through the air conveying conduits into the main passageway of the pump-tube wherein the air flow within the conduits is induced by the vacuum in the main passageway of the tube. This vacuum produces a continuous flow of air in the conduits which aids in removal of fluids which have migrated from the chest area through the opening at the distal end portion of the tube and through the Heimlich valve. While the '442 patent thus teaches the withdrawal of blood and other body fluids from the chest area, there is no disclosure of consideration for the problem of reinfusion of blood back into the patient. SUMMARY OF THE INVENTION

It is an object of this invention to provide for the continuous collection of blood and other body fluids from the chest cavity and for the continuous reinfusion of such collected fluids back into the patient in order to minimize the amount of time that the blood remains out of the body. It is a further object of this invention to minimize the length of time that blood withdrawn from the chest cavity remains outside of the patient. The minimization of pooling of the blood outside of the patient's body and before return to the patient prevents decay or other damage to the blood as a result of contact with foreign substances such as the walls of a collection sump and the like. This invention also obviates the loss of substantial amounts of intravascular volume (blood) outside the body which is a necessary disadvantage of present reservoir methods of collection. In this invention, a system is provided for continuous withdrawal of blood from the chest or other wound cavity of a patient and reinfusion of blood into the patient.

The continuous withdrawal and reinfusion system of this invention includes a withdrawal member for insertion into the chest or other wound cavity of a patient, the withdrawal member including a blood removal chamber which extends into the chest cavity of the patient. The withdrawal member further includes a withdrawal passage which terminates at the blood removal chamber, which withdrawal passage is in fluid communication with blood removed from said chest cavity. The withdrawal member further includes a one¬ way valve mounted in the blood removal chamber to allow withdrawal of blood from the chest cavity into the blood removal chamber but preventing the direct return thereof into the chest cavity. The withdrawal and refusion system of this invention further includes a collection chamber positioned above the withdrawal apparatus. A transfer line is mounted in fluid communication with the withdrawal passage of the withdrawal member and with the collection chamber for the transfer of blood from the chest cavity into the blood removal chamber, through the withdrawal passageway of said withdrawal member and through the transfer line into the collection chamber. The withdrawal member includes an aspirator passageway in fluid communication with air at atmospheric pressure, the aspirator passageway extending within the withdrawal member parallel to the withdrawal passageway and terminating at the blood removal chamber of the withdrawal member for introducing air into the withdrawal passage simultaneously with entry of blood into the withdrawal passage. The collection chamber has mounted therewith a source of continuous negative or vacuum air pressure which applies a negative pressure within the collection chamber and transfer line such that the negative pressure in the transfer line induces the flow of air from the aspirator passageway into the collection chamber and withdrawal passageway to transfer blood from the withdrawal passage, through the transfer line, and into the collection chamber. A reinfusion line is attached to the collection chamber and includes an intravenous needle at its distal end for insertion into the patient such that blood which is continuously withdrawn from the chest cavity of the patient is continuously returned to the patient, thereby minimizing the amount of time that such withdrawn blood is out of the body of the patient. This description of the invention is intended as a summary only. The detailed features of the preferred embodiment will be described and the claims will set forth the patentable subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. l is a schematic view of the system of the preferred embodiment of this invention for continuous removal of blood- from the chest cavity and reinfusion into the patient; Fig. 2 is a side view in section of the pump-tube or withdrawal member of this invention;

Fig. 3 is a side view in section of the collection chamber of this invention; Fig. 4 is a flow chart of apparatus for determining the flow rate of blood being reinfused into the patient and other information;

Fig. 5 is a view of the display provided by the blood flow rate apparatus of Fig. 4; Fig. 6 is a side view in longitudinal section of an alternative embodiment of the pump-tube apparatus or blood withdrawal tube of this invention; and

Fig. 7 is a transverse, sectional view taken along lines 7—7 of Fig. 6. DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to Fig. 1, the apparatus A and method for the continuous aspiration and reinfusion of blood during or after surgery is shown. The apparatus A includes a surgical pump-tube or withdrawal member generally designated as 10 in Fig. 1 and illustrated in section in Fig. 2. The pump-tube apparatus 10 provides for the removal of blood and other body fluids (hereinafter collectively referred to simply as "blood") from the chest during and after surgery. While the apparatus A has application in other wound cavities of a patient, the chest region of the human body is particularly difficult to provide for the withdrawal of blood from because the chest cavity outside the lungs is maintained at negative pressure or vacuum. Any intrusion of positive pressure into the chest cavity outside the lungs may cause the collapse of the lungs. Therefore, blood removal from the chest cavity must take- place without transfer of air or other gas under positive pressure into the chest cavity. U.S. Patent No. 4,382,442 of Jones provides apparatus and method for accomplishing the removal of blood from the chest cavity during and after surgery. As will be seen from a more detailed description of the blood withdrawal member 10, the blood withdrawal member 10 is substantially similar to the pump-tube apparatus illustrated in U.S. Patent No. 4,382,442.

Referring to Fig. 1 and Fig. 2, a fluid maintenance supply generally designated as 30 is provided to drip a saline solution or other maintenance fluid through a drip chamber 30 and maintenance fluid line 30c into a maintenance fluid inlet lOa of the pump-tube apparatus 10. The pump-tube apparatus 10 includes a withdrawal passage 10c which is attached to a suitable flexible tube or transfer line 16 which extends into attachment with collection chamber inlet 20a of collection chamber 20. The collection chamber 20 also includes inlet 20b (identified in Fig. 2) which is attached to a tubular member 21 which extends into attachment with a vacuum system 25 (Fig. l) which is the vacuum system typically provided by a hospital and available in operating rooms and the like. The collection chamber 20 is attached through blood filter

22 to drip chamber 23, which is attached to a conduit or line 24 which terminates in a distal end having a suitable intravenous needle (not shown) for insertion into the patient so that blood collected in the drip chamber 23 is reinfused into the patient.

An electronic drop counter 40 is positioned adjacent to drip chamber 30a which collects intravenous fluid dripping from the fluid supply bag 30b. A second fluid drop counter 41 is positioned about drip chamber

23 mounted below collection chamber 20. The blood drop counters 40 and 41 are utilized in a suitable flow rate calculator generally designated as 50 (Fig. 4) in order to determine the flow rate of blood returning to the patient.

Referring to Fig. 2, the pump-tube apparatus or member 10 includes a hollow cylindrical outer member or housing lOd which is reduced or necked-down at its proximal end portion lOe to form an opening lOf. The other or distal end of the pump-tube apparatus 10 tapers to a circular opening lOh. A one-way valve member, such as Heimlich or duck-bill valve disclosed in U.S. Patent 4,382,442 is mounted in the open distal end lOh of the cylindrical member lOd for allowing flow of blood in the direction of arrows 31 but preventing the flow of blood or gas in the direction opposite to the arrows 31, that is, preventing the return flow or other intrusion of liquid or gas into the chest cavity of the patient. The withdrawal tube 10c is mounted centrally within the hollow cylindrical member lOd. The withdrawal tube 10c is also cylindrical and thus includes an interior cylindrical bore herein designated as lOi. The withdrawal tube terminates at end 10j sufficient distance from the opening lOh of distal end lOg of the outer cylindrical member lOd of the pump- tube apparatus to provide a blood removal chamber C which extends in the chest cavity of the patient and in which the one way valve V is mounted. An annular space generally designated as 10k is formed between the internally positioned withdrawal tube 10c and the inner wall of the outer cylindrical housing lOd of the pump- tube apparatus. The withdrawal tube 10c is mounted in the proximal opening lOf and extends outwardly therefrom into a suitable connection (not shown) with the transfer line 16 leading to the collection chamber 20. Inlet 10a is formed in the outer housing lOd of the pump tube apparatus 10 for the introduction of intravenous fluid. Inlet 10a is connected to line 30c (Fig. 1) for fluid communication with the drip chamber 30a and intravenous bag 30b. The actual connection between the inlet 10a and the transfer line 30c is not illustrated but may be of any suitable type. An air inlet generally designated as 15 is also formed in the outer housing of the pump tube apparatus 10. The air inlet 15 includes a tubular inlet portion 10b, which receives an air filter 15b such that air entering the outer end 15a of the air inlet is filtered before entering the annular area 10k between the withdrawal passage 10c and the outer housing lOd. In use, the distal end of the pump-tube apparatus

10 is inserted into the patient's chest cavity during or after an operation. As described in U.S. Patent No. 4,382,442, pressure differential between the chest cavity side of the Heimlich valve V, where arrows 31 are located, and the negative pressure within the blood removal chamber C provides for the one-way transfer of blood through the Heimlich or duck-bill valve, which is made of a flexible rubberized tube as disclosed in U.S. Patent No. 4,382,442. The introduction of filtered, ambient air from line 15a, through air filter 15b and pump-tube inlet 10b into the annular area 10k is represented by arrows 32. Air flowing through the annular area 10k of the pump tube apparatus flows into the internal inlet lOj of the central withdrawal tube 10c. The introduction of filtered, ambient air flowing downwardly within the annular area 10k of the pump tube into the region of blood collection chamber C and into the withdrawal tube 10c is induced by the vacuum within the collection chamber 20 which created a vaccuum in the transfer line 16 and withdrawal passage 10c. The mixing of the air flowing within annular area 10k with the blood passing from the chest and into the blood collection chamber C aspirates the blood as the blood enters inlet lOj of the withdrawal tube 10c to enhance upward movement of the blood through transfer line 16 toward the collection chamber 20. The blood withdrawal is also enhanced by any mixture of maintenance fluid from line 30c with the air induced into the annular area 10k and ultimate mixing of both the air and maintenance fluid with the blood entering the inlet lOj of the withdrawal passage 10c.

The purpose of the one-way or back flow valve V such as the Heimlich valve at the opening or mouth lOh of the outer tube lOd is to prevent the chest cavity from being exposed to atmospheric pressure, which could cause the lungs to collapse and create a life- threatening situation. The utilization of the one-way or backflow valve V prevents air from flowing into the chest cavity, which is typically under a slight vacuum (5 to 15 cm of water) in order to keep the lungs inflated and expanded. While the backflow valve of the Heimlich type valve V as disclosed in U.S. Patent No. 4,382,442, is a preferred embodiment because it is small, simple, reliable, inexpensive and can pass large pieces or gelled globules such as coagulated blood without plugging, there may be other one-way valves which can also properly function in a manner similar to the Heimlich valve V. The purpose of the intravenous maintenance fluid supply 30 is to infuse glucose, saline or other aqueous maintenance fluids for mixing with blood removed from the patient prior to reinfusion into the patient. Several beneficial effects result, including a continuous cleansing of the aspiration or withdrawal tube 10c and washing of blood from the wall of the bore lOi of the withdrawal tube 10c. Also, utilization of maintenance fluids dilutes the blood thereby reducing its natural clotting tendency.

Referring to Fig. 3, the collection chamber 20 is a generally cylindrical, hollow container converging to a bottom outlet 26c and having an upper, circular top 20d which has tubular inlets 20a and 20b. Tubular inlet 20a is attached to the transfer line 16 for the flow of aspirated blood from the pump-tube 10 into the hollow, cylindrical interior 20e of the collection chamber 20. As previously described, a suitable vacuum system such as the type readily available in hospitals and numbered 25 in Fig. 1 is attached to the inlet 20b through vacuum line 21.

The collection chamber 20 for receiving the blood/intravenous fluid/air mixture from line 16 should be held at some constant vacuum through the collection/reinfusion procedure of this invention regardless of the amount of blood or fluid being aspirated. This may be accomplished in most operating and intensive care areas utilizing a reliable source of regulated vacuum 25. A third tubular outlet 20f is integrally formed in the top 20d to house a vacuum relief valve 26 to prevent the vacuum within the collection chamber 20 from exceeding a predesignated level. The valve 26 may be of the type available at Smart Products, Inc., Part No. 205, which allows for adjustment of spring loading of the relief valve to the desired level of vacuum. An air filter (not shown) may be mounted onto the relief valve 26 to filter air entering through- the inlet 2Of. A suitable dome-shaped filter 27 is provided in the upper portion of the collection chamber of the interior 20e of the collection chamber 20 and may have a pore size of approximately 170 microns. It is contemplated that other shapes of filters such as circular, cylindrical or conical may also be used. One of the reasons for the filter 27 is to limit the effect of vacuum-produced excess foaming. Collection chamber bottom outlet 20c is attached to reinfusion line portion 24a, which in turn is attached to the drip chamber 23 shown in Fig. 1, which attaches to the remainder of the reinfusion line 24. The lower or distal end of the reinfusion line 24 includes a suitable intravenous needle for the reintroduction of blood and other fluids in combination with any suitable intravenous fluid into the patient.

Referring to Fig. 4, the blood flow reporting calculator 50 is illustrated in flowchart form. The infra-red sensor beams numbered 1 and 2 represent the fluid flow monitors 40 and 41. The flow from the collection chamber 20 into the drip chamber 23 is actually a flow of blood and maintenance fluid. Utilizing a suitable microprocessor 51, the flow rate of blood and maintenance fluid through the fluid monitor 41 is calculateed. In order to determine the net flow rate of the blood itself being returned to the body, the microprocessor 51 subtracts the flow rate of the maintenance fluid "A" identified in Fig. 5 from the total fluid flow rate measured by flow monitor 41 to provide a net flow rate such as "25" (in Fig. 5) in cc/hr. for blood only. The maintenance fluid A is actually the fluid flowing from intravenous fluid bag 30b. Suitable flow monitors may be designed by persons of ordinary skill in the art utilizing the standard /12511

-13- drop counters IV-Mate manufactured by Invivo Research, Inc. of Orlando, Florida. Additionally, a suitable bubble detector as is known in the art, and identified as 22 in Fig. 1 is mounted in the transfer line 24 just below collector outlet 20c for providing transduced electrical signals to the microprocessor 51 so that the microprocessor 51 can display and provide an alarm in the event of detection of bubbles within the blood being returned to the patient. As illustrated in Fig. 5, it is within the scope of this invention to provide the blood flow calculator 50 with a calculator for determining the flow rate of a second maintenance fluid "B". The second maintenance fluid identified in Fig. 5 as maintenance fluid B, is introduced into a second pump-tube apparatus 10 provided at another location in the patient's chest or elsewhere and also connected to the same collection chamber 20. In the event that a second maintenance fluid B and second pump-tube apparatus is utilized, the microprocessor 51 will receive signals from a third blood flow monitor and will compute a net blood flow rate subtracting the flow rate of both maintenance fluids A and B from the fluid flowing into the collector 20. The blood flow calculator 50 may also include a suitable alarm to signal audibly and visually actual blood flow reaching flow limits, i.e., flow below minimum or maximum levels in terms of flow per unit time or total flow.

It is also within the scope of this invention to connect the second pump-tube apparatus to a second collection chamber identical to the collection chamber 20 such the blood being drawn from the second location in the patient has its own separate supply of vaccuum. If two collection chambers are used with two pump-tube devices, then the outlet of the second collection chamber should connect to the outlet of the first collection chamber above the bubble detector so that the fluid flow calculator 50 will be able to measure the combined flow of blood and maintenance fluids returning to the patient. The microprocessor may be further programmed to show the blood flow rate over time as illustrated in the display of Fig. 5. A suitable bubble detector is available from Ultrasonic Bubble Detectors of Zevex of Salt Lake City, Utah.

Referring now to Figs. 6 and 7, an alternate pump- tube apparatus generally designated as 60 is illustrated. The pump-tube apparatus 60 is an integral or one-piece unit which can be extruded for ease in manufacturing. The alternate pump-tube apparatus 60 is a solid cylindrical member generally designated as 60a which includes a large central withdrawal bore 60b and smaller fluid inlet bores 60c, 60d and 60e. One of the bores 60c-e is for induced circulating air. Another of the bores 60c-e is for maintenance fluid and another of the bores 60c-e is for other purposes, such as monitoring the vacuum pressure in the chamber C . In Fig. 6, the alternate pump-tube 60 includes a distal cylindrical portion 60f which extends from the multi- bore section illustrated in Fig. 7 and terminates in an open end 60g wherein a suitable one-way valve such as the Heimlich valve V is mounted.

Testing This invention has been tested using prototypes with dogs and pigs in vivo and with human blood in vitro. In each of these tests, the blood has been maintained nearly intact at the molecular level upon withdrawal and reinfusion, remaining suitable for replenishing the blood lost during surgery and eliminating reliance upon the introduction of homologous blood products.

To evaluate this invention on humans, written consent was obtained from eleven normal volunteers and 500 cc of whole blood was drawn from each volunteer. This blood was cycled through the invention. In the early trials the timed reinfusion was as short as 30 seconds for the first pass to an average infusion time of less than 5 minutes.

Each volunteer's blood was tested before being circulated through the invention. Samples were drawn to ensure normality of clotting factors and blood elements. Each patient thereby served as his own control. Blood was tested for cellular integrity immediately after it was drawn. The blood was then continuously passed through the invention and sampled at 10 minutes, 1 hour and 3 hours. Tests evaluated potential changes in formed blood elements, including red blood cells, white blood cells and platelets, and coagulation factors.

The minimal rise of free hemoglobin measurements after 3 hours of passage through the invention showed that 99.95% of the red blood cells remained intact or unhemolyzed. The control values for blood before retrieval of 2.4 mg/dL rose only to 3.8 mg/dL, 3.2 mg/dL and 5.5mg/dL after 10 minutes, l hour and 3 hours, respectively, of introduction to the invention. (Values of 5 mg/dL or below are considered within normal limits for this test.)

Platelet concentrations corrected for dilution showed a progressive rise such that at 3 hours, 85% of the platelets introduced were reinfused from an initial baseline first pass return of 59%. However, after passage through the invention, the "activated platelets" increased from control ranges of 3-13% to post 3-hour ranges of 21-39%.

Coagulation proteins were minimally affected as measured by D-Dimer values which remained normal (<0.5) throughout the experiment. Over 65% of the fibrinogen was maintained intact after exposure to the invention.

Indirect indicators of the integrity of the device-transported blood, including potassium and LDH, did not rise above baseline values.

In summary, the data collected from the tests indicate an improvement in the quality of blood reinfused using the invention as compared to currently available reservoir technology. Having described the invention above, various modifications of the techniques, procedures, material and equipment will be apparent to those in the art. It is intended that all such variations within the scope and spirit of the appended claims be embraced thereby. For example, while this invention has been described in the environment of removal of blood from the chest cavity, it should be understood that this invention has application in any other surgery where blood loss and replenishment is an issue, such as thoracic, vascular and orthopedic surgeries.

Claims

CLAIMS :

1. A system for continuous withdrawal of blood from a patient and re-infusion of the withdrawn blood into the patient, comprising: a withdrawal member for insertion into the chest cavity of a patient, said withdrawal member including a blood removal chamber and which extends into the wound cavity of a patient, said withdrawal member including a withdrawal passage which terminates at said blood removal chamber which is in fluid communication with blood removed from said wound cavity, said withdrawal member including a one-way valve mounted in said blood removal chamber to allow the withdrawal of blood from said wound cavity into said blood removal chamber but prevent the return of air or other fluid into said wound cavity; a collection chamber positioned above said withdrawal member; a transfer line mounted in fluid communication with said withdrawal passage of said withdrawal member and with said collection chamber for transfer of blood from said wound cavity into said blood removal chamber, through said withdrawal passage of said withdrawal member and said transfer line into said collection chamber; said withdrawal member including a port exposed to ambient air; said withdrawal member including an aspirator passageway in fluid connection with said supply of ambient air, said aspirator passageway terminating at said blood removal chamber of said withdrawal member for introducing ambient air into said withdrawal passage simultaneously with entry of blood removed from the patient's wound cavity into said withdrawal passage; said collection chamber having mounted therewith a source of negative air pressure which applies a negative pressure within said collection chamber, said transfer line and said withdrawal passage to cooperate with ambient air from said aspirator passageway to transfer blood from said withdrawal passage in said withdrawal member, through said transfer line and into said collection chamber; and a reinfusion line attached to said collection chamber and to said patient such that blood continuously withdrawn from the wound cavity of the patient is continuously returned to said patient.

2. The system of claim 1, including: said withdrawal member including a fluid entry port in fluid communication with said aspirator passageway; and a supply of maintenance fluid including a maintenance fluid line attached to said fluid entry port for continuous delivery of maintenance fluid into said blood removal chamber for mixing with blood in said blood removal chamber for continuous delivery of maintenance fluid with the blood being continuously collected and re-infused into said patient.

3. The system of claim 1, wherein: said source of continuous negative pressure is the standard vacuum source available in hospitals.

4. The system of claim 1, including; a vacuum relief valve mounted in fluid communication with collection chamber to regulate the vacuum pressure in said collection chamber.

5. The system of claim 1, wherein: said one-way valve is a Heimlich-type valve.

6. The system of claim 2, including: a blood and maintenance fluid flow monitor mounted with said re-infusion line to continuously determine the flow rate of blood and maintenance fluid through said re-infusion line into said patient.

7. The system of claim 6, including: a maintenance fluid flow monitor mounted with said maintenance fluid line to continuously determine the flow of maintenance fluid into said aspirator passageway.

8. The system of claim 2, including: a blood and maintenance fluid flow monitor mounted with said re-infusion line to continuously determine the flow rate of blood and maintenance fluid through said re-infusion line into said patient; a maintenance fluid flow monitor mounted with said maintenance fluid line to continuously determine the flow of maintenance fluid into said aspirator passageway; and calculator means for determing the net flow of blood returning to the patient through said reinfusion line.

9. The system of claim 2, wherein said maintenance fluid is a normal saline solution.

10. A system for continuous withdrawal of blood from the chest cavity of a patient and return to the patient during and after surgery, comprising: withdrawal means for mounting partially into said chest cavity for removal of blood from the chest cavity of the patient, said withdrawal means including a one-way valve allowing removal of blood from the chest cavity but preventing the re-entry thereof; said withdrawal means including a withdrawal passageway and ambient air supply means for supplying air to said withdrawal passageway to aid in transfer of blood flow through said withdrawal passage; a collection chamber in fluid connection with said withdrawal passage; a continuous supply of vacuum attached to said collection chamber for exerting a vacuum on said collection chamber to transfer blood removed from the chest cavity to said collection chamber; and a re-infusion line attached to said collection chamber and extending to said patent for continuously transferring blood collected in said collection chamber to said patient; and, flow rate calculation means mounted with said re-infusion line for measuring the flow rate of blood flowing from said collection chamber into said patient.

11. The system of claim 10, including: said withdrawal member including a fluid entry port in fluid communication with said aspirator passageway; and a supply of maintenance fluid including a maintenance fluid line attached to said fluid entry port for continuous delivery of maintenance fluid into said blood removal chamber for mixing with blood in said blood removal chamber for continuous delivery of maintenance fluid with the blood being continuously collected and re-infused into said patient.

12. The system of claim 10, wherein: said source of continuous negative pressure is the standard vacuum source available in hospitals.