Evaluation of a new blood autotransfusion device

J

THORAC CARDIOV ASC SURG

92:936-943, 1986

Evaluation of a new blood autotransfusion device A new autotI1lMfusion device was evaluated in dogs. The device uses citrate phosphate dextrose as the blood anticoagulant and automatically delivers the agent in a ratio approximating that found in banked blood. Bleeding, aspiration, and autotransfusion of approximately 3 estimated blood volumes produced small changes in hematologic and coagulation studies. Blood electrolytes stayed within normal ranges. Activated clotting times stayed within normal range after autotransfusion of 2 blood volumes but increased slightly after 3 blood volume tI1lMfusions. No significant histopathologic changes were found in any organ system. Rapid infusion of citrated blood causes myocardial depression, which can be reversed by giving calcium. Overall performance of the device was excellent, suggesting further documentation in a clinical setting and evaluation with human blood.

John M. Toomasian, C.C.P., Gary Schneiderman, Ph.D., Gail M. DeSmet, A.S.c.P., and Robert H. Bartlett, M.D., Ann Arbor, Mich.

Autotransfusion is the process of collecting and reinfusing blood lost from hemorrhage. It is applied where shed blood can be collected at the time of a sterile operation or from a sterile body cavity such as the pleural space. Although autotransfusion has been studied extensively and practiced clinically for the last 50 years.l-' it has been widely used only as an adjunct to cardiac operations for patients supported by cardiopulmonary bypass. Intraoperative autotransfusion has been successfully applied in millions of patients having cardiac operations and also in patients with hemorrhage resulting from trauma, vascular operations, orthopedic operations, and hemothorax. The advantages of autotransfusion compared with transfusion of banked blood include no chance for allergic reactions, no chance of transmitting disease, less effect on body temperature, minimal loss of platelets and clotting factors, no storage requirements, and potentially less expense. Factors limiting the widespread use of autotransfusion relate to the lack of availability of adequate devices and the complexity of existing devices. Shed blood must be anticoagulated, collected, defoamed and filtered, prepared for reinfusion, and infused with minimal damage to blood components. The device should be simple and reliable and should function without the aid From the Department of Surgery, University of Michigan, Ann Arbor, Mich. Received for publication June 24, 1985. Accepted for publication Jan. 9, 1986. Address for reprints: Robert H. Bartlett, M.D., University of Michigan Hospital, 2920B Taubman, Ann Arbor, Mich. 48109.

936

of a technician. Anticoagulation is not a problem during cardiac operations because the patient is given heparin before cardiopulmonary bypass. The autotransfusion apparatus itself is quite simple, but it is a part of the large cardiopulmonary bypass system that requires continuous attention by the perfusionist. The system is not, however, applicable to other types of hemorrhage. Several autotransfusion devices have been released into the marketplace within recent years. One system (American Bentley, Irvine, Calif.)" was a modification of a cardiopulmonary bypass system. Anticoagulation was achieved by aspirating blood and a heparin solution alternately. Filtering and defoaming was done with a conventional cardiotomy reservoir, and reinfusion was carried out with a roller pump. This system required a technician, and even with consistent monitoring, anticoagulation was sporadic. The blood became heparinized, which complicated any bleeding problems. The device was also susceptible to problems with air and particulate matter emboli.':" The device was withdrawn from the market because of these problems, despite widespread and successful use. Another device (Sorenson Research Co., Inc., Salt Lake City, Utah) 5 was introduced that used either citrate or heparin as the anticoagulant and was designed to provide controlled delivery of the anticoagulant at the tip of a suction wand as blood was aspirated. Blood was filtered and collected in a plastic bag that had to be disassembled from the vacuum apparatus before reinfusing. It is available currently in modified design for use in conjunction with cell washing devices. Cell washing centrifuges have been modified for use

Volume 92 Number 5

Blood autotransfusion device 9 3 7

November 1986

To Patient

Blood Bag Holder

Fig. 1. Autotransfusion system.

in the operating room for a variety of operative procedures." Shed blood is collected in excess heparin anticoagulant and centrifuged. The concentrated red cells are washed with saline solution, then reinfused into the patient. The supernatant plasma from centrifugation containing heparin, clotting factors, and platelets is discarded. The Cell Saver System device (Haemonetics Corp., Braintree, Mass.) is an example of such a device. These systems overcome the anticoagulation and filtration problems, but platelets and clotting factors from blood collected in the system are lost. The equipment is expensive and requires a technician for operation. A new autotransfusion system has been developed to meet the following criteria: (l) simple to set up and use, (2) completely disposable, (3) requires no external hardware or technician, (4) uses citrate anticoagulant in the proper ratio, and (5) allows salvage and reinfusion of a large quantity of blood with minimal hemolysis and with rninimallosses of platelets and coagulation factors. This report describes an in vivo evaluation of this device.

Methods Autotransfusion system. The autotransfusion system (ATS) (Thoratec BLOOOSTAT, Thoratec Laboratories Corp., Berkeley, Calif.) is diagrammed in Fig. 1. The device is supplied ready for use in a sterile package, and is completely disposable. The device is positioned on an IV pole, attached to unregulated wall suction, and primed. A vacuum levelwithin the range of 50 to 80 mm Hg is automatically set for blood aspiration by an integral vacuum regulator built onto the blood reservoir. The system achieves blood anticoagulation by automatically mixing staridard citrate-phosphate-dextrose (CPO) solution* with the blood as it is aspirated. The CPO is delivered near the tip of the suction wand in a ratio of blood to CPO within the inclusive range of 5 to 10, similar to that used in a standard unit of banked whole blood (nominally 7.0). ·CPD solution. Each deciliter contains 327 mg of citric acid (monohydrate) USP, 2.63 gm of sodium citrate (dihydrate) USP, 222 mg of monobasic sodium phosphate (monohydrate) USP, and 2.55 gm of dextrose (monohydrate) USP.

The Journal of Thoracic and Cardiovascular Surgery

938 Toomasian et al.

Table I. Changes in serum chemistry Base preop. Sodium (mfiq/L) Potassium (mEq/L) Bicarbonate (mEq/L) Chloride (mEq/L) Glucose (rng/dl) Total bilirubin (mg/dl) Creatinine (mg/dl) Calcium (rng/dl) Urea nitrogen (rng/dl) Phosphorus (mgl dl) Protein (gm/dl) Albumin (gm/dl) SGOT (lUlL) SGPT (lUlL) LDH (lUlL) Alkaline phosphatase (lUlL)

147.7 4.3 21.8 114.1 94.0 0.32 0.85 9.3 16.3 4.2 7.0 1.2 25.2 33.1 298.0 53.9

± 1.3 ± 0.2 ± 2.4 ± 1.5 ± 17.8 ± 0.16 ± 0.22 ± 0.4 ± 4.1 ± 0.9 ± 0.6 ± 0.2 ± 2.0 ± 11.9 ± 190.4 ± 31.2

Post-ATS 155.5 ± 4.3 ± 22.4 . ± 112.4 ± 140.0 ± 0.25 ± 0.89 ± 10.9 ± 12.9 ± 7.4 ± 4.9 ± 0.8 ± 29.1 ± 50.3 ± 156.3 ± 48.2 ±

3.7* 0.8 3.3 2.4 46.5t 0.14 0.20 2.4 3.7 1.8* 0.6* 0.1* 14.6 45.3 139.7 27.9

24 Hours postop. 147.7 3.8 22.2 112.6 74.1 0.28 0.81 8.8 10.5 3.6 6.1 1.1 251.0 99.4 345.9 188.8

± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±

3.6 0.3* 1.9 2.4 19.4t 0.13 0.23 0.53* 5.2t 1.0 0.5t 0.1 245.8t 92.6t 244.3 143.7t

Legend: Mean values ± standard deviation. SGOT, Serum glutamic oxatoacetic transaminase. SGPT, Serum glutamic pyruvic transaminase. LDH, Lactic dehydrogenase. 'Significant (p < 0.001) compared with baseline. tSignificant (p < 0.05) compared with baseline.

The vacuum regulator, valved delivery lines, and orifice diameters are designed to maintain the blood/ citrate ratio constant under variable conditions of use. The blood reservoir is a hard-shell plastic cardiotomy reservoir that contains a 120 ~m polyurethane blood filter coated with antifoam A. The anticoagulated blood collects in the blood reservoir, where it is grossly filtered and defoamed. The blood drains from the reservoir by gravity through a one-way valve into the integral blood reinfusionbag when the bag is placed in the lower of two positions. Any air that accumulates in the blood bag can be readily removed through a closed circuit line that runs from the blood bag back to the blood reservoir (Fig. 1). Raising the blood bag to the upper hook on the IV pole allows for transfusion back to the recipient after it passes through a transfusion filter. Another one-way valve in the reinfusion filter extension set limits retrograde blood flow into the reinfusion bag when it is in the lower position. The closed-loop valved system allows for continuous blood collection and repeated reinfusion of aspirated blood volumes by alternately lowering and raising the blood reinfusion bag. There is no interruption of vacuum for blood aspiration at any point in the cycle. Animal evaluation. Eleven conditioned mongrel dogs, weighing 16 to 36 kg each, were studied. The animals were anesthetized with sodium pentobarbital (30 tug] kg), and their lungs mechanically ventilated with air (14 ml/kg with no positive end-expiratory pressure). The

neck and groin areas were shaved and painted with povidone-iodine (Betadine) for operation. Leads were placed to monitor the electrocardiogram, and the animal was draped in a supine position. A femoral arterial catheter was placed and connected to a pressure transducer, and also served as the site for all subsequent blood sampling. A wide variety of blood electrolytes were measured, as shown in Table I. In addition blood was drawn for baseline hematologic and coagulation determinations, including hematocrit, platelet count, white blood cell count, prothrombin time,' partial thromboplastin time," thrombin time," fibrinogen,to fibrin degradation products," plasma hemoglobin," and aerobic and anaerobic blood cultures. A large neck well was created by exposing skin, subcutaneous tissue, and muscle with self-retaining retractors. The carotid artery was ligated and cannulated proximally with a No. 10 Fr. polyvinylchloride catheter. The jugular vein was ligated and cannulated proximally with a 12 gauge catheter to serve as the blood reinfusion site. The carotid artery catheter was directed into the neck well and opened to allow brisk bleeding. One bleedingreinfusion cycle comprised bleeding and aspiration until 1% of the body weight (10% of the estimated blood volume or 10 ml/kg) had been shed, collected in the device, and reinfused into the animal. The volumes of blood aspirated and CPD added by the device were recorded. Thirty milliliters of saline solution were rinsed through the suction wand after each bleed. No addition-

Volume 92 Number 5 November 1986

Blood autotransfusion device

CPO Rich _

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20

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500

15

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Fig. 2. Blood/citrate ratios in 275 cycles of blood aspiration and reinfusion.The ideal range of blood/citrate ratio is 5 to 10. n = number of cycles in designated range of ratios.

al fluids were administered intravenously. The volume ratio of blood to CPD (R) was calculated. The blood was reinfused from the autotransfusion system to the venouscatheter. Calcium chloride (0.5 gm) was administered before or during reinfusion of the citrate anticoagulated blood if the systolic blood pressure fell below 100 mm Hg. At the completion of this cycle measurements were taken. The autotransfusion cycle was repeated 25 times. After each cycle the heart rate, blood pressure, and rectal temperature were recorded and activated clotting time (ACT) was measured from the device. ACT was measured by the method described by Baden and colleagues" using the ACTester (Tri-Med Corp., Huntington Beach, Calif.) and tubes containing Platelin Plus Activator (General Diagnostics, Morris Plains, N. J.) After every five cycles hemodynamics were stabilized for 10 minutes, at which time blood samples were taken for hematologic, coagulation, and blood gas measurements. After 25 cycles the cannulas were removed and the animal allowed to revive. Further blood samples for hematologic, coagulation, and chemical measurements and blood cultures were drawn immediately after operation and 24 hours later. Additional cultures were taken from the normal saline solution rinsed through the ATS before and after the procedure. Twenty-four hours after the procedure the animals were observed, and killed after blood samples were drawn. A complete necropsy was performed to check for emboli and other organ abnormalities. Two methods of blood aspiration were used to evaluate citrate delivery under two conditions of clinical usage: full blood and foam (air-blood). Full blood aspiration consisted of completely submerging the sue-

An111al ACT

Pre Op 5

10

15

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Fig. 3. Mean and standard deviation in activated clotting time (ACT) in samples from animals and ATS device. One cycle = 10% blood volume shed and reinfused.

tion tip in the pool of blood. Foam aspiration consisted of collecting blood mixed with air at the air-blood interface of the blood pool. These two methods were alternated every five cycles. Blood was reinfused into the animal either under pressure (300 mm Hg) or by gravity. A blood pressure cuff was used to infuse the blood under pressure, whereas blood infused by gravity was hung on the IV pole and allowed to drip in freely. These two methods were alternated every five cycles.

Results Ten dogs survived without apparent side effects. These animals were free standing and appeared to be healthy 24 hours after the procedure. One dog died of cardiac arrest and persistent metabolic acidosis immediately after the operation. During all experiments blood pressure and pulse showed changes expected with hemorrhage. Rectal temperature stayed between 37° and 41 ° C. The test period of 25 cycles of blood and reinfusion (2.5 to 3 blood volumes) lasted 2.7 to 3.5 hours (mean 3.16 ± 0.31 hours). Blood/CPD ratio data are shown in Fig. 2. A total of 275 ATS cycles were conducted in the 11 dogs. With the exception of five separate data points, all ratio values fell within the range of 5 to 10. One data point was between 4 and 5. Four data points were greater than 10 but less than 11. There was no statistical difference in blood/ CPD ratios in full blood or foam aspiration. The degree to which air was aspirated with blood during the foam cycles was not quantified in this study. One CPD-deficient data point (R = 11) was consis-

The Journal of

9 4 0 Toomasian et al.

Thoracic and Cardiovascular Surgery

500

50

40

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400

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20

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o

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200

100

I

,

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,

I

10

15

I

20

Cycles

Fig. 4. Mean and standard deviation in hematocrit (Het), white blood cells (WBC), and plasma hemoglobin (Hb) in samples from animals. One cycle = 10% blood volume shed and reinfused.

Fig. 5. Mean and standard deviation for fibrinogen, platelet count, and fibrin degradation products (FDP) in sample from animals. One cycle = 10% blood volume shed and reinfused.

tent with an air-CPD lock found in the CPD delivery line, obstructing delivery of CPD to the suction tip. The air lock was manually dislodged during blood aspiration, avoiding a higher R value and the potential of thrombosis within the device. Excessive CPD delivery (R < 5) is associated with partial or total obstruction of the tip of the suction wand. Suction wand obstruction can be caused by tissue or by blood clots. A clotted tip can be replaced or cleaned to ensure no obstruction during aspiration. A large thrombus was observed in the blood reservoir during the first cycle of one individual experiment, despite the R value being between 5 and 10. The experiment was continued and the thrombus cleared from the reservoir by the reinfusion microfilter. No additional thrombosis could be identified. Activated clotting times are shown in Fig. 3. The added CPD rendered total anticoagulation (ACT greater than 600 seconds) in all blood volumes collected by the ATS. Baseline ACT values from the dogs ranged from 68 to 151 seconds (mean 101 ± 22 seconds). As autotransfusion cycling continued, mean ACT values gradually increased to 121 ± 49 seconds after the autologous transfusion of 1 total blood volume, 181 ± 96 seconds after 2 total blood volumes, and 185 ± 150 seconds after the completion of 25 cycles.These changes appeared to be associated with metabolic acidosis and hyperventilation that developed from the continued bleeding and reinfusion (2.5 to 3 total blood volumes). The arterial blood pH fell as low as 7.14 (mean 7.30 ± 0.09) from baseline (mean 7.39 ± 0.03). Carbon dioxide tensions increased to 41 ± 3 mm Hg

compared with baseline (31 ± 4). These animals were treated aggressively with sodium bicarbonate and increased ventilatory rate toward the end of the procedure, because they became acidotic. Reversal of the acidosis was consistent with lower ACT values. Hematologic and coagulation studies (mean and standard deviation) are shown in Figs. 4, 5, and 6. The overall volume of diluting fluid infused (citrate and normal saline solutions) was 1,700 ± 200 ml or 68 ml/kg over the course of each experiment. Clotting factor screen tests (prothrombin time, partial thromboplastin time, thrombin time) stayed within normal ranges. On average, the hematocrit value decreased 2% to 35% (mean 17%) from baseline. Plasma hemoglobin level increased from 5 to 63 mg/dl (mean 22 mg/dl) from baseline levelsof 5 to 39 mg/dl (mean 13 mg/dl), The 24 hour postoperative plasma hemoglobin levelwas within baseline ranges. White blood cell counts increased slightly during the experiment, and were slightly elevated 24 hours after operation. By cycles 15 to 25, platelet counts decreased from 4% to 37% (mean 28%) from baseline and were stable at those levels 24 hours after operation. Fibrinogen concentration decreased 30% to 45% (mean 27%) from baseline, but almost doubled from baseline values after 24 hours. Fibrin degradation products were stable throughout the procedure. The results of serum chemistry measurements are shown in Table I. Sodium, potassium, chloride, bicarbonate, total bilirubin, creatinine, calcium, urea nitrogen, and albumin values were within normal ranges throughout the procedure. Glucose and phosphorus

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Blood autotransfusion device

November 1986

levels rose slightly to high normal values by the end of autotransfusion, and were normal by 24 hours after the procedure. Total protein declined slightly, but was normal by 24 hours. The only significant changes in chemistry were in liver enzymes: serum glutamic oxaloacetic and pyruvic transaminases, lactic dehydrogenase, and alkaline phosphatase. These values were higher at 24 hours than baseline or postoperative samples. Reinfusion of shed blood was accomplished by either gravity or pressure. Infusion of citrated blood at a rate greater than 100 ml/rnin often caused hypotension, bradycardia, and myocardial depression. In this study, administration of 0.5 gm of calcium chloride reversed these events. Slower gravity reinfusion of blood produced no significant fluctuation in heart rate or blood pressure. Calcium supplements were not necessary during gravity reinfusion. Each dog received an average of 2 to 3 gm of calcium chloride during the experiment, usually administered during pressure reinfusion of the blood. Minimum time required to aspirate and infuse I U of blood was 4 to 5 minutes. No morbidity was observed before necropsy. Gross observation after the animals were killed showed mild inflammation and edema at the surgical site. Histopathologic findings showed no significant lesions of any of the major organ systems attributable to the experimental procedure. Two animals had mild pulmonary atelectasis. One animal had severe diffuse polymorphonuclear leukocyte infiltration suggestive of the recovery stage of pneumonia. The surgical procedure was not thought to have influenced these conditions. One additional dog was observed to have chronic peritonitis and a mesenteric granuloma, which was not related to the surgical procedure. Blood cultures in eight of the II dogs were negative. In one dog, the 24 hour postoperative culture was positive for alpha Streptococcus and Staphylococcus aureus, suggestive of common skin contaminants. In a second dog, the preoperative blood culture was positive for Pseudomonas cepacia and Staphylococcus epidermidis. but all subsequent cultures were negative. In a third experiment S. aureus was cultured from one ATS device postoperatively, but no corresponding positive cultures were found in the recipient animal. There were no signs of septicemia in any dog. One dog died immediately after autotransfusion. Bloodgas values indicated severe metabolic acidosis that was probably associated with bleeding arid reinfusion of citrated blood. All blood cultures were negative, and autopsy revealed no remarkable changes. Each ATS circuit was disassembled after the procedure. The suction tip, blood reservoir, reinfusion bag,

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Seconds

PTT

12 10 8 6

~-~---_5------~-i"

·

·

i--.

TT

2

1 Wook Pro Pro Op

5

10

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20

25

24 Houro Poot Do

Fig. 6. Mean and standard deviation for partial thromboplastin time (PlT), prothrombin time (PT), and thrombin time (TT) in samples from animals. One cycle = 10% blood volume shed and reinfused.

valves, and transfusion filter were examined. No thrombi were found in any of the tubes or valves. The suction tip and wand were also free of thrombus formation. The interior of the blood collection reservoir was the only area of involvement. A few small soft clots were found in the reservoir and transfusion filter in some experiments. No clots appeared on the outlet portion of the reservoir, filters, or other components. Discussion

The current study shows relatively small changes in hematologic and coagulation tests with autotransfusion using this device and the protocol described. Changes in hematocrit, fibrinogen, and platelet count are the result of hemodilution with the CPD and saline solutions. White blood cell count was elevated, consistent with bleeding and autotransfusion." Coagulation screen tests yielded results within the normal range throughout the procedure. There was no increase in fibrin degradation products and no evidence of consumption coagulopathy. Electrolytes were also minimally affected by the ATS. Elevations in phosphorus and glucose concentrations may be related to the CPD infusion. Elevations in serum glutamic oxaloacetic and pyruvic transaminases, lactic dehydrogenase, and alkaline phosphatase levels may have been caused by decreased liver blood flow during hemorrhage and reinfusion during autotransfusion. In other laboratory studies of autotransfusion systems, Klebanoff and colleaguesI 5 showed the early Bentley system to induce no significant elevation in plasma hemoglobin and only a mild decrease in hemat-

The Journal of Thoracic and Cardiovascular Surgery

9 4 2 Toomasian et al.

ocrit and hemoglobin. Subsequent studies have shown that blood autotranfused with this device from the peritoneum can be complicated by hemolysis, platelet dysfunction, and a consumption coagulopathy.":" Reported complications from clinical use of autotransfusion include thrombocytopenia, hemolysis,acidosis, and losses in clotting factors. These relate to hydration, surgical site, and excessive suction or misuse of the autotransfusion device. Microfiltration of the autotransfused blood may reduce consumption coagulopathy." The design of the current system includes multiple filters and reduced suction to minimize potential traumatic side effects. Cell washers have been used widely, and many of the problems related to autotransfusion are reduced.v 20. 21 These systems provide concentrated red cells, although the plasma collected is discarded. Many of the problems associated with autotransfused blood from serosal surfaces are minimized. The system is expensive, however, and requires more time to process the blood. In the current study, none of the above problems were encountered. The neck well model was chosen to thoroughly study the hematologic changes of blood on the device. Clinical operative conditions would differ significantly, and complications such as hemolysis, thrombocytopenia, and consumption coagulopathy may be related more to the surgical site and tissue thromboplastins, not to the autotransfusion device. Citrate proved to be an effective anticoagulant; other autotransfusion systems require systemic heparinization." 22 The use of citrate avoided systemic anticoagulation and the bleeding problems associated with heparin. In our study, the blood/citrate ratio was similar to banked blood (5.0 to 10.0). Rapid reinfusion (greater than 100 ml/rnin) was associated with a drop in blood pressure, which was relieved with administration of calcium. Slower gravity reinfusion of blood was associated with no change in blood pressure. Administration of calcium before reinfusion of the blood under pressure prevented changes in blood pressure or heart rate. Cardiac depression from rapid infusion of citrated blood has been demonstrated in several studies.":" In conclusion, the problem of maintaining an appropriate blood/citrate ratio under variable conditions has been solved in the design of this device. Under ideal test conditions, anticoagulation was effective, hematologic side effects were minimal, and the autotransfusion system was shown to be safe. We wish to thank the several individuals who contributed their time in this study. Sherrie Coleman supervised the

preoperative and postoperative care of the laboratory animals. Clarence Chrisp, D.V.M., performed all the animal necropsy procedures. We wish to thank lab team members Mary Burton, Dilip Dos, Robert Ernst, Greg Helmer, John Oltean, and Howard Smith for their help during each procedure.

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REFERENCES Thurer RL, Hauer JM: Autotransfusion and bloodconservation. Curr Probl Surg 19:98-156, 1982 Hauer JM, Thuner RL, Dawson BR, eds., Autotransfusion, Amsterdam, 1981, Elsevier/North Holland, pp 1-152 Klebanoff G. Early clinical experience with a disposable unit for the intraoperative salvage and reinfusion of blood loss. Am J Surg 120:718-722, 1970 Duncan SE, Klebanoff G, Rogers W. Patient experience in intraoperative autotransfusion. Rev Surg 31: 121-124, 1974 Noon GP, Solis RT, Natelson EA. A simple method of intraoperative autotransfusion. Surg Gynecol Obstet 143:65-70, 1976 Keeling MM, Gray LA, Brink MA, Hillerich VK, Bland KI. Intraoperative autotransfusion. Experience in 725 consecutive cases. Ann Surg 175:536-541, 1983 DADE Diagnostics, Inc. DADE thromboplastin C. DADE pamphlet Ll031O. Revised April, 1982 DADE Diagnostics, Inc. Actin Activated cephaloplastin reagent. DADE pamphlet Ll0293. Revised January, 1982 Penner JA. Experience with the thrombin clotting time assay for measuring heparin activity. Am J Clin Pathoi 61:645-653, 1974 DADE Diagnostics, Inc. DATA-F. Fibrinogen determination reagent. DADE pamphlet Ll0407. Revised February, 1982 DADE Diagnostics, Inc.: Fibrin(ogen) degradation products (FDP) detection set. A product of the DATA-F system. DADE pamphlet Ll0044-C. Revised November, 1981 Moore GL, Ledford ME, Merydith A. A micromodification of the Drabkin hemoglobin assay for measuring plasma hemoglobin in the range of 5 to 2000 tng]dl. Biochem Med 26:167-173, 1981 Baden JP, Sonnenfield M, Ferlic RM, Sellers RD. The BaSon test. A rapid bedside test for control of heparin therapy. Surg Forum 22: 172-174, 1971 Wilson JD, Taswell HF. Autotransfusion. Historical review and preliminary report on a new method. Mayo Clin Proc 43:26-35, 1968 Klebanoff G, Phillips J, Evans W. Use of a disposable autotransfusion unit under varying conditions of contamination. Am J Surg 120:351-354, 1970 Silva R, Moore EE, Bar-Or D, Galloway BW, Wright DE. The risk:benefit of autotransfusion. Comparison to banked blood in a canine model. J Trauma 24:557-564, 1984 Oller DW, Rice CL, Herman CM, Cochran RC, Homer

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LD, John DA, Kingsley JR, Foum WJ. Heparin vs citrate anticoagulation in autotransfusion. J Surg Res 20:330340, 1976 Symbas PN. Autotransfusion from hemothorax. Experimental and clinical studies. J Trauma 12:689-695, 1972 Reul GJ, Solis RT, Greenberg SD, Mattox RL, Whisennard HH. Experience with autotransfusion in the surgical management of trauma. Surgery 76:546-555, 1974 Schaff HV, Hauer J, Gardner TJ, Donahoo JS, Watkins L, Gott VL, Brawley RK. Routine use of autotransfusion following cardiac surgery. Experience in 700 patients. Ann Thorac Surg 27:493-499, 1979 Moran JM, Babka R, Silberman S, Rice PL, Pifane R, Sullivan HJ, Montoya A. Immediate centrifugation of oxygenator contents after cardiopulmonary bypass. J THORAC CARDIOVASC SURG 76:510-517, 1977 Klebanoff G. Intraoperative autotransfusion with the Bentley ATS-100. Surgery 84:708-712, 1978

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23 Killen DA, Grogan EL, Gower RE, Collins HA. Response of canine plasma-ionized calcium and magnesium to the' rapid infusion of acid-citrate-dextrose (ACD) solution. Surgery 70:736-743, 1971 24 Buckberg G, Cooper N, Brazier JR, Hottenrott C, Maloney JV. Depression of myocardial function following transfusion of ACD stored blood, Acute fluid replacement in the therapy of shock, T.I Malinin, ed., New York, 1974, Stratton Intercontinental Medical Book Corp., pp 91-97 25 Bunker JP, Bendixem HH, Murphy AJ. Hemodynamic effects of intravenously administered sodium citrate. N Engl J Med 266:372-377, 1962 26 Jennings ER, Beland AJ, Cope JA, Ellestad MH, Monroe C, Sladle OW. Citrate toxicity and the use of anticoagulant acid citrate dextrose for extracorporeal circulation. Surg Gynecol Obstet 120:997-1008, 1965 27 Watkins E. Experimental citrate intoxication during massive blood transfusion. Surg Forum 4:213-219, 1954