Cardiovascular Drugs and Therapy 4: 269-272, 1990 9 Kluwer Academic Publishers, Boston. Printed in U.S.A.
Porcine Heparin Increases Postoperative Bleeding in Cardiopulmonary Bypass Patients Leigh I.G. lverson, Francis G. Duhaylongsod, J. Nilas Young, Roger R. Ecker, Coyness L. Ennix Jr, Richard L. Moretti, M. Farrar, R. Hayes, J. Lee, Ivan A. May CardiothoracicSurgeryDepartment.SamuelMerrittHospital, Oakland, CA, USA
Summary. One hundred thirteen patients undergoing cardiopulmonary bypass were randomly assigned to receive either bovine or porcine heparin. Heparin was infused at 4.5 mg/kg during bypass and administered at the lesser of 70 units/kg or 5000 units/dose at 12-hour intervals postoperatively. Platelet counts decreased to 45r~ of preoperative levels during the first 3 days postoperatively (porcine, 44 ~ 13~, n
= 50; bovine, 46 _+ 15~), but returned to preoperative levels by the seventh postoperative day. The average blood loss in the porcine heparin group significantly exceeded that of the bovine heparin group (porcine, 1350.7 _+ 727.8 ml; bovine, 1059.6 = 381.0 ml; p < .01). Consequently, the platelet transfusion requirement was greater in the porcine heparin group (porcine, 1.7 _+ 3.9 units; bovine, 0.5 _+ 1.7 units; p < .05); however, blood and blood component (with the exception of platelets) administration was not significantly different between the two groups. The four patients taking anticoagulants or antiinflammatory agents in the porcine group required a mean of 8.5 units of red blood cells (RBC) plus supplemental platelets. The seven such patients in the bovine group received a mean of 3.0 units of RBC and no platelets. Thus, the use of porcine heparin resulted in a generalized increase in postoperative bleeding with increased manage-
ment problems in patients undergoing cardiopulmonary bypass.
Key Words. thrombocytopenia, platelet aggregation, cardiopulmonary bypass, heparin, postoperative bleeding, protamine
Platelet counts following eardiopuhuonary bypass are 30-50% of preoperative levels [1]. Furthermore, only about one-half of these platelets exhibit normal function. Postoperatively, these values can decrease further through the development of heparin-induced thromboeytopenia [2, 3]. In patients receiving continuous intravenous heparin therapy, the incidence of thromboeytopenia is higher in those patients administered bovine heparin than in those receiving porcine heparin [4]. Thus, porcine heparin might be considered the preparation of choice to minimize platelet loss following cardiopuhnonary bypass. However, other
factors need to be considered. In addition to the effects of heparin [5, 6], platelet loss has been attributed to mechanical damage or adhesion to foreign surfaces [7], aggq'egation induced by ADP released from hemolyzed red blood cells [8], protamine sulfate [5], or heparin-protamine sulfate complexes [9]. Additionally, there is little correlation between the incidence of excessive postoperative bleeding anti the degree of thromboeytopenia [10, 11]. Furthermore, protamine may interfere with the development of heparininduced thromboeytopenia [12]. Therefore, we undertook a prospective randomized study to determine whether bovine or porcine heparin was superior in minimizing either postoperative thrombocytopenia or blood loss.
Materials and Methods One-hundred thirteen patients undergoing cardiopulmonary bypass were randomly assigned to receive either bovine heparin or porcine heparin. One patient in the bovine gToup and two in the porcine gq'oup died. Patients with incomplete records, those with a history of bleeding, and those with excessive postoperative bleeding that required surgical correction were excluded. The management of the patient was dictated by the patient's clinical condition, and the use of blood products was in no way altered by the study. Bovine (Riker Laboratories) and porcine (Invonex Laboratory) heparin preparations were administered intraveneously during cardiopulnmnary bypass to maintain a circulating level of 4.5 mg/kg body weight. Heparin levels were monitored at 30-minute intervals with a Hepcon (Hemotee Inc.) analyzer. Following bypass, excessive heparin was neutralized with protamine sulfate (Upjohn Co.). Postoperatively, heparin Address for correspondenceand reprint requests: Leigh I.G. Iverson, MD, 365 Hawthorne Avenue, Suite 301. Oakland, CA 946093102, USA. 269
270
Iverson et al
was administered subcutaneously every 12 hours at the lesser of 70 units/kg body weight or 5000 units per dose. Platelet counts were determined preoperatively, immediately following bypass, at 4 hours, and at 1, 3, and 7 days postoperatively. Blood loss was recorded at 1, 2, 4, and 8 hours postoperatively, then at 8-hour intervals thereafter until bleeding ceased. Additionally, the presence of circulating heparin antibody was assayed preoperatively in 38 patients in the bovine group and 39 patients in the porcine group. Heparin antibody was determined using a modification of the method described by Cimo et al. [13]. Whole blood and blood products were administered intraoperatively and postoperatively to maintain a blood hemoglobin of 10 g ~ or to correct a presumed coagulation defect in the face of diffuse abnormal bleeding. Statistical analysis was performed using the twosample Student's t test for independent samples to assess the differences in mean values of platelet counts, blood loss, bypass times, and component transfusion requirements between the two groups and the ehi-square test to assess the differences in the presence of circulating heparin antibody. For the purpose of these analyses, statistical significance was accepted at the p < 0.05 level.
Results No significant differences between the bovine and porcine groups were found with regards to age, weight, height, sex ratio, prebypass platelet counts, or duration of eardiopulmonary bypass (bovine, 93.4 -+ 26 minutes vs. porcine, 95.1 +- 23.4 minutes; p value not significant).
Changes in platelet count There was a significant decrease in platelet count following bypass in both groups (Table 1). The lowest values were found 3 days after surgery. By the seventh postoperative day, values had term'ned to prebypass levels. No significant differences between the two groups were found in the mean platelet counts or in the incidence of patients with low platelet counts at any postoperative time (Table 1). These results were unaffected by the exclusion of patients receiving supplemental platelets or by excluding the seven patients in the bovine group or the four patients in the porcine group taking anticoagulants or antiinflammatory agents. A difference in platelet count was found between the bovine and porcine groups with respect to the test
Table 1. Cha~tges i~ platelet co~ttt d~rittg at~d lbllowb~g cardiop~d,u.mr!! bypass Platelet count ( x l 0 :~)
Time Prebypass 0 horn's postb33)ass 4 hours postbypass 1 day postbypass 3 days postbypass 7 days postb>q)ass
Bovine heparin (n = 54) 243 125 135 114 Ill 298
• • • • • •
60 40 50 46 37 100
Porcine heparin (n = 50) 238 127 134 107 105 295
• 60 • 38 • 38 • 34 • 31 _+ 102
The decrease from prebypass values to postbypass values was significant (p < 0.001) in both groups. When the data were treated as paired values, the decrease from 4 hours to 1 day was significant in both .kn'oups (p < (I.(12).
for heparin antibody. In the bovine group, a positive test for heparin antibody was associated with lower platelet counts for the first 3 days following bypass (Table 2). In the porcine heparin group those with a positive test for heparin antibody had a slightly higher platelet count 4 hours after surgery, but there were no significant differences associated with a positive antibody test in the porcine group at other times.
Blood loss Patients who received the porcine heparin tended to bleed significantly more than did those who were treated with the bovine preparation (Table 3). The average blood loss for the 1)orcine heparin group was 1350.7 +- 727.8 ml, whereas the bovine heparin group lost 1059.6 _+ 381 ml (p < .01, Table 3). This difference correlated with shorter bleeding times for the bovine heparin group. At 24 hours following surgery, 9 of 47 in the bovine group had stopped bleeding compared with only 1 of 48 in the porcine hel)arin group (p < .01). Blood products administered The increased blood loss experienced by the porcine heparin group was reflected in the significantly greater utilization of platelet transfusions in this group. Although the mean values for the units of blood (whole and packed cells) and other blood component therapy administered suggested greater application in the porcine heparin gn'oup, this did not approach statistical significance. The average number of units of whole blood and packed red cells transfused in the porcine-heparin treated group was 2.4 _+ 2.1 units compared with 2.1 ___ 2.0 units (NS) for the bovine-
Hcpari, a,d Post-Operative Bleeding
271
Table 2, Rclationship behvccn the t~rescncc qt" hepaH, a nlilmd!l a,d plo h'h.l ('o,,ls .lblhm'blg ca rdiolmhnona rg bypass Platelet count ( >< 1(1 a) Time
Positive
Percent of prebypass count Negative
P.sitive
Negative
p value
0.01 0.01 0.05 NS
Bovine heparin PrebYlmSS 4 hours postbyl)ass 1 day postbypass 3 days postbypass 7 days postbypass
251 102 8s 91 263
+ 59 +_ 37 +_ 2,1 • 22 * 75
2-16 * 62 145 * 50 Ii2 +_ ?,9 117 • ?,,q 3111 +_ 1114
42 3X aS 98
-+_ 9 + I0 + 7 • 27
__ 5,"; +_ 14 45 • 14 48 • 15 12.q + 31
Pm'cine heparin L' Prebypass 4 hours postbypass 1 day postbypass 3 days postbypass 7 days l)ostbypass
225 150 1111 111 2.q,~
+_ 33 - 21 + 22 m :?;8 + 55
232 t :-~-1 12,1) + 41 11)4 + 32 1(17, +_ :-I1 3117 + 23
-67 +_ 11 4-1 +_ ,q 46 : 17 1112 * 34
5({ = 32 45 +_ 13 44 § 113o - 32
-0.1)5 NS NS NS
NS - not signilicant. :'Positive: n - lit negative: n 2,";. "Positive: n - .q: negative: n - 31).
Table 3. ('Omlmrism~ qf blood h~ss a.d hh~.l pr.dnc! rCldm'cmcnl I.,hccr
Group Bovine heparin (n = 311) Porcine heparin In 30) p value
b,.'i.e . . d p.rcim. ]w}.~,'i. gr~ml)S
Ho.d loss (roll
Red cells transfused (units I
Platebts transfused (units)
Other components transfllsed* (units)
1059.6 "- 381 1>~51).7 +_ 72s < .()1
2.1 z 2 2.-1 • 2.1 NS
0.5 +_ 1.7 1.7 + 3.9 < .o5
2.5+_3 2.7+2 NS
* Fresh-fl'ozen tJasma - cry[qn-ecipitate.
heparin treated group. Platelet transfusions were u t i l i z e d in a s i g n i f i c a n t l y g T e a t e r n u m b e r in t h e p o f cine h e p a r i n g r o u p (1.7 • :-}.9 u n i t s , vs. 0.5 • 1.7 u n i t s , p < .05). W h e r e a s 11 of 50 p a t i e n t s in t h e p o f cine h e p a r i n ZToup r e q u i r e d p l a t e l e t s , only 3 of t h e 55 p a t i e n t s in t h e b o v i n e h e p a r i n g~'oup w a r r a n t e d such t h e r a p y . O t h e r blood c o m p o n e n t t h e r a p y [i.e., f r e s h fl'ozen p l a s m a ( F F P ) a n d e r y o p r e e i p i t a t e (erypl)t)l w e r e also u s e d in g T e a t e r n u m b e r in t h e p o r c i n e h e p a r i n g r o u p t h a n in t h e b o v i n e h e p a r i n ZTOUp (2.7 -+ 2.8 u n i t s vs. 2.5 • 3.1 u n i t s , NS). A n a l y s i s of t h e p a t i e n t s on d r u g t h e r a p y ( a n t i c o a g ulants or antiinflammatory agents) shows a significant d i f f e r e n c e (p < .05) b e t w e e n t h e t w o g~'oups in t h e use of p l a t e l e t t r a n s f u s i o n . All fore" p a t i e n t s r e c e i v i n g ant i c o a g u l a n t s o r a n t i i n f l a m m a t o r y a g e n t s in t h e p o r c i n e gYoup r e q u i r e d s u p p l e m e n t a l p l a t e l e t s , w h e r e a s n o n e of t h e s e v e n d r u g t h e r a p y p a t i e n t s in t h e b o v i n e gYoup r e c e i v e d p l a t e l e t s . 0 n l y 3 of t h e 55 p a t i e n t s in t h e b o v i n e h e p a r i n gToup r e q u i r e d p l a t e l e t s , w h e r e a s 11
of 50 p a t i e n t s in t h e p o r c i n e g r o u p r e q u i r e d p l a t e l e t supplementation. Discussion
Our data do not supl)ort the concept that porcine hepatin is superior to bovine heparin for the postoperative m a n a g e m e n t of cardiopuhnonary bypass patients. On the contrary, patients who received the porcine prepar a t i o n t e n d e d to b l e e d m o r e a n d l o n g e r t h a n did patients who were administered bovine heparin. The finding of p r o l o n g e d b l e e d i n g t i m e s r e c o r d e d in t h e l ) o r e i n e - h e p a r i n t r e a t e d gq'oup is c o n s i s t e n t w i t h t h e s i g n i f i c a n t l y i n c r e a s e d p l a t e l e t t r a n s f u s i o n req u i r e m e n t . T h e fore" p a t i e n t s in t h e p o r c i n e g r o u p w h o w e r e r o u t i n e l y t a k i n g a n t i c o a g u l a n t s or a n t i i n f l a m m a t o r y a g e n t s p r i o r to s u r g e r y r e q u i r e d s u p p l e m e n t a l p l a t e l e t s a n d five or m o r e u n i t s of r e d blood cells following s u r g e r y . T h r e e of t h e s e f o u r w e r e r e e x a m i n e d s m ' g i e a l l y for e x e e s s i v e b l e e d i n g . I n all t h r e e
272
Iverson el al
eases, bleeding arose from generalized seeping rather than from a speeifie locus. The fourth individual was not r e e x a m i n e d surgieally but lost in exeess of 2.5 1 of blood postoperat, ively. In eontrast, none of the seven p a t i e n t s in the bovine gxoup who were t a k i n g antieoa g u l a n t s or a n t i i n f l a m m a t o r y a g e n t s r e q u i r e d surgieal r e e x a m i n a t i o n for excessive bleeding, although two did lose in excess of 2.5 1 of blood. T h e s e o b s e r v a t i o n s point to a relationship b e t w e e n the use of the porcine h e p a r i n and s e v e r e b l e e d i n g p r o b l e m s in this subgToup of p a t i e n t s . P r o t a m i n e neutralization of heparin m a y also affeet the d e v e l o p m e n t of t h r o m b o c y t o p e n i a . T h e r e is evidence that h e p a r i n - i n d u e e d t h r o m b o e y t o p e n i a requires an intact hemolytic eomplement sequenee [15]. Various ratios of heparin and p r o t a m i n e d e p l e t e hemolytic c o m p l e m e n t a c t i v i t y in both plasma and serum [6]. Thus, p r o t a m i n e sulfate neutralization of excess heparin following b y p a s s m a y p r e v e n t or delay the onset of h e p a r i n - i n d u e e d t h r o m b o e y t o p e n i a by depleting hemolytic complement. W h a t e v e r the mechanism, our r e s u l t s are in agTeement with o t h e r s 110, 11] who have failed to find a relationship b e t w e e n thromboeytopenia and p o s t o p e r a t i v e bleeding. Commercial h e p a r i n is a h e t e r o g e n o u s p r e p a r a tion with r e s p e c t to the molecular weight, electrical charge, and a n t i t h r o m b i n II1 affinity [16-18]. Various fractions isolated from eommereial heparin differ in t h e i r anticoagulant activity, injurious effects on platelets, and promotion of bleeding. In a rabbit model s y s t e m , excessive b l e e d i n g was associated with a heparin fl'aetion of low a n t i t h r o m b i n I I I affinity and little a n t i t h r o m b o t i e a c t i v i t y I17]. This fl'aetion was isolated from porcine h e p a r i n and m a y account tbr the increase in b l e e d i n g we o b s e r v e d in ore" p a t i e n t s receiving porcine heparin. In ore" study, a relationship b e t w e e n low platelet counts and a positive t e s t for heparin a n t i b o d y was seen in the bovine ga'oup. P l a s m a fl'om heparininduced t h r o m b o e y t o p e n i e p a t i e n t s contains a factor that induces p l a t e l e t agg-regation in the presence of heparin [17]. This factor is associated with an immunoglobulin, s u g g e s t i n g an immune process. H o w e v e r , the low p l a t e l e t counts p e r s i s t e d for only 3 d a y s in p a t i e n t s with a positive t e s t tbr heparin antibody and (lid not p r e c e d e the induction of thrombocytopenia. N e i t h e r excessive bleeding nor the use of blood and blood p r o d u c t s was assoeiated with a positive t e s t for h e p a r i n antibody. Hence, it does not al> p e a r t h a t t h e s e p a t i e n t s w e r e at any risk with r e g a r d to the use of the bovine heparin, w h e r e a s patients using a n t i c o a g u l a n t s or a n t i i n f l a m m a t o r y a g e n t s were at risk with r e s p e e t to the use of the porcine heparin preparation.
Acknowledgment The authors wish to thank Kathy Gomez, Linda SeMdge, and Doris Dantes for technieal and editorial assistance in the t)reparation of this manuscript.
References 1. Parker-Williams EJ. Platelets in prosthesis and pumps. Clbt Hacmotol 1972:1:413. 2. Gollub S, Ulin AW. Heparin induced throlnbocytopenia in man. J Lab CIbt Mcd 1962;59:430-434. 3. Jkeub HG, Bell WR. Disseminated intravascular coa~,mlation du,-ing heparin therapy. A u , I , t e r , Med 1974;81):477481. 4, Bell WR, Royall RM. Heparin-associated thrombocytopenia: A comparison of three heparin preparations. N E , g l d 31ed 1980;303:902-907. 5. Eika C. On the mechanism of platelet ag~n'egation induced by heparin, protamine and polybrene. S c , , d d H , e m , t o l 1972;9:247. 6. Thompson C, Fm-bes ('D, Martin E, et al. Potentiation of the platelet aKm'egati(m and adhesion by heparin both in vivo and in vitro. Cliu Sci 1,t17;-1:44:21. 7. McKenna R, Backman F, Whittaker B, eta]. The hem,)static mechanism after open heart surgery I1. Frequency of abnormal platelet functions (luring and after extracorpm'eal circulation. J Th,rm" Cardi,r Surg 1975;70:2,qS-30S. ,% O'Brian .JR, Etherink, t(m M. Jamieson S. Refractory state .f platelet agt,n'egation with m~tior operati(ms. L,,(.el 1971;2: 741- 743. 9. Hershgold E,J, Pasquini F.. Christiansen D. Effect of heparin-protamine complexes (m in vitro platelet aggrc.~ation. I I I Ci)ngl'eSs (If the International Society on Thrmnh.sis and Haem()stasis, Washington, I)C, 1972:204. 10. Pike OM, Marquiss JE, Weiner RS, et al. A study ofplatelet counts during cardioptflmonary bypass. Tr, u,,fusi,~ 1972; 12:119-121. 1I. Sehmidt PJ, Peden J C, Brecker G, et al. Thr(mfl~oeytopenia and bleeding tendency after extracorporeal circulatitm. 3,' E m.ll J Med 1i161:265:1l S l - 1185. I2. Rent R, Ertel N, Eisenstein R, et al. Complement activation by interaction of polyanions and polycati,ms. 1. Heparin-protamine induced consumption of coml)lement. ,] Imm , , o / 1976;23:2(;4. 13. Cimo PL, Moake 3, Weinger R, et al. Heparin induced thrombocytol)enia. Association with a platelet ag~rregating factor and arterial thrombosis. Am J Hemahd 1979;6:125. 14. Abbott WM, Warnock DF, Austen WG. Relationship ,f heparin source to the incidence of delayed hemorrhage. J Sur[I Rex 1977;22:593. 15. Cines DB, t(aywin P, Bimt M, et al. Heparin ass.dated thrombocytopenia. N Emil J Med 1980;14:788-7.q5. 16. Huisse M, Guillin M, Bezeaud A, et al. Hel)arin associated thromboeytopenia. In vitro effects of different molecuhn" weight heparin fractions, l'hromh Res 198:2:27:485. 17. Ockeltbrd PA, Carter CJ, Cerskus CA, et al. Conlparisoll of the in rive hemorrhagic effects of a low antithrombin-lll affinity heparin fl'action. Thromb Re.s 1982;27:679. 18. Salzman EW, Rosenberg RD, Smith MH, et al. Effect of heparin and heparin fl'actions on l)latelet agtzregation, d ('IM I , uesl 1980;65:64-(;(i.
Porcine Heparin Increases Postoperative Bleeding in Cardiopulmonary Bypass Patients Leigh I.G. lverson, Francis G. Duhaylongsod, J. Nilas Young, Roger R. Ecker, Coyness L. Ennix Jr, Richard L. Moretti, M. Farrar, R. Hayes, J. Lee, Ivan A. May CardiothoracicSurgeryDepartment.SamuelMerrittHospital, Oakland, CA, USA
Summary. One hundred thirteen patients undergoing cardiopulmonary bypass were randomly assigned to receive either bovine or porcine heparin. Heparin was infused at 4.5 mg/kg during bypass and administered at the lesser of 70 units/kg or 5000 units/dose at 12-hour intervals postoperatively. Platelet counts decreased to 45r~ of preoperative levels during the first 3 days postoperatively (porcine, 44 ~ 13~, n
= 50; bovine, 46 _+ 15~), but returned to preoperative levels by the seventh postoperative day. The average blood loss in the porcine heparin group significantly exceeded that of the bovine heparin group (porcine, 1350.7 _+ 727.8 ml; bovine, 1059.6 = 381.0 ml; p < .01). Consequently, the platelet transfusion requirement was greater in the porcine heparin group (porcine, 1.7 _+ 3.9 units; bovine, 0.5 _+ 1.7 units; p < .05); however, blood and blood component (with the exception of platelets) administration was not significantly different between the two groups. The four patients taking anticoagulants or antiinflammatory agents in the porcine group required a mean of 8.5 units of red blood cells (RBC) plus supplemental platelets. The seven such patients in the bovine group received a mean of 3.0 units of RBC and no platelets. Thus, the use of porcine heparin resulted in a generalized increase in postoperative bleeding with increased manage-
ment problems in patients undergoing cardiopulmonary bypass.
Key Words. thrombocytopenia, platelet aggregation, cardiopulmonary bypass, heparin, postoperative bleeding, protamine
Platelet counts following eardiopuhuonary bypass are 30-50% of preoperative levels [1]. Furthermore, only about one-half of these platelets exhibit normal function. Postoperatively, these values can decrease further through the development of heparin-induced thromboeytopenia [2, 3]. In patients receiving continuous intravenous heparin therapy, the incidence of thromboeytopenia is higher in those patients administered bovine heparin than in those receiving porcine heparin [4]. Thus, porcine heparin might be considered the preparation of choice to minimize platelet loss following cardiopuhnonary bypass. However, other
factors need to be considered. In addition to the effects of heparin [5, 6], platelet loss has been attributed to mechanical damage or adhesion to foreign surfaces [7], aggq'egation induced by ADP released from hemolyzed red blood cells [8], protamine sulfate [5], or heparin-protamine sulfate complexes [9]. Additionally, there is little correlation between the incidence of excessive postoperative bleeding anti the degree of thromboeytopenia [10, 11]. Furthermore, protamine may interfere with the development of heparininduced thromboeytopenia [12]. Therefore, we undertook a prospective randomized study to determine whether bovine or porcine heparin was superior in minimizing either postoperative thrombocytopenia or blood loss.
Materials and Methods One-hundred thirteen patients undergoing cardiopulmonary bypass were randomly assigned to receive either bovine heparin or porcine heparin. One patient in the bovine gToup and two in the porcine gq'oup died. Patients with incomplete records, those with a history of bleeding, and those with excessive postoperative bleeding that required surgical correction were excluded. The management of the patient was dictated by the patient's clinical condition, and the use of blood products was in no way altered by the study. Bovine (Riker Laboratories) and porcine (Invonex Laboratory) heparin preparations were administered intraveneously during cardiopulnmnary bypass to maintain a circulating level of 4.5 mg/kg body weight. Heparin levels were monitored at 30-minute intervals with a Hepcon (Hemotee Inc.) analyzer. Following bypass, excessive heparin was neutralized with protamine sulfate (Upjohn Co.). Postoperatively, heparin Address for correspondenceand reprint requests: Leigh I.G. Iverson, MD, 365 Hawthorne Avenue, Suite 301. Oakland, CA 946093102, USA. 269
270
Iverson et al
was administered subcutaneously every 12 hours at the lesser of 70 units/kg body weight or 5000 units per dose. Platelet counts were determined preoperatively, immediately following bypass, at 4 hours, and at 1, 3, and 7 days postoperatively. Blood loss was recorded at 1, 2, 4, and 8 hours postoperatively, then at 8-hour intervals thereafter until bleeding ceased. Additionally, the presence of circulating heparin antibody was assayed preoperatively in 38 patients in the bovine group and 39 patients in the porcine group. Heparin antibody was determined using a modification of the method described by Cimo et al. [13]. Whole blood and blood products were administered intraoperatively and postoperatively to maintain a blood hemoglobin of 10 g ~ or to correct a presumed coagulation defect in the face of diffuse abnormal bleeding. Statistical analysis was performed using the twosample Student's t test for independent samples to assess the differences in mean values of platelet counts, blood loss, bypass times, and component transfusion requirements between the two groups and the ehi-square test to assess the differences in the presence of circulating heparin antibody. For the purpose of these analyses, statistical significance was accepted at the p < 0.05 level.
Results No significant differences between the bovine and porcine groups were found with regards to age, weight, height, sex ratio, prebypass platelet counts, or duration of eardiopulmonary bypass (bovine, 93.4 -+ 26 minutes vs. porcine, 95.1 +- 23.4 minutes; p value not significant).
Changes in platelet count There was a significant decrease in platelet count following bypass in both groups (Table 1). The lowest values were found 3 days after surgery. By the seventh postoperative day, values had term'ned to prebypass levels. No significant differences between the two groups were found in the mean platelet counts or in the incidence of patients with low platelet counts at any postoperative time (Table 1). These results were unaffected by the exclusion of patients receiving supplemental platelets or by excluding the seven patients in the bovine group or the four patients in the porcine group taking anticoagulants or antiinflammatory agents. A difference in platelet count was found between the bovine and porcine groups with respect to the test
Table 1. Cha~tges i~ platelet co~ttt d~rittg at~d lbllowb~g cardiop~d,u.mr!! bypass Platelet count ( x l 0 :~)
Time Prebypass 0 horn's postb33)ass 4 hours postbypass 1 day postbypass 3 days postbypass 7 days postb>q)ass
Bovine heparin (n = 54) 243 125 135 114 Ill 298
• • • • • •
60 40 50 46 37 100
Porcine heparin (n = 50) 238 127 134 107 105 295
• 60 • 38 • 38 • 34 • 31 _+ 102
The decrease from prebypass values to postbypass values was significant (p < 0.001) in both groups. When the data were treated as paired values, the decrease from 4 hours to 1 day was significant in both .kn'oups (p < (I.(12).
for heparin antibody. In the bovine group, a positive test for heparin antibody was associated with lower platelet counts for the first 3 days following bypass (Table 2). In the porcine heparin group those with a positive test for heparin antibody had a slightly higher platelet count 4 hours after surgery, but there were no significant differences associated with a positive antibody test in the porcine group at other times.
Blood loss Patients who received the porcine heparin tended to bleed significantly more than did those who were treated with the bovine preparation (Table 3). The average blood loss for the 1)orcine heparin group was 1350.7 +- 727.8 ml, whereas the bovine heparin group lost 1059.6 _+ 381 ml (p < .01, Table 3). This difference correlated with shorter bleeding times for the bovine heparin group. At 24 hours following surgery, 9 of 47 in the bovine group had stopped bleeding compared with only 1 of 48 in the porcine hel)arin group (p < .01). Blood products administered The increased blood loss experienced by the porcine heparin group was reflected in the significantly greater utilization of platelet transfusions in this group. Although the mean values for the units of blood (whole and packed cells) and other blood component therapy administered suggested greater application in the porcine heparin gn'oup, this did not approach statistical significance. The average number of units of whole blood and packed red cells transfused in the porcine-heparin treated group was 2.4 _+ 2.1 units compared with 2.1 ___ 2.0 units (NS) for the bovine-
Hcpari, a,d Post-Operative Bleeding
271
Table 2, Rclationship behvccn the t~rescncc qt" hepaH, a nlilmd!l a,d plo h'h.l ('o,,ls .lblhm'blg ca rdiolmhnona rg bypass Platelet count ( >< 1(1 a) Time
Positive
Percent of prebypass count Negative
P.sitive
Negative
p value
0.01 0.01 0.05 NS
Bovine heparin PrebYlmSS 4 hours postbyl)ass 1 day postbypass 3 days postbypass 7 days postbypass
251 102 8s 91 263
+ 59 +_ 37 +_ 2,1 • 22 * 75
2-16 * 62 145 * 50 Ii2 +_ ?,9 117 • ?,,q 3111 +_ 1114
42 3X aS 98
-+_ 9 + I0 + 7 • 27
__ 5,"; +_ 14 45 • 14 48 • 15 12.q + 31
Pm'cine heparin L' Prebypass 4 hours postbypass 1 day postbypass 3 days postbypass 7 days l)ostbypass
225 150 1111 111 2.q,~
+_ 33 - 21 + 22 m :?;8 + 55
232 t :-~-1 12,1) + 41 11)4 + 32 1(17, +_ :-I1 3117 + 23
-67 +_ 11 4-1 +_ ,q 46 : 17 1112 * 34
5({ = 32 45 +_ 13 44 § 113o - 32
-0.1)5 NS NS NS
NS - not signilicant. :'Positive: n - lit negative: n 2,";. "Positive: n - .q: negative: n - 31).
Table 3. ('Omlmrism~ qf blood h~ss a.d hh~.l pr.dnc! rCldm'cmcnl I.,hccr
Group Bovine heparin (n = 311) Porcine heparin In 30) p value
b,.'i.e . . d p.rcim. ]w}.~,'i. gr~ml)S
Ho.d loss (roll
Red cells transfused (units I
Platebts transfused (units)
Other components transfllsed* (units)
1059.6 "- 381 1>~51).7 +_ 72s < .()1
2.1 z 2 2.-1 • 2.1 NS
0.5 +_ 1.7 1.7 + 3.9 < .o5
2.5+_3 2.7+2 NS
* Fresh-fl'ozen tJasma - cry[qn-ecipitate.
heparin treated group. Platelet transfusions were u t i l i z e d in a s i g n i f i c a n t l y g T e a t e r n u m b e r in t h e p o f cine h e p a r i n g r o u p (1.7 • :-}.9 u n i t s , vs. 0.5 • 1.7 u n i t s , p < .05). W h e r e a s 11 of 50 p a t i e n t s in t h e p o f cine h e p a r i n ZToup r e q u i r e d p l a t e l e t s , only 3 of t h e 55 p a t i e n t s in t h e b o v i n e h e p a r i n g~'oup w a r r a n t e d such t h e r a p y . O t h e r blood c o m p o n e n t t h e r a p y [i.e., f r e s h fl'ozen p l a s m a ( F F P ) a n d e r y o p r e e i p i t a t e (erypl)t)l w e r e also u s e d in g T e a t e r n u m b e r in t h e p o r c i n e h e p a r i n g r o u p t h a n in t h e b o v i n e h e p a r i n ZTOUp (2.7 -+ 2.8 u n i t s vs. 2.5 • 3.1 u n i t s , NS). A n a l y s i s of t h e p a t i e n t s on d r u g t h e r a p y ( a n t i c o a g ulants or antiinflammatory agents) shows a significant d i f f e r e n c e (p < .05) b e t w e e n t h e t w o g~'oups in t h e use of p l a t e l e t t r a n s f u s i o n . All fore" p a t i e n t s r e c e i v i n g ant i c o a g u l a n t s o r a n t i i n f l a m m a t o r y a g e n t s in t h e p o r c i n e gYoup r e q u i r e d s u p p l e m e n t a l p l a t e l e t s , w h e r e a s n o n e of t h e s e v e n d r u g t h e r a p y p a t i e n t s in t h e b o v i n e gYoup r e c e i v e d p l a t e l e t s . 0 n l y 3 of t h e 55 p a t i e n t s in t h e b o v i n e h e p a r i n gToup r e q u i r e d p l a t e l e t s , w h e r e a s 11
of 50 p a t i e n t s in t h e p o r c i n e g r o u p r e q u i r e d p l a t e l e t supplementation. Discussion
Our data do not supl)ort the concept that porcine hepatin is superior to bovine heparin for the postoperative m a n a g e m e n t of cardiopuhnonary bypass patients. On the contrary, patients who received the porcine prepar a t i o n t e n d e d to b l e e d m o r e a n d l o n g e r t h a n did patients who were administered bovine heparin. The finding of p r o l o n g e d b l e e d i n g t i m e s r e c o r d e d in t h e l ) o r e i n e - h e p a r i n t r e a t e d gq'oup is c o n s i s t e n t w i t h t h e s i g n i f i c a n t l y i n c r e a s e d p l a t e l e t t r a n s f u s i o n req u i r e m e n t . T h e fore" p a t i e n t s in t h e p o r c i n e g r o u p w h o w e r e r o u t i n e l y t a k i n g a n t i c o a g u l a n t s or a n t i i n f l a m m a t o r y a g e n t s p r i o r to s u r g e r y r e q u i r e d s u p p l e m e n t a l p l a t e l e t s a n d five or m o r e u n i t s of r e d blood cells following s u r g e r y . T h r e e of t h e s e f o u r w e r e r e e x a m i n e d s m ' g i e a l l y for e x e e s s i v e b l e e d i n g . I n all t h r e e
272
Iverson el al
eases, bleeding arose from generalized seeping rather than from a speeifie locus. The fourth individual was not r e e x a m i n e d surgieally but lost in exeess of 2.5 1 of blood postoperat, ively. In eontrast, none of the seven p a t i e n t s in the bovine gxoup who were t a k i n g antieoa g u l a n t s or a n t i i n f l a m m a t o r y a g e n t s r e q u i r e d surgieal r e e x a m i n a t i o n for excessive bleeding, although two did lose in excess of 2.5 1 of blood. T h e s e o b s e r v a t i o n s point to a relationship b e t w e e n the use of the porcine h e p a r i n and s e v e r e b l e e d i n g p r o b l e m s in this subgToup of p a t i e n t s . P r o t a m i n e neutralization of heparin m a y also affeet the d e v e l o p m e n t of t h r o m b o c y t o p e n i a . T h e r e is evidence that h e p a r i n - i n d u e e d t h r o m b o e y t o p e n i a requires an intact hemolytic eomplement sequenee [15]. Various ratios of heparin and p r o t a m i n e d e p l e t e hemolytic c o m p l e m e n t a c t i v i t y in both plasma and serum [6]. Thus, p r o t a m i n e sulfate neutralization of excess heparin following b y p a s s m a y p r e v e n t or delay the onset of h e p a r i n - i n d u e e d t h r o m b o e y t o p e n i a by depleting hemolytic complement. W h a t e v e r the mechanism, our r e s u l t s are in agTeement with o t h e r s 110, 11] who have failed to find a relationship b e t w e e n thromboeytopenia and p o s t o p e r a t i v e bleeding. Commercial h e p a r i n is a h e t e r o g e n o u s p r e p a r a tion with r e s p e c t to the molecular weight, electrical charge, and a n t i t h r o m b i n II1 affinity [16-18]. Various fractions isolated from eommereial heparin differ in t h e i r anticoagulant activity, injurious effects on platelets, and promotion of bleeding. In a rabbit model s y s t e m , excessive b l e e d i n g was associated with a heparin fl'aetion of low a n t i t h r o m b i n I I I affinity and little a n t i t h r o m b o t i e a c t i v i t y I17]. This fl'aetion was isolated from porcine h e p a r i n and m a y account tbr the increase in b l e e d i n g we o b s e r v e d in ore" p a t i e n t s receiving porcine heparin. In ore" study, a relationship b e t w e e n low platelet counts and a positive t e s t for heparin a n t i b o d y was seen in the bovine ga'oup. P l a s m a fl'om heparininduced t h r o m b o e y t o p e n i e p a t i e n t s contains a factor that induces p l a t e l e t agg-regation in the presence of heparin [17]. This factor is associated with an immunoglobulin, s u g g e s t i n g an immune process. H o w e v e r , the low p l a t e l e t counts p e r s i s t e d for only 3 d a y s in p a t i e n t s with a positive t e s t tbr heparin antibody and (lid not p r e c e d e the induction of thrombocytopenia. N e i t h e r excessive bleeding nor the use of blood and blood p r o d u c t s was assoeiated with a positive t e s t for h e p a r i n antibody. Hence, it does not al> p e a r t h a t t h e s e p a t i e n t s w e r e at any risk with r e g a r d to the use of the bovine heparin, w h e r e a s patients using a n t i c o a g u l a n t s or a n t i i n f l a m m a t o r y a g e n t s were at risk with r e s p e e t to the use of the porcine heparin preparation.
Acknowledgment The authors wish to thank Kathy Gomez, Linda SeMdge, and Doris Dantes for technieal and editorial assistance in the t)reparation of this manuscript.
References 1. Parker-Williams EJ. Platelets in prosthesis and pumps. Clbt Hacmotol 1972:1:413. 2. Gollub S, Ulin AW. Heparin induced throlnbocytopenia in man. J Lab CIbt Mcd 1962;59:430-434. 3. Jkeub HG, Bell WR. Disseminated intravascular coa~,mlation du,-ing heparin therapy. A u , I , t e r , Med 1974;81):477481. 4, Bell WR, Royall RM. Heparin-associated thrombocytopenia: A comparison of three heparin preparations. N E , g l d 31ed 1980;303:902-907. 5. Eika C. On the mechanism of platelet ag~n'egation induced by heparin, protamine and polybrene. S c , , d d H , e m , t o l 1972;9:247. 6. Thompson C, Fm-bes ('D, Martin E, et al. Potentiation of the platelet aKm'egati(m and adhesion by heparin both in vivo and in vitro. Cliu Sci 1,t17;-1:44:21. 7. McKenna R, Backman F, Whittaker B, eta]. The hem,)static mechanism after open heart surgery I1. Frequency of abnormal platelet functions (luring and after extracorpm'eal circulation. J Th,rm" Cardi,r Surg 1975;70:2,qS-30S. ,% O'Brian .JR, Etherink, t(m M. Jamieson S. Refractory state .f platelet agt,n'egation with m~tior operati(ms. L,,(.el 1971;2: 741- 743. 9. Hershgold E,J, Pasquini F.. Christiansen D. Effect of heparin-protamine complexes (m in vitro platelet aggrc.~ation. I I I Ci)ngl'eSs (If the International Society on Thrmnh.sis and Haem()stasis, Washington, I)C, 1972:204. 10. Pike OM, Marquiss JE, Weiner RS, et al. A study ofplatelet counts during cardioptflmonary bypass. Tr, u,,fusi,~ 1972; 12:119-121. 1I. Sehmidt PJ, Peden J C, Brecker G, et al. Thr(mfl~oeytopenia and bleeding tendency after extracorporeal circulatitm. 3,' E m.ll J Med 1i161:265:1l S l - 1185. I2. Rent R, Ertel N, Eisenstein R, et al. Complement activation by interaction of polyanions and polycati,ms. 1. Heparin-protamine induced consumption of coml)lement. ,] Imm , , o / 1976;23:2(;4. 13. Cimo PL, Moake 3, Weinger R, et al. Heparin induced thrombocytol)enia. Association with a platelet ag~rregating factor and arterial thrombosis. Am J Hemahd 1979;6:125. 14. Abbott WM, Warnock DF, Austen WG. Relationship ,f heparin source to the incidence of delayed hemorrhage. J Sur[I Rex 1977;22:593. 15. Cines DB, t(aywin P, Bimt M, et al. Heparin ass.dated thrombocytopenia. N Emil J Med 1980;14:788-7.q5. 16. Huisse M, Guillin M, Bezeaud A, et al. Hel)arin associated thromboeytopenia. In vitro effects of different molecuhn" weight heparin fractions, l'hromh Res 198:2:27:485. 17. Ockeltbrd PA, Carter CJ, Cerskus CA, et al. Conlparisoll of the in rive hemorrhagic effects of a low antithrombin-lll affinity heparin fl'action. Thromb Re.s 1982;27:679. 18. Salzman EW, Rosenberg RD, Smith MH, et al. Effect of heparin and heparin fl'actions on l)latelet agtzregation, d ('IM I , uesl 1980;65:64-(;(i.
