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Platelet support for cardiopulmonary bypass surgery
Platelet support for cardiopulmonary bypass surgery After we discontinued the use of fresh blood for cardiopulmonary bypass surgery, we routinely provided platelet concentrates for the patients. To ascertain if this was necessary, patients paired for procedure and age were given either 4 units of platelets (Group I) or no platelets (Group ll). Platelet counts were obtained preoperatively; hourly during bypass; immediately, ~ hour, and 3 to 4 hours after bypass; and daily for 7 postoperative days. In the 60 patients evaluated, a significant difference between mean platelet counts could not be demonstrated at any time. Total blood use and the total time required for post bypass hemostasis was not significantly different between the two groups. The degree of thrombocytopenia could not be correlated with bypass time. Platelet concentrates or fresh blood are not needed prophylactically for cardiopulmonary bypass surgery, and their usage should be reserved for the occasional patient who manifests thrombocytopenia as well as hemorrhagic complications.
Sally A. Harding, M.D., Mohammed A. Shakoor, M.D., and Alfred J. Grindon, M.D., Baltimore, Md.
The recent increase in cardiopulmonary bypass surgery due primarily to aorta-coronary bypass procedures has placed everincreasing demands on institutions and blood suppliers for more blood and blood products. In the past, a varying proportion of the blood provided for these patients was freshly drawn. As commercial blood has become less desirable and blood components have become more widely accepted, a fresh blood substitute, composed of packed cells, fresh-frozen plasma, and platelet concentrates used along with stored blood, has become more practical. At the present time, nine to fourteen per cent of all institutions routinely transfuse platelet concentrates in all patients undergoing cardiopulmonary bypass, whereas twenty-eight per cent regularly reserve platelet concentrates for these individuals. 1 The present study compares patients in two matched groups, to deterFrom the Departments of Laboratory Medicine and Anesthesiology, Johns Hopkins Hospital, Baltimore, Md. 21205. Received for publication Feb. 13, 1975.
350
mine if there is a correlation between morbidity (evaluated by blood usage and length of postoperative hospitalization) or thrombocytopenia and the receipt of platelet concentrates after bypass. Materials and methods
Sixty patients were paired for age and type of operative procedure (listed in Table I). The patients underwent cardiopulmonary bypass for periods ranging from 15 to 180 minutes with the aid of a Sarns doubleroller pump and a Harvey bubble oxygenator. The pump oxygenator was primed with 2 L. of lactated Ringer's solution, 50 c.c. of 50 per cent dextrose in water, and 80 mg. of heparin. The time spent in control of bleeding was defined as the time from the termination of bypass until the patient arrived in the intensive care unit, since the time required to close the wound was approximately the same in each case. Stored blood ( 2 to 5 days old) was used during and after bypass and postoperatively. Group I patients received 4 units of platelet
Volume 70 Number 2 August, 1975
Platelet support in cardiopulmonary bypass
concentrate immediately after bypass was terminated; Group II received no platelet concentrates. Neither group received any fresh blood. We agreed before undertaking the study that platelets would be available for all patients; if platelet concentrates were considered necessary by the operating team for a patient assigned to Group II, that patient would be deleted from the study. Any member of Group I who inadvertently was not given the 4 units of platelet concentrate would also be deleted. Seven patients were deleted from the study for the following reasons: 2 patients from American Heart Association Class IV, 1 assigned to each group, died in the immediate postoperative period; 1 patient in the treatment group was removed from the study because he did not receive the platelet concentrates, and 4 patients in the control group were removed because they were given platelets to support massive transfusion (mean blood transfused was 25 units). Platelet counts were obtained before induction of anesthesia; each hour on bypass; immediately, ~ hour, and 3 to 4 hours after bypass; and daily for 7 days. Platelet counts were obtained with a Coulter thrombocounter." Results The average age, bypass time, and time spent in control of bleeding in both groups, the amount of blood used (intraoperative and total), and the number of days of postoperative hospitalization are shown in Table II. No significant difference could be demonstrated between the groups with regard to any of these variables. Although there was a large individual variation in platelet counts in the two groups (Fig. 1), no significant difference in mean platelet counts at any particular time interval was observed (Fig. 2). There was no significant correlation in the control group between the nadir in platelet count and the time on bypass (r = 0.32). In both groups, the nadir in platelet count occurred on the second postoperative day, and platelet counts
35 1
Table I Procedure Coronary artery bypass Aortic valve replacement Mitral valve replacement Atrial septal defect repair Repair tetralogy of Fallot
Mean age (yr.)
22 10 14 8 6
54 46 47 22 16
Group 1*
I Group lIt
Table II
Average age (yr.) 40.3 (± 7.2):1: 43.8 (± 7.4) Average bypass time (min.) 113 (± 19.2) 108 (± 17.4) Bleeding control and 95 (± 13.4) 106 (± 13) closure time (min.) Total blood used (units) 8.4 (± 1.6) 8.2 (± 1.8) Intraoperative blood 1,627 (±374) 1,789 (±376) used (rnl.) Duration of postoperative 19.4 (±4.6) 17.5 (±6.2) hospitalization (days) 'Four units of platelet concentrates given. tNo platelets given. tMean ±2 S.E.M.
had returned to preoperative levels by the sixth postoperative day (Fig. 2). Discussion Most studies of patients undergoing cardiopulmonary bypass surgery have demonstrated a postoperative decrease in platelet count. In many, however, hemorrhagic problems could not be closely correlated with this thrombocytopenia.v" Some workers have been able to correlate decreased platelet numbers with an increased length of perfusion'''"; in contrast, other studies, like ours, have not shown this correlation." 4 Furthermore, some studies showed maximum thrombocytopenia immediately or within a few hours postoperatively,': 0, 10, 11 whereas other work has demonstrated the same type of thrombocytopenic pattern seen in our patients, with the nadir occurring 2 days postoperatively."- 12 It is possible that the explanation for these discrepancies' may be found in the great variability in oxygenators. Although Woods and co-workers'? found no difference in blood loss between patients
The Journal of
352
Harding, Shakoor, Grindon
Thoracic and Cardiovascular Surgery
400 350
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300
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Fig. 1. Distribution of platelet counts for all patients.
300r
e----. Group I
250 .
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-E E
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Fig. 2. Platelet counts in patients subjected to cardiopulmonary bypass with 4 units of platelet concentrate (Group I) or no platelets (Group II). (Mean ± 2 S.E.M.)
who received platelet concentrates and those who did not, the blood received by the control group during bypass and postoperatively was freshly drawn and contained viable platelets. A similar difficulty is seen in the study by Pike and coworkers,' who used stored blood for transfusion and then examined postoperative thrombocytopenia
and hemorrhage. Some of their patients received 1 or 2 units of fresh whole blood postoperatively, equivalent to 4 units of stored platelet concentrate. However, the data did not distinguish between those patients who received fresh blood and those who did not. Because of the inconclusive nature of these studies, we attempted to ex-
Volume 70 Number 2 August, 1975
Platelet support in cardiopulmonary bypass
amine the need for viable platelets (provided as platelet concentrate rather than fresh blood) in a prospective fashion. In the present study, no viable platelets were provided other than as platelet concentrates. The two groups of patients in our study were relatively equivalent in age and mean bypass time. In the 60 cases studied, we were able to demonstrate no signficant difference in platelet count at any time postoperatively in the two groups. The mean platelet count was slightly higher immediately after perfusion in the group receiving platelets, as would be expected. However, even here the incremental difference was not statistically significant. In addition, the two groups exhibited no difference in morbidity as evaluated by blood transfused, the operative time spent in control of bleeding, or postoperative hospital stay. A patient who manifests thrombocytopenia as well as hemorrhagic complications may need platelet support. Four such patients in our control group were deleted from the study because they required platelets to support massive transfusion. However, the use of platelet concentrates or fresh blood has been shown to be generally unnecessary for patients undergoing cardiopulmonary bypass, and these products should not be prophylactically administered or routinely reserved. However, we suggest that cardiopulmonary bypass patients with excessive bleeding should be evaluated by the same criteria as any other patient with a hemorrhagic diathesis, and appropriate therapy should be provided. We acknowledge the cooperation of Drs. Robert Brawley and Vincent Gott, Division of Cardiac Surgery, for allowing us to study their patients.
353
REFERENCES Roche, J. K., and Stengle, J. M.: Open-Heart Surgery and the Demand for Blood, J. A. M. A. 225: 1516, 1973. 2 Bull, B. S., Schneiderman, M. A., and Brecher, G.: Platelet Counts With Coulter Counter, Am. J. Clin. Patho!. 44: 678, 1965. 3 Gralnick, H. R., and Fischer, R. D.: The Hemostatic Response to Open-Heart Operations, J. THORAc. CARDIOVASC. SURG. 61: 909, 1971. 4 Pike, O. M., Marquiss, J. E., Weiner, R. S., and Breckenridge, R. T.: A Study of Platelet Counts During Cardiopulmonary Bypass, Transfusion 12: 119, 1972. 5 Gomes, M. M. R., and McGoon, D. c.. Bleeding Patterns After Open-Heart Surgery, J. THORAc. CARDIOVASC. SURG. 60: 87, 1970. 6 Signori, E. E., Penner, J. A., and Kahn, D. R.: Coagulation Defects and Bleeding in OpenHeart Surgery, Ann. Thorac. Surg. 8: 521, 1969. 7 Gans, H., and Krivit, W.: Problems in Hemostasis During Open-Heart Surgery, Ann. Surg. 115: 353, 1962. 8 Schmidt, P. J., Peden, J. C., Jr., Brecher, G., and Baranovsky, A.: Thrombocytopenia and Bleeding Tendency After Extracorporeal Circulation, N. Eng!. J. Med. 265: 1181, 1961. 9 Anderson, M. N., and Hambraeus, G.: Physiologic and Biochemical Responses to Prolonged Extracorporeal Circulation, Ann. Surg. 153: 592, 1961. 10 Brecher, G., and Galletti, P.: Heart-Lung Bypass, Principles and Techniques of Extracorporeal Circulation. New York, Grune & Stratton, Inc., 1962, pp. 260-267. 11 Brown, I. W., and Smith, W.: Hematologic Problems Associated With the Use of Extracorporeal Circulation for Cardiovascular Surgery, Ann. Intern. Med. 49: 1035, 1958. 12 McKenzie, F. N., DhaII, D. P., Arfors, K. E., Nordlund, S., and Matheson, N. A.: Blood Platelet Behaviour During and After Open Heart Surgery, Br. Med. J. 2: 795, 1969. 13 Woods, J. E., Taswell, H. F., Kirklin, J. W., and Owen, C. A., Jr.: The Transfusion of Platelet Concentrates in Patients Undergoing Heart Surgery, Mayo Clin. Proc. 42: 318, 1967.
Sally A. Harding, M.D., Mohammed A. Shakoor, M.D., and Alfred J. Grindon, M.D., Baltimore, Md.
The recent increase in cardiopulmonary bypass surgery due primarily to aorta-coronary bypass procedures has placed everincreasing demands on institutions and blood suppliers for more blood and blood products. In the past, a varying proportion of the blood provided for these patients was freshly drawn. As commercial blood has become less desirable and blood components have become more widely accepted, a fresh blood substitute, composed of packed cells, fresh-frozen plasma, and platelet concentrates used along with stored blood, has become more practical. At the present time, nine to fourteen per cent of all institutions routinely transfuse platelet concentrates in all patients undergoing cardiopulmonary bypass, whereas twenty-eight per cent regularly reserve platelet concentrates for these individuals. 1 The present study compares patients in two matched groups, to deterFrom the Departments of Laboratory Medicine and Anesthesiology, Johns Hopkins Hospital, Baltimore, Md. 21205. Received for publication Feb. 13, 1975.
350
mine if there is a correlation between morbidity (evaluated by blood usage and length of postoperative hospitalization) or thrombocytopenia and the receipt of platelet concentrates after bypass. Materials and methods
Sixty patients were paired for age and type of operative procedure (listed in Table I). The patients underwent cardiopulmonary bypass for periods ranging from 15 to 180 minutes with the aid of a Sarns doubleroller pump and a Harvey bubble oxygenator. The pump oxygenator was primed with 2 L. of lactated Ringer's solution, 50 c.c. of 50 per cent dextrose in water, and 80 mg. of heparin. The time spent in control of bleeding was defined as the time from the termination of bypass until the patient arrived in the intensive care unit, since the time required to close the wound was approximately the same in each case. Stored blood ( 2 to 5 days old) was used during and after bypass and postoperatively. Group I patients received 4 units of platelet
Volume 70 Number 2 August, 1975
Platelet support in cardiopulmonary bypass
concentrate immediately after bypass was terminated; Group II received no platelet concentrates. Neither group received any fresh blood. We agreed before undertaking the study that platelets would be available for all patients; if platelet concentrates were considered necessary by the operating team for a patient assigned to Group II, that patient would be deleted from the study. Any member of Group I who inadvertently was not given the 4 units of platelet concentrate would also be deleted. Seven patients were deleted from the study for the following reasons: 2 patients from American Heart Association Class IV, 1 assigned to each group, died in the immediate postoperative period; 1 patient in the treatment group was removed from the study because he did not receive the platelet concentrates, and 4 patients in the control group were removed because they were given platelets to support massive transfusion (mean blood transfused was 25 units). Platelet counts were obtained before induction of anesthesia; each hour on bypass; immediately, ~ hour, and 3 to 4 hours after bypass; and daily for 7 days. Platelet counts were obtained with a Coulter thrombocounter." Results The average age, bypass time, and time spent in control of bleeding in both groups, the amount of blood used (intraoperative and total), and the number of days of postoperative hospitalization are shown in Table II. No significant difference could be demonstrated between the groups with regard to any of these variables. Although there was a large individual variation in platelet counts in the two groups (Fig. 1), no significant difference in mean platelet counts at any particular time interval was observed (Fig. 2). There was no significant correlation in the control group between the nadir in platelet count and the time on bypass (r = 0.32). In both groups, the nadir in platelet count occurred on the second postoperative day, and platelet counts
35 1
Table I Procedure Coronary artery bypass Aortic valve replacement Mitral valve replacement Atrial septal defect repair Repair tetralogy of Fallot
Mean age (yr.)
22 10 14 8 6
54 46 47 22 16
Group 1*
I Group lIt
Table II
Average age (yr.) 40.3 (± 7.2):1: 43.8 (± 7.4) Average bypass time (min.) 113 (± 19.2) 108 (± 17.4) Bleeding control and 95 (± 13.4) 106 (± 13) closure time (min.) Total blood used (units) 8.4 (± 1.6) 8.2 (± 1.8) Intraoperative blood 1,627 (±374) 1,789 (±376) used (rnl.) Duration of postoperative 19.4 (±4.6) 17.5 (±6.2) hospitalization (days) 'Four units of platelet concentrates given. tNo platelets given. tMean ±2 S.E.M.
had returned to preoperative levels by the sixth postoperative day (Fig. 2). Discussion Most studies of patients undergoing cardiopulmonary bypass surgery have demonstrated a postoperative decrease in platelet count. In many, however, hemorrhagic problems could not be closely correlated with this thrombocytopenia.v" Some workers have been able to correlate decreased platelet numbers with an increased length of perfusion'''"; in contrast, other studies, like ours, have not shown this correlation." 4 Furthermore, some studies showed maximum thrombocytopenia immediately or within a few hours postoperatively,': 0, 10, 11 whereas other work has demonstrated the same type of thrombocytopenic pattern seen in our patients, with the nadir occurring 2 days postoperatively."- 12 It is possible that the explanation for these discrepancies' may be found in the great variability in oxygenators. Although Woods and co-workers'? found no difference in blood loss between patients
The Journal of
352
Harding, Shakoor, Grindon
Thoracic and Cardiovascular Surgery
400 350
-
300
.i
E
;;- 250 0
x
~ ....J a.. 150
·•• · =
100
·
en
I-
w
-
£
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0
200
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0
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POD 2
POD 5
Fig. 1. Distribution of platelet counts for all patients.
300r
e----. Group I
250 .
0----<>
Group II
-E E
;;-
2
x
en
I-
w
....J W le[
....J
c,
50
Pre-Op
1
~B)'paSi
2 Immed. (HrIJ~Polt.BYPOSS
1/2
3
2
3
4
(Hrso)-.o+-I._-----Post-operative
00)'1------., 5
6
7
Fig. 2. Platelet counts in patients subjected to cardiopulmonary bypass with 4 units of platelet concentrate (Group I) or no platelets (Group II). (Mean ± 2 S.E.M.)
who received platelet concentrates and those who did not, the blood received by the control group during bypass and postoperatively was freshly drawn and contained viable platelets. A similar difficulty is seen in the study by Pike and coworkers,' who used stored blood for transfusion and then examined postoperative thrombocytopenia
and hemorrhage. Some of their patients received 1 or 2 units of fresh whole blood postoperatively, equivalent to 4 units of stored platelet concentrate. However, the data did not distinguish between those patients who received fresh blood and those who did not. Because of the inconclusive nature of these studies, we attempted to ex-
Volume 70 Number 2 August, 1975
Platelet support in cardiopulmonary bypass
amine the need for viable platelets (provided as platelet concentrate rather than fresh blood) in a prospective fashion. In the present study, no viable platelets were provided other than as platelet concentrates. The two groups of patients in our study were relatively equivalent in age and mean bypass time. In the 60 cases studied, we were able to demonstrate no signficant difference in platelet count at any time postoperatively in the two groups. The mean platelet count was slightly higher immediately after perfusion in the group receiving platelets, as would be expected. However, even here the incremental difference was not statistically significant. In addition, the two groups exhibited no difference in morbidity as evaluated by blood transfused, the operative time spent in control of bleeding, or postoperative hospital stay. A patient who manifests thrombocytopenia as well as hemorrhagic complications may need platelet support. Four such patients in our control group were deleted from the study because they required platelets to support massive transfusion. However, the use of platelet concentrates or fresh blood has been shown to be generally unnecessary for patients undergoing cardiopulmonary bypass, and these products should not be prophylactically administered or routinely reserved. However, we suggest that cardiopulmonary bypass patients with excessive bleeding should be evaluated by the same criteria as any other patient with a hemorrhagic diathesis, and appropriate therapy should be provided. We acknowledge the cooperation of Drs. Robert Brawley and Vincent Gott, Division of Cardiac Surgery, for allowing us to study their patients.
353
REFERENCES Roche, J. K., and Stengle, J. M.: Open-Heart Surgery and the Demand for Blood, J. A. M. A. 225: 1516, 1973. 2 Bull, B. S., Schneiderman, M. A., and Brecher, G.: Platelet Counts With Coulter Counter, Am. J. Clin. Patho!. 44: 678, 1965. 3 Gralnick, H. R., and Fischer, R. D.: The Hemostatic Response to Open-Heart Operations, J. THORAc. CARDIOVASC. SURG. 61: 909, 1971. 4 Pike, O. M., Marquiss, J. E., Weiner, R. S., and Breckenridge, R. T.: A Study of Platelet Counts During Cardiopulmonary Bypass, Transfusion 12: 119, 1972. 5 Gomes, M. M. R., and McGoon, D. c.. Bleeding Patterns After Open-Heart Surgery, J. THORAc. CARDIOVASC. SURG. 60: 87, 1970. 6 Signori, E. E., Penner, J. A., and Kahn, D. R.: Coagulation Defects and Bleeding in OpenHeart Surgery, Ann. Thorac. Surg. 8: 521, 1969. 7 Gans, H., and Krivit, W.: Problems in Hemostasis During Open-Heart Surgery, Ann. Surg. 115: 353, 1962. 8 Schmidt, P. J., Peden, J. C., Jr., Brecher, G., and Baranovsky, A.: Thrombocytopenia and Bleeding Tendency After Extracorporeal Circulation, N. Eng!. J. Med. 265: 1181, 1961. 9 Anderson, M. N., and Hambraeus, G.: Physiologic and Biochemical Responses to Prolonged Extracorporeal Circulation, Ann. Surg. 153: 592, 1961. 10 Brecher, G., and Galletti, P.: Heart-Lung Bypass, Principles and Techniques of Extracorporeal Circulation. New York, Grune & Stratton, Inc., 1962, pp. 260-267. 11 Brown, I. W., and Smith, W.: Hematologic Problems Associated With the Use of Extracorporeal Circulation for Cardiovascular Surgery, Ann. Intern. Med. 49: 1035, 1958. 12 McKenzie, F. N., DhaII, D. P., Arfors, K. E., Nordlund, S., and Matheson, N. A.: Blood Platelet Behaviour During and After Open Heart Surgery, Br. Med. J. 2: 795, 1969. 13 Woods, J. E., Taswell, H. F., Kirklin, J. W., and Owen, C. A., Jr.: The Transfusion of Platelet Concentrates in Patients Undergoing Heart Surgery, Mayo Clin. Proc. 42: 318, 1967.