Reduction of blood usage in open heart surgery

Preoperative clinical assessment of hemostatic function in patients scheduled for a cardiac operation

BACKGROUND

Bleeding during and after cardiac operations is usually attributed to inadequate surgical hemostasis or cardiopulmonary bypass-induced disorders of hemostasis. Patient-related factors often are neglected.

METHODS

Articles published between 1976 and 1996 on the preoperative assessment of surgical patients were reviewed to determine the clinical elements most likely to predict increased perioperative blood requirements.

RESULTS

Preoperative assessment is based on a carefully conducted interview (history of bruising, petechiae, recent or excessive bleeding after operation, chronic drug therapy) and physical examination. A standardized questionnaire to enhance the reliability of the assessment is presented. Thus, patients at high risk of being transfused can be identified early on and may be enrolled in various programs designed to decrease bleeding and the need for allogeneic blood transfusions.

CONCLUSIONS

Clinical assessment of hemostatic function before cardiac operations is both effective and efficient. It obviates the need for routine laboratory testing and favors the introduction of blood conservation strategies early on during the process of care.

Blood conservation in small adults undergoing valve surgery

OBJECTIVES

A substantial reduction in transfusion requirements for cardiac surgical procedures has been reported. Many of these reports have been described in patients undergoing coronary artery bypass grafting. Patients suffering from rheumatic heart disease in India are usually small and also anemic. This study was conducted to assess blood conservation methods for cardiac valve surgery in this subset of patients.

DESIGN

This was a prospective, randomized study.

SETTING

The study was performed in a New Delhi tertiary care hospital, and the patients were referred from the northern states of India.

PARTICIPANTS

One hundred fifty consecutive patients undergoing elective valve surgery using cardiopulmonary bypass were included. The mean age was 27.7 years and mean weight was 45.2 kg.

INTERVENTIONS

The patients were divided into three groups of 50 each. Group 1 received autologous fresh blood donated before bypass, and both a cell saver and membrane oxygenator were used. The oxygenator contents at the end of perfusion were processed by cell saver. Group 2 patients were reinfused with autologous blood only, and group 3 was a control group. In groups 2 and 3, the blood that remained in the oxygenator at the conclusion of cardiopulmonary bypass was reinfused. A hematocrit of less than 25% was considered an indication for transfusion in the postoperative period.

MEASUREMENTS AND MAIN RESULTS

The mean preoperative hematocrit was 35.5%. A mean of 361.1 mL of autologous blood was collected from group 1 and 303.3 mL from group 2. Group 1 required 15 units of bank blood, group 2, 90 units (p < 0.001), and group 3, 102 units (p < 0.001). Seventy-eight percent of group 1 patients did not receive any donor blood. There was no significant difference in chest tube drainage among the three groups.

CONCLUSIONS

In this unique group of patients whose mean body weight was only 45 kg, autologous blood alone did not decrease blood bank requirements but when combined with a cell saver and membrane oxygenator greatly reduced the need for donor blood.

The impact of intraoperative autotransfusion on cardiac surgery. A prospective randomized double-blind study

The effect of intraoperative autotransfusion during coronary artery bypass grafting was studied in a randomized double-blind trial involving 38 patients. Nineteen patients had the collected RBCs washed and autotransfused (autotransfusion group), while the remaining patients had their washed cells discarded (control group). Postoperative hemoglobin and hematocrit values were similar. Exposure to banked blood was markedly decreased in the autotransfusion group compared with the control group. In addition, the mean volume of banked packed RBCs transfused per patient was significantly less in the autotransfusion group compared with the control group. Platelet utilization also was markedly decreased in the autotransfusion group. Cryoprecipitate and fresh frozen plasma utilization also was less in the autotransfusion group than in the control group, but this did not reach statistical significance. We conclude that the intraoperative use of autotransfusion decreases the volume of homologous blood products transfused, which results in reduced exposure of the patients to banked blood products.

The stratification of cardiac surgical procedures according to use of blood products: a retrospective analysis of 1480 cases

The use of blood products in 1480 consecutive cases of adult cardiac surgical procedures over a period of 15 mth was studied retrospectively using the database of the Department of Anaesthesia of the Institut de Cardiologie de Montréal. Use of blood products was compared in patients having (1) coronary artery bypass grafting, (2) valvular surgery, (3) or a combination of 1 and 2. First operations were compared with reoperations. Overall, the use of homologous blood products was greatest in patients of Group 3, intermediate in patients of Group 2, and smallest in patients of Group 1. Reoperations were associated with an increase in intraoperative transfusion of packed red blood cells, but postoperative chest drainage was similar to first operations. When all blood products (packed red blood cells, fresh frozen plasma and platelets) were taken into consideration, patients undergoing primary CABG or valve surgery were the least exposed to homologous blood donors (five and six units transfused respectively). Repeat CABG was associated with an intermediate exposure to homologous blood products (eight units). Finally, primary and repeat combined procedures, and repeat valve surgery were associated with the greatest exposure to foreign blood products (10, 13 and 10 units respectively). The data presented in this study provide a rational basis for stratification of procedures according to the expected use of blood products, particularly in view of future studies which may be planned to examine the efficiency of blood conservation strategies.

Comparative study of cell saver and ultrafiltration nontransfusion in cardiac surgery

Hemoconcentration for the establishment of no-donor blood transfusion in open heart surgery was assessed in regard to both the saving of protein and platelets and the exclusion of free hemoglobin. Two different types of hemoconcentrator were compared: the ultrafilter (group I, 6 patients) and the Cell Saver (group II, 6 patients). The total serum protein level, expressed as the percent recovery of the preoperative value, after hemoconcentration was significantly higher in group I (group I versus group II: total serum protein, 118% versus 87% [p less than 0.05]; fibrinogen, 77% versus 50% [p less than 0.01]; immunoglobulin, 83% versus 60% [p less than 0.01]). The platelets also seemed to be well preserved after hemoconcentration in group I. Although the exclusion of free hemoglobin from plasma was inferior in group I compared with group II, the postoperative plasma free hemoglobin level did not increase in group I. We conclude that use of the Cell Saver in nontransfusion cardiopulmonary bypass might cause a severe depletion of various proteins and that the ultrafilter is both safer and more useful if employed routinely.

Predonated autologous blood use in elective cardiac surgery

The risks of homologous blood transfusion are well documented and recently increased with the emergence of acquired immunodeficiency syndrome. Preoperative autologous donation has been suggested to reduce these risks. This is a report concerning 104 consecutive adult autologous donors (group 1) who had an elective cardiac operation. A similar group of 111 patients operated on during the same period but without autologous blood donation was used for comparison (group 2). Both groups contained similar numbers of patients with coronary artery disease, valvular disease, and mixed lesions, and both had several patients with atrial septal defects. Group 2 patients (mean age, 67.8 years) were significantly older than group 1 patients (mean age, 58.9 years) (p less than 0.05). The mean donation in group 1 was 4.1 units, but 12 (11.5%) had to discontinue donations. Increasing angina in 10 (12.2%) of the 82 patients with coronary artery disease was the most common complication, and necessitated hospitalization in two instances. In 77 (75.5%) of the 102 group 1 patients who had operation and 23 (21%) of the 110 group 2 patients, no homologous blood products were required. Group 1 patients used significantly less homologous fresh frozen plasma (0.1 unit versus 0.97 unit; p less than 0.005) and packed red blood cells (0.6 unit versus 2.1 units; p less than 0.001) than group 2 patients. Group 1 patients received 3.3 and 3.1 units of autologous packed cells and plasma, respectively. No complications of autologous transfusion were seen. Predonation of autologous blood is an effective, safe method of reducing homologous blood requirements in elective cardiac operations, but it does carry some risk, especially in patients with coronary artery disease.

Homologous blood use and conservation techniques for cardiac surgery in the United Kingdom

The transfusion laboratories of 32 cardiothoracic surgical centres for adults were surveyed to determine the donor blood requirement for open heart surgery in the United Kingdom. Details of the transfusion practice and the use of blood conservation techniques were sought from a representative senior cardiac anaesthetist at each centre. Suitable data were received from 24 transfusion laboratories (75%) and 29 anaesthetists (90%). The mean (SD) blood use was 5.07 (1.53) units per operation. Seven centres routinely transfused fresh frozen plasma to all patients postoperatively. Experience with autologous deposit (three centres), "cell separators" (four centres), and the reinfusion of shed mediastinal blood (four centres) was limited. Prebypass phlebotomy for postbypass reinfusion (14 centres) and the infusion of residual oxygenator blood (27 centres) were the conservation techniques most commonly applied. In only nine centres was a postoperative normovolaemic anaemia to a haemoglobin concentration of less than 100 g/l accepted. Applying blood conservation techniques more widely would help to maintain blood supplies and reduce morbidity and mortality related to transfusion.

Transfusion of predonated autologous blood in elective cardiac surgery

Despite blood conservation techniques, the average transfusion requirement in patients undergoing elective cardiac surgical procedures remains 1 to 3 units. We studied the efficacy of predonated autologous blood in decreasing homologous transfusion in two matched groups of 58 patients each. Group 1 received homologous blood perioperatively, and Group 2 was transfused with predonated autologous blood. An average of 1.97 units was predonated in Group 2 over 18 days. This resulted in a decline in whole blood hemoglobin concentration of 2.2 gm/dl. No complications resulted from phlebotomy in this ambulatory population consisting predominantly of patients with coronary artery disease. Transfusion of an average of 1.7 units of autologous blood in Group 2 reduced the volume of homologous transfusion by 46% compared with Group 1 (p less than .01). In Group 1, 38% of patients required no homologous transfusion compared with 64% in Group 2 (p less than .02). There were no complications related to autologous blood transfusion. Total transfusion requirement was related to the length of cardiopulmonary bypass. We conclude that autologous predonation is a simple, safe, and cost-effective method of reducing homologous transfusion and thereby decreasing the risk of transfusion-related reactions and infections.

Intravenous esmolol for the treatment of supraventricular tachyarrhythmia: results of a multicenter, baseline-controlled safety and efficacy study in 160 patients. The Esmolol Research Group

Efficacy and safety of esmolol in the treatment of supraventricular tachyarrhythmias (SVT) was evaluated in this open-label, baseline-controlled, multicenter study. One hundred sixty patients with SVT received an intravenous infusion of esmolol in doses ranging from 25 to 300 micrograms/kg/min for up to 24 hours. All of the 160 patients were evaluated for safety, and 147 of them were eligible for evaluation of therapeutic response. Therapeutic response was defined as greater than or equal to 15% reduction in the average baseline heart rate of conversion to normal sinus rhythm. Seventy-nine percent (116 of 147) of the patients exhibited a therapeutic response. The cumulative percentage response increased significantly with increasing esmolol doses up to 200 micrograms/kg/min. The mean (+/- SEM) dose of esmolol producing a therapeutic response was 97.2 +/- 5.5 micrograms/kg/min. Among all patients (n = 160), 39% exhibited hypotension. In 58% of these patients, hypotension resolved with or without adjustment of the esmolol dose while the infusion continued; among almost all of the remaining patients, hypotension resolved within 30 minutes after esmolol was discontinued. Most patients at risk for adverse effects during beta blockade (i.e., those with diabetes mellitus, congestive heart failure, asthma, etc.) tolerated esmolol therapy, and there were no clinically important trends among the reported changes in laboratory variables. The results of the study indicate that esmolol is effective and well tolerated for the treatment of SVT.

Determinants of blood utilization during myocardial revascularization

Blood transfusion during cardiac surgical procedures has steadily decreased, but little information is available regarding the factors that determine its necessity or amount. To determine the predictors of blood utilization during myocardial revascularization, 441 consecutive patients undergoing primary myocardial revascularization were studied. Forty-four patients (10%) received blood during hospitalization with a mean transfusion of 0.3 +/- 1.4 units per patient. Age, sex, weight, body surface area, preoperative hematocrit, blood volume, and red blood cell volume were examined univariately for trends. All demonstrated a statistically significant trend for both need and amount of transfusion (p less than 0.001). Neither number of grafts nor duration of cardiopulmonary bypass demonstrated statistically significant trends. All univariately significant factors were evaluated by multivariate logistic regression analysis. Red cell volume was the best predictor of the need for transfusion (p less than 0.001), followed by age. No other factors improved predictive capabilities. We conclude that preoperative red cell mass and age are the principal determinants of the need for and quantity of blood transfused during myocardial revascularization. Use of this information may greatly improve the efficiency of ordering blood before operation.

A new method of autotransfusing blood drained after cardiac surgery

Ideally, autotransfusion after cardiac surgical procedures should offer the protection of underwater-seal drainage and involve additional cost to the patients only if their blood is reinfused. A technique of returning the patient's postoperatively drained blood that employs these features and that we have found to be safe, simple, and cost-effective is presented.

The efficacy of postoperative autotransfusion in patients undergoing cardiac operations

The efficacy of postoperative autotransfusion in lowering the requirement for banked-blood transfusion was studied in two groups, each having 168 patients, who underwent cardiac operations between April, 1979, and May, 1980. A Sorenson autotransfusion system was available for use in the autotransfusion group, whereas the control group received routine closed mediastinal drainage. Of the autotransfusion group, 81% met the criterion for autotransfusion (mediastinal losses of 450 ml or more during 4 hours), but only 61% of the autotransfusion group actually received autologous blood (mean autotransfusion volume, 399 +/- 25 ml). The patients receiving autologous blood required significantly less banked blood than their matched controls (447 +/- 60 ml and 744 +/- 83 ml, respectively; p less than 0.001). In the subgroup of patients with large mediastinal losses (more than 1,250 ml), this difference was even greater (autotransfusion, 642 ml compared with control, 1,145 ml; p less than 0.01). Postoperative autotransfusion is a simple, safe, and cost-effective method to reduce dependence on banked blood, especially when mediastinal losses are large. Obtaining maximum benefit requires familiarity of staff with the system and use of a consistent protocol.

Fluosol-DA: an artificial blood for total cardiopulmonary bypass

The isolated, in situ pig heart model was used to determine if Fluosol could support myocardial function during cardiopulmonary bypass. Fourteen pigs were utilized; 7 underwent studies of myocardial metabolism (coronary blood flow and vascular resistance, myocardial oxygen consumption and extraction, lactate extraction, and adenosine triphosphate and creatine phosphate levels), and 7 underwent studies of myocardial contractility and compliance (intraventricular balloon measurements). Each study was carried out utilizing one hour of control hemic perfusion, followed by one hour of Fluosol perfusion, and followed by a third hour of a return of hemic perfusion. The results documented that in the vented, beating, nonischemic heart, myocardial metabolism and functional measurements are maintained during an hour of Fluosol perfusion. However, because of an increased level of ionized calcium during Fluosol perfusion, myocardial functional measurements document significantly increased contractility. The increased contractility is associated with an increase in anaerobic metabolism. The latter contributes to a decline in the high-energy phosphate level following a return of hemic perfusion as the heart recovers from the increased work load placed on it during Fluosol perfusion. It is concluded that here is sufficient oxygen-carrying capacity in Fluosol-DA to maintain cardiac function during perfusion in the large animal model. However, the carrier solution for the Fluosol must be adjusted to appropriate electrolyte content to avoid adverse effects on the myocardium.

Blood conservation techniques

Increasing numbers of operations requiring cardiopulmonary bypass have been accompanied by greater demands for blood resources. Improved techniques of blood conservation have diminished the average blood requirements per operation and have increased the percent of operations that can be done without homologous blood. The conservation of blood can be planned according to each patient's requirements. The techniques include preoperative blood donation, intraoperative withdrawal of blood, reinfusion of oxygenator blood, autotransfusion of blood after heparin neutralization, autotransfusion after wound closure, and hemodilution. The availability of techniques for filtration, centrifugation, and washing of blood have improved the safety of autotransfusion. The techniques that gives the best cost/benefit ratio appear to be preoperative withdrawal of blood, reinfusion of centrifuged oxygenator contents, and reinfusion of filtered blood from chest drainage.

Maximal conservation and minimal usage of blood products in open heart surgery

Open heart surgery has previously been associated with the use of large volumes of blood products. This paper describes methods of blood conservation and a simple method of intraoperative autotransfusion that together have resulted in minimal blood product usage in elective open heart surgery cases. This has reduced our dependence on blood bank supplies for the performance of elective open heart surgery.

The use of blood and blood components in 1,769 patients undergoing open-heart surgery

There has been a decrease in the use of whole blood and red cell transfusions during and after open-heart operations in the greater Kansas City area from an average of slightly more than 9 units per patient from 1969 through 1971, to just over 3 units per patient from 1975 through 1977. In 1977, 1,256 patients, or 71% of 1,769 patients, underwent coronary artery bypass exclusively and had an average transfusion utilization of 2.6 units. All other open-heart operations averaged 4.7 units per patient. Hemodilution and the acceptance of hematocrits between 25 and 30% in open-heart operations are probably the main factors responsible for lower transfusion use per patient, while the increased proportion of patients undergoing coronary artery bypass accounts for a further decrease in the average amount of blood used per patient. It is of note that blood transfused to patients having an open-heart operation was not significantly fresher than blood for routine use, yet hemostasis was not a problem as evidenced by the small use of fresh-frozen plasma in 67 patients (3.8%) and platelet concentrates in 42 patients (2.4%).

Blood conservation during myocardial revascularization

A prospective study of blood utilization in 50 consecutive patients undergoing elective coronary artery bypass was undertaken. Blood was removed from all patients during induction of anesthesia and reinfused after bypass (mean, 675 ml). Intraoperatively, all discard suction was routed through a regionally heparinized collecting and processing system, and the resulting red cell concentrate was transfused. At the conclusion of bypass, all blood remaining in the pump oxygenator was retained for transfusion. After operation, shed mediastinal blood was collected in a sterile, filtered collection system and transfused. Normovolemic anemia was accepted in hemodynamically stable patients. The mean amount of patients' blood salvaged by the intraoperative system was 259 ml (range, 0 to 724 ml) and by the postoperative system, 194 ml (range, 0 to 564 ml). Ninety-four percent (47/50) of the patients received no bank blood or blood products during their hospital stay. No patients received bank blood intraoperatively or during the first 24 hours following operation. There were no complications attributable to blood salvage techniques.

Autotransfusion following cardiac operations: a randomized, prospective study

To evaluate the safety and effectiveness of the collection and retransfusion of postoperatively shed mediastinal blood as part of a multifaceted approach to blood conservation following cardiac operation, 113 patients were randomized into either an autotransfusion group (54 patients) or a control group (59 patients). Intraoperative and postoperative hemodilution was practiced in all patients. The clinical safety of this technique was confirmed by the lack of septic, hematological, pulmonary, renal, or hepatic complications. However, in this setting where blood conservation is already aggressively practiced, the ability of the technique to further reduce the use of banked blood following cardiac surgical procedures was not demonstrated.

Fresh autologous blood in open-heart surgery. Influence on blood requirements, bleeding and platelet counts

The role of fresh autologous blood on haemostasis was studied in 30 patients undergoing aortic valve replacement. All the patients were extremely haemodiluted during the perfusion by using a non-haemic priming solution and withdrawal of 15% of the blood volume at the start of operation. In half of the patients, the autologous blood was retransfused immediately after the termination of perfusion. In the other half, donor blood was given in this period, while the retransfusion of autologous blood was delayed until three hours postoperatively. An increase of circulating platelets was found after the withdrawal of blood and replacement with double the amount of Ringer's acetate. Significantly less donor blood and plasma was transfused in the patients receiving early transfusion of autologous blood. An average reduction of 36% donor blood and 45% plasma was obtained. The blood losses were also less in these patients, but the differences were not significant.