Blood loss and bank blood requirement in coronary bypass surgery

The effect of postoperative normovolaemic anaemia and autotransfusion on blood saving after internal mammary artery bypass surgery

The efficacy of two blood conservation techniques in decreasing and in preventing the use of homologous blood products was retrospectively studied in 150 patients undergoing internal mammary artery bypass surgery. Patients were matched according to prebypass blood haemoglobin (Hb) content and body surface area and were allocated to one of three groups: in the patients of group 1 (n = 50), normovolaemic anaemia (NA) was accepted postoperatively (haematocrit [Hct] was accepted to a minimum level of 25%); the patients of group 2 (n = 50) were treated with postoperative autotransfusion (AT) of mediastinal shed blood and acceptance of NA. Group 3 (n = 50) contained control patients, not treated with NA or with AT (Hct was accepted to a minimum level of 30%). Patients of group 1 required 3.0 +/- 0.3 units of homologous blood products, but the patients of groups 2 and 3 received significantly more (p less than 0.01) units: 3.9 +/- 0.2 and 4.5 +/- 0.3 units. No donor blood products were needed in 36%, 9% and 5% of the patients in groups 1, 2 and 3 respectively. The net postoperative blood loss was similar in the groups: 1229 +/- 92 ml in group 1, 1098 +/- 74 ml in group 2 and 1243 +/- 72 ml in group 3. However, total blood loss (1982 +/- 135 ml), including the retransfused part (954 +/- 89 ml), was significantly larger (p less than 0.01) in group 2, than in groups 1 and 3.(ABSTRACT TRUNCATED AT 250 WORDS)

Plateletpheresis before redo CABG diminishes excessive blood transfusion

BACKGROUND

Blood conservation remains an important element for patients undergoing cardiac operations with cardiopulmonary bypass. Preoperative platelet-rich plasma (PRP) harvest is an autologous blood conservation method. The efficacy of preoperative PRP harvest and post-cardiopulmonary bypass reinfusion on postoperative bleeding and need for postoperative blood transfusion was evaluated in patients undergoing redo coronary artery bypass grafting in a prospective, randomized manner.

METHODS

All adult patients admitted for redo coronary artery bypass grafting entered into the study. The PRP harvest aim was 20% or more of the total estimated circulating platelets. Immediately preoperatively three sequestration cycles were performed. The PRP was reinfused after weaning from cardiopulmonary bypass. One hundred seven parameters/patient were recorded. There were 20 patients in the RPR group and 20 controls (without PRP harvest).

RESULTS

Patient characteristics, operative data, and preoperative hematologic parameters did not differ between the groups. In the PRP group, the mean platelet count in the PRP was 864 +/- 139 x 10(3)/microL, and the platelet yield was 27% +/- 5% (range, 20% to 37%). The average total chest tube blood loss was 423 mL (PRP) compared with 1,462 mL (controls; p < 0.001). Fourteen patients in the control group required blood transfusions postoperatively compared with only 1 patient in the PRP group (p < 0.001). Postoperative fluid requirements were also significantly greater in the control group (p < 0.001). Postextubation gas exchange was significantly better in the PRP group compared with controls (p < 0.01). Postoperative ventilation time and intensive care stay were significantly shorter in patients in the PRP group.

CONCLUSIONS

A preoperative PRP harvest of 20% or more of the total platelets and reinfusion of the PRP after cardiopulmonary bypass resulted in significantly less postoperative blood loss and decreased fluid and blood transfusion requirements compared with controls. Postextubation gas exchange, ventilation time, and time required in the intensive care unit were also better, and the method was found cost-effective.

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.

Autotransfusion after coronary artery bypass surgery: is there any benefit?

Postoperative salvage autotransfusion of shed mediastinal blood, using the cardiotomy reservoir, is an inexpensive technique whose efficacy and safety are evaluated in this study. We randomized 75 consecutive patients into two groups. The autotransfusion group (n = 42) received autotransfusion after the completion of the coronary artery bypass grafting (CABG) until the drainage was < or = 50 mL per hour for 2 consecutive hours. The control group (n = 33) was treated with standard chest drainage. Both groups received homologous blood transfusion when the hematocrit fell below 30%. Packed red cells were required post-operatively in 84.8% of the control group and 80.9% of the autotransfusion group (p = NS). Postoperative colloid fluid replacement (excluding autotransfusion fluid) did not differ significantly between the groups. The prothrombin time was significantly higher in the autotransfusion group 24 hours postoperatively (p = 0.03). The fibrin degradation products were elevated only in the serum of the autotransfusion patients (p < 0.002). More febrile patients were seen in the autotransfusion group although not significantly more than the controls. The autotransfusion group received more red cells than the control group, but it lost more red cells in the mediastinal drains. In conclusion, the autotransfusion of shed mediastinal blood has not proved beneficial in reducing the postoperative requirements in homologous blood in patients undergoing coronary artery bypass grafting (CABG).

Intraoperative predonation contributes to blood saving

The merits of reinfusing prebypass-removed autologous blood (intraoperative predonation) to salvage blood and improve postoperative hemostasis are still debated, specifically for patients at a higher risk for bleeding. To evaluate the effect of intraoperative predonation on the platelet count, blood hemoglobin content, and blood saving postoperatively, we retrospectively studied 100 matching patients. All patients underwent internal mammary artery bypass surgery resulting in a considerable blood loss postoperatively. Intraoperative predonation (800 ml), reinfusion of the residual volume of the extracorporeal circuit, autotransfusion of shed blood, and acceptance of normovolemic anemia postoperatively was the approach adopted in 50 patients (group 1). A similar blood salvage program, excluding intraoperative predonation, was carried out in the other 50 patients (group 2), and these served as the control group. The platelet counts and blood hemoglobin content were significantly higher postoperatively (p < 0.01) in the predonated patients than in the control patients. However, the net blood loss, the amount of retransfused shed blood, and the blood requirements postoperatively were significantly less (p < 0.01) in the predonated patients than in the control patients, whereas 65% of the predonated patients versus 10% of the control patients did not need any donor blood products. In conclusion, predonation reduces the postoperative blood loss and thereby importantly ameliorates the blood-saving effect of a blood salvage program after IMA procedures.

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.

Effects of intraoperative plasmapheresis on blood loss in cardiac surgery

Intraoperative platelet-rich plasmapheresis allows autotransfusion of fresh, undamaged platelets and clotting factors at the completion of the operation. To evaluate this technology, we randomly assigned 100 consecutive patients who were to undergo an elective coronary bypass procedure and had normal clotting studies into the experimental (plasmapheresis) or the control group. Characteristics of both groups were similar, including average age (61.4 years versus 61.3 years [experimental versus control group]), sex (78% male versus 74% male), preoperative weight (80.9 kg versus 80.2 kg), preoperative red cell mass (1,989 mL versus 1,890 mL), perfusion time (102 minutes versus 106 minutes), and coagulation studies. Both internal mammary arteries were used in 68% of the patients. All patients had preoperative and postoperative blood volume determinations and complete clotting studies. Sixty-two variables related to bleeding were analyzed. Strict indications for transfusion were a hemoglobin level less than 7 g/100 mL in patients younger than 70 years and a hemoglobin level less than 8 g/100 mL in patients older than 70 years. The group receiving intraoperative plasmapheresis had a significant reduction in operative red cell mass loss (1,050 +/- 43 mL versus 1,226 +/- 61 mL; p = 0.021), a reduction in the average homologous transfusion (0.67 +/- 0.15 unit versus 1.8 +/- 0.25 units; p = 0.0002), and an increase in the percentage of patients not requiring blood transfusions (66% versus 32%; p = 0.001). This technique is useful in reducing postoperative blood loss and homologous transfusions.

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.

Transfusion of patients undergoing cardiopulmonary bypass

Although certain hematologic changes that occur as a consequence of cardiopulmonary bypass are unique, their influence on the transfusion requirements of open-heart surgical patients is not different from that on other bleeding patients. While knowledge of the peculiarities of open-heart surgery is important for the blood bank medical director, this clinical situation can be managed using the basic principles of component therapy as they apply to other clinical situations.

Effect of cardiopulmonary bypass on the pharmacokinetics of drugs

The cardiopulmonary bypass apparatus must temporarily substitute for the cardiac and pulmonary function of the patient undergoing heart surgery. In order to meet the metabolic needs of the patient and the technical demands of the surgeon, within the limits of engineering technology, a number of major alterations are made in normal physiology. The patient is typically cooled to 27 degrees C and perfused with a non-pulsatile flow of blood which has been diluted with saline to a haematocrit in the mid-20s. Blood flow and pressure are often considerably less than normal. Blood coagulation is prevented by administration of a massive dose of heparin. Central redistribution of blood flow, elaboration of stress-reactant hormones, and fluid and electrolyte shifts occur in response to these changes. In the postoperative period, these alterations are reversed, and normal physiology is restored. Effects upon the pharmacokinetics of drugs are anticipated. The clearance of many drugs may be reduced. Protein binding is diminished by haemodilution, but may rise above normal in the postoperative period for basic drugs which bind to alpha 1-acid glycoprotein. Changes in volume of distribution depend upon the opposing influences of protein binding and reduced peripheral perfusion. Previous studies on the pharmacokinetics of drugs during and after cardiopulmonary bypass illustrate many of these effects. The clearance of digoxin, fentanyl, and the cephalosporins is reduced after cardiopulmonary bypass, and the volume of distribution of cefazolin is increased during cardiopulmonary bypass. Studies of digitoxin and propranolol are also reviewed. Many of the investigations in this area of study have been limited by logistical and methodological factors. Thus, the effects of cardiopulmonary bypass on the pharmacokinetics of drugs are incompletely understood, and the subject merits further attention.

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.

Routine use of autotransfusion following cardiac surgery: experience in 700 patients

An autotransfusion technique has been developed for collection and reinfusion of shed mediastinal blood. This system has been routinely applied in the postoperative management of 592 consecutive adult and 108 pediatric cardiac surgical patients. Two hundred seventy-one adult patients (46%) and thirty-six pediatric patients (33%) actually received autologous blood. Autotransfusion volume ranged from 50 to 21,350 ml per patient. In 1976 at our institution, homologous transfusion requirements averaged 8.4 +/- 0.7 units per adult patient. During 1978, with the routine use of postoperative autotransfusion, bank blood transfusions were lowered to 4.2 +/- 0.3 units per patient (p less than 0.001). In contrast to perioperative autotransfusion techniques, collection and reinfusion of shed mediastinal blood is particularly useful for intravascular volume replacement in patients with serious postoperative bleeding.