A comparative study of cardiopulmonary bypass with nonblood and blood prime

Blood conservation in cardiac surgery. Preliminary results with an institutional commitment

To evaluate the effect of blood conservation in cardiac surgery, use of blood products was analyzed in patients undergoing CABG before and after implementation of blood conservation techniques. Age, sex, coronary anatomy, ejection fraction, cardiopulmonary bypass time, and the preoperative hematocrit, platelet count, and clotting studies were similar in both groups. Methods of blood conservation included autologous transfusion of blood withdrawn before bypass, autotransfusion of shed mediastinal blood, strict protocols for transfusion, and acceptance of normovolemic anemia. With blood conservation, 25.5% of patients received no transfusions and 54.9% received blood only. Significant reductions (p less than 0.001) were achieved in the transfusion of blood from 6.8 +/- 2.4 to 2.3 +/- 2.6 units per patient and of plasma from 2.5 +/- 2.2 to 0.6 +/- 2.0 units per patient. Reductions in the use of platelets and cryoprecipitate were substantial, although not significant. Total donor exposure was reduced significantly from 13.1 +/- 7.3 to 4.3 +/- 6.7 donors per patient. The postoperative hematocrit was significantly lower and remained so at discharge. However, 30 days later there was no difference. This reduction in transfusion requirements decreased costs and donor exposure.

Chalk in the prime

After observations of cloudiness in the perfusion circuit at open intracardiac operations, laboratory experiments showed a precipitate in a Hartmann's solution (compound sodium lactate solution, Ringer-lactate) and sodium bicarbonate based priming fluid used for cardiopulmonary bypass. The precipitate was found to consist of calcium carbonate crystals. The crystals were not dissolved by adding plasma proteins, nor were they sufficiently cleared from the extracorporeal circuit by a 40 microns filter in the arterial line. The crystals may embolise in microvascular beds and thus be a cause of postoperative morbidity. The practice of adding sodium bicarbonate to the pump prime may be unnecessary.

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.

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.

The cell saver during cardiac surgery: does it save?

Conservation and autotransfusion of autologous blood have been proposed as a means to decrease the homologous blood requirements of cardiac surgery. Use of the Haemonetics Cell Saver System to salvage blood shed in the sterile surgical field resulted in a net saving of 105 +/- 88.7 ml of packed red cells in 20 patients undergoing cardiopulmonary bypass. The system is not a cost-effective way to save blood or decrease homologous blood requirements during routine cardiac operations.

Effects of hypothermia, hemodilution, and pump oxygenation on organ water content, blood flow and oxygen delivery, and renal function

Hypothermia, hemodilution, and the pump-oxygenator each contribute important effects during cardiopulmonary bypass. We studied their separate effects with a 2(3) factorial, completely fixed experimental design in 16 adult male mongrel dogs. Animals undergoing hypothermia were cooled to 25 degrees +/- 1 degree C. In dogs having hemodilution, hematocrit was adjusted to 25 +/- 2%. An analysis of variance was used to determine the effects of hypothermia, hemodilution, and pump oxygenation. The experiments show that hemodilution produces increased water content in tissue and that edema is greatest in heart and gastrointestinal organs. The pump-oxygenator decreased flow to the subendocardium, whereas hemodilution increased subendocardial flow. Both hypothermia and pump oxygenation diminished flow to the outer kidney cortex, and hemodilution augmented flow to this region. Hypothermia and pump oxygenation decreased and hemodilution raised renal free-water clearance. Although none affected glomerular filtration rate, hypothermia increased filtration fraction while hemodilution diminished it. Hypothermia lessened cerebral cortical flow, an effect opposite that of hemodilution. Thus, hemodilution opposes the adverse effect of hypothermia or pump oxygenation on blood flow, oxygen delivery, or renal function. Increased water content in gastrointestinal organs and myocardium accompanies the beneficial vascular and renal effects of hemodilution.

Oxygen transport to tissue under normovolemic moderate and extreme hemodilution during coronary bypass operation

Oxygen transport to tissue was studied in 12 patients undergoing coronary bypass operation under normovolemic moderate and extreme hemodilution. Normovolemic moderate hemodilution (15 ml per kilogram of body weight), carried out immediately after induction of anesthesia, decreased the mean hematocrit from 0.43 to 0.33. Simultaneously, the cardiac index and the left ventricular filling pressure increased slightly but the systemic oxygen transport was reduced by 20%. The subcutaneous tissue oxygen tension (PO2) was approximately 40 mm Hg after induction of anesthesia and underwent a transient increase during moderate hemodilution. During cardiopulmonary bypass and extreme hemodilution, the mean hematocrit declined to 0.16. Concurrently, the mean tissue PO2 fell sharply and reached a minimum of 14 mm Hg at deepest hypothermia. After decannulation and reinfusion of autologous blood, the PO2 rose to 30 mm Hg. In general, total-body oxygen consumption changed along with tissue PO2. Blood lactate concentration underwent a clear increase in the early phase of extracorporeal circulation and remained rather stationary thereafter. No perioperative myocardial infarctions were encountered, and each patient made an uneventful recovery.

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%).

Moderate and extreme haemodilution in open-heart surgery: evaluation of haemolysis, cell damage and protein changes

Clinical chemical data from patients operated upon in moderate and extreme haemodilution have been compared. Haemolysis was more pronounced during and after moderate dilution that in extreme dilution. A slight liver damage was found post-operatively after moderate dilution. Several changes were of about the same magnitude in both groups: Serum CK increased, reaching maximal activity 3-18 h after operation. An acute phase reaction of plasma proteins took place post-operatively, except that the concentration of complement C-3 dropped during the first days after operation. The serum levels of phosphate were positively correlated to several of the acute phase proteins.

Control of heparinization by activated clotting time during bypass with improved postoperative hemostasis

Heparin and protamine dosages monitored during open-heart operations by activated clotting time (ACT) have been reported to be superior to dosage schedules based on body weight or body surface area. To evaluate the automated ACT, 114 consecutive open-heart operations performed between October, 1974, and December, 1975, were studied. Fifty-eight operations prior to April, 1975, using a standard heparin-protamine protocol (Group I) were compared with 56 operations from April to December, 1975, monitored with an automated ACT (Group II). The two groups were similar with respect to surgical procedures, pump time, and perfusion techniques. The protamine/heparin ratio was 25% less in Group II compared with Group I, and the 12-hour postoperative blood loss was 48% less in Group II. The automated ACT is a reliable, rapid, and simple test that has resulted in improved hemostasis following cardiac operation.

Reduction of blood usage in open heart surgery

A series of 142 adult patients undergoing open-heart surgery were studied. All known blood-conservativing methods were utilized in an attempt to use as little blood as possible. Hemodilution, autologous transfusion, prevention of wasting of blood, and management of postoperative anemia were the measures employed. An average of 2.66 units of blood were given per patient during the entire hospital stay. Twenty patients were not given any blood at all. The patients were removed from cardiopulmonary bypass without difficulty when the hematocrit reading was in the high teens or low twenties. Later in the postoperative period the patients seemed to progress without difficulty with hematocrit readings of 22 to 25 percent.