Low Molecular Weight Dextran in Open Heart Surgery: Effect on Coagulation Factors and on Red Cell Antibody Activity*

Abstract

Low molecular weight (40,000) dextran is being extensively used in open heart surgery to minimize the amount of donor blood required and to inhibit red cell aggregation. At equal concentrations, its effects on blood coagulation were less than those of standard dextran plasma substitutes; but in the very high concentrations used in open heart surgery its effects were greater. Addition of low molecular weight dextran to normal plasma caused a gross precipitate and striking inhibition of coagulation. Factor VIII (antihemophilic factor) and fibrinogen were partially removed with the precipitate. Patients subjected to open heart surgery had lower levels of these two clotting factors in their plasma when dextran was used, but it is not certain whether this loss occurred in vivo, or during separation of the plasma from red cells (and precipitate) prior to testing. No proof was obtained in this series of cases that low molecular weight dextran increased the tendency to bleed, but the results indicate that this would be a likely possibility with the use of larger amounts. The low molecular weight dextran had a slight tendency to induce red cell aggregation by itself. It potentiated the aggregative effect of Polybrene and the agglutinating effect of a saline Rh antibody. On the other hand, it inhibited agglutination of red cells induced by an Rh antibody in a high protein medium. It thus appears likely that high concentrations of low molecular weight dextran in the blood of a patient could lead to erroneous conclusions in compatibility tests.

Blood Replacement

“…PERKINS [1123], DYBKJAER [372] and KROLL [840] used large amounts of dextran 40 (sometimes 15 0 /0 solution) in 5 0 /0 glucose in their in vitro experiments. The precipitation caused by this was probably due to dilution of the electrolyte concentration and the "water excluding effect".…”

Coagulation Parameters Following Extracorporeal Circulation Using Acid‐Citrate‐Dextrose Blood Buffered with Tris (Hydroxymethyl) Aminomethane (THAM)

“…Storage of ACD blood for 24 to 48 hours before perfusion may be responsible for the decrease in Factor V but an influence of the dextran on this substance cannot be ruled 0ut. 7 One patient of the nine on ACD blood and dextran had abnormal thromboplastin generation (TGT) the morning following the operation, accounting for the long average figures Volume 7…”

Treatment of Shock with Dextrans and Gelatins

“…As with clinical dextran, however, additive effects are t o be anticipated. If 2 g/kg = 20 ml/kg or more are administered in the course of extracorporeal perfusions, clot formation is inhibited and post-operative blood loss increased [28,47,54,55,89,162,198,2101. I n vitro studies with clinically relevant concentrations of low molecular weight dextran reveal that it interferes with clotting and with fibrinogen [114, 1151.…”