Prophylaxis of postoperative thromboembolism with dextran 70: improvements of efficacy and safety.

The value of routine thromboprophylaxis with dextran 70 was evaluated and methods of increasing efficacy and safety were studied. In a retrospective study, in which routine prophylaxis with dextran 70 alternated with no prophylaxis in four two-year periods, the use of dextran 70 reduced the incidence of fatal pulmonary embolism after major surgery to one third of the incidence found during periods with no prophylaxis. In a prospective study on postoperative deep-vein thrombosis (DVT) detected by the fibrinogen test, the combination of dextran 70 and dihydroergotamine (DHE) compared to dextran 70 alone reduced the incidence of DVT in patients with hip fractures from 31 to 3%. In patients with other diagnoses no potentiating effect was seen. The incidence of severe dextran-induced anaphylactic reaction (DIAR) in Sweden during 1975-1979 was 0.025 per unit of dextran 70, equivalent to 0.037-0.05 per patient. The prevention of DIAR by hapten inhibition was attempted in three multicenter studies using dextran 1 (Mw 1 000 daltons) employing different doses and modes of administration. After injection of 20 ml dextran 1 before infusion of clinical dextran in 41 099 patients only one patient developed severe DIAR (0.002%), which is significantly lower than the incidence observed after the preinjection of half this dose in 29 252 patients (0.024%). Admixture of 20 ml dextran 1 to 500 ml clinical dextran did not prevent fatal DIAR. By hapten inhibition with 3 g dextran 1 before the first infusion of dextran 40 or 70, these agents can be more safely used in thromboprophylaxis, volume replacement and enhancement of blood flow.