Use of aspirin in haemorrhagic shock.

Haemorrhagic shock was induced in two similar groups of dogs for two hours. One group received aspirin before shock and the other group served as a control. When blood was retransfused the PVR which was markedly elevated during shock returned to pre-shock value in the aspirin group but was elevated 100 per cent in the control group, despite correction of a cidosis. Aspirin reduces collagen-induced platelet aggregation and thereby inhibits the formation of platelet micro-emboli without affecting the coagulationfactors. This effect of aspirin is thought to be responsible for the lowering of the elevated PVR to pre-shock values in the aspirin group following retransfusion. Because of the metabolic acidosis associated with the shock state, concurrent administration of sodium bicarbonate is recommended when transfusing shocked patients with blood. A clinical trial of aspirin in early treatment of shocked patients as well as for prophylaxis in high risk situations is justified.