Influence of propofol on erythrocyte morphology, blood viscosity and platelet function.

The intravenous anaesthetic propofol has been associated with cardiovascular side effects. We therefore studied its influence on blood viscosity, erythrocytes and platelet aggregation. Blood from healthy volunteers was incubated with propofol concentrations of 0, 5, 10, 20, 40, 80, 200, and 500 microg/ml plasma. Whole blood viscosity (shear rates 94.5 and 0.1 s(-1)), plasma viscosity, erythrocyte morphology and platelet aggregation (PFA-100 system) were determined. These parameters were also measured in vivo in 9 patients prior to anaesthesia, after induction, before the end and 1 h after the end of propofol anaesthesia. Propofol induced a slight, dose-dependent echinocytic shape transformation of erythrocytes in vitro, indicating a preferential intercalation of the drug in the outer hemileaflet of the membrane. Neither whole blood nor plasma viscosity were affected in vitro. In vivo, no change in erythrocytes shape was seen, but plasma and whole blood viscosity at high shear rate (94.5 s(-1)) were decreased at the end of anaesthesia, which may be due to some extent to plasma dilution. Platelet aggregation with epinephrine was decreased both in vitro and in vivo. We conclude that propofol interacts with the erythrocyte membrane without affecting blood and plasma viscosity and decreases platelet aggregation, which may have clinical implications.