[Effect of barbiturates on myocardial metabolism and hemodynamics].

In 31 patients with congenital heart disease effects of 5 mg/kg thiopental or 1 mg/kg methohexital on hemodynamics, inotropic state, myocardial metabolism and myocardial oxygen consumption were investigated after cardiac surgery (basic neuroleptanalgesia). In comparison to a control group both barbiturates caused a decrease in stroke volume and arterial pressure. This, however, was mainly attributable to venous pooling and not to a negative inotropic effect. In accordance with the changes in hemodynamics there was a remarkable decrease in myocardial oxygen consumption (5 mg/kg thiopental: Eg--17,7%; 1 mg/kg methohexital: Eg--11,7%). It could be demonstrated that arterial and coronarvenous lactate correlated directly with plasma concentrations of barbiturates. Furthermore it may be possible that the slight increase in free fatty can have deleterious effects on myocardial glucose metabolism. No significant alterations in serum electrolytes concentrations were observed. Plasma concentrations of thiopental and methohexital were determined by specific gaschromatography. In spite of the great interindividual variation of plasma barbiturate concentration there was an equilibrium between arterial and coronarvenous barbiturate levels within two minutes.