Comparison of the immediate effects of etomidate, propanidid and thiopentone on haemodynamics, coronary bloodflow and myocardial oxygen consumption.

Since cardiovascular depression at induction is among the most common complications of anesthesia this comparative study was undertaken. Unpremedicated dogs (n = 16) were induced with 3 mg/kg piritramide i.v. and normoventilated (N2O/O2 = 2/1). In 8 animals 0.8 and 1.6 mg/kg Etomidate and 5.0 and 10.0 mg/kg thiopentone and in 8 further dogs 5.0 and 10.0 mg/kg Propanidid were tested. Equipotent doses of Thiopentone and Propanidid caused a marked myocardial depression, which was seen in a decrease in stroke volume and max dp/dt and in an increase of leftventricular end-diastolic pressure and pulmonary arterial pressure. The increased myocardial O2- cosumption mainly due to the rise in heart rate was covered after Thiopentone by an increase of coronary bloodflow (measured with a pitot-catheter) and an increase of arterio-coronaryvenous difference in oxygen. As the latter decreased after Propanidid, it appeared that Propanidid has coronary dilatory properties. The results demonstrated the uneconomic work of the heart under the influence of Thiopentone and Propanidid. In contrast to this the cardiovascular system after Etomidate remained nearly unaffected. The data of this study suggest the use of Etomidate rather than Thiopentone and Propanidid in cases of shock syndrome, heart and/or coronary insufficiency.