Abstract

Changes in cardiac index (CI) and estimated systemic vascular resistance (ESVR) were assessed non-invasively using pulsed Doppler ultrasound during induction of anaesthesia. Ninety-six ASA I patients were allocated randomly to one of four groups to receive alfentanil 8 micrograms kg-1 followed by a dose of thiopentone, methohexitone, propofol or etomidate sufficient to obtund the eyelash reflex. CI increased significantly by 8% 1 min after administration of both methohexitone (P < 0.05) and propofol (P < 0.05), returning to pre-induction values thereafter. CI increased after thiopentone but the increase was not statistically significant. There was a significant decrease in CI of 16% after induction with etomidate (P < 0.001). ESVR decreased significantly from pre-induction values by 18% after methohexitone (P < 0.001) and 23% after propofol (P < 0.001). ESVR in the thiopentone group decreased, but this was not statistically significant. ESVR increased significantly by 12% 1 min after induction of anaesthesia with etomidate (P < 0.05) and then decreased towards pre-induction values. The results suggest that the cardiostability of etomidate may not be as complete in all groups of patients as previous studies have suggested.