Etomidate has become an important induction agent in high-risk patients because of its cardiovascular stability. Its unwanted side-effects such as pain on injection and thrombophlebitis could be significantly reduced by a new (medium chain triglyceride and soya bean) emulsion formulation. Propofol is solved in a mixture of long chain triglyceride and soya bean emulsion. In this double-blind, randomized study we compared the haemodynamic effects, the patients' sensations, signs of thrombophlebitis and postoperative nausea and vomiting (PONV) following injection of both drugs.

METHODS

Following premedication with 2 mg Lormetazepam p.o. in 50 patients per group, anaesthesia was induced with either 0.51 mg etomidate in lipid emulsion or 3.04 mg propofol per kg bw. No opioid or benzdiazepine was given i.v. before induction. After injection of the tested drug, the cannula was removed. Changes in blood pressure and heart rate were recorded as well as signs of discomfort during and after injection (pain, burning, tension, cold). Venous sequelae were assessed for 5 days after injection to register signs of thrombophlebitis.

RESULTS

Demographic data showed no difference between the two groups. After propofol more often a fall in blood pressure was seen. Pain (25 vs 1 pt), burning 19 vs 1), tension 15 vs 3), cold (35 vs 17) after injection was registered significantly more often in the propofol group, whereas myocloni predominated in the etomidate group (13 vs 6) P < 0.05, chi-squared-test). No difference was seen in PONV in either groups.

CONCLUSIONS

Etomidate formulated in a medium chain lipid emulsion causes significant less discomfort for the patients than propofol, which is solved in a long chain formulation. Myocloni, however, occur significantly more frequently after etomidate than after propofol.