Hämodynamische Wirkungen von 3 unterschiedlichen Dosierungen des Induktions-hypnotikums Eltanolon bei koronarchirurgischen Patienten

Eltanolone is a new steroid anaesthetic agent that is a 5-β reduced derivative of progesterone. In the present study we investigated the haemodynamic effects of eltanolone or thiopentone in patients scheduled for coronary artery bypass grafting. Methods. After obtaining approval of the institutional ethics committee and informed patient consent, 40 patients (age 45-70 years, ASA III and IV, ejection fraction >50%, cardiac index >2.5 1/min per m²) were randomly assigned to four groups, each containing 10 patients: After premedication with 2 mg flunitrazepam, anaesthesia was induced with 3 mg/ kg thiopentone in group 1, 0.5 mg/kg eltanolone in group 2, 0.75 mg/kg eltanolone in group 3, 1.0 mg/kg eltanolone in group 4. Each patient additionally received 3 μg/kg fentanyl after induction and 0.1 mg/kg pancuronium. Heart rate, mean arterial pressure, pulmonary arterial pressure, central venous pressure, pulmonary artery occlusion pressure and cardiac output were recorded in the awake state, 2 min after induction of anaesthesia, and 1 and 5 min after intubation. Cardiac index and systemic vascular resistance were calculated. Results. Two minutes after induction, mean arterial pressure was significantly lower than the baseline (P<0.05) in each group. Mean arterial pressure changes were more prominent in the case of eltanolone, but intergroup tests did not reveal significant differences between the four groups. There was a fall in cardiac index in all groups, and these changes reached the level of significance only in the thiopentone patients. The most obvious difference between eltanolone and thiopentone was systemic vascular resistance. It dropped significantly 2 min after induction with eltanolone at all dosages. In contrast, there was an increase in systemic vascular resistance following induction of anaesthesia with thiopentone. Intergroup tests also showed significantly (P<0.05) lower systemic vascular resistance 1 and 5 min after intubation with eltanolone compared to thiopentone. Discussion. Mean arterial pressure reduction induced by eltanolone is most likely the result of the combination of a decrease in cardiac contractility and peripheral vasodilatation. In contrast, mean arterial pressure reduction in the case of thiopentone seems to be exclusively related to the negative inotropic properties of the drug. Results of a dosage finding study [5] with eltanolone revealed an AD₅₀ of 0.33 mg/kg. In our study 0.5 mg/kg eltanolone brought all the patients to sleep within 2 minutes. The haemodynamic results do not show any significant difference up to twofold dosage. Therefore, the therapeutic margin seems to be large. Because of considerable interindividual variability additional studies in larger collectives are required for definitive evaluation of the drug.