Induction of anaesthesia with eltanolone at different rates of infusion in elderly patients

Abstract

We have determined the effective dose of eltanolone (pregnanolone) required to induce anaesthesia in 30 ASA I and II patients aged 60 yr and over. Eltanolone 4 mg ml-1 was administered at a rate of 300 ml h-1 (group 1), 600 ml h-1 (group 2) or 1200 ml h-1 (group 3) until loss of consciousness, as judged by loss of verbal contact with the patient. Anaesthesia was induced successfully in all patients. The slower rates of induction were associated with a significant increase in induction time (ANOVA, P < 0.01) and a decrease in the induction dose (P < 0.01). There was a significant reduction in systolic arterial pressure after induction of anaesthesia in groups 2 and 3 (MANOVA, P < 0.01). This study suggests that the induction dose of eltanolone in unpremedicated older patients should not exceed 0.6 mg kg-1.

Ventilatory effects of eltanolone during induction of anaesthesia: comparison with propofol and thiopentone

“…Using eltanolone 0.75 mg kg 91 we found that 30 % of patients were apnoeic for greater than 30 s, with 13 % being apnoeic for more than 60 s. This is a greater incidence than reported by many earlier authors [6,7,15,16] but, except for one study [16], smaller doses of eltanolone were used. After a prior dose of fentanyl, and a dose of 0.59-0.89 mg kg 91 , given over a range of times, Myint, Peacock and Reilly [12] reported that 37 % of their patients were apnoeic for more than 30 s. All patients studied by Kallela and colleagues [17] using eltanolone 0.8 mg kg 91 were apnoeic for more than 60 s, probably because of the generous dose of alfentanil given before induction.…”

“…Further investigation of eltanolone may provide different estimates of the relative potency, which could alter the interpretation of our results. Also, although administration of a pre-calculated bolus dose of induction agent over approximately 30 s is common clinical practice, other methods, for example less rapid administration to a clinical end-point such as cessation of counting, could result in different dose requirements and ventilatory effects [12][13][14].…”