Dose of alfentanil needed to obtain optimal intubation conditions during rapid-sequence induction of anaesthesia with thiopentone and rocuronium

Background. The primary aim of the present study was to determine the dose of alfentanil that must be added to a rapid-sequence induction (RSI) regimen using thiopentone and rocuronium to obtain optimal intubation conditions in > 95% of the individuals. Methods. A total of 60 ASA I patients were randomly allocated to five different alfentanil dose groups (0, 15, 30, 45, or 60 mu g kg(-1)). A blinded dose of alfentanil followed by thiopentone 4 mg kg(-1) and rocuronium 1 mg kg(-1) was administered in rapid succession, and tracheal intubation was attempted 40 s thereafter. The relationship between the alfentanil dose and the probability of optimal intubation conditions was determined by non-linear logistic regression analysis. Blood pressure (BP) changes were recorded continuously using an intra-arterial catheter. Results. The success rate of optimal intubation conditions increased with increasing doses of alfentanil. The alfentanil dose needed to obtain optimal intubation conditions in > 95% of the patients was 36.4 (CI 33.4-39.4) mu g kg(-1). In 12 patients, the systolic BP declined to < 90 mm Hg during the 3 min immediately after intubation. Conclusion. Adding 36-40 mu g kg(-1) alfentanil to a regimen of thiopentone and rocuronium during RSI of anaesthesia may significantly increase the success rate of optimal intubation conditions. Significant hypotension requiring vasopressor treatment may occur.