Alfentanil during rapid sequence induction with thiopental 4 mg/kg and rocuronium 0.6 mg/kg: tracheal intubation conditions.

BACKGROUND: Opioids have become an integral part of anaesthesia induction. We aimed to determine the dose of alfentanil needed to obtain perfect tracheal intubation conditions during rapid sequence induction with standard doses of thiopental and rocuronium, where laryngoscopy was initiated 55 s after commencement of drug administration. The influence of covariates (sex, body weight, age, alfentanil plasma concentration at laryngoscopy) was tested. METHODS: Eighty-four healthy individuals were randomly assigned to receive one of the seven assessor-blinded alfentanil doses (0, 10, 20, 30, 40, 50 and 60 µg/kg) in conjunction with thiopental 4 mg/kg and rocuronium 0.6 mg/kg. For drug administration, 15 s was allowed. Laryngoscopy was initiated 40 s after rocuronium and tracheal intubation concluded within 70 s after commencement of drug administration. Alfentanil doses associated with 50%, 90% and 95% probability of perfect intubation conditions were determined with logistic regression. Multiple logistic regressions were used to test the influence of covariates. The relationship between alfentanil dose and concentration at laryngoscopy was analysed with linear regression. The effects of covariates on plasma concentrations of alfentanil were tested with multiple linear regressions. RESULTS: Perfect intubation conditions of 95% probability was obtained with 56 µg/kg (confidence intervals 44-68). None of the covariates were significant predictors of perfect intubation conditions. Alfentanil plasma concentration correlated with dose and increased with increasing body weight (1.7 ng/ml/kg). CONCLUSION: Perfect intubation conditions during rapid sequence induction can be obtained with clinically relevant doses of alfentanil in most healthy patients anaesthetized with thiopental 4 mg/kg and rocuronium 0.6 mg/kg.

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 microg 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) microg kg-1. In 12 patients, the systolic BP declined to <90 mm Hg during the 3 min immediately after intubation. CONCLUSION: Adding 36-40 microg 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.