Remifentanil and propofol without muscle relaxants or with different doses of rocuronium for tracheal intubation in outpatient anaesthesia

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Background:The use of muscle relaxants in outpatient anaesthesia is controversial; some authors recommend an induction regimen including propofol and opioids without muscle relaxants. This study evaluated the requirements for rocuronium after remifentanil/propofol.Methods:We examined in four groups of ASA I-II patients (n=30 for each) the intubating conditions three minutes after induction of anaesthesia with remifentanil 0.5 μg kg−1 min−1, propofol 2 mg kg−1 without muscle relaxants or with different doses of rocuronium (0.6 mg kg−1, 0.45 mg kg−1, 0.3 mg kg−1) applying the criteria proposed by the Copenhagen Consensus Conference. In the second part of the study the time course of neuromuscular block was determined by electromyography using train-of-four (TOF) stimulation. To this end, another 60 ASA I-II patients were randomly assigned to receive remifentanil 0.5 μg kg−1 min−1, propofol 2 mg kg−1 and either rocuronium 0.6 mg kg−1, 0.45 mg kg−1, 0.3 mg kg−1, or 0.3 mg kg−1 followed by neostigmine 40 μg kg−1 and atropine 20 μg kg−1 at a T1 recovery of 10% (n=15 for each).Results:Intubating conditions were good or excellent in 30 patients after rocuronium 0.6 mg kg−1 and in 18 patients when rocuronium was omitted (P<0.01). After 0.45 mg kg−1 and 0.3 mg kg−1 rocuronium the numbers were 29 and 30 patients, respectively. Reducing rocuronium from 0.6 mg kg−1 to 0.45 mg kg−1 or 0.3 mg kg−1 increased the onset time from 136 (35) s to 199 (34) s and 249 (52) s (mean (SD)), (P<0.01); the clinical duration decreased from 38 (10) min to 24 (8) min and 16 (5) min, respectively (P<0.01); and the duration to a TOF-ratio of 0.8 decreased from 60 (11) min to 45 (9) min and 34 (7) min (P<0.01). After rocuronium 0.3 mg kg−1 this time interval further decreased to 22 (3) min when neostigmine was given at a T1 of 10% (P<0.01 compared with spontaneous recovery after rocuronium 0.3 mg kg−1).Conclusion:After remifentanil/propofol intubation conditions were poor in 40% of patients without muscle relaxants; adding reduced doses of rocuronium to this regimen improved the intubation conditions significantly. In addition, reducing the initial dose of rocuronium markedly shortened its time course of action.

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