Summary

Background and objective: In some situations, the use of muscle relaxants (neuromuscular blocking drugs) are undesirable or contraindicated. We compared intubating conditions without muscle relaxants in premedicated patients receiving either alfentanil 40 μg kg−1 or remifentanil 2, 3 or 4 μg kg−1 followed by propofol 2 mg kg−1.

Methods: In a randomized, double-blind study, 80 healthy patients were assigned to one of four groups (n = 20). After intravenous atropine, alfentanil 40 μg kg−1 or remifentanil 2, 3 or 4 μg kg−1 were injected over 90 s followed by propofol 2 mg kg−1. Ninety seconds after administration of the propofol, laryngoscopy and tracheal intubation were attempted. Intubating conditions were assessed as excellent, good or poor on the basis of ease of lung ventilation, jaw relaxation, laryngoscopy, position of the vocal cords, and patient response to intubation and slow inflation of the endotracheal tube cuff.

Results: Seven patients who received remifentanil 2 μg kg−1 and one patient who received remifentanil 3 μg kg−1 could not be intubated at the first attempts. Excellent intubating conditions (jaw relaxed, vocal cords open and no movement in response to tracheal intubation and cuff inflation) were observed in those who received either alfentanil 40 μg kg−1 (45% of patients) or remifentanil in doses of 2 μg kg−1 (20%), 3 μg kg−1 (75%) or 4 μg kg−1 (95%). Overall, intubating conditions were significantly better (P < 0.05), and the number of patients showing excellent conditions were significantly higher (P < 0.05) in patients who received remifentanil 4 μg kg−1 compared with those who received alfentanil 40 μg kg−1 or remifentanil 2 μg kg−1. No patient needed treatment for hypotension or bradycardia.

Conclusions: Remifentanil 4 μg kg−1 and propofol 2 mg kg−1 administered in sequence intravenously provided good or excellent conditions for tracheal intubation in all patients without the use of muscle relaxants.