Context: Muscle relaxants used to facilitate tracheal intubation have disadvantages.
Objective: This study was designed to evaluate the dose requirements for remifentanil combined with thiopental for optimal lightwand intubation without muscle relaxants.
Design: Prospective randomised controlled study.
Setting: A tertiary care teaching hospital.
Patients: Ninety-six patients requiring general anaesthesia for elective surgery.
Interventions: Patients received remifentanil 1, 2, or 3 μg kg(-1) (group R1, R2, R3, each n = 32) as a slow bolus infusion over 60 s, followed by thiopental 5 mg kg(-1). Ninety seconds after remifentanil administration, lightwand intubation was attempted and intubation time was recorded. Intubating conditions were considered excellent if there was no patient movement or cough, good if coughing occurred once or twice after intubation and poor if persistent movement or cough occurred after intubation. Excellent or good intubating conditions were regarded as clinically acceptable. The duration of apnoea was recorded.
Main outcome measures: Intubating conditions and the duration of apnoea.
Results: Lightwand intubation was successful at the first attempt in all patients except for two in group R1. The intubating conditions were more acceptable in groups R2 and R3 than in group R1 (97 and 100 vs. 63%, P < 0.01). Intubation time was shorter in group R3 than in group R1 (22 ± 8 vs. 33 ± 18 s, P < 0.01). There was no significant difference in intubation time and conditions between groups R2 and R3. The mean duration of apnoea was prolonged in group R3 compared with group R2 (10.2 ± 2.1 vs. 4.6 ± 1.6 min, P < 0.01).
Conclusion: Our results suggest that remifentanil 2 or 3 μg kg(-1) combined with thiopental 5 mg kg provides acceptable conditions for lightwand intubation without muscle relaxants. Spontaneous ventilation returns more rapidly following remifentanil 2 μg kg(-1) than with remifentanil 3 μg kg(-1).