BACKGROUND: Studies have shown that tracheal intubation can be facilitated safely and effectively after induction of anesthesia with hypnotic and opioid without employing any muscle relaxants. Remifentanil is a new, ultra-short acting, selective mu-receptor agonist. The goal of our present study was to evaluate the appropriate induction dose of remifentanil with propofol for tracheal intubation without employing any muscle relaxants.

METHODS: We have assessed intubating conditions in three groups of 45 ASA I or II Patients. Each group received intravenous dosage of 2 mg/kg of propofol with remifentanil 1µgram/kg (Group I), 2µgram/kg (Group II) or 3µgram/kg (Group III), respectively. No muscle relaxant was administered. Intubating conditions were assessed based on jaw relaxation, vocal cord position, vocal cord movement, airway reaction, and movement of limbs. Intubating conditions, mean arterial blood pressure and heart rate were measured just before induction (T00, baseline), before intubation (T0), 1 minute after intubation (T1), 2 minutes after intubation (T2) and 3 minutes after intubation (T3).

RESULTS: Intubating conditions were clinically acceptable in 26.7, 86.7 and 93.3% of patients, after 1, 2 or 3µgram/kg administration of remifentanil, respectively. Clinically acceptable intubating conditions were significantly more in Group II and III when compared with Group I (P<0.05). Both HR (heart rate) and MAP (mean arterial pressure) were significantly lower in Group III when compared with Group I before intubation (T0), 1 minute after intubation (T1), 2 minutes after intubation (T2) and 3 minutes after intubation (T3) (P<0.05).

CONCLUSIONS: We conclude that 2-3µgram/kg of remifentanil may reliably provide 'good' to 'excellent' conditions for tracheal intubation when administered after administration of 2 mg/kg propofol. The conditions for intubation were significantly better in patients receiving 2 mg/kg of propofol followed by 2-3µgram/kg of remifentanil than those receiving 1µgram/kg of remifentanil.