Effect of nitrous oxide on pain due to rocuronium injection: A randomised, double-blind, controlled clinical trial

Abstract

A prospective, randomised, double-blind, placebo-controlled study was carried out to determine the effect of nitrous oxide (N 2 O) on the frequency and severity of pain and withdrawal reactions after injection of rocuronium. Eighty ASA physical status I and II patients undergoing general anaesthesia for elective surgery were enrolled. The patients were randomised to receive 100% oxygen (O 2 ), or 50% N 2 O in O 2 for 3 minutes followed by a subparalysing dose of rocuronium 0.06 mg/kg. After induction of anaesthesia with thiopentone 5 mg/kg, an intubating dose of rocuronium 0.6 mg/kg was given. The patients were observed after injection of rocuronium 0.06 mg/kg, and asked to rate pain in the arm on a 4-point (0-3) verbal rating scale (none, mild, moderate or severe). After the intubating dose of rocuronium, withdrawal reactions were recorded. Thirty-six patients (90%) in the group N 2 O and 15 patients (37.5%) in the group O 2 reported no pain (P < 0.001). The pain was mild in 1 (2.5%) and 9 (22.5%) patients in N 2 O and O 2 groups, respectively (P = 0.006). Moderate pain occurred in 2 (5%) patients in group N 2 O and 15 (37.5%) patients in group O 2 (P = 0.001). Severe pain was reported by one patient in each group (P = 0.47). Withdrawal response after an intubating dose of rocuronium was observed in 6 (15%) and 18 (45%) patients in the N 2 O and O 2 groups, respectively (P < 0.05). Inhalation of 50% N 2 O in O 2 reduces the incidence and severity of pain and the withdrawal reactions associated with rocuronium injection.

Keywords

• Nitrous oxide
• pain
• rocuronium