Effect of nitrous oxide inhalation on induction dose ofpropofol, induction time, oxygen saturation, and hemodynamicresponses to laryngoscopy and intubation

Context Nitrous oxide enhances the anesthetic potential of other agents and thereby reduces their requirement.AimsThis study aimed to determine the effect of nitrous oxide inhalation on the induction dose of propofol, induction time, oxygen saturation, and hemodynamic responses to laryngoscopy and intubation.Settings and designThis was a randomized, prospective clinical trial.Participants and methodsA total of 150 surgical patients ASA status I and II were included in the study. Patients in group A inhaled 66% nitrous oxide in oxygen for 3 min, whereas in group B, 100% oxygen was used. In both the groups, patients were administered a propofol bolus 20 mg every minute intravenously after 3 min of gas inhalation until induction was achieved. Loss of response to verbal command and no response to jaw thrust were considered the endpoint of induction. Patients were then intubated after administration of suxamethonium 2 mg/kg.ResultsThe mean dose of propofol required for induction was significantly lower in group A compared with group B (30.4 ± 26.17 vs. 101.87 ± 26.19), as was the induction time (1.52 ± 1.31 vs.5.09 ± 1.33). Heart rate was comparable throughout the study period. At induction, group A had a significantly higher mean arterial pressure (MAP) (94.51 ± 16.21 vs. 86.57 ± 15.47). At 5 and 10 min, MAP was significantly high in group B and significantly high oxygen saturation was observed at induction (99.81 ± 0.46 vs. 99.96 ± 0.26). No patient developed desaturation (SpO 90%) during the study.ConclusionInhalation of 66% nitrous oxide for 3 min significantly reduced the induction time and the dose of propofol, prevented a precipitous decrease in MAP at induction, and effectively attenuatedstress response to laryngoscopy and intubation without desaturation.