title: Residual sleepiness after N2O sedation: a randomized control trial [ISRCTN88442975].
abstract: BACKGROUND: Nitrous oxide (N2O) provides sedation for procedures that result in constant low-intensity pain. How long do individuals remain sleepy after receiving N2O? We hypothesized that drug effects would be apparent for an hour or more. METHODS: This was a randomized, double blind controlled study. On three separate occasions, volunteers (N = 12) received 100% oxygen or 20% or 40% N2O for 30 min. Dependent measures included the multiple sleep latency test (MSLT), a Drug Effects/Liking questionnaire, visual analogue scales, and five psychomotor tests. Repeated measures analysis of variance was performed with drug and time as factors. RESULTS: During inhalation, drug effects were apparent based on the questionnaire, visual analogue scales, and psychomotor tests. Three hours after inhaling 100% oxygen or 20% N2O, subjects were sleepier than if they breathed 40% N2O. No other drug effects were apparent 1 hour after inhalation ceased. Patients did not demonstrate increased sleepiness after N2O inhalation. CONCLUSION: We found no evidence for increased sleepiness greater than 1 hour after N2O inhalation. Our study suggests that long-term effects of N2O are not significant.
authors.affiliation: University of Iowa, Department of Anesthesia, 200 Hawkins Drive, 6 JCP, Iowa City, IA 52242-1079. lance-lichtor@uiowa.edu
authors.forename: J Lance
authors.initials: JL
authors.lastname: Lichtor
authors.forename: Bradford S
authors.initials: BS
authors.lastname: Lane
authors.forename: M Bridget
authors.initials: MB
authors.lastname: Zimmerman