The subjective, behavioral and cognitive effects of subanesthetic concentrations of isoflurane and nitrous oxide in healthy volunteers.
James P Zacny, G Sparacino, P Hoffmann, R Martin, J L Lichtor
Psychopharmacology April 1, 1994 DOI: 10.1007/bf02249330 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Randomized controlled trial Double-blind Peer reviewed |
|---|---|
| Sample size | 9 |
| Population | Healthy volunteers |
| Interventions | Isoflurane Nitrous oxide |
| Dose | Isoflurane 0.0, 0.3, 0.6%; Nitrous oxide 0, 20, 40% |
| Duration | Inhalation period with 5-minute post-inhalation recovery assessment |
| Measures | visual analog scales, standardized drug effects inventory, reaction time, eye-hand coordination, immediate and delayed free recall |
| Key findings | Isoflurane produced greater psychomotor impairment and unique subjective effects (confusion, sedation, reduced control) compared to nitrous oxide, while both impaired memory. |
Abstract
A prospective, crossover, double-blind trial was conducted in nine healthy volunteers in which the subjective, psychomotor and memory effects of isoflurane (0.0, 0.3 and 0.6%) and nitrous oxide (N2O) (0, 20 and 40%) were examined. Dependent measures included visual analog scales and a standardized drug effects inventory (subjective effects), reaction time and eye-hand coordination (e.g., psychomotor performance), and immediate and delayed free recall (memory). There were some similarities in subjective effects between the two inhaled drugs (e.g., increased ratings of "drunk" and "spaced out"), but isoflurane had effects which N2O did not have. Isoflurane but not N2O increased visual analog scale ratings of "confused," "sedated," and "carefree," and decreased ratings of "in control of thoughts" and "in control of body." An odor was detected with isoflurane and it was disliked. Psychomotor performance was more grossly impaired during isoflurane inhalation than during N2O inhalation. Psychomotor recovery from both agents was rapid and complete so that 5 min after the inhalation period had ceased, performance had returned to baseline levels. Both isoflurane and nitrous oxide impaired immediate and delayed free recall. The feasibility of using isoflurane in conscious sedation procedures is discussed.