Bradford S. Lane

Awakening, clinical recovery, and psychomotor effects after desflurane and propofol anesthesia.

We compared postanesthetic and residual recovery of desflurane versus propofol anesthesia.Twenty volunteers were anesthetized for 1 h at 1-wk intervals with either propofol (induction) plus desflurane (1.25 minimum alveolar anesthetic concentration) in O2 (PD), propofol plus desflurane in N2 O-O2 (PDN), propofol plus propofol infusion with N2 O-O2 (PPN), or desflurane (induction) plus desflurane in O2 (DD). Awakening and clinical recovery were measured. Psychomotor skills (attention, coordination, reactive skills, and memory) were tested before and 1, 3, 5, and 7 h after anesthesia. Awakening was fastest in Group PDN. At 1 h after anesthesia, the subjects given desflurane for maintenance (PD, PDN, and DD) performed significantly (P < 0.05-0.01) better in several psychomotor tests compared with those whose anesthesia was maintained with propofol (PPN). However, subjects met criteria for home readiness as fast after PPN as after PDN anesthesia (mean times +/- SE until fitness for discharge were 126 +/- 20, 81 +/- 14, 70 +/- 7, and 106 +/- 14 min after PD, PDN, PPN, and DD, respectively). Awakening and early psychomotor recovery for as long as 1 h after anesthesia is faster after desflurane than after propofol, but there was no difference in time to home readiness or in residual effects thereafter between propofol and desflurane with N2 O in O2. (Anesth Analg 1996;83:721-5)

Sleep tendency as a measure of recovery after drugs used for ambulatory surgery

Background Although tests of psychomotor function indicate that drug effects after ambulatory anesthesia are short-lived, patients often feel washed out for long periods of time. Among the psychomotor tests that measure different motor and cognitive functions, none directly measures sleepiness or alertness. The authors hypothesized that sleepiness, measured by a sleep latency test, would be a more sensitive indicator of drug effect after an anesthetic than psychomotor tests. The second objective was to determine a sedation regimen that produced the least residual effect. Methods On four separate occasions, volunteers (N = 12) received an injection of propofol 2.5 mg/kg; propofol 2.0 mg/kg and fentanyl 2 &mgr;g/kg; propofol 2.0 mg/kg and midazolam 2 mg/70 kg; or midazolam 0.07 mg/kg and fentanyl 2 &mgr;g/kg. Dependent measures included the multiple sleep latency test (MSLT), Maddox Wing and digit symbol substitution tests, auditory and visual reaction times, and a divided attention task. Results The multiple sleep latency test demonstrated sleepiness up to 4 h after injection, and in some patients, sleepiness continued up to 8 h afterward. Psychomotor function was impaired only at 2 h after injection of the drug combination. Conclusion The multiple sleep latency test may be a more sensitive measure of a drugs effect than other tests of psychomotor function. For up to 8 h after an injection of midazolam and fentanyl, patients must consider driving or operating heavy machinery unsafe activities.

Alcohol after midazolam sedation: does it really matter?

Patients who arrive home several hours after ambulatory surgery may drink alcohol. The extent to which the residual effects of drugs used in ambulatory surgery interact with alcohol, perhaps potentiating alcohol effects, is not known. Accordingly, the purpose of this study was to determine whether intravenous midazolam had residual effects that would interact with alcohol consumed 4 h after the midazolam injection. Healthy male volunteers (n = 16) participated in a double-blind, randomized, placebo-controlled crossover trial. Subjects were studied four times successively with 1 wk between trials. On each test day the subjects randomly received by slow intravenous injection (30 s) either saline or 0.1 mg/kg of midazolam. Four hours after injection, the subjects consumed a beverage that either did or did not contain 0.7 g/kg of alcohol. Before and 1, 3, 5, and 7 h after injection (and before and 1 and 3 h after beverage consumption), psychomotor performance and mood were assessed. Whereas both midazolam and alcohol alone had effects on the dependent measures in this study, there were no significant interactions between the two drugs (i.e., potentiation of alcohol effects by midazolam or poten-tiation of midazolam by alcohol). We conclude that the effects of a short-acting benzodiazepine used in ambulatory surgery have probably dissipated by the time a patient arrives home, and that effects from alcohol ingested at home will probably not be influenced by the recent administration of a short-acting benzodiazepine such as midazolam.

The interaction between alcohol and the residual effects of thiopental anesthesia

BackgroundDuring ambulatory surgery, barbiturates, such as thiopental, may impair psychomotor performance several hours after administration. It was hypothesized that if patients drink alcohol 4 h after thiopental injection, the increase in psychomotor impairment would be greater than that seen after alcohol ingestion alone. MethodsTwelve healthy men volunteered to participate in a double-blind, placebo-controlled, crossover study with a Latin square design. On each testing day, the subjects received intravenous injections of either 5 mg/kg of 2.5% thiopental or an equal volume of saline for 30 s. Four hours after injection, the subjects consumed a beverage with or without 0.7 g/kg alcohol. Psychomotor performance and mood were assessed at five times: prior to injection, at 1 h and 3 h after injection, and at 1 h and 3 h after consumption of beverage. ResultsBoth thiopental and alcohol had strong independent effects on the dependent measures in this study. In addition, body sway, one of the nine psychomotor tests used to assess impairment, was greater after thiopental and alcohol than after alcohol alone. Of eleven adjectives used to assess mood, lightheadedness was cited most frequently after a combination of thiopental and alcohol than after each alone. ConclusionsBased on our tests of performance and mood, an interaction between thiopental and alcohol is evident; in addition, the interaction between both drugs may exert deleterious effects on higher levels of central nervous system integration.

Residual sleepiness after N2O sedation: a randomized control trial [ISRCTN88442975]

BackgroundNitrous 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.MethodsThis 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.ResultsDuring 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.ConclusionWe 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.