The purpose of this study was to compare the effectiveness of intramuscular and intranasal midazolam used as a premedication before intravenous conscious sedation. Twenty-three children who were scheduled to receive dental treatment under intravenous sedation participated. The patients ranged in age from 2 to 9 years (mean age, 5.13 years) and were randomly assigned to receive a dose of 0.2 mg/kg of midazolam premedication via either intramuscular or intranasal administration. All patients received 50% nitrous oxide and 50% oxygen inhalation sedation and local anesthetic (0.2 mL of 4% prilocaine hydrochloride) before venipuncture. The sedation level, movement, and crying were evaluated at the following time points: 10 minutes after drug administration and at the times of parental separation, passive papoose board restraint, nitrous oxide nasal hood placement, local anesthetic administration, and initial venipuncture attempt. Mean ratings for the behavioral parameters of sedation level, degree of movement, and degree of crying were consistently higher but not significant in the intramuscular midazolam group at all 6 assessment points. Intramuscular midazolam was found to be statistically more effective in providing a better sedation level and less movement at the time of venipuncture than intranasal administration. Our findings indicate a tendency for intramuscular midazolam to be more effective as a premedication before intravenous sedation.
Midazolam; Dentistry; Sedation; Pediatrics; Intramuscular; Intranasal
The effects of chloral hydrate and/or nitrous oxide were assessed in the mouse staircase test. In this paradigm, the number of steps ascended is thought to reflect locomotor activity, whereas the number of rears is an index of anxiety. Chloral hydrate alone produced a dose-dependent decrease in the number of rears but no change in the number of steps ascended except at the highest dose. Nitrous oxide alone produced a concentration-related increase in the number of steps ascended but no change in rearing. When the two drugs were combined, nitrous oxide appeared to potentiate the rearing suppressant activity of chloral hydrate. Analysis of our experimental findings suggests that chloral hydrate exerts a specific anxiolytic drug effect that can be potentiated by concurrent treatment with nitrous oxide.
The purpose of this study was to compare efficacy and safety of oral chloral hydrate (CH) and promethazine (PZ) for sedation during electroencephalography (EEG) in children.
In a parallel single-blinded randomized clinical trial, sixty 1-10 year old children referred to EEG Unit of Shahid Sadoughi Hospital from January 2010 to February 2011 in Yazd, Iran, were evaluated. They were randomized to receive orally 70 mg/kg chloral hydrate or promethazine 1 mg/kg. The primary outcome was efficacy in adequate sedation and successful recording of EEG. Secondary outcome included clinical side effects, time from administration of the drug to adequate sedation, caregiver's satisfaction on a Likert scale, and total stay time in EEG Unit.
Twenty four cases with mean age 2.9±1.9 years were evaluated. Adequate sedation (Ramsay sedation score of four) was obtained in 43.3% of PZ and 100% of CH group (P=0.00001). Also in 70% of PZ and 96.7% of CH group, EEG was successfully recorded (P=0.006). So, CH was a more effective drug. In CH group, EEG was performed in shorter time after taking the drug (32.82±9.6 vs 52.14±22.88 minutes, P<0.001) and the parents waited less in the EEG unit (1.29±0.54 vs 2.6±0.59 hours, P<0.001). They were also more satisfied (4.6±0.6 scores vs 3.1±1.4 scores, P=0.001). Mild side effects such as vomiting in 20% of CH (n = 6) and agitation in 6.6% of PZ group (n = 2) were seen. No significant difference was seen from viewpoint of side effects frequency between the two drugs.
The results of the present study showed that chloral hydrate can be considered as a safe and more effective drug in sedation induction for sleep EEG in children.
Chloral hydrate; Promethazine; EEG; Sedation
This study measured changes in adult performance following prolonged exposure (90 minutes) to nitrous oxide at psychosedative levels. Using a repeated-measures randomized blind design, experimenters exposed 12 subjects to four treatment combinations. These included: room air for 90 minutes (baseline); 100% oxygen for 90 minutes; nitrous oxide-oxygen sedation for 90 minutes followed by 100% oxygen for 2 minutes; and 90 minutes of nitrous oxide-oxygen sedation followed by 10 minutes of 100% oxygen. Following each treatment, participants were asked to perform six standard neuropsychological tests together with a rating scale measurement where subjects self-evaluated their respective levels of alertness. The tests were: digit span; digit symbol; paced auditory serial addition; controlled word association; letter cancellation; and grooved pegboard. Two-way analysis of variance revealed significant differences between mean scores for treatments on only two tests, grooved pegboard (P less than 0.05) and controlled word association (P less than 0.05). There was also a significant difference in mean scores obtained for the rating scale (P less than 0.001). These findings indicate that psychomotor performance and verbal fluency were affected by prolonged exposure to nitrous oxide even after recovery periods. No impairment of vigilance, immediate memory, or mental tracking could be detected as measured by the other tests. Subjective reports by the subjects accurately reflected their underlying impaired status.
The aim of this study was to compare both the behavioral and physiological effects of 2 drug regimens in children: chloral hydrate (CH), meperidine (M), and hydroxyzine (H) (regimen A) versus midazolam (MZ), M, and H (regimen B). Patients between 24 and 54 months of age were examined by crossover study design. Behavior was analyzed objectively by the North Carolina Behavior Rating System and subjectively through an operator and monitor success scale. Physiological data were recorded every 5 minutes and at critical points throughout the appointment. Sixteen patients completed this study. No significant differences in behavior were noted by the North Carolina Behavior Rating System or the operator and monitor success scale. A quiet or annoyed behavior was observed 93% and 90% of the time for regimen A and regimen B, respectively. Using the operator and monitor success scale, 63% of regimen A and 56% of regimen B sedations were successful. No statistically significant differences were noted in any of the physiological parameters between the 2 regimens. Ten episodes of hemoglobin desaturation were detected with regimen A sedations. There were no differences between the sedative drug regimens CH/M/H and MZ/M/H for behavioral outcomes or physiological parameters.
Conscious sedation; Midazolam; Chloral hydrate; Children
Fifteen consecutive pediatric patients ranging from 3 to 5 years old were selected to receive one of three sedative/hypnotic techniques. Group 1 received oral chloral hydrate 50 mg/kg, and groups 2 and 3 received intramuscular ketamine 2 mg/kg and 3 mg/kg, respectively. In addition to ketamine, patients in groups 2 and 3 received transmucosal intramuscular injections of meperidine and promethazine into the masseter muscle. Sedation for the satisfactory completion of restorative dentistry was obtained for over 40 min on average in the chloral hydrate group, but completion of dental surgery longer than 40 min was achieved in groups 2 and 3 only by intravenous supplements of ketamine.
To determine whether bispectral analysis (BIS) changes during nitrous oxide (N2O) sedation in anxious children undergoing extraction of primary teeth.
In this prospective study 45, ASA physical status I children, aged between 7 to 12 years and scheduled for primary teeth extraction under N2O/O2 sedation are included. At baseline (T0) and during the sedation procedure (T1-6); BIS levels, Ramsay Sedation Scores (RSS), oxygen saturation (Sp02), and heart rate (HR) were recorded at one-minute intervals. Forty percent N2O in O2 was given by a nasal hood, and N2O concentration was enhanced to 60% in a two-minute period. Paired measurements of BIS levels with Observer’s Assessment of Alertness and Sedation (OAA/S) scores were obtained during sedation procedure.
Since 5 patients refused application of the nasal hood, a total 40 of the original 45 subjects completed the study. Mean age and weight of the children were 9.5 ± 1.4 years and 23.7 ± 9.7 kg, respectively. Nitrous oxide inhalation produced no changes in BIS levels despite a sedation level in OAA/S scores were observed at 40–60% N2O concentrations.
BIS values do not change during N2O/O2 sedation and the BIS monitor is not appropriate to evaluate the depth of sedation provided by N2O/O2 during primary teeth extraction in children.
Nitrous oxide sedation; Bispectral index; Anxiety; Ramsay sedation scale
Four different methanotrophs expressing soluble methane monooxygenase produced 2,2,2-trichloroacetaldehyde, or chloral hydrate, a controlled substance, during the oxidation of trichloroethylene. Chloral hydrate concentrations decreased in these cultures between 1 h and 24 h of incubation. Chloral hydrate was shown to be biologically transformed to trichloroethanol and trichloroacetic acid by Methylosinus trichosporium OB3b. At elevated pH and temperature, chloral hydrate readily decomposed and chloroform and formic acid were detected as products.
Background: Until recently, midazolam sedation was routinely used in our institution for bone marrow aspirates and lumbar punctures in children with cancer. It has been perceived by many doctors and nurses as being well tolerated by children and their families.
Aim: To compare the efficacy of inhalational general anaesthesia and midazolam sedation for these procedures.
Methods: A total of 96 children with neoplastic disorders, who received either inhalational general anaesthesia with sevoflurane, nitrous oxide, and oxygen (GA) or sedation with oral or nasal midazolam (SED) as part of their routine preparation for procedures were studied. The experiences of these childen were examined during their current procedure and during their first ever procedure. Main outcome measures were the degree of physical restraint used on the child, and the levels of distress and pain experienced by the child during the current procedure and during the first procedure. The family‘s preference for future procedures was also determined.
Results: During 102 procedures under GA, restraint was needed on four occasions (4%) when the anaesthetic mask was first applied, minimal pain was reported, and children were reported as distressed about 25% of the time. During 80 SED procedures, restraint was required in 94%, firm restraint was required in 66%, the child could not be restrained in 14%, median pain score was 6 (scale 0 (no pain) to 6 (maximum pain)), and 90% of the parents reported distress in their child. Ninety per cent of families wanted GA for future procedures. Many families reported dissatisfaction with the sedation regime and raised concerns about the restraint used on their child.
Conclusions: This general anaesthetic regime minimised the need for restraint and was associated with low levels of pain and distress. The sedation regime, by contrast, was much less effective. There was a significant disparity between the perceptions of health professionals and those of families with respect to how children coped with painful procedures.
The effects of a series of concentrations of the narcotics, ethyl carbamate and chloral hydrate, have been determined on the consumption of oxygen by fertilized and unfertilized eggs of the sea urchin Arbacia punctulata. In the fertilized eggs the effects of the two inhibitors on cell division were also examined. The following observations were made: 1. Assuming that the narcotic acts upon a single catalyst in the unfertilized egg the degree to which the consumption of oxygen is inhibited in this resting cell can be related to the narcotic concentration by an expression derived from the law of mass action. 2. To account for the relation between the concentration of the narcotic and its effect on respiration in the fertilized eggs, it is necessary to conclude that in them the narcotic acts on two parallel respiratory systems. The experimental data can be quantitatively predicted (1) if the reaction of the narcotic on the two systems is governed by the law of mass action and (2) if 40 per cent of the oxygen consumption is mediated by one system, the "activity" system, and the remainder by the other, the "resting" or "basal" system. 3. The mass law constants applying to the resting system in the fertilized egg are similar to those for the single system functioning in the unfertilized egg so that these two respiratory systems are probably identical. 4. The concentrations of the narcotics just sufficient to abolish cell division affect primarily the activity system, the existence of which was inferred from the respiratory experiments. It is concluded that normal cell division requires specifically the normal function of the activity system, that in fact the energy for cell division is made available through that system.
In rats, the jaw-opening reflex is elicited by activation of a nociceptive receptor by the electric stimulation of the tooth pulp. This study was undertaken to assess the effects of 30% nitrous oxide and 30% nitrous oxide with idazoxan, an alpha 2-adrenergic antagonist, on this reflex. Each rat received electric stimulation for the jaw-opening reflex at 3, 5, 7, 10, 15, and 20 min after both the start of inhalation and the withdrawal of 100% oxygen or 30% nitrous oxide in oxygen. Idazoxan, 400 micrograms/ kg, was administered intravenously at the start of the inhalation period. Amplitudes significantly decreased during inhalation of nitrous oxide, but they returned gradually to control levels after cessation of nitrous oxide inhalation. In the cases of 100% oxygen, 100% oxygen with idazoxan, and 30% nitrous oxide in oxygen with idazoxan, amplitudes did not change from controls during and after 30% nitrous oxide inhalation. The latency remained unchanged irrespective of the treatment. Since in rats the degree of inhibition by 30% nitrous oxide in oxygen is partially diminished by administration of idazoxan, we conclude that nitrous oxide affects an alpha 2-adrenergic receptor in the central nervous system.
Intravenous sufentanil, an analog of fentanyl, was compared to diazepam for conscious sedation in ambulatory dental outpatients. Ten patients undergoing the surgical removal of impacted third molars served as subjects in a double-blind, within-subject, single crossover study. Sedation was achieved with a combination of 30% nitrous oxide/70% oxygen by nasal mask and either diazepam (0.05—0.15 mg/kg) or sufentanic (0.05—0.15 μg/kg) titrated to a clinical endpoint of altered speech and relaxation. Intraoperative physiologic monitoring, patients' and the oral surgeon's subjective estimates of efficacy and psychomotor recovery were used to compare the two treatments. Both patients (eight of 10) and surgeons (six of 10) preferred sufentanil sedation. No significant differences were noted between treatments for psychomotor recovery. These preliminary data in a small sample suggest that sufentanil produces adequate conscious sedation in dental outpatients and should be evaluated further with larger patient samples.
For dental outpatients undergoing conscious sedation, recovery from sedation must be sufficient to allow safe discharge home, and many researchers have defined "recovery time" as the time until the patient was permitted to return home after the end of dental treatment. But it is frequently observed that patients remain in the clinic after receiving permission to go home. The present study investigated "clinical recovery time," which is defined as the time until discharge from the clinic after a dental procedure. We analyzed data from 61 outpatients who had received dental treatment under conscious sedation at the Hiroshima University Dental Hospital between January 1998 and December 2000 (nitrous oxide-oxygen inhalation sedation [n = 35], intravenous sedation with midazolam [n = 10], intravenous sedation with propofol [n = 16]). We found that the median clinical recovery time was 40 minutes after nitrous oxide-oxygen sedation, 80 minutes after midazolam sedation, and 52 minutes after propofol sedation. The clinical recovery time was about twice as long as the recovery time described in previous studies. In a comparison of the sedation methods, clinical recovery time differed (P = .0008), being longer in the midazolam sedation group than in the nitrous oxide-oxygen sedation group (P = .018). These results suggest the need for changes in treatment planning for dental outpatients undergoing conscious sedation.
This study examined the effects of age on the behavior of mice administered one of two benzodiazepines with and without nitrous oxide. Young (3 wk +/- 3 days) and adolescent (7 wk +/- 3 days) male DBA-2 mice were administered oral diazepam (2.0 or 3.5 mg/kg), midazolam (0.75 or 1.2 mg/kg), or a placebo in combination with 50% nitrous oxide/50% oxygen, or room air. The mouse staircase model was used, where the number of rears (NR) served as an index of anxiety, and the number of steps ascended (NSA) as an index of sedation. No significant differences in the responses between the ages were noted. Nitrous oxide seemed to increase the NR and NSA, whereas the benzodiazepines alone did not affect behavior. These DBA-2 mice may represent a strain that is less sensitive to the anxiolytic-sedative effects of the benzodiazepines than are other strains.
This study compared the incidence of vomiting and the sedative effectiveness of ketamine to a ketamine-prornethazine combination in pediatric dental patients. Twenty-two patients with American Society of Anesthesiologists' classification I physical status who were between the ages of 21 and 43 months were randomly divided into 2 groups. The control group received 10 mg/kg of ketamine orally, whereas the experimental group received 10 mg/kg of ketamine and 1.1 mg/kg of promethazine orally. Nitrous oxide in oxygen was supplemented between 35 and 50%. Each patient received 1 or 2 quadrants of restoration by one operator. Heart rate, blood pressure, and oxygen saturation were monitored and recorded during the treatment. Crying, alertness, movement, and overall general behavior were rated using the scale by Houpt et al. A dentist-anesthesiologist conducted the vital sign monitoring and behavioral assessment. Ketamine combined with promethazine eliminated the incidence of vomiting. A 2 x 2 chi-square contingency table showed a statistical difference between the 2 groups at P < .05 (control group, 27%; experimental group, 0%). Ketamine alone yielded better sedations than the combined agents as shown by the Mann-Whitney U statistical analysis (P < .05). Ketamine and a ketamine-promethazine combination are effective in the sedation of pediatric dental patients.
Recent studies have questioned our previous understanding on the effect of nitrous oxide on muscle relaxants, since nitrous oxide has been shown to potentiate the action of bolus doses of mivacurium, rocuronium and vecuronium. This study was aimed to investigate the possible effect of nitrous oxide on the infusion requirements of cisatracurium.
70 ASA physical status I-III patients aged 18-75 years were enrolled in this randomized trial. The patients were undergoing elective surgery requiring general anesthesia with a duration of at least 90 minutes. Patients were randomized to receive propofol and remifentanil by target controlled infusion in combination with either a mixture of oxygen and nitrous oxide (Nitrous oxide/TIVA group) or oxygen in air (Air/TIVA group). A 0.1 mg/kg initial bolus of cisatracurium was administered before tracheal intubation, followed by a closed-loop computer controlled infusion of cisatracurium to produce and maintain a 90% neuromuscular block. Cumulative dose requirements of cisatracurium during the 90-min study period after bolus administration were measured and the asymptotic steady state rate of infusion to produce a constant 90% block was determined by applying nonlinear curve fitting to the data on the cumulative dose requirement during the study period.
Controller performance, i.e. the ability of the controller to maintain neuromuscular block constant at the setpoint and patient characteristics were similar in both groups. The administration of nitrous oxide did not affect cisatracurium infusion requirements. The mean steady-state rates of infusion were 0.072 +/- 0.018 and 0.066 +/- 0.017 mg * kg-1 * h-1 in Air/TIVA and Nitrous oxide/TIVA groups, respectively.
Nitrous oxide does not affect the infusion requirements of cisatracurium.
ClinicalTrials.gov NCT01152905; European Clinical Trials Database at http://eudract.emea.eu.int/2006-006037-41.
The visually evoked potential (VEP) is an electrical signal generated by the occipital cortex in response to light stimulation of the retina. The clinical importance of the VEP consists in the diagnosis of optic nerve diseases and others ocular diseases. For experimental studies of VEP in experimental animals anesthesia is frequently required. Our study sought VEP changes depending on the type and depth of anesthesia.
Methods: this study evaluated VEPs in 20 Wistar rats under two anesthetics. Ten rats were anesthetized with sevoflurane and ten rats with chloral hydrate.
Results: The amplitudes, latencies and morphology of the VEP varied with the depth of anesthesia. The latency of VEP increases with the depth of anesthesia and the amplitude of the waves becomes more positive once the anesthesia decreases under sevoflurane and more negative under chloral hydrate. The variability of VEP was different under the two anesthetics with greater peak latencies under sevoflurane than under chloral hydrate at the same depth of anesthesia.
In conclusion: it is important to know the influence of the anesthetic and the depth of anesthesia over VEPS, because they may constitute a confounding factor in studying VEP in different diseases of optic nerve or eyeball.
visual evoked potentials; sevoflurane; chloral hydrate
Anaesthetics may target ionotropic glutamate receptors in brain cells to produce their biological actions. Membrane-bound ionotropic glutamate receptors undergo dynamic trafficking between the surface membrane and intracellular organelles. Their subcellular distribution is subject to modulation by changing synaptic inputs and determines the efficacy and strength of excitatory synapses. It has not been explored whether anaesthesia has any impact on surface glutamate receptor expression. In this study, the effect of general anaesthesia on expression of N-methyl-d-aspartate (NMDA) receptors in the surface and intracellular pools of cortical neurones was investigated in vivo.
General anaesthesia was induced by intraperitoneal injection of chloral hydrate in adult male mice. Surface protein cross-linking assays were performed to detect changes in distribution of NMDA receptor subunits (NR1, NR2A, and NR2B) in the surface and intracellular compartments of cerebral cortical neurones.
Chloral hydrate did not alter the total amounts of NR1, NR2A, and NR2B proteins in cortical neurones. However, the drug reduced NR1 proteins in the surface pool of these neurones, and induced a proportional increase in NR1 in the intracellular pool. Similar redistribution of NR2B subunits was observed between the two distinct pools. The changes in NR1 and NR2B were rapid and remained throughout the duration of anaesthesia. NR2A proteins were not altered in the surface or intracellular pool in response to chloral hydrate.
These data demonstrate that subcellular expression of NR1 and NR2B in cortical neurones is sensitive to anaesthesia. Chloral hydrate reduces surface-expressed NMDA receptors (specifically NR2B-containing NMDA receptors) in these neurones in vivo.
anaesthetics; cerebral cortex; glutamate receptor; NR1; NR2A; NR2B
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.
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.
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.
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.
The phenomenon of diffusion hypoxia is commonly believed to occur unless nitrous oxide-oxygen inhalation sedation is followed by "washout" with 100% oxygen for 5 minutes upon termination of the flow of nitrous oxide. When systematically studied, however, this phenomenon generally appears to be unfounded. The present study evaluated the effect of breathing room air instead of 100% oxygen in healthy (ASA 1) human volunteers following administration of sedative concentrations of nitrous oxide. The occurrence of hypoxia was determined objectively, using pulse oximetry and a standardized psychomotor skills test (Trieger test). Diffusion hypoxia was not observed using these criteria.
Pain at the site of rocuronium injection is a common side-effect in pediatric patients. This prospective, randomized, double-blind study evaluated the efficacy of a combination of nitrous oxide and lidocaine pretreatment on withdrawal response during rocuronium injection in children.
Sixty six pediatric patients, ages 5 to 12 years, were randomly assigned to two groups. The oxygen group received 100% oxygen, and the nitrous oxide group received 50% N2O in oxygen over 2 min. After anesthesia was induced with 2.5% thiopental sodium 5 mg/kg and manual occlusion of the forearm was performed, 1% lidocaine 1 mg/kg was injected over 15 sec. After the occlusion was released, 0.1% rocuronium 0.6 mg/kg was injected over 5 sec. Patient response to rocuronium injection was graded using a 4-point scale.
Overall incidence of withdrawal movements was significantly lower in the nitrous oxide group (1 patients; 3.1%) than in the oxygen group (8 patients; 25.8%) (P = 0.013). No patient in the nitrous oxide group displayed arm or generalized movement (grade 3 or 4) associated with rocuronium injection.
This study demonstrated that a combination of inhaled 50% N2O in O2 and 1 mg/kg lidocaine pretreatment significantly reduced the incidence of rocuronium-induced withdrawal movements in pediatric patients compared with lidocaine pretreatment alone.
Lidocaine; Nitrous oxide; Rocuronium; Withdrawal
Poor quality of sleep among alcoholics and persons undergoing alcohol withdrawal has been described as a possible cause of alcohol relapse. It has been suggested earlier that nitrous oxide gas has a significant effect on the signs of alcohol withdrawal syndrome (AWS) and thus might be expected to reduce sleep disturbance during withdrawal. The aim of the present study was to investigate sleep quality during alcohol withdrawal, to evaluate the correlation between sleep quality and the severity of AWS and alcohol craving, and to determine if nitrous oxide treatment does counteract withdrawal's effects on the quality of sleep. Voluntary patients (n = 105) admitted to the A-Clinic detoxification center with AWS were included in the study. The AWS patients were randomly assigned to one of the following 45-minute gas treatments: (1) nitrous oxide/oxygen; (2) normal air/O2; and (3) medical (normal) air. The study was single-blind by design. Sleep quality was assessed after these treatments during the inpatient period; sleep time, sleep efficiency and the fragmentation of sleep were recorded by wrist-worn actigraphs. Severity of AWS was evaluated by the Clinical Institute Withdrawal Assessment of Alcohol Scale (CIWA-Ar) and that of alcohol dependence and craving by the Obsessive Compulsive Drinking Scale [OCDS] and the Severity of Alcohol Dependence Data (SADD) questionnaire.
The fragmentation index and the time awake while in bed were both much above the reference values for the Finnish population. These values reflect the restless and disturbed night sleep of the subjects. The only statistically significant effects between the treatment groups were found in the correlations of CIWA-Ar (severity of AWS) scores, OCDS-scores (alcohol craving) and coffee consumption, all of which were positively associated with movement time and negatively with total sleep time and sleep efficiency. The sleep quality of patients treated with nitrous oxide gas did not differ from the sleep quality of those treated with normal air.
The severity of AWS and coffee consumption had the most significant negative impact on sleep quality. According to our results, nitrous oxide gas does not differ from placebo in its effect on sleep quality during alcohol withdrawal.
The ProSeal™ laryngeal mask (PLMA) is increasingly being used as an airway device for laparoscopic surgery. Its silicone cuff allows diffusion of nitrous oxide, carbon dioxide and other gases with resultant rise in its intracuff pressure during anesthesia. The present study was designed to investigate the intracuff pressure changes during anesthesia with and without nitrous oxide in patients undergoing laparoscopic surgery lasting up to two hours.
Materials and Methods:
One hundred patients, American Society of Anesthesiologists physical status 2 and 3, undergoing general anesthesia with muscle paralysis, were randomized into two groups of 50 patients each to receive an anesthetic gas mixture containing either oxygen and nitrous oxide (group N) or oxygen and air (group A). Following insertion of an appropriate size PLMA, its cuff was inflated with air to an intracuff pressure of 45 mm Hg. The cuff pressure was measured every 10 minutes for the entire course of anesthesia. The position of the device was also assessed fiberoptically and postoperative airway complications were recorded.
The maximum intracuff pressure recorded in group N was 103 ± 4.7 mm Hg vs. 45.5 ± 1.5 mm Hg in group A. The percentage rise in cuff pressure every 10 minutes was also highly significant (P < 0.001) being maximum in first 10 min in group N. The incidence of postoperative airway complications was comparable between the two groups.
The results of this study demonstrate that the intracuff pressure of the PLMA increases progressively over time when the breathing gas mixture contains nitrous oxide.
Anaesthetics; gases; nitrous oxide; equipment; laryngeal mask airway
Although numerous studies have assessed subjective effects of nitrous oxide, few studies have analyzed for sex differences. Since sex differences have been reported in subjective effects of several drugs such as opioids, nicotine and alcohol, we sought to determine if sex modulates the subjective effects of the inhalant, nitrous oxide, in healthy volunteers.
Thirty-eight females and seventy-two males from nine studies that were conducted in our laboratory were included in this retrospective analysis. All experimental studies utilized randomized, placebo controlled, repeated measures designs in which subjects inhaled 30% nitrous oxide in oxygen and 100% oxygen (placebo). Dependent measures in this analysis were subjective effects measured at baseline and 15 min into the inhalation period.
Nitrous oxide produced a number of subjective effects, including those that could be considered abuse liability-related (“elated,” “having pleasant thoughts,” drug liking), but sex did not modulate these effects.
Females and males showed similar subjective responses to 30% nitrous oxide. Future prospective studies might assess other concentrations, other measures (choice, analgesic response), and other inhaled general anesthetics to more comprehensively characterize the role of sex in response to inhalants.
Nitrous Oxide; Subjective effects; Sex differences; Gender; Healthy volunteer
Alcohol-drinking status has been shown to modulate the reinforcing and subjective effects of a number of drugs. We have previously published two studies on the modulating effects of alcohol-drinking status on choice for, and subjective effects of, nitrous oxide, but the results were equivocal. Using a methodology different from our previous studies, we sought to determine in a more definitive fashion the degree to which the choice of nitrous oxide and its subjective effects were modulated by drinking status.
Four concentrations of nitrous oxide (0, 20, 30, 40%) were administered to 16 moderate drinkers (MDs) and 16 light drinkers (LDs) across four 3.5-h sessions. During experimental sessions, subjects first completed two 10-min sampling trials in which one of the nitrous oxide concentrations and placebo (100% oxygen) were inhaled. Subjective and psychomotor tests were given 5 min into each sampling trial. During the subsequent choice period, subjects were allowed to choose what they wanted to inhale (drug, placebo, or “drug-free air") on nine contiguous 5-min choice trials.
Choice of nitrous oxide was modulated by drinking status: MDs but not LDs chose nitrous oxide significantly more times than placebo, and MDs also chose nitrous oxide significantly more times than did LDs. At each active nitrous oxide concentration, MDs reported more abuse liability-related subjective effects, especially at the 20% and 30% concentrations.
The results of the present study provide more conclusive evidence that choice as well as subjective effects of nitrous oxide are modulated by alcohol-drinking status.
Nitrous oxide; Preference; Choice; Reinforcing effects; Subjective effects; Psychomotor; Inhalants; Human