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At least 19 recordsLinked to original sources
PubMed1991

Vecuronium infusion requirements in children during halothane-narcotic-nitrous oxide, isoflurane-narcotic-nitrous oxide, and narcotic-nitrous oxide anesthesia.

We were interested in determining the infusion rate of vecuronium required to maintain approximately 95% neuromuscular blockade in children during halothane-narcotic-nitrous oxide (0.8% end-tidal concentration), isoflurane-narcotic-nitrous oxide (1.0% end-tidal concentration), or narcotic-nitrous oxide anesthesia. Neuromuscular blockade was monitored by recording the electromyographic activity (Datex NMT) of the adductor pollicis muscle resulting from supramaximal stimulation of the ulnar nerve at 2 Hz for 2 s at 10-s intervals. Effective vecuronium infusion requirements averaged 1.5 +/- 0.1 micrograms.kg-1.min-1 (mean +/- SEM) during isoflurane-narcotic-nitrous oxide anesthesia, 1.9 +/- 0.1 micrograms.kg-1.min-1 during halothane-narcotic-nitrous oxide anesthesia, and 2.4 +/- 0.3 micrograms.kg-1.min-1 during narcotic-nitrous oxide anesthesia. Infusion requirements significantly decreased after the first 30 min of infusion in the presence of both potent inhalation anesthetics, but did not change with time during narcotic-nitrous oxide anesthesia. There was no evidence of decreasing infusion requirements during prolonged vecuronium infusion (2.5 h). There was no difference in the rate of spontaneous or pharmacologically induced recovery between anesthetic groups. The mean recovery index (T25-75) after termination of the infusion was 13.7 min.

Anesthesia, General↗
PubMed1992

Advantages and guidelines for using nitrous oxide.

Nitrous oxide is useful as an adjunct to methoxyflurane anesthesia and prolonged halothane anesthesia. Nitrous oxide is also useful in the debilitated patient in which the potent volatile anesthetics induce excessive cardiovascular depression. Finally nitrous oxide is useful for smoothing an inadequate anesthetic plane induced by the potent volatile anesthetics.

Adjuvants, Anesthesia↗
PubMed1991

The relationship between the anoxic sensitivity and the extent of sensitization by nitrous oxide.

Nitrous oxide reacts during irradiation to increase the yield of .OH, a radical many believe to be a major cause of lethality. Logically, one would expect N2O to be a radiation sensitizer. In some instances it is, while in others it is not. In some cases we can explain why N2O fails to sensitize; factors such as dose rate, cell concentration, buffer composition and ionic strength all influence when N2O will sensitize and, if it sensitizes, by what magnitude. Based on the results presented here with multiple strains of procaryotic and eucaryotic cells, we believe the anoxic sensitivity is another critical factor that governs whether N2O will sensitize. Our data, with data from the literature, show a relationship between the anoxic sensitivity and the N2O enhancement ratio. N2O does not sensitize in vitro unless the anoxic sensitivity (inactivation constant, k) is less than approximately 0.2 daGy-1.

Animals↗
PubMed1990

No finding of increased myocardial ischemia during or after carotid endarterectomy under anesthesia with nitrous oxide.

Nitrous oxide (N2O) has been implicated as a cause of myocardial ischemia. We investigated whether substitution of N2O for a portion of the anesthesia supplied by isoflurane increased myocardial ischemia in patients at risk for such ischemia. Seventy patients having carotid endarterectomies (63 patients) or other carotid surgery (seven patients) were prospectively, randomly assigned to an anesthetic regimen that included or excluded N2O. All other aspects of anesthetic management were similar, except for greater concentrations of oxygen and isoflurane in patients not given N2O. Perioperative monitoring for myocardial ischemia and infarction included 12- or 5-lead electrocardiography, transesophageal echocardiography, and creatine kinase isoenzyme levels. By transesophageal echocardiographic or electrocardiographic criteria, 44% of patients given oxygen but only 21% of those given N2O had myocardial ischemia intraoperatively (P = 0.065). Similarly, myocardial infarction, identified by changes in creatine kinase isoenzymes, occurred in only one patient given N2O but in three given oxygen (not significantly different). Thus we found no trend indicating a greater incidence of myocardial ischemia or infarction associated with the use of N2O.

Aged↗
PubMed1990

Effects of intravenous administration of local anesthetics on the renal sympathetic nerve activity during nitrous oxide and nitrous oxide-halothane anesthesia in the cat.

The effects of subseizure doses of lidocaine and bupivacaine administered intravenously (i.v.) on mean arterial pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA) were studied in cats anesthetized with nitrous oxide (N2O)-O2 and N2O-O2-halothane (1%). In cats anesthetized with N2O-O2, MAP decreased briefly (P less than 0.01) and then returned to the initial level within a minute after the i.v. injection of lidocaine (5 mg/kg, 10 mg/kg). RSNA increased at first and then decreased slightly. In cats with denervated baroreceptors, the change in RSNA after lidocaine 5 mg/kg i.v. was similar to that in cats with intact baroreceptors. In contrast, MAP, HR and RSNA decreased significantly (P less than 0.01) after i.v. injection of lidocaine during N2O-O2-halothane anesthesia. The effects of bupivacaine on RSNA were similar to those of lidocaine. It is concluded that cardiovascular depression following intravenous local anesthetics during N2O-O2-halothane anesthesia may be caused by both a decreased sympathetic activity and a direct depressant effect on the myocardium.

Anesthesia, Inhalation↗
PubMed1991

Recovery profile after desflurane-nitrous oxide versus isoflurane-nitrous oxide in outpatients.

Thirty-eight healthy outpatients undergoing elective surgical procedures lasting 1-3 h were randomly assigned to receive either desflurane 3% (approximately 0.5 MAC) or isoflurane 0.6% (approximately 0.5 MAC) for maintenance of general anesthesia with nitrous oxide 60% in oxygen after a standardized induction sequence consisting of fentanyl 3 micrograms.kg-1, thiopental 4 mg.kg-1, and succinylcholine 1-1.5 mg.kg-1, intravenously. Although anesthetic conditions were similar during operations in the two treatment groups, significant differences were noted in the recovery profiles as measured by elimination kinetics, psychometric testing, and visual analog scales (to assess subjective feelings). The time required for the end-tidal concentration to decrease by 50% was 2.5 +/- 0.8 min for desflurane vs. 9.5 +/- 3.4 min for isoflurane (mean +/- standard deviation [SD]). Times to awakening and ability to follow simple commands were significantly shorter after desflurane than after isoflurane (5.1 +/- 2.4 vs. 10.2 +/- 7.7 min 6.5 +/- 2.3 min vs. 11.1 +/- 7.9 min, respectively). Postoperatively, patients who received desflurane exhibited less impairment of cognitive function (as measured using the Digit-Symbol Substitution Test) than did those who received isoflurane. Furthermore, visual analog scores indicated that patients receiving desflurane experienced significantly less discomfort (pain), drowsiness, fatigue, clumsiness, and confusion in the early postoperative period. We conclude that desflurane may offer clinical advantages over isoflurane when used for maintenance of anesthesia during outpatient surgical procedures.

Adult↗
PubMed1991

Comparison of sufentanil-nitrous oxide anaesthesia with fentanyl-nitrous oxide anaesthesia in geriatric patients undergoing major abdominal surgery.

We have measured haemodynamic changes and plasma concentrations of catecholamines during sufentanil-nitrous oxide and fentanyl-nitrous oxide anaesthesia in a controlled, randomized, double-blind study of 20 geriatric patients (age 65-86 yr) undergoing major abdominal surgery. Fentanyl 7 micrograms kg-1 followed by infusion of 3 micrograms kg-1 h-1 was compared with sufentanil 1 micrograms kg-1 followed by 0.4 micrograms kg-1 h-1. The opioid was supplemented with 60-67% nitrous oxide in oxygen. Haemodynamic changes, plasma concentrations of catecholamines (by high pressure liquid chromatography) and opioids (by radioimmunoassay), and myocardial lactate extraction were measured in the awake state, and at defined times during anaesthesia and surgery. Haemodynamic state was stable during induction and tracheal intubation in both groups, while during stressful operative periods there were increases in mean arterial pressure (17% in the fentanyl group; 11% in the sufentanil group), heart rate (fentanyl 20%, sufentanil 14%) and plasma concentrations of catecholamines (adrenaline: fentanyl 316%, sufentanil 86%; noradrenaline: fentanyl 78%, sufentanil 186%) in both groups. Sufentanil was similar to fentanyl in attenuating the haemodynamic and hormonal responses to surgical stimulation. In two patients in the fentanyl group and three in the sufentanil group, myocardial lactate production was observed temporarily, indicating myocardial ischaemia caused by surgical stress.

Abdomen↗
PubMed1989

Randomized comparison of outcome after propofol-nitrous oxide or enflurane-nitrous oxide anaesthesia in operations of long duration.

A randomized, prospective, comparative study was performed to evaluate induction characteristics, haemodynamic changes and recovery in 60 ASA I-II patients undergoing mainly gynaecological laparotomies with either propofol or thiopentone-enflurane anaesthesia. The propofol group (n = 30) received 2 mg.kg-1 propofol for induction of anaesthesia followed by propofol infusion. The thiopentone-enflurane group (n = 30) received thiopentone 4 mg.kg-1 for induction followed by enflurane (0.5-2 per cent). All patients received nitrous oxide (66 per cent] in oxygen begun one minute after tracheal intubation, and fentanyl (1.5 micrograms.kg-1) four minutes prior to induction. Other drugs administered during or after anaesthesia were similar among the groups. Haemodynamic measurements were similar between propofol and enflurane groups except after tracheal intubation when the mean arterial pressure was lower in the propofol group (P less than 0.05). The propofol group had significantly less (P less than 0.01) emesis in the recovery room than the enflurane group. The propofol group experienced significantly less (P less than 0.05) dizziness, depression/sadness and hunger than the enflurane group in the postoperative period as assessed with a visual analogue questionnaire. We conclude that propofol provided better outcome than enflurane in terms of these nonvital but annoying outcome measures after relatively long intra-abdominal operations.

Adult↗
PubMed1989

[Nitrous oxide in anesthesia--present status of the use of nitrous oxide, risks for patients and personnel and treatment of side effects].

Mechanisms of some effects of nitrous oxide have recently been elucidated. Its antinociceptive action depends partly on the involvement of the endorphinergic system. Although vitamin B 12 becomes biologically inactive in the presence of nitrous oxide, this certainly is of no clinical consequence in exposures lasting less than eight hours. Should exposures last over 8 hours, effects of vitamin B 12 inactivation can be compensated for by administration of folinic acid. In contrast, professional exposure to trace levels of nitrous oxide seems not to interfere with human health. Furthermore, closed circle apparatus should be used and operating room air be well scavenged when nitrous oxide is used.

Anesthesia, Inhalation↗
PubMed1990

Randomized comparison of recovery after propofol-nitrous oxide versus thiopentone-isoflurane-nitrous oxide anaesthesia in patients undergoing ambulatory surgery.

A randomized, prospective study was performed to compare recovery characteristics in 41 ASA physical status I-II patients scheduled for ambulatory surgery with either propofol or thiopentone-isoflurane anaesthesia. Particular attention was focused on the recovery time needed to meet discharge criteria. The propofol group received propofol 2 mg.kg-1 for induction followed by propofol infusion (6-9 mg.kg-1.h-1) 1 min after intubation. The thiopentone-isoflurane group received thiopentone 4 mg.kg-1 for induction followed by isoflurane (0.5-2%) 1 min after endotracheal intubation. Other drugs administered during or after anaesthesia were similar between the groups. The propofol group had significantly (P less than 0.05) faster clinical recovery than the isoflurane group with respect to times to response to commands, eye opening, orientation, ability to stand and void, tolerance to oral fluids, "home-readiness", and recovery of perceptual speed. Patients in the propofol group had significantly less (P less than or equal to 0.05) emesis than the patients given isoflurane. We conclude that in patients undergoing ambulatory surgery propofol infusion is preferable to thiopentone-isoflurane anaesthesia, because it may allow faster discharge home.

Adult↗
PubMed1975

[The use of nitrous oxide as a contrast medium during fractionated gas encephalography in halane-nitrous-oxide anesthesia].

40 children were employed as test cases in fractionated gas encephalography using Halan-nitrous oxide anesthesia, and the level of cerebrospinal pressure, the röntgenoparent quality of the extracerebral spaces and the duration of postencephalographical symptoms were examined using air and nitrous oxide as contrast media. In the course of the examination the cerebrospinal pressure showed a tendency to rise when air was introduced, to fall when nitrous oxide was introduced. After instillation of N2O however the filling of the subarachnoid space was over so quickly that it could not be included in the assessment. Sufficient röntgenograms were obtained for all diagnostic demands through 'hybrid filling', (introduction of nitrous oxide into the ventricles, introduction of air into the subarachnoid spaces). With the aid of the results obtained from this examination attempts will be made to derive differentiated indications for filling with nitrous oxide.

Adolescent↗
PubMedDate not supplied

The differential cost of anesthesia and recovery with propofol-nitrous oxide anesthesia versus thiopental sodium-isoflurane-nitrous oxide anesthesia.

STUDY OBJECTIVE: To assess the recovery room profile of propofol in outpatient anesthesia and to compare it to the profile of a standard technique. DESIGN: A comparative, randomized, double-blind, third-party open study. SETTING: Ambulatory Surgery Center at The Emory Clinic. PATIENTS: Ninety-nine ASA physical status I, II, or III nonpregnant female patients who had been diagnosed as needing breast biopsies. INTERVENTIONS: All patients were given 1 microgram/kg of fentanyl prior to induction. Those in the propofol group were induced with 2.0 to 2.5 mg/kg of propofol and maintained with a 100 to 200 microgram/kg/min infusion of propofol with nitrous oxide (N2O) in oxygen (O2). In the thiopental sodium-isoflurane group, patients were induced with 4.0 to 5.0 mg/kg of thiopental sodium and maintained with isoflurane and N2O in O2. MEASUREMENTS AND MAIN RESULTS: Recovery from anesthesia was assessed by an evaluator who was unaware of the anesthetic technique used for each patient. Immediate recovery time was measured in terms of awakening, response to verbal command, and orientation to time and place. A brief postoperative follow-up questionnaire was completed to assess the patients' subjective feelings regarding their ability to eat, concentrate, and resume normal activities. In the thiopental sodium-isoflurane group, 15 of 50 patients (30%) had nausea and vomiting, but in the propofol group, only 4 of 49 patients (8.1%) had nausea and vomiting (p less than 0.01). The latter group resumed normal activity (i.e., reading and watching television) 7.93 +/- 0.76 hours postanesthesia, whereas the thiopental sodium-isoflurane group resumed normal activity 17.02 +/- 1.21 hours postanesthesia (p less than 0.001). Patients in the propofol group returned to work in an average of 1.5 +/- 0.09 days, compared with 2.0 +/- 0.09 days for the thiopental sodium-isoflurane group (p less than 0.001). CONCLUSIONS: The propofol group needed less nursing care and returned to more productive activity earlier than did the thiopental sodium-isoflurane group.

Ambulatory Surgical Procedures↗
PubMed1992

Continuous intravenous propofol with nitrous oxide for ocular surgery. A comparison with etomidate, alfentanil, nitrous oxide and isoflurane.

Propofol, administered intravenously for induction and as a continuous maintenance anaesthetic with nitrous oxide, was compared, in a group of elderly patients scheduled for ophthalmic surgery, with an anaesthetic technique (etomidate, alfentanil, nitrous oxide and isoflurane) specifically chosen to be haemodynamically stable and evanescent in action. Both techniques resulted in similar effects on blood pressure after induction, intubation and surgical incision, but propofol did not prevent increases in heart rate as effectively at these times. Furthermore, during maintenance anaesthesia, cardiovascular stability and anaesthetic depth were more easily achieved in the group where etomidate, alfentanil and isoflurane were used. Propofol decreased intra-ocular pressure after intubation, while in both groups recovery was rapid with no significant complications. A subgroup of patients receiving alpha-methyldopa had significantly longer post-anaesthetic recovery times.

Aged↗
PubMed1990

Effect of scavenging on ambient levels of nitrous oxide in ambulances.

Nitrous oxide scavenging devices have not been tested in the prehospital setting. We studied two nitrous oxide scavenging devices and their effect on ambient levels of nitrous oxide in the patient compartment of a stationary ambulance. We compared the ambient levels of gas when nitrous oxide scavenging was in use versus when it was not. In addition, we evaluated the effect of two different mask designs on ambient levels of nitrous oxide. With eight healthy male volunteers acting as their own controls using a series of mask/scavenger combinations, we found that there was a significant difference in the ambient levels of nitrous oxide when a scavenger was in use. The mean time-weighted average was 776 parts per million/min when no scavenger was used. When gas scavenging was in use, the mean time-weighted average never exceeded 150 parts per million/min. (P less than .0001). There was no significant difference between nitrous oxide scavengers or between the masks tested in their effect on nitrous oxide ambient levels in the atmosphere. We conclude that nitrous oxide scavengers are effective in lowering nitrous oxide ambient levels in the prehospital setting and merit consideration as adjuncts to nitrous oxide delivery systems in this setting.

Air Pollutants, Occupational↗
PubMed1992

Benzodiazepine receptor mediation of behavioral effects of nitrous oxide in mice.

Nitrous oxide produces behavioral effects, the underlying mechanism of which is not known. In the mouse staircase test, exposure to nitrous oxide caused a reduction in rearing activity, an effect similar to that produced by benzodiazepines in this paradigm, when its opioid action on locomotion is blocked by naloxone. In this study, we tested whether effects of nitrous oxide might be mediated by benzodiazepine receptors, using chlordiazepoxide as a control. The abilities of nitrous oxide and chlordiazepoxide to reduce rearing were significantly attenuated in mice pretreated with the benzodiazepine receptor blocker flumazenil or rendered tolerant to benzodiazepines. These findings suggest an involvement of benzodiazepine receptors in mediation of certain behavioral effects of nitrous oxide.

Animals↗