Recovery characteristics of propofol anaesthesia, with and without nitrous oxide: a comparison with halothane/nitrous oxide anaesthesia in children.

Few studies have examined whether nitrous oxide influences the recovery characteristics of propofol anaesthesia. The present study examined the effect of nitrous oxide on the recovery characteristics of propofol anaesthesia, and compared these data with those for halothane/nitrous oxide anaesthesia. Sixty children aged 3-12 years were assigned at random to receive one of three maintenance regimens: propofol with or without nitrous oxide (70%) or halothane/nitrous oxide (70%). During propofol/N2O anaesthesia, the infusion rate of propofol (180 +/- 39 micrograms.kg-1.min-1) required to maintain the mean arterial pressure and heart rate within 20% of the baseline values was significantly less than that during propofol/O2 (220 +/- 37 micrograms.kg-1.min-1; P < 0.005). The time from discontinuation of anaesthesia to eye-opening (11 +/- 6 min), to response to commands (12 +/- 6 min), and to return of full wakefulness (21 +/- 10 min) after propofol/N2O were similar to those after propofol/O2, but significantly less (by approximately 30%) than those after halothane (P < 0.05). The overall incidence of emesis after propofol/N2O (53%) was greater than that after propofol/O2 (17%, P < 0.05) and comparable to that after halothane/N2O (58%). These data suggest that N2O has little effect on the rate of recovery after propofol, but significantly increases the incidence of postoperative emesis, thereby attenuating one of the main attributes of propofol anaesthesia.

Interaction of vecuronium and atracurium during halothane anaesthesia in children.

The combination of vecuronium and atracurium was studied in 60 children of ASA physical status 1 or 2. In part I, the dose-response relationships were determined in 30 children who were randomly assigned to receive a single bolus of 0.02, 0.025 or 0.03 mg kg-1 of vecuronium or 0.075, 0.01 or 0.0125 mg.kg-1 of atracurium. The evoked electromyogram of the adductor pollicis brevis muscle to train-of-four stimulation was monitored. The speed of onset of the neuromuscular blockade was determined by a 95% depression of the train-of-four whereas the recovery index was established at 75% recovery of T1. In part II, 30 children were randomly assigned to receive 2 x ED95 of vecuronium, 2 x ED95 of atracurium, or a combination of 1 x ED95 of vecuronium + 1 x ED95 of atracurium. This study showed that the ED50 and ED95 for vecuronium were 0.021 mg.kg-1 and 0.037 mg.kg-1 and for atracurium 0.11 mg.kg-1 and 0.30 mg.kg-1, respectively. The slopes of the dose-response relationships were significantly different (p < 0.001). With vecuronium alone, the speed of onset of neuromuscular blockade was significantly slower (p < 0.001) and the duration of action less (p < 0.001) than that with atracurium alone or with the combination. There were no differences between atracurium and the combination of both medications. The recovery index was similar for all groups. We conclude that the dose-response relationships of vecuronium and atracurium in children undergoing halothane anaesthesia are not parallel and the neuromuscular effects of vecuronium and atracurium are neither additive nor synergistic. While vecuronium has a shorter duration of action than atracurium, this feature is not apparent when it is combined with atracurium in equipotent doses. Recovery is rapid and not prolonged when these two drugs are combined.

Sevoflurane versus isoflurane: induction and recovery characteristics with single-breath inhaled inductions of anesthesia.

Because of its nonpungent odor and low blood-gas solubility coefficient, sevoflurane might be an ideal drug for single-breath inhaled induction of anesthesia. Fifty ASA grade I-III ambulatory surgical patients (18-76 yr old) received a single-breath induction with either 5.0% sevoflurane or 5.0% isoflurane (randomized) in a 1:1 N2O/O2 mixture. Anesthesia was maintained with the same anesthetic in 70% N2O until the end of surgery, when anesthetics were abruptly discontinued. Induction times (loss of eyelash reflex) were similar for sevoflurane (75 +/- 3 s, mean +/- se) and isoflurane (67 +/- 4 s, P = not significant). Sevoflurane patients were less likely to have complications during induction (P < 0.005); coughing occurred more frequently with isoflurane (P < 0.001). During induction, heart rate increased with both sevoflurane (from 73 +/- 3 to 90 +/- 4 bpm, P < 0.05) and isoflurane (from 70 +/- 2 to 92 +/- 2 bpm, P < 0.05); the increase with isoflurane was greater than that with sevoflurane. Times to eye opening for sevoflurane (8.1 1 +/- 1.0 min) did not differ significantly from those for isoflurane (10.6 +/- 1.3 min). Patients opened their eyes at lower end-tidal minimum alveolar anesthetic concentration (MAC)-fractions of sevoflurane (0.12 +/- 0.01 MAC) than isoflurane (0.15 +/- 0.01 MAC, P < 0.01). During recovery, patients who received sevoflurane felt less clumsy (P < 0.001) and less confused (P < 0.005) but had higher pain scores (P < 0.005) than those who received isoflurane. Sevoflurane is more suitable than isoflurane for single-breath induction, because it produces a smoother induction with a lower incidence of complications and better patient acceptance.

Pharmacodynamics of high-dose vecuronium in children during balanced anesthesia.

To compare the speed of onset, intubating conditions, duration of action, and recovery from neuromuscular blockade with vecuronium to those with succinylcholine, 40 ASA physical status 1 or 2 children (ages 2-9 yr) were studied during N2O-O2-opioid anesthesia. Each child was randomly assigned to receive a bolus dose of one of the following muscle relaxants: succinylcholine 2.0 mg/kg (n = 10), vecuronium 0.1 mg/kg (n = 10), vecuronium 0.2 mg/kg (n = 10), or vecuronium 0.4 mg/kg (n = 10). The evoked electromyogram of the abductor digiti minimi to train-of-four stimulation was monitored. We found that with succinylcholine, the time to 95% twitch depression (speed of onset, mean +/- SD), 24 +/- 7 s, was significantly less than that with each dose of vecuronium: 0.1 mg/kg, 83 +/- 21 s; 0.2 mg/kg, 58 +/- 17 s; and 0.4 mg/kg, 39 +/- 11 s, respectively (P less than 0.05). The time to laryngoscopy and intubation did not differ significantly between succinylcholine (48 +/- 10 s) and vecuronium 0.4 mg/kg (57 +/- 13 s); however, both were significantly less than than with vecuronium 0.1 and 0.2 mg/kg (P less than 0.005). The intubating conditions were excellent in 100% of patients. The duration of action was least with succinylcholine (5.7 +/- 1.5 min) and increased with increasing doses of vecuronium: 0.1 mg/kg, 23.9 +/- 5.1 min; 0.2 mg/kg, 55.2 +/- 11.6 min; and 0.4 mg/kg, 74.6 +/- 9.9 min, respectively (P less than 0.001). The recovery index was most rapid with succinylcholine (1.6 +/- 0.4 min) and was slowest with vecuronium 0.4 mg/kg (22.6 +/- 2.1 min) (P less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

The relationships of medical libraries to Regional Medical Program planning.

The development of Regional Medical Program legislation is summarized and the activities of the new Division of Regional Medical Programs of the National Institutes of Health are described. The first grants for regional medical programs were activated 1 July 1966, and as of 30 June 1967, forty-nine had been awarded out of a possible total of fifty-five. The importance of excellent medical library facilities within each region, especially in all major teaching hospitals, with extensions down to the level of the community hospitals, was emphasized, and the concept of the community hospital as a learning center utilizing the most modern library concepts and teaching devices was commended. The Medical Library Association was asked whether training programs were being developed which would produce the numbers of personnel needed to staff the increased number of medical libraries of the future and whether new training programs were needed for service at the community hospital level.