A prospective study of liver function in infants and children exposed to daily isoflurane for several weeks.

Eleven infants and children presenting for daily radiotherapy for a period of at least 2 weeks were anaesthetised with isoflurane in 33% oxygen and nitrous oxide. They were unpremedicated and given no other agents to supplement anaesthesia. The average number of exposures was 24 (SD 11; range 10-39) and the total anaesthetic time per exposure varied between 15 and 30 minutes. Liver function was assessed by determining serum total bilirubin, aspartate amino transferase, gamma glutamyl transferase and alkaline phosphatase before the start of treatment and at 5-daily intervals thereafter. There was no measurable change in any of these determinants of liver function. All children accepted daily induction of anaesthesia with isoflurane. Induction, maintenance and recovery from anaesthesia were uncomplicated.

An evaluation of tests of psychomotor function in assessing recovery following a brief anaesthetic.

This study was designed to evaluate the usefulness of three commonly used tests of psychomotor function and one test of short-term memory in assessing recovery from a brief nitrous oxide, oxygen and halothane anaesthetic. Twenty-six female patients undergoing minor gynaecological surgery were allocated to one of three treatment groups depending on premedication (placebo, low dose and high dose). Immediate recovery was most rapid in the placebo group. Both the tests of simple reaction time and picture recall were able to differentiate between the post-anaesthetic recovery of the high-dose group and that of the other two groups. Neither component of the letter cancellation test showed a clear difference in recovery pattern. Tests of critical flicker fusion were too unreliable to be of use in clinical decision making. Our results suggest that tests of reaction time and memory were more sensitive than letter cancellation in assessing recovery.

Reversal of profound paralysis: use of large doses of edrophonium to antagonize vecuronium and pancuronium induced neuromuscular blockade.

The ability to evoke reversal of dense vecuronium- and pancuronium-induced paralysis (T1 10% of control) with edrophonium 1.0 mg.kg-1 was studied using train-of-four nerve stimulation and electromyographic monitoring. Two different end-points, train-of-four ratios of 0.5 and 0.7, were used to define "adequate reversal", and the results for both relaxants were compared. Reversal was reliable and rapid for vecuronium if either ratio was used with times of 2.8 (1.5) and 9 (3) min required to achieve ratios of 0.5 and 0.7, respectively. However, if the block was due to pancuronium, reversal was unreliable with 2 of 9 and 4 of 9 patients not achieving ratios of 0.5 and 0.7, respectively. Reversal was also markedly prolonged in this group with a mean time of 37 (23) min to achieve a ratio of 0.7, and in almost half these patients a supplementary dose of edrophonium was required.

Fade profiles during spontaneous offset of neuromuscular blockade: vecuronium and gallamine compared.

The characteristics of the train-of-four (TOF) response have been studied electromyographically during the onset and the spontaneous offset of neuromuscular blockade induced with vecuronium or gallamine. During the onset of blockade, at 75% depression of initial twitch height, gallamine was associated with significantly more TOF fade than vecuronium. Both agents were associated with significantly less fade during onset than during spontaneous offset. When the two neuromuscular blocking drugs were compared during spontaneous offset they showed a similar degree of fade during early offset (up to 50% recovery of initial twitch height). However, during late spontaneous offset, when the initial twitch height had recovered to 75% of control values, vecuronium was associated with more fade than gallamine.

Assessment of a new nasopharyngeal airway.

A new design of nasopharyngeal airway, which incorporates an introducer, was compared with a standard red rubber airway. The new airway was more frequently of the correct length, but the incidence of bleeding (12.5%) was not significantly different from that with the red rubber airway (27.5%).

Relationship between single twitch depression and train-of-four fade: influence of relaxant dose during onset and spontaneous offset of neuromuscular blockade.

The characteristics of the train-of-four (TOF) response were studied electromyographically during onset and spontaneous offset of neuromuscular blockade with bolus doses of vecuronium (ED95, and ED95 X 2). During onset of blockade there was less fade with the larger than the smaller dose of vecuronium, demonstrating a variable and dose-related relationship between the ratio of height of the initial twitch, T1, and fourth twitch, T4. With both doses TOF fade was more pronounced during recovery than during onset of block, but at the same T1 values during offset, both doses were associated with similar degrees of fade during recovery. Thus with bolus doses of vecuronium the T4 ratio during recovery bears a fixed relationship to initial T1 depression that is independent of dose.

Assessment of a new hypnotic imidazo-pyridine (zolpidem) as oral premedication.

1 A new imidazo-pyridine hypnotic (zolpidem 10 mg and 20 mg) was compared with placebo as premedication before general anaesthesia in female patients undergoing minor gynaecological surgery. Efficacy and tolerance before and after anaesthesia were assessed. Psychomotor testing was used to study recovery from anaesthesia. 2 Both doses of zolpidem produced good sedation pre-operatively but only the higher dose was associated with anterograde amnesia. 3 Premorbid anxiety scores were low in the group of patients studied and were unaffected by either dose of zolpidem. 4 There were no significant effects on the course of anaesthesia. However, postoperatively there was a tendency for wake-up to be delayed in those patients who received either dose of zolpidem. 5 Postoperative recovery, as indicated by tests of psychomotor performance, was noticeably delayed with a dose of 20 mg compared with placebo whilst psychomotor performance had returned towards baseline levels 3 h after wake-up in those patients who had received placebo. The zolpidem 10 mg group was intermediate. 6 Zolpidem may be a suitable premedicant when hypnosis and amnesia only are required.

Vecuronium and phaeochromocytoma. A report of two cases using different modes of administration.

Two patients presenting for removal of phaeochromocytoma are described. Vecuronium was used to provide neuromuscular blockade by two different methods of administration: an infusion and a large bolus dose. Both gave satisfactory results and we suggest that vecuronium may be the neuromuscular blocking agent of choice for patients with phaeochromocytoma.

Response to carbon dioxide after oral midazolam and pentobarbitone.

Midazolam (15 mg), pentobarbitone (100 mg) and a placebo were administered orally to nine male volunteers in double-blind crossover studies and the effect on the ventilatory response to carbon dioxide was observed for periods of 6 hours. It was concluded that neither drug caused any significant degree of respiratory depression.

Sedation for local anaesthesia. Comparison of intravenous midazolam and diazepam.

Intravenous midazolam and diazepam have been compared as sedatives during surgery performed under local anaesthesia. Satisfactory conditions were produced by both drugs. No difference was detected in the rate of recovery, but a highly significant greater degree of amnesia followed the use of midazolam.

Carbon dioxide response curves following midazolam and diazepam.

The ventilatory response to carbon dioxide was measured in volunteers before, and at intervals after the i.v. administration of midazolam 0.075 mg kg-1 and diazepam 0.15 mg kg-1. In the doses used neither drug caused any statistically significant respiratory depression and there were no differences between the drugs.