Comparison of sevoflurane and halothane for outpatient dental anaesthesia in children.

In a prospective, randomized, double-blind clinical study, we have studied 100 children, aged 2-12 yr, to compare halothane and sevoflurane in outpatient dental anaesthesia. All patients were unpremedicated and received inhalation induction using nitrous oxide in oxygen supplemented with either halothane (maximum inspired concentration 5%) or sevoflurane (maximum inspired concentration 8%). Time to loss of the eyelash reflex was more rapid using sevoflurane although time to adequate anaesthesia (to allow insertion of a mouth prop) was slower in the sevoflurane group. The incidence of cardiac arrhythmia was higher during halothane (62%) than during sevoflurane anaesthesia (28%) (P < 0.005) and the arrhythmias were more often ventricular in origin. The two agents were comparable in terms of ease of use and quality of anaesthesia, and times to eye opening and satisfying discharge criteria were similar. We conclude that sevoflurane has qualities that have made halothane the most used inhalation agent for children, and that it is superior to halothane in dental outpatients where cardiac arrhythmias are a particular problem.

Cardiovascular effects of doxacurium, pancuronium and vecuronium in anaesthetized patients presenting for coronary artery bypass surgery.

The cardiovascular effects of bolus doses of doxacurium 0.037 mg kg-1 were compared with those following equipotent doses of pancuronium (0.09 mg kg-1) and vecuronium (0.075 mg kg-1) and with those following high-dose doxacurium (0.075 mg kg-1), in patients with coronary artery disease. Anaesthetic technique comprised premedication with lorazepam, papaveretum and hyoscine, induction with diazepam, fentanyl, thiopentone, atropine and suxamethonium, and the trachea was intubated. At least 20 min later, during stable nitrous oxide in oxygen anaesthesia, a single bolus of neuromuscular blocking drug was administered and the effects measured at 1, 5 and 10 min. There was a small decrease in heart rate following doxacurium 0.075 mg kg-1, but no other significant or dose-related changes in mean heart rate, arterial pressure or cardiac index with doxacurium. Similar results were found following vecuronium, but the reduction in heart rate was more pronounced. In contrast, significant increases in mean arterial pressure, heart rate and cardiac index occurred after pancuronium.

Glycopyrronium requirements for antagonism of the muscarinic side effects of edrophonium.

We have compared, in 60 adult patients, the cardiovascular effects of glycopyrronium 5 micrograms kg-1 and 10 micrograms kg-1 given either simultaneously or 1 min before edrophonium 1 mg kg-1. Significant differences between the four groups were detected (P less than 0.001). Both groups receiving 10 micrograms kg-1 showed increases in heart rate of up to 30 beat min-1 (95% confidence limits 28-32 beat min-1). Use of glycopyrronium 5 micrograms kg-1 provided greater cardiovascular stability and, given 1 min before the edrophonium, was sufficient to minimize early, edrophonium-induced bradycardias. This low dose of glycopyrronium provided good control of oropharyngeal secretions.

Clinical experience and plasma laudanosine concentrations during the infusion of atracurium in the intensive therapy unit.

Twenty patients in the intensive care unit received an infusion of atracurium to permit mechanical ventilation. The duration of infusion ranged from 38 to 219 h and the average rate of infusion during the study was 0.76 mg kg-1 h-1. In 14 patients an increase in atracurium requirement occurred within the first 72 h of the infusion. Recovery from neuromuscular blockade after a prolonged infusion was sufficiently rapid to avoid pharmacologically induced reversal. In six patients maximum plasma concentrations of laudanosine were 1.9-5 micrograms ml-1, and there was no evidence of cerebral excitation.

Assessment of the Datex Relaxograph during anaesthesia and atracurium-induced neuromuscular blockade.

The Datex Relaxograph is a recently introduced electromyographic monitor of neuromuscular transmission. It has been assessed in patients requiring neuromuscular blockade and the results compared with those obtained simultaneously with a force transducer. There was a good correlation between the two methods of measurement for both twitch height and train-of-four ratio (correlation coefficients 0.93 and 0.97, respectively). The Datex Relaxograph proved easy to use in the clinical setting.

Comparison of infusions of alfentanil or pethidine for sedation of ventilated patients on the ITU.

Sedation was studied in 30 patients requiring overnight ventilation in the intensive therapy unit (ITU). Patients received an infusion of either alfentanil or pethidine, supplemented with midazolam. The infusion rates were adjusted to provide optimal sedation as judged by a nurse, and measurements were made of quality of sedation, recovery and serum cortisol concentration. In addition, blood concentrations of alfentanil were measured to permit pharmacokinetic and pharmacodynamic analysis. Satisfactory sedation was achieved in both groups. The required infusion rate for alfentanil was between 0.4 and 0.5 micrograms kg-1 min-1. Recovery was good in both groups, apart from one patient in the alfentanil group, in whom recovery was greatly prolonged and alfentanil pharmacokinetics were abnormal. A difference was found in the metabolic response to surgery between the two groups, the response in the alfentanil group being significantly less marked.

Anaesthesia with ICI 35,868 monitored by the cerebral function analysing monitor (CFAM).

Ten patients who received bolus doses of the cremophor formulation of ICI 35,868 were monitored using the Cerebral Function Analysing Monitor (CFAM). Visual inspection of the traces obtained showed an easily recognizable pattern which was associated with an increasing depth of anaesthesia. Statistical analysis showed a high correlation between venous blood levels of the drug and changes recorded by the CFAM, although there was marked inter-patient variation. It is suggested that this variation is due to the effect of a time-lag between changes in drug concentration in the brain and venous blood.

Influence of sample site on blood concentrations of ICI 35868.

Simultaneous blood samples from an artery, a peripheral vein and a central vein were analysed for ICI 35868 concentrations following an induction dose of 2.0 mg kg-1 administered i.v. over 60 s, to five patients before cardiac surgery. Up to 60 s after the end of the administration of the drug there were wide differences in drug concentration between the sampling sites. Thus, any attempt to correlate effect with blood concentration over this early period would be problematic. From 60 s there were no significant differences in drug concentration between the three sites. Thus, as long as the mixing period is allowed for, peripheral venous sampling provides an acceptable alternative to arterial puncture in studies to correlate drug effect and concentration and for pharmacokinetic investigations.

Disoprofol and fentanyl for total intravenous anaesthesia.

Ninety patients undergoing a variety of surgical procedures were anaesthetised with a disoprofol infusion and increments of fentanyl. The first 40 patients constituted a preliminary dose finding study and the subsequent 50 patients a dose comparison study. The second 50 patients were alternately allocated to receive a maintenance infusion of disoprofol 150 or 200 micrograms/kg/minute. Fentanyl (1 microgram/kg) at induction was followed by further small increments when indicated. Maintenance dosage of 200 micrograms/kg/minute provided good operating conditions and rapid uncomplicated recovery in spontaneously breathing patients, while 150 micrograms/kg/minute proved inadequate to prevent patient movement.