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.

No abstract

No abstract

A trial was undertaken in children to compare the use of halothane and isoflurane in outpatient dental anaesthesia. A wholly inhalation technique was chosen and nitrous oxide in oxygen was delivered from a Boyle's machine via a coaxial (Bain) breathing system and was supplemented with either halothane or isoflurane. Isoflurane produced significantly fewer arrhythmias than halothane but the induction of anaesthesia took longer and proved more difficult.

In this double-blind study, we have allocated randomly 40 ASA I-III patients to one of four groups. After a standard anaesthetic induction, patients received vecuronium 0.08 mg kg-1 or 0.10 mg kg-1, or atracurium 0.4 mg kg-1 or 0.5 mg kg-1. Using an electromyogram (Datex Relaxograph) the train-of-four (TOF) response was measured during onset of and recovery from neuromuscular block. A greater degree of fade of TOF was observed with atracurium during onset of neuromuscular block than with equivalent doses of vecuronium. During recovery of neuromuscular transmission, vecuronium was associated with more fade than atracurium. The differences in the TOF profiles of these two drugs may be important when judging the adequacy of antagonism of neuromuscular block using the TOF response.

No abstract

Changes in arterial oxygen tensions in nine anaesthetized patients during controlled ventilation with either 79% nitrous oxide in oxygen or air only, were measured continuously using an intra-arterial oxygen electrode. When the patients were ventilated with the mixture, there was a significant increase in PaO2 of 2.74 +/- 1.08 kPa (P less than 0.002) over control values obtained while the subjects were awake and breathing air spontaneously. Changing the inspired gas from nitrous oxide in oxygen to air while ventilation was held constant resulted in a significant decrease in PaO2 of 2.22 +/- 0.94 kPa (P less than 0.001). However, these PaO2 values were not statistically significantly different from control values. We conclude that continuous accurate measurement of arterial oxygen tension is feasible provided that corrections are made in the electrode system for anaesthetic gases. We also found that the increase in PaO2 when 79% nitrous oxide in 21% oxygen was used, when compared with air, was lower than values proposed by previous investigators. The decrease in PaO2 when the inspired gas was changed back to room air was less than that found by others and there was no evidence of hypoxia when patients were ventilated on air alone after inspiring the mixture.

Summary Sixty unpremedicated patients undergoing short urological and gynaecological procedures