Reversal of benzodiazepine sedation with the antagonist flumazenil.

The effectiveness of the benzodiazepine antagonist, flumazenil, was evaluated in a randomized double-blind clinical study in which diazepam 0.2 mg kg-1 or midazolam 0.1 mg kg-1 was used for i.v. sedation. We studied 120 day-case patients undergoing gastroscopy and treated with either flumazenil 0.1-2 mg or placebo after the procedure. Psychometric assessment of four aspects of recovery over a 3-h period showed that flumazenil attenuated the sedative effects of the benzodiazepines, but did not antagonize the sedation completely. For patients sedated with diazepam, there was a significant effect of flumazenil on speed of motor co-ordination after 90 min (P less than 0.01), and for those given midazolam a similar effect was found at 20 min (P less than 0.01). However, after 3 h all four groups of patients had not returned to baseline performance in accuracy of motor co-ordination (P less than 0.01) and cortical arousal (P less than 0.05), and the two groups sedated with diazepam still displayed memory deficits (P less than 0.05). Flumazenil did not attenuate the subjective experience of sedation as measured by visual analogue scales. These results indicate that sedation is multidimensional, differentially affecting the hierarchy of cognitive functions. In day-cases, antagonism of benzodiazepine sedation with flumazenil would not hasten the safe discharge of patients.

Isoflurane with either 100% oxygen or 50% nitrous oxide in oxygen for caesarean section.

Two hundred mothers undergoing general anaesthesia for Caesarean section were allocated randomly to receive either 100% oxygen (group 100) or 50% nitrous oxide in oxygen (group 50), both supplemented with isoflurane. In each group the concentrations of isoflurane were chosen to deliver 1.5 MAC for the first 5 min after induction and 1.0 MAC thereafter. The mean umbilical venous PO2 was greater in group 100 for emergency sections (P = 0.001). Babies born to mothers in group 100 required less resuscitation than those in group 50 (P = 0.04) and there was a tendency to higher Apgar scores at 1 min in group 100, although this was not statistically significant. There were no instances of awareness, although two patients in group 100 and three in group 50 reported dreaming. This study confirms earlier findings that the use of 100% oxygen can significantly improve fetal oxygenation during Caesarean section, with particular benefit in emergency cases. This is associated with a lower incidence of neonatal resuscitation.

Cognitive and functional competence after anaesthesia in patients aged over 60: controlled trial of general and regional anaesthesia for elective hip or knee replacement.

OBJECTIVE: To determine the influence of general or regional anaesthesia on long term mental function in elderly patients. DESIGN: Prospective study of patients randomly allocated to receive general or regional anaesthesia. SETTING: The patients' homes and a large teaching hospital in Cardiff. SUBJECTS: 146 Patients aged 60 and over scheduled for elective hip or knee replacement. MAIN OUTCOME MEASURES: Scores achieved in tests of cognitive function and functional competence. RESULTS: 72 Patients were allocated to receive general anaesthesia and 74 regional anaesthesia. Anaesthetic technique did not influence the duration of the operation, time to mobilisation postoperatively, requirements for analgesia after the operation, or duration of stay in hospital. Three months after the operation there was an improvement in the score for the recognition component (76 ms, 95% confidence interval 9 to 144) and the response component (82 ms, 5 to 158) of the choice reaction time in the group receiving general anaesthesia compared with the group receiving regional anaesthesia. This was the only significant difference between the two groups in the assessments of cognitive and functional competence. Eleven patients receiving regional anaesthesia and 12 receiving general anaesthesia reported that their memory and concentration were worse than before the operation, but this was not confirmed by testing. CONCLUSION: Cognitive and functional competence in elderly patients was not detectably impaired after either general or regional anaesthesia when attention was paid to the known perioperative influences on mental function.