British journal of anaesthesia
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We have reviewed randomized controlled trials to assess the effectiveness and safety of anaesthetics which omitted nitrous oxide (N2O) to prevent postoperative nausea and vomiting (PONV). Early and late PONV (6 and 48 h after operation, respectively), and adverse effects were evaluated using the numbers-needed-to-treat (NNT) method. In 24 reports with information on 2478 patients, the mean incidence of early and late vomiting with N2O (control) was 17% and 30%, respectively. ⋯ Omitting N2O had no effect on complete control of emesis or nausea. The NNT for intraoperative awareness with a N2O-free anaesthetic was 46 compared with anaesthetics where N2O was used. This clinically important risk of major harm reduces the usefulness of omitting N2O to prevent postoperative emesis.
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Randomized Controlled Trial Comparative Study Clinical Trial
Extradural analgesia with clonidine and fentanyl compared with 0.25% bupivacaine in the first stage of labour.
Conventional extradural analgesia during labour with 0.25-0.375% bupivacaine may induce motor weakness and subjective sensory deficit, reducing maternal satisfaction. Even in a regimen for ambulatory extradural analgesia (0.1% bupivacaine-fentanyl 2 micrograms ml-1), a potential for proprioreception impairment exists, which may impair safe ambulation. We have combined fentanyl with clonidine for extradural analgesia in labour, and compared its effects with 0.25% bupivacaine, in a randomized, double-blind study. ⋯ Patients in group 2 had a much higher incidence of motor weakness (P < 0.01), impaired perception of pinprick (P < 0.01) and impaired distal joint proprioception (P < 0.05) than group 1. We conclude that clonidine 120 micrograms-fentanyl 50 micrograms provided comparable extradural analgesic efficacy as 0.25% bupivacaine for the first stage of labour. Furthermore, unwanted neurological effects were significantly less.
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Comparative Study Clinical Trial Controlled Clinical Trial
Cognitive failures after general anaesthesia for day-case surgery.
Patients are normally thought to have recovered from general anaesthesia within a few hours after day-case surgery. Previous recovery studies using objective psychometric tests showed a return to baseline values within this period. Nevertheless, patients are advised about what activities they should not undertake in the subsequent 24 h because it is feared that the residual anaesthetic effects may impair their ability. ⋯ Using the cognitive failures questionnaire, a standard measure of performance of everyday tasks, 54 patients were asked to report their own performance after general anaesthesia for the 3 days after discharge from hospital: 30 local anaesthetic patients were studied for comparison. The general anaesthesia group reported a highly significant greater incidence of cognitive failures after anaesthesia compared with the local anaesthesia group. This suggests that the residual effects of anaesthesia persist beyond 24 h.
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Randomized Controlled Trial Clinical Trial Controlled Clinical Trial
Fuzzy logic control of inspired isoflurane and oxygen concentrations using minimal flow anaesthesia.
In order to evaluate the performance of feedback fuzzy logic control of inspired oxygen and isoflurane concentrations, we studied 30 patients undergoing discectomy for lumbar (n = 26) or cervical (n = 4) disc herniation. Patients were allocated random to one of two groups: a standard group (n = 15) with low flow anaesthesia (1.2-1.3 litre min-1) and manual control of gas concentrations; and a fuzzy group (n = 15) with minimal flow (0.5 litre min-1) and fuzzy logic feedback control of gas concentrations. Fuzzy logic control achieved and maintained very accurately the desired isoflurane concentration. ⋯ Delivery and costs of oxygen and nitrous oxide were significantly lower in the fuzzy group (P < 0.01). Accumulation of foreign gases was observed in one patient during low flow and in 11 patients during minimal flow anaesthesia. In conclusion, fuzzy logic control of inspired oxygen and isoflurane concentration during minimal flow anaesthesia was reliable and reduced anaesthetic gas delivery and costs.
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Randomized Controlled Trial Clinical Trial
Effect of ondansetron on nausea and vomiting after middle ear surgery during general anaesthesia.
The efficacy of ondansetron 4 mg and 8 mg was compared with placebo in the reduction of postoperative nausea, retching and vomiting (PONV) after middle ear surgery during general anaesthesia, in 75 patients, in a double-blind and randomized study. Both doses of ondansetron were predictors for a decrease in PONV and the number of doses of rescue antiemetic needed per patient (droperidol: from 0.72 in the placebo group to 0.32 in both the 4-mg and 8-mg groups). No reduction in PONV was observed in patients with a history of motion sickness, whereas in patients without a history of motion sickness, ondansetron reduced both the proportion of patients suffering from PONV from 53% to 20% (P < 0.05) and of those needing droperidol from 53% to 17% (P < 0.05).