British journal of anaesthesia
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Stained, quick setting resin was injected into the thoracic paravertebral spaces of six cadavers to assess the suitability of this material for delineating the spread of injected substances in an area of the human body which is being re-evaluated currently as a repository for analgesic drugs. The distribution and spread of the resin in relation to intercostal spaces, vertebral bodies and the spinal cord were noted, and compared with other studies.
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Randomized Controlled Trial Clinical Trial
Use of i.m. ranitidine for the prophylaxis of aspiration pneumonitis in obstetrics.
Twenty patients who underwent elective Caesarean section received ranitidine 150 mg by mouth 8-14 h, and 50 mg i.m. 90 min, before surgery. Intraoperative gastric aspiration resulted in contents with a pH greater than 2.5 and volume less than 25 ml in all patients (mean pH 6.5 (SD 0.8); mean volume 9.0 (SD 7.2) ml). Sixty patients in labour, who received ranitidine 50 mg i.m. 6-hourly, underwent emergency surgery. ⋯ Ranitidine medication resulted in a mean aspirated gastric volume of 31.4 (26.6) ml and pH of 5.3 (2.1); five of 30 patients had a pH less than 2.5. The addition of sodium citrate 0.3 mol litre-1 resulted in gastric pH greater than 2.5 in all patients and a mean gastric volume of 43.2 (38.3) ml. The group who received only sodium citrate 0.3 mol litre-1 had a mean pH of 5.3 (1.1) and a mean volume 122.7 (98.2) ml.
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This study has examined the effects of inhaled nitrous oxide on the N1 and P2 components of the cortical auditory evoked potentials (AEP) in the latency interval 80-300 ms after the stimulus. The amplitudes, latencies and thresholds of the AEP were measured at a range of end-tidal nitrous oxide concentrations (0%, 10%, 20%, 40%) in 10 subjects with normal hearing. ⋯ A study of the effect of stimulus intensity on AEP amplitude showed that the amplitude change with nitrous oxide was accounted for largely by systematic increase in evoked potential threshold. Subjective pure tone thresholds were not affected by the concentrations of nitrous oxide used, indicating that the AEP changes were independent of subjective hearing level.
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Randomized Controlled Trial Clinical Trial
Use of the post-tetanic count to monitor recovery from intense neuromuscular blockade in children.
The post-tetanic count was investigated as a method of monitoring intense neuromuscular blockade in children. One of five myoneural blockers (atracurium, vecuronium, pancuronium, tubocurarine or alcuronium) was given to groups of six children during nitrous oxide-oxygen-halothane anaesthesia. ⋯ The interval between the appearance of the first post-tetanic response and the first train-of-four response was typically 5-10 min for the intermediate-acting agents vecuronium and atracurium, and 20-30 min for the long-acting agents pancuronium, alcuronium and tubocurarine. A post-tetanic count of 6 with alcuronium and tubocurarine, or 7 with vecuronium, atracurium and pancuronium indicated that recovery of the first train-of-four response was imminent.
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The incidence of immediate postoperative hypoxaemia following general anaesthesia was studied using a pulse oximeter in 120 ASA category I and II patients during transport to the recovery room. Thirty-two percent of those not given oxygen during transport developed desaturation (SaO2 less than 90%) in spite of receiving 100% oxygen for 5 min before transport. ⋯ None of the patients given oxygen 2 litre min-1 via a nasopharyngeal catheter during transport exhibited an SaO2 less than 90%. The only variable which correlated with the development of desaturation was the duration of anaesthesia.