Anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Patient-controlled alfentanil. Target-controlled infusion for postoperative analgesia.
We have compared the opioid effects of a patient-demand, target-controlled infusion of alfentanil (n = 10), with patient-controlled bolus administration of morphine (n = 10) following major spinal surgery in Chinese patients aged from 11 to 67 years. The same general anaesthesia regimen was used in all patients. One group of patients were given intra-operative morphine analgesia followed by postoperative intravenous morphine patient-controlled analgesia, while the other group received an intra-operative target-controlled infusion of alfentanil. ⋯ There was a significantly (p < 0.001) lower respiratory rate in the alfentanil group compared with patients receiving morphine at, clinically assessed, equianalgesia. The predicted plasma alfentanil concentrations increased rapidly from about 30 ng.ml-1 during the first 4 h to around 100 ng.ml-1 at the end of the 24-h study period. The precision of the target-controlled infusion system was 75.4% and the mean prediction error (bias) 58.1%, suggesting an underestimation of the measured alfentanil concentrations by the alfentanil infusion system in these Chinese patients.
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Comparative Study
The importance of the expiratory pause. Comparison of the Mapleson A, C and D breathing systems using a lung model.
A physical lung model simulating spontaneous respiration was used to investigate the influence of the respiratory pattern on the efficiency of the Mapleson A, C and D breathing systems. It is shown that the Mapleson A system is always the most efficient breathing system and that its performance is relatively independent of the respiratory pattern. When the expiratory pause is minimal, the Mapleson C system is almost as efficient as the Mapleson A, but becomes ever less efficient as the expiratory pause increases. ⋯ With a longer expiratory pause, this system's efficiency approaches that of the Mapleson A. The experimental results are compared with predictions generated by a mathematical model. There is good agreement between the two, validating the mathematics used.
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Randomized Controlled Trial Comparative Study Clinical Trial
The addition of tenoxicam to prilocaine for intravenous regional anaesthesia.
The analgesic effects of tenoxicam 20 mg added to prilocaine in a standard Bier's block (group 2) was studied in 45 patients who had their Colles' fractures reduced under intravenous regional anaesthesia, and compared both to a control group (group 1), and to a group who received a standard Bier's block combined with the same dose of tenoxicam given intravenously into the contralateral arm (group 3). Patients in group 2 obtained significantly better analgesia than group 1, as judged by a longer time before first additional analgesia was required (p < 0.05), less total analgesic consumption (p < 0.01), and lower pain scores (p < 0.01). These benefits were not obtained by patients in group 3.
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Randomized Controlled Trial Clinical Trial
Gas kinetics during nitrous oxide analgesia for labour.
Hypoxaemia may occur after hyperventilation with nitrous oxide during labour. The purpose of this study was to assess whether diffusion hypoxia is a contributory factor. Twenty-four parturients were randomly allocated to receive 50 or 70% nitrous oxide in oxygen. ⋯ The oxygen saturation did not differ between the groups with a lowest median value of 96% before the start of nitrous oxide inhalation. Two parturients had episodes of desaturation. Both had low end-tidal oxygen concentrations in association with the desaturation but, as the end-tidal nitrous oxide concentrations were low, the desaturations could not be attributed to diffusion hypoxia.
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Randomized Controlled Trial Comparative Study Clinical Trial
Acid aspiration prophylaxis for emergency Caesarean section.
Over a 3.5 year period, 384 patients requiring emergency Caesarean section under general anaesthesia received at random one of six acid aspiration prophylaxis regimens as soon as the decision was made for surgery. In the first phase of the study, sodium citrate administered orally 0.3 M, 30 ml (group C, n = 120) was compared with metoclopramide 10 mg administered intravenously and sodium citrate (group MC, n = 65). In the second phase, all patients received sodium citrate, and either intravenous administration of ranitidine 50 mg (group RC, n = 50), omeprazole 40 mg (group OC, n = 50), ranitidine 50 mg with metoclopramide 10 mg (group RMC, n = 50) or omeprazole 40 mg with metoclopramide 10 mg (group OMC, n = 49). ⋯ The proportion of patients with pH < 3.5 and volume > 25 ml in the C and MC groups (43/185) was greater than that in the OC, RC, OMC and RMC groups (18/199, p < 0.001). Ranitidine and omeprazole administered intravenously were equally effective adjuncts to sodium citrate in reducing gastric acidity for emergency Caesarean section. Compared with sodium citrate alone, the addition of either ranitidine, omeprazole or metoclopramide alone did not reduce gastric volume while small reductions in gastric volume were seen with the addition of metoclopramide and either ranitidine or omeprazole.