British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Evaluation of the usefulness of intrathecal bupivacaine infusion for analgesia after hip and knee arthroplasty.
Spinal anaesthesia in 47 ASA I-III patients was induced with 0.5% bupivacaine 2 ml via a 28-gauge spinal catheter (L3-4 interspace) and 0.5-ml increments were given if needed before or during hip or knee arthroplasty. Intrathecal 24-h infusions consisted of 0.5% bupivacaine 0.4 ml h-1 (2 mg h-1) (n = 12), 0.5% bupivacaine 0.2 ml h-1 (1 mg h-1) (n = 12) or saline (n = 11) (12 exclusions). Patients received oxycodone 0.1-0.14 mg kg-1 i.m. for rescue analgesia. ⋯ The incidence of nausea and vomiting was similar in all groups. Although an effective analgesic, intrathecal infusion of bupivacaine 2 mg h-1 cannot be recommended for routine pain relief because of the risk of increasing spinal block. Technical problems (19%) also reduced the overall efficacy of the continuous intrathecal analgesic regimen.
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We describe the use of heparinase-guided thrombelastography in the assessment of a parturient who had been anticoagulated with heparin for suspected thromboembolic disease. Reversal of the heparin effect in the heparinase-treated sample facilitated administration of protamine and successful subarachnoid analgesia for delivery.
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Comparative Study
Efficacy of intraoperative heat administration by ventilation with warm humidified gases and an oesophageal warming system.
We measured changes in body temperature in 12 hypothermic (mean aural temperature 34.4 (SD 1.0) degrees C) pigs during general anaesthesia with an open abdominal cavity and the effect of two warming systems: heating of inspired gases to 39 degrees C (intratracheal temperature) and oesophageal warming to 39 degrees C by a water perfused oesophageal heat exchanger. Each animal underwent both treatments and the control period in random sequence. Each condition was studied over 1 h. ⋯ Anaesthesia, room temperature and relative humidity, amount and temperature of infusions and extension of exposed visceral surfaces were standardized. Mean decrease in body temperature was 1.0 (0.7) degree C (P < 0.005) without warming and 0.6 (0.2) degree C (P < 0.005) with heated inspired gases: this difference was not statistically significant. Oesophageal warming was very efficient as mean body temperature did not change significantly (-0.1 (0.2) degree C; ns).
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We have examined the role of benzodiazepine receptors in nitrous oxide-induced neuronal depression in rats. The changes in neuronal excitability induced by nitrous oxide and the benzodiazepine inverse agonist, Ro15-4513, were monitored by measurement of visual evoked potentials (VEP). ⋯ However, the same concentrations of Ro15-4513 antagonized nitrous oxide-induced depression of VEP amplitudes. We conclude that antagonism of nitrous oxide-induced depression by Ro15-4513 indicates that at least part of the decreased neuronal excitability caused by nitrous oxide could be ascribed to interactions with the GABAA receptor complex.
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We have studied the influence of motivation of care providers on the incidence and duration of postoperative hypoxaemia in the recovery room. In a prospective, switch-back designed cohort study, we have compared the incidence of low pulse oximeter saturation values (SpO2) during pre-intervention, intervention and post-intervention phases. Low SpO2 values were classified as either hypoxaemia (SpO2 < or = 90%, minimum duration 1 min) or artefact. ⋯ The number of patients who had severe hypoxaemia for more than 5 min decreased from 13 to 1 (RR 0.08, CI 0.02-0.36; P < 0.01). In the post-intervention period, the incidence of hypoxaemia returned to pre-intervention values. The results of this study suggest that motivation of care providers to prevent and treat low SpO2 is an important determinant of postoperative hypoxaemia in the recovery room.