British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Prevention of hypothermia during hip surgery: effect of passive compared with active skin surface warming.
We have measured aural canal (core) and skin temperatures, and body heat content in 45 patients undergoing elective hip arthroplasty. They received general anaesthesia which included thiopentone, vecuronium and enflurane and nitrous oxide in oxygen. ⋯ Core temperature and mean body heat content decreased significantly during surgery in groups 1 and 2 (aural canal temperature 1.5 and 1.0 degrees C, and mean body heat content 287 and 189 kJ, respectively), while in group 3 these variables remained near preoperative values (P = 0.001). Mean skin and hand temperatures decreased in the control group, increased in the active warming group and were unchanged in the passive warming group (P < 0.005), indicating that the forced heated air system was very efficient in providing thermal homeostasis during surgery, while the metallized plastic sheet was able to insulate the skin only from radiant and convective heat losses, without attenuating the reduction in core temperature.
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Randomized Controlled Trial Clinical Trial
Alkalinization of local anaesthetic for intra-articular instillation during arthroscopy.
Intra-articular instillation of a local anaesthetic agent for pain relief after arthroscopy has not been shown consistently to be beneficial. Alkalinization of a local anaesthetic agent may be expected to improve onset time, quality and duration of the block. ⋯ There were no differences in any of these measurements at any time between the groups, except that the group which received intraarticular saline had significantly lower pain scores 8 h after operation than the groups which had alkalinized or plain prilocaine. We conclude that prilocaine, at both pH values, is ineffective in producing postoperative analgesia but as there were patients who received no analgesic agents and who had very little pain, we may also conclude that arthroscopy is not a consistently painful procedure and is not a good model for assessing the efficacy of local anaesthetic agents.
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We have assessed the effect of lengthening the expiratory limb of an Ayre's T-piece from 0.5 to 10 m for ventilation with a Nuffield series 200 ventilator and Newton valve, as this equipment is potentially suitable for infants and young children during anaesthesia for magnetic resonance imaging (MRI). We used lung models with compliances and resistances representative of the respiratory system with intubated trachea of a neonate, infant and child weighing 15-20 kg. The effects on ventilation were small, being greatest with the largest lung model where the longer T-piece resulted in a reduction in tidal volume from 261 to 236 ml and an increase in intrinsic and extrinsic positive end-expiratory pressure from 0.20 to 0.32 kPa and from 0.14 to 0.25 kPa, respectively. Such changes are unlikely to be clinically important and can be obviated by using the ventilator with the standard valve in children weighing 15-20 kg.
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Cholinesterase inhibitors antagonize neuromuscular block produced by mivacurium, but some may also decrease its metabolism by inhibiting pseudocholinesterase. These opposing interactions were examined in rats anaesthetized with pentobarbitone. After spontaneous recovery from an initial bolus dose of 0.03 mg kg-1, mivacurium was infused to produce 80-90% block of gastrocnemius muscle twitch. ⋯ Edrophonium, pyridostigmine and neostigmine reduced the subsequent maximum block, compared with the change in saline control, by 3%, 19% and 35%, respectively. Correspondingly, the time to recovery of T1 to 50% was decreased by 20%, 58% and 62%. In rats, acetylcholinesterase-mediated antagonism of neuromuscular block predominated over decreased pseudocholinesterase-mediated metabolism, such that prior administration of a cholinesterase inhibitor did not prolong the neuromuscular blocking effects of mivacurium.
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Randomized Controlled Trial Comparative Study Clinical Trial
Effect of nabilone on nausea and vomiting after total abdominal hysterectomy.
In a prospective, double-blind study, we have examined the effect of preoperative nabilone on postoperative nausea and vomiting (PONV). Sixty women, less than 70 yr old, undergoing total abdominal hysterectomy, were allocated randomly to receive either nabilone 2 mg or metoclopramide 10 mg orally 90 min before induction of anaesthesia. ⋯ Data from 53 patients were analysed: the incidences of nausea and vomiting for the metoclopramide group were 70% and 67%, respectively; the corresponding values for the nabilone group were 73% and 54%. These differences were not significant.