British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
Effect of heat conservation during and after major abdominal surgery on muscle protein breakdown in elderly patients.
Changes in mean body temperature and muscle protein metabolism were studied in elderly patients undergoing large bowel surgery. Two groups were studied: in one, efforts were made to maintain the patients normothermic during and after surgery by warming the fresh gases, the i.v. fluids, by placing warmed cotton padding around the exposed parts of the body and by covering the patients with a metallized plastic sheet in the recovery period. ⋯ The excretion of the amino acid 3-methylhistidine (3-MeH), an indicator of muscle protein breakdown, and urea nitrogen loss were measured in the urine collected the day before, and on the 2nd and 4th postoperative days. Prevention of heat loss during and after surgery caused a significant decrease in muscle protein degradation and nitrogen loss.
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Conventional anaesthetic techniques do not allow for the automatic control of end-tidal halothane concentration and, therefore, brain concentration cannot be predicted. In this study, eight dogs were ventilated with halothane in oxygen using a new closed-loop anaesthetic breathing system which provided a constant end-tidal concentration. During the first 60 min the end-tidal concentration was maintained at 0.87 vol% (1 MAC). ⋯ Measured uptake differed from theoretically calculated uptake by 18.3-57.6%, depending on the model used. Measured arterial and cerebral venous concentrations differed from theoretically calculated values by 7% and 17.5%, respectively. It was shown that the required end-tidal concentrations can be obtained rapidly and accurately, and that brain tissue concentrations can be predicted within certain limits.
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Comparative Study
Emergency intubation of the trachea facilitated by suxamethonium. Observations in obstetric and general surgical patients.
The relationship between the time of onset of neuromuscular blockade and the time at which laryngoscopy was attempted was studied in patients presenting for emergency obstetric or emergency general surgical procedures. "Train-of-four" stimulation and visual observation of the evoked twitch response in the hand were used as a measure of the degree of neuromuscular blockade. The attendant anaesthetist was unaware of the response to the peripheral nerve stimulator. Intubation preceded complete neuromuscular blockade; in the obstetric patients there was no correlation between the two times. The use of a peripheral nerve stimulator should allow the anaesthetist to perform intubation in emergency situations with a greater degree of safety.
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Pure suxamethonium chloride does not produce in vitro contracture of skeletal muscle from swine which are susceptible to malignant hyperpyrexia (MH), but does induce MH in vivo. It is suggested that suxamethonium chloride induces MH because the fasciculations which it causes lead to an increase in the myoplasmic calcium concentration.
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of the incidence and nature of cardiac arrhythmias occurring during isoflurane or halothane anaesthesia. Studies during dental surgery.
Seventy-six Chinese patients aged between 15 and 30 yr, undergoing 3rd molar extraction, were randomly allocated to two groups. One group received halothane and the other isoflurane. The incidence of arrhythmia during surgery under anaesthesia with isoflurane was significantly less than with halothane. ⋯ The frequency and nature of arrhythmias during surgery on right and left sides were similar. In three patients a slight decrease in arterial pressure was recorded in association with the arrhythmia, but on stopping the stimulus, both rhythm and arterial pressure returned to normal. The incidence of arrhythmia with halothane in the Chinese population in this study was significantly higher than that reported previously in non-Chinese patients.