Anaesthesia
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The three currently available paper radioallergosorbent tests ('suxamethonium', alcuronium and thiopentone) were evaluated. 'Suxamethonium' radioallergosorbent test (which employs choline conjugated to paper discs) proved to be reliable in the detection of allergy to neuromuscular blockers, which were confirmed as the most common cause of anaphylactic reaction during general anaesthesia. Thiopentone radioallergosorbent test may also be useful, and is recommended in conjunction with 'suxamethonium' radioallergosorbent test in the preliminary investigation of reactions. Patients with positive 'suxamethonium' radioallergosorbent test usually require further testing, including alcuronium radioallergosorbent test, skin testing with a wide range of drug concentrations or leucocyte histamine release test.
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Three groups of 10 ASA 1 patients were studied to determine the incidence of hypoxaemia (oxygen saturation less than or equal to 90%) using pulse oximetry during induction of 'mask' anaesthesia, and whether simple oxygenation techniques could prevent its occurrence. We also surveyed all anaesthetists in three major hospitals to ascertain their techniques for this method of anaesthesia. Anaesthesia was induced in all patients with thiopentone and maintained with nitrous oxide and isoflurane. ⋯ Thirty-seven percent of anaesthetists who responded to the survey either did not apply positive pressure ventilation before establishment of spontaneous breathing, or only did so if apnoea was prolonged. Only one anaesthetist fully pre-oxygenated patients lungs. We conclude that to avoid the likely occurrence of hypoxaemia during induction of mask anaesthesia, a minimum of a few breaths pre-oxygenation is necessary.
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Randomized Controlled Trial Clinical Trial
The effects of midazolam on cerebral blood flow and oxygen consumption. Interaction with nitrous oxide in patients undergoing craniotomy for supratentorial cerebral tumours.
Cerebral blood flow and the cerebral metabolic rate of oxygen were measured in 30 patients during craniotomy for supratentorial cerebral tumours by a modification of the Kety-Schmidt technique using Xenon 133 intravenously. Anaesthesia was induced with midazolam 0.3 mg/kg, fentanyl and pancuronium, and maintained with midazolam as a continuous infusion, fentanyl, pancuronium and nitrous oxide in oxygen or oxygen in air. The concentration of midazolam in the blood of 10 patients was about 300 ng/litre during two measurements; the patients' lungs were ventilated with N2O in oxygen. ⋯ The concentration of midazolam in the blood of the third group of 10 patients was doubled to 600 ng/litre during the second flow measurement; the patients' lungs were ventilated with oxygen in air. No relationship was found between the dose of midazolam and cerebral blood flow or oxygen consumption. Nitrous oxide in combination with midazolam also had no effect on these variables.