British journal of anaesthesia
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Prolonged anaesthesia with nitrous oxide inactivates vitamin B12 and impairs DNA synthesis in bone marrow cells. The use of parenteral folinic acid in the prevention of these toxic effects has been studied in 11 patients, ventilated artificially with nitrous oxide in oxygen for 24 h. ⋯ They were assessed morphologically and with the deoxyuridine suppression test. Folinic acid 30 mg immediately before anaesthesia and 30 mg 12 h later, prevented the toxic effects of nitrous oxide in four out of five patients, whereas smaller amounts of folinic acid (between 3 and 36 mg in 24 h), were ineffective.
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Treatment with drugs and exposure to many environmental chemicals results in enzyme induction. However, the clinical significance of increased (or altered) metabolism of the inhaled anaesthetics appears to be trivial. Enzyme induction does not affect the conduct of inhalation anaesthesia. ⋯ Whether induction of halothane biotransformation and the production of reactive intermediates may lead to hepatoxicity is not yet settled. It is quite clear that induction, in the presence of hypoxia, leads to hepatic necrosis in rats. However, a similar relationship has not been established in surgical patients.
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Comparative Study Clinical Trial Controlled Clinical Trial
Extradural morphine for the relief of pain following caesarean section.
Thirty patients took part in a double-blind trial to compare morphine 10 mg i.m. with morphine 5 mg into the extradural space for pain relief following Caesarean section. With the extradural route the mean time to first analgesia was 7.95 h compared with 4.75 h for the i.m. route. ⋯ There was a small but definite advantage in the use of the extradural route for the initial dose of morphine. No serious side-effects were noted in either group.
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A description is given of a new microprocessor-based device for EEG analysis. The Cerebral Function Analysing Monitor (CFAM) analyses the EEG amplitude and frequency distribution. It produces a detailed plot of amplitude trends and separate traces of the percentage activity in each of the classical EEG frequency bands. ⋯ Discontinuation of nitrous oxide resulted in a marked increase in EEG amplitude and an increase in alpha and beta band activity. Discontinuation of halothane resulted in smaller alterations in the CFAM trace. This device provides easily interpreted processed EEG data and merits further investigation.