British journal of anaesthesia
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The contributions of aerobic and anaerobic muscle metabolism to the heat produced in porcine malignant hyperthermia were studied in seven Pietrain pigs. Oxygen consumption measurements were used to calculate the increase in muscle temperature as a result of aerobic metabolism and this was compared with the observed muscle temperature. The results show that in the initial stage of porcine malignant hyperthermia heat production is largely aerobic in origin. Terminally, aerobic metabolism can account for about half the observed temperature increase.
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The effect of the physical characteristics of the carrier gas on the output of automatic plenum vaporizers was studied. The Vapor and Fluomatic halothane output at all dial settings was highest with oxygen as the carrier gas, as compared with helium and nitrous oxide and was a function of carrier gas viscosity at all dial settings. The output of the Fluotec Mark 2 at the 0.5 and 1% settings was highest with nitrous oxide as the carrier gas, but at 2, 3 and 4% settings it was highest with oxygen; at the 0.5% and 1% dial settings it was a function of carrier gas density, but at 2%, 3% and 4% it was a function of carrier gas viscosity.
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Pulmonary gas distribution, functional residual capacity (FRC), closing capacity (CC), arterial oxygen tension (PaO2) and alveolar-arterial oxygen tension gradient (PAO2-PAO2) were measured in seven subjects before and after the induction of extradural analgesia for routine surgery. It was found that pulmonary gas distribution was within normal limits throughout the study, although there were two patients in whom airway closure occurred consistently within the tidal volume. ⋯ CC and FRC were substantially unchanged by the induction of extradural analgesia. Changes in (PAO2-PaO2) and PaO2 were usually not large, and are apparently related to factors other than changes in lung geometry.
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Comparative Study
Effect of lithium and rubidium on the sleeping time caused by various intravenous anaesthetics in the mouse.
The effects of acute and long-term lithium (LiCl) and rubidium chloride (RbCl) treatments on the sleeping time caused by intravenous thipentone, methohexitone, ketamine, propanidid. Althesin and diazepam were studied in white mice. ⋯ Both LiCl and RbCl, given acutely, enhanced the sleeping time caused by diazepam. The rectal temperatures were lower in the LiCl-treated mice than in the control and RbCl-treated mice.