British journal of anaesthesia
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We have measured the effects of 0.5, 1.0 and 1.5 MAC (minimum alveolar concentration) end-tidal concentrations of sevoflurane on intracranial pressure (ICP), cerebral perfusion pressure (CPP), mean arterial pressure (MAP), central venous pressure and heart rate in hypocapnic dogs (PaCO2 3.2-3.7 kPa) and compared the data with those produced by equi-MAC concentrations of enflurane and halothane. Enflurane and halothane caused small but significant increases in ICP at 0.5, 1.0 and 1.5 MAC, but there were no changes with sevoflurane. However, sevoflurane caused a considerable decrease in MAP with consequent decrease in CPP. We conclude that sevoflurane should be a suitable agent for neuroanaesthesia and is preferable to either enflurane or halothane.
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We have studied the neuromuscular effects of pipecuronium, vecuronium and their combination in 130 ASA group I or II patients. Patients were anaesthetized with 0.8% halothane and 60% nitrous oxide in oxygen. Neuromuscular block was recorded as the evoked thenar mechanomyographic response to train-of-four stimulation of the ulnar nerve (2 Hz at 10-s intervals). ⋯ The calculated doses producing 50% depression of the first twitch height were 15.6, 16.9 and 15.0 micrograms kg-1 for the pipecuronium, vecuronium and pipecuronium-vecuronium combination groups, respectively. Isobolographic and algebraic (fractional) analyses were used to assess quantitatively the combined neuromuscular effect of pipecuronium and vecuronium and to define the type of interaction between these drugs. The interaction between pipecuronium and vecuronium was found to be additive.