Anesthesiology
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The ability of edrophonium and neostigmine to antagonize nondepolarizing neuromuscular blockade produced by steady-state infusions of atracurium, pancuronium, and vecuronium was studied in 71 adult patients anesthetized with nitrous oxide and halothane. Infusion rates of blocking drugs were adjusted so that single twitch depression as measured by the evoked integrated EMG of the hypothenar muscles was kept at 10% of control. Two minutes after the termination of the infusion either edrophonium (0.75 mg/kg) or neostigmine (0.05 mg/kg) was administered. ⋯ Increasing the dose of edrophonium to 1.0 mg/kg produced single twitch values of 0.90 at 5 min postreversal but did not increase the rate of recovery of the train-of-four fade ratio. Neostigmine reversal of pancuronium, on the other hand, generally produced T4/T1 ratios of greater than 0.70 in 20-30 min. Although the pattern of recovery seen after reversal of vecuronium was in general quite similar to that seen after atracurium, two patients in the vecuronium-edrophonium group showed delayed recovery and also failed to respond significantly to subsequent doses of neostigmine.(ABSTRACT TRUNCATED AT 250 WORDS)
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Isoflurane (ISF)-induced hypotension causes equal reductions of cerebral blood flow (CBF) and the cerebral metabolic rate for oxygen (CMRO2) so that no disturbance of cerebral energy stores or metabolites occurs. While hypocapnia during ISF-induced hypotension causes a further reduction of CBF, the effects on cerebral energy stores and metabolites produced by combining hypocapnia with ISF-induced hypotension are not known. This study examined the effect of hypocapnia (PaCO2 = 20 mmHg) on CMRO2, the electroencephalogram (EEG), and levels of adenine nucleotides, phosphocreatine, lactate, pyruvate, and glucose in brain tissue in 12 dogs during ISF-induced hypotension. ⋯ CMRO2 was reduced by approximately 27%. Thirty minutes after restoration of normocapnia with normotension, cerebral metabolites remained unchanged and CMRO2, and the power of the alpha, beta-1, and beta-2 spectra of the EEG returned to control values. These results suggest no adverse effect on cerebral metabolism or function during hypocapnia combined with ISF-induced hypotension.