British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
Effect of isoflurane and sevoflurane on the magnitude and time course of neuromuscular block produced by vecuronium, pancuronium and atracurium.
We have compared the ability of equipotent concentrations of isoflurane and sevoflurane to enhance the effect of non-depolarizing neuromuscular blocking drugs. Ninety ASA I and II patients of both sexes, aged 18-50 yr, were stratified into three blocker groups (Vec, Pan and Atr), to undergo neuromuscular block with vecuronium (n = 30), pancuronium (n = 30) or atracurium (n = 30), respectively. Within each group, patients were allocated randomly to one of three anaesthetic subgroups to undergo maintenance of anaesthesia with: (1) alfentanil-nitrous oxide-oxygen (n = 10); (2) alfentanil-nitrous oxide-oxygen-isoflurane (n = 10); or (3) alfentanil-nitrous oxide-oxygen-sevoflurane (n = 10) anaesthesia. ⋯ In the Vec and Pan groups, a total dose of 40 micrograms kg-1 of vecuronium or pancuronium, respectively, was given, and in the Atr group a total dose of atracurium 100 micrograms kg-1. Each blocker was given in four equal doses and administered cumulatively. We showed that 0.95% isoflurane and 1.70% sevoflurane (corresponding to 0.8 MAC of each inhalation anaesthetic, omitting the MAC contribution of nitrous oxide) augmented and prolonged the neuromuscular block produced by vecuronium, pancuronium and atracurium to a similar degree.
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Case Reports
Reducing the potential morbidity of an unintentional spinal anaesthetic by aspirating cerebrospinal fluid.
We describe two cases where we attempted to reduce the adverse effects of inadvertent spinal anaesthesia by aspirating local anaesthetic-contaminated cerebrospinal fluid (CSF). Analysis of this CSF for its local anaesthetic concentration revealed that we were able to recover 51% and 39% of the administered lignocaine. It is suggested that such aspiration may be a helpful additional measure to the supportive management of this complication.
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In a previous study, logistic regression analysis was used to determine the association of independent fixed patient factors with the incidence of postoperative nausea and vomiting (PONV). Female sex, previous history of PONV, use of postoperative opioids, previous history of motion sickness and an interaction between male sex and previous history of PONV were combined in an equation from which risk of PONV could be estimated. The present study was designed to test this equation in a group of patients with wide selection criteria. ⋯ The equation predicted an overall probability of PONV of 27.4%. If the model was used to define individual patients as predicted to have or not to have PONV, it was correct only 71% of the time. However, there was good agreement between the actual incidences of PONV and those predicted among the 16 risk groups created by the model.
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We have compared cardiorespiratory variables in anaesthetized piglets whose lungs were ventilated with oxygen in nitrous oxide (N2O group) or nitrogen (N group) after right ventricular carbon dioxide boluses (0.5 or 1 ml kg-1; n = 12) or slow graded injections (n = 6). Boluses affected all variables studied significantly (P < 0.05) except mean systolic arterial pressure. Significant changes in PE'CO2 (P = 0.012) and PaO2 (P = 0.048) values were observed in the N2O group. ⋯ Volumes and time required to induce a 50% increase in mean pulmonary arterial pressure differed significantly between groups (P < 0.05). We conclude that nitrous oxide worsened the effects of rapid and slow carbon dioxide emboli on cardiopulmonary variables. Rapid carbon dioxide embolism altered respiratory and haemodynamic variables, while slow carbon dioxide embolism changed only respiratory variables.