British journal of anaesthesia
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The effects of atracurium and alcuronium on the evoked mechanical and electromyographic responses of the adductor pollicis were investigated in 30 adult patients. The ulnar nerve was stimulated with trains of four supramaximal pulses of 0.2 ms duration and a frequency of 2 Hz at intervals of 20 s. The mechanical response was measured using a strain gauge force transducer and the evoked compound action potential (ECAP) was recorded simultaneously using a Medelec MS91 electromyography system. ⋯ There was no significant quantitative difference between the rates of antagonism of alcuronium and atracurium when assessed by the mechanical first response ratio. Electromyographic first response and electromyographic and mechanical train-of-four ratios recovered more rapidly in the atracurium group. These findings suggest that the differences between mechanical and electromyographic measurements of neuromuscular blockade are drug-specific and are more pronounced during the onset of blockade than during its antagonism by neostigmine.
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Comparative Study
Changes in plasma vasopressin concentration in association with coronary artery surgery or thymectomy.
Plasma vasopressin concentrations in 14 patients undergoing coronary artery surgery were compared with those in eight patients undergoing thymectomy. Vasopressin concentrations increased similarly in both groups on sternotomy. A second, and more marked increase was noted in the patients requiring cardiopulmonary bypass. Haemodynamic stimuli could be responsible in both groups and might explain both the similarities and the differences between the groups.