Canadian journal of anaesthesia = Journal canadien d'anesthésie
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Case Reports
Failure of a lidocaine test dose to identify subdural placement of an epidural catheter.
We report the failure of a test dose of 3 ml lidocaine 1.5 per cent with 15 micrograms epinephrine to identify subdural placement of an epidural catheter in a parturient. Thirty-five minutes after injection of 13 ml lidocaine 1.5 per cent, intended to provide epidural analgesia, the patient developed an extensive sensory neural blockade. Some motor control was maintained and sympathetic block was incomplete. ⋯ Subdural injections are uncommon and unpredictable in their occurrence. Test doses do not consistently identify misplaced catheters. A negative response to a test dose does not guarantee that extensive neural blockade will not occur during epidural analgesia.
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Assessment and accurate replacement of blood loss during primary craniosynostosis repair is difficult due to patient size and surgical technique. Eighty-five charts of all patients undergoing primary craniosynostosis repair over a 15-year period were reviewed to determine blood loss and to assess blood transfusion practices both intraoperatively and postoperatively. Blood loss was calculated on the basis of estimated red cell mass (ERCM). ⋯ Intraoperatively, 70 per cent of all patients were appropriately managed with respect to blood transfusion. Postoperatively only 29 per cent of patients receiving transfusions were transfused appropriately. At our institution, intraoperative blood transfusion practices are appropriate, but postoperative transfusions are frequently unnecessary.
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The potency of atracurium was determined in five patients with moderate to severe generalized myasthenia gravis undergoing thymectomy. Train-of-four stimulation was applied to the ulnar nerve and the force of contraction of the adductor pollicis was measured. Cumulative dose-response curves were obtained during thiopentone-nitrous oxide-fentanyl anaesthesia. ⋯ Ten normal patients were studied in the same manner. Their ED50, ED90 and ED95 were 0.13 +/- 0.01, 0.21 +/- 0.02 and 0.24 +/- 0.03 mg.kg-1, respectively. These results demonstrated that, in patients with moderate to severe generalized myasthenia gravis, atracurium was 1.7-1.9 times as potent as in normal individuals.