Canadian journal of anaesthesia = Journal canadien d'anesthésie
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A clinical incident involving an undetected disconnection occurred during the use of a CPRAM coaxial breathing circuit. The flow resistance of this circuit was evaluated and compared with that of a Bain circuit to determine the factors involved. A differential pressure transducer was used to monitor the pressure drop across each circuit during simulation of controlled ventilation with a fresh gas flow of 6 L.min-1. ⋯ Since the ventilator low pressure alarm was preset to 9.2 cm H2O, the alarm provided a warning with the Bain but not the CPRAM. The elevated flow resistance of the CPRAM circuit was attributed to a restriction in the flow area at the patient end of the circuit. Capnographs or adjustable low-pressure alarms provide more reliable monitoring for breathing circuit disconnects.
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A case of respiratory depression which occurred following administration of epidural meperidine during Caesarean section is described. Epidural meperidine, 75 mg (10 mg.ml-1) was given after delivery of the infant to provide postoperative analgesia. Oxygen desaturation (SaO2 90%) and a decrease in respiratory rate (4.min-1) were noted 30 min after epidural meperidine was administered. ⋯ Vascular absorption of meperidine from the epidural venous plexus is the most probable explanation for this case of early respiratory depression. We recommend a maximum bolus dose of 50 mg of epidural meperidine for pain management after Caesarean section. It is also important to monitor oxygen saturation continuously during the intraoperative period, and to monitor the patient closely in the recovery room for at least one hour for evidence of respiratory depression.
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The neuromuscular effects of ketamine, at cumulative doses of 2.5 and 10 mg.kg-1 iv, were studied by electromyographically quantifying the thumb response evoked by ulnar nerve stimulation in 25 monkeys anaesthetized with pentobarbital-N2O-O2. Ketamine alone at these doses had no neuromuscular effects. ⋯ These results indicate that ketamine does not act on the postjunctional acetylcholine receptor. It plays a secondary role in neuromuscular block, possibly by prejunctional or postjunctional effects independent of receptor occupation.