British journal of anaesthesia
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Serial measurements of haemodynamic variables were performed at 1-min intervals in nine ASA I, unpremedicated patients before and for 5 min after induction of anaesthesia with propofol 2.5 mg kg-1. End-tidal carbon dioxide concentration was maintained within the normal range. Stroke volume and left ventricular function were measured by Doppler and cross-sectional echocardiography at the aortic valve. ⋯ There was a decrease at all time points in systolic, mean and diastolic arterial pressure. There was an initial increase in heart rate and cardiac output, with a subsequent decrease to less than baseline. There was an initial decrease in systemic vascular resistance followed by partial recovery, and a delayed decrease in left ventricular function as measured by peak aortic blood flow velocity and acceleration.
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Randomized Controlled Trial Comparative Study Clinical Trial
Ketamine for caudal analgesia in children: comparison with caudal bupivacaine.
Fifty children undergoing inguinal herniotomy were allocated randomly to three groups to receive a caudal injection of either 0.25% bupivacaine 1 ml kg-1 with or without ketamine 0.5 mg kg-1 or ketamine 0.5 mg kg-1 with normal saline 1 ml kg-1. There was no significant difference in quality of pain relief, postoperative behaviour or analgesic requirements between the ketamine group and the two other groups. The bupivacaine-ketamine mixture provided better analgesia than the bupivacaine solution alone. Side effects such as motor weakness or urinary retention were not observed in the ketamine group.
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The relationship between analgesic activity, measured as the hot plate reaction time, and respiratory depression, measured as ventilatory frequency, was investigated in mice for a variety of mu opioid receptor agonists with differing selectivities for mu receptors compared with delta receptors. There was a weak correlation between analgesia and respiratory depression for opioids with the greatest selectivity for mu opioid receptors compared with delta receptors, such as alfentanil. ⋯ Etorphine, which has almost equal affinity for mu, delta and, incidentally, kappa receptors, showed a strong correlation between analgesia and respiratory depression. We conclude that the predictability of the degree of respiratory depression produced by a given analgesic dose of an opioid appears to decrease with its selectivity for mu opioid receptors, at least in the mouse.