British journal of anaesthesia
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Comparative Study
Jugular bulb cannulation: description of a cannulation technique and validation of a new continuous monitor.
We have compared in vivo oxygen saturation recordings obtained from the Oximetrix 3 with in vitro measurements using the Instrumentation Laboratories 282 Co-Oximeter. The small mean difference (0.85%) and close limits of agreement (-4% to 6%) are close enough for clinical purposes, provided in vivo calibration is performed after insertion of the fibreoptic catheter and repeated at least every 12 h. Continuous monitoring of jugular bulb oxygen saturation during intensive care of brain injured patients is now possible using fibreoptic technology. This technique may be of value in detecting global ischaemia, and as a predictor and monitor of cerebral perfusion pressure therapy.
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Randomized Controlled Trial Clinical Trial
Propofol and midazolam act synergistically in combination.
We have studied interactions between i.v. propofol and midazolam for induction of anaesthesia in 200 unpremedicated female patients undergoing elective gynaecological surgery. Using end-points of "hypnosis" (loss of response to verbal command) and "anaesthesia" (loss of response to a 5-s transcutaneous tetanic stimulus), we determined dose-response curves for propofol and midazolam alone and in combination. ⋯ The reduction in arterial pressure at induction was the same for the combination as for the individual agents. The cause of the synergism was not clear, but may have been interaction at CNS GABAA receptors.
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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.