British journal of anaesthesia
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Estimation of analgesia in anaesthetized children is often imprecise, and consequently, anaesthesiologists commonly evaluate children's response to surgical stimulation by movement or haemodynamic changes. In adults reflex pupillary dilatation has been demonstrated to be a very sensitive measure of noxious stimulation, correlated with opioid concentrations. The autonomic nervous control changes with age, raising the hypothesis that mechanisms involved in pupillary autonomic functions regarding both sympathetic and parasympathetic components may also differ between adults and children. In this pilot study, we tested the hypothesis that the pupillary reflex dilatation might allow assessment of noxious stimulation and analgesic effect of alfentanil in children under sevoflurane anaesthesia, as an alternative to haemodynamic and bispectral measures. ⋯ PD is a more sensitive measure of noxious stimulation than the commonly used variables of heart rate, arterial blood pressure and BIS in children anaesthetized with sevoflurane.
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We measured the effect of two weight adjusted i.v. doses (0.2 mg per 70 kg and 0.4 mg per 70 kg) of the potent opioid buprenorphine on analgesia and respiratory depression in healthy volunteers. The aim of the study was to compare buprenorphine's behaviour with respect to the occurrence of ceiling (or apparent maximum) in these typical micro-opioid protein-(MOP) receptor effects. ⋯ While buprenorphine's analgesic effect increased significantly, respiratory depression was similar in magnitude and timing for the two doses tested. We conclude that over the dose range tested buprenorphine displays ceiling in respiratory effect but none in analgesic effect.