Propofol versus alfentanil to prevent movement responses during uterine curettage.

BACKGROUND: Propofol anaesthesia is frequently associated with movement responses in non-paralysed patients. Opioids decrease the probability of movement during noxious stimulation. Heart rate variability and frontal electromyography (EMG), which are related to subcortical functions, may be more closely related than surface electroencephalography (EEG) to movement responses to noxious stimulation. METHODS: Eighty-two patients scheduled for uterine dilatation and curettage were randomized to receive at the first intra-operative movement either a supplemental alfentanil bolus, 0.5 mg intravenously, or a supplemental propofol bolus, 0.7 mg/kg intravenously. The incidences of recurring movement during the procedure were compared between the two groups. The associations of a measure of heart rate variability (Anemon index), heart rate, EMG and two EEG variables with movement responses were evaluated. RESULTS: The incidences of recurring movement were 73% and 38% in the alfentanil and propofol groups, respectively [difference, 35%; 95% confidence interval, 9-56%; P= 0.014 between the groups). The Anemon index, heart rate, EMG and surface EEG variables displayed mainly reactive associations with movement responses. CONCLUSION: During uterine curettage under propofol-alfentanil-nitrous oxide anaesthesia, a propofol bolus of 0.7 mg/kg was more effective in preventing the recurrence of movement responses than an alfentanil bolus of 0.5 mg. Several physiological variables may be used to track significant arousal reactions, but not to predict them.

EEG spectral entropy, heart rate, photoplethysmography and motor responses to skin incision during sevoflurane anaesthesia.

BACKGROUND: Analgesia is a part of balanced anaesthesia, but direct indicators of nociception do not exist. We examined the relationship between motor reactions and physiological variables during skin incision in sevoflurane anaesthesia and hypothesized that nociception could be detected and graded by significant changes in these variables. METHODS: Thirty-one women scheduled for abdominal hysterectomy participated in the study. Anaesthesia was induced with fentanyl (1 microg kg(-1)), propofol (1 mg kg(-1)) and sevoflurane. Skin incision was performed 14 min after induction during 1.6% end-tidal sevoflurane anaesthesia without neuromuscular blockade. Electrocardiography (ECG), photoplethysmography (PPG) and electroencephalography (EEG) were registered, and a range of variables was computed from these signals. The postincision values, normalized with respect to their preincision values, of movers vs. non-movers were compared. The variables showing significant differences between movers and non-movers were used to develop a logistic regression equation for the classification of patients into movers or non-movers. RESULTS: Twenty-six patients were eligible for analysis, and 12 (46%) displayed a motor reaction to skin incision (movers). Many ECG, PPG and EEG-related variables showed significant differences between the pre- and postincision periods. The best classification performance, assessed by leave-one-out cross-validation, between movers and non-movers was achieved with the combination of response entropy of EEG, RR-interval and PPG notch amplitude. The corresponding equation yielded 96% correct classification with 90% sensitivity and 100% specificity. The classification performance of any single variable alone was considerably worse. CONCLUSION: Combination of information from different sources may be required for monitoring the adequacy of analgesia during anaesthesia.