British journal of anaesthesia
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Meta Analysis
Propofol anaesthesia and postoperative nausea and vomiting: quantitative systematic review of randomized controlled studies.
We have analysed randomized controlled studies which reported the incidence of postoperative nausea and vomiting (PONV) after propofol anaesthesia compared with other anaesthetics (control). Cumulative data of early (0-6 h) and late (0-48 h) PONV were recorded as occurrence or non-occurrence of nausea or vomiting. Combined odds ratio and number-needed-to-treat were calculated for propofol as an induction or maintenance regimen, early or late outcomes, and different emetic events. ⋯ This may be clinically relevant. In all other situations the difference between propofol and control may have reached statistical significance but was of doubtful clinical relevance. Treatment efficacy should be established within a defined range of control event rates for meaningful estimates of efficacy and for comparisons.
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Randomized Controlled Trial Clinical Trial
Does intrathecal fentanyl produce acute cross-tolerance to i.v. morphine?
We have examined the hypothesis that intrathecal fentanyl at operation can increase postoperative i.v. morphine requirements. We studied 60 patients undergoing Caesarean section. All received intrathecal 0.5% plain bupivacaine 2 ml combined with either fentanyl 0.5 ml (25 micrograms) (group F) (n = 30) or normal saline 0.5 ml (group S) (n = 30). ⋯ Up to 6 h after delivery there was no difference in postoperative morphine requirements or pain scores. Between 6 h and 23 h there was a 63% increase in morphine requirements in group F. We consider the most likely explanation for this finding to be that intrathecal fentanyl induced acute spinal opioid tolerance.
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Randomized Controlled Trial Clinical Trial
Propofol attenuates formation of lipid peroxides in tourniquet-induced ischaemia-reperfusion injury.
We studied 20 adult ASA I patients undergoing elective peripheral surgery allocated randomly to one of two groups. In the propofol group (n = 9) anaesthesia was induced with propofol and fentanyl followed by continuous infusion of propofol. In the control group (n = 11), after induction of anaesthesia with thiopentone and fentanyl, anaesthesia was maintained with isoflurane. ⋯ In the propofol group this was significant only at 30 min (1.85 (0.03) vs 1.74 (0.04) mumol litre-1). TBARS concentrations of reperfused muscle tissue were significantly higher than pre-reperfusion concentrations in the control group (70.30(10.06) vs 52.13 (5.73) nmol/g wet tissue). We conclude that propofol attenuated ischaemia-reperfusion-induced lipid peroxidation in the therapeutic doses used in anaesthesia.
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We have studied in 12 patients the effect of desflurane in nitrous oxide on the electroencephalogram (EEG) and the early cortical auditory evoked response (AER). After induction with desflurane, patients' lungs were ventilated to maintain three different end-expiratory concentrations of desflurane (1.5, 3 and 6%) during four consecutive 10-min periods before surgery. As the end-expiratory concentration of desflurane was increased, Pa and Nb (AER) amplitudes decreased and their latencies increased, and spontaneous EEG showed an increase in amplitude and a slowing of frequency. ⋯ From regression slopes, mean percentage changes of each variable were calculated for a 1 MAC change in desflurane concentration, Pa amplitude showed the largest change (mean 49% (95% confidence interval 40-56%) decrease for a 1 MAC increase). This was greater than that of F95 for a similar confidence interval, indicating better resolution. This study confirms that the early cortical AER is affected by desflurane in a similar manner to that of other anaesthetic agents and as such remains the most promising EEG derived measure of depth of anaesthesia.