British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Effect of percutaneous local anaesthetics on pain reduction during pulse dye laser treatment of portwine stains.
We have used EMLA, 4% amethocaine gel and placebo for facial portwine stains, for a period of 1 h, in a double-blind study. After removal of the preparations from the skin surface, each area was treated with six pulses of the laser, each 5 mm in diameter. ⋯ Twenty nine patients completed the study and statistical analysis of the results indicated that both EMLA and 4% amethocaine gel were superior to placebo (P < 0.001). However, when EMLA and 4% amethocaine gel were compared, the amethocaine preparation was significantly better (P < 0.05, VAS; P < 0.005 VRS) than EMLA in reducing pain caused by the laser treatment.
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We have studied dose requirements, recovery times and pharmacokinetics of rocuronium in 32 intensive care patients. After an initial dose of 50 mg, rocuronium was administered as maintenance doses of 25 mg whenever two responses to train-of-four (TOF) stimulation reappeared (bolus group; n = 27) or by continuous infusion to maintain one response in the TOF (infusion group; n = 5). Median requirements for rocuronium were 27.4 (range 14.5-68.3) mg h-1 and 43.7 (30.9-50.3) mg h-1 in patients in the bolus and infusion groups, respectively. ⋯ The plasma concentration profile (n = 12) was described adequately by a two-compartment model. Mean plasma clearance (Cl), steady-state distribution volume (Vss), mean residence time (MRT) and elimination half-life (T1/2 beta) were 3.16 (SD 1.15) ml kg-1 min-1, 769 (334) ml kg-1, 262 (120) min and 337 (163) min, respectively. Recovery times, Vss, MRT, and T1/2 beta differed from previously published data obtained after rocuronium infusion of moderate duration in surgical patients.
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In order to investigate haemodynamic response and catecholamine release during anaesthesia with xenon, we conducted a study on 28 pigs which were allocated randomly to one of four groups: total i.v. anaesthesia with pentobarbitone and buprenorphine, and xenon anaesthesia with inspiratory concentrations of 30%, 50% or 70%, respectively, supplemented with pentobarbitone. Haemodynamic variables were measured using arterial and Swan Ganz catheters. Depth of anaesthesia was monitored using spectral edge frequency analysis. ⋯ Adrenaline concentrations were reduced significantly in all groups. Xenon anaesthesia was associated with a high degree of cardiovascular stability. Significant reduction in adrenaline concentrations at inspiratory xenon concentrations of 30% and 50% can be explained by analgesic effects of xenon below its MAC value.
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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.