British journal of anaesthesia
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Meta Analysis Comparative Study
Meta-analytic comparison of prophylactic antiemetic efficacy for postoperative nausea and vomiting: propofol anaesthesia vs omitting nitrous oxide vs total i.v. anaesthesia with propofol.
Data from two published and one new meta-analysis were reviewed to compare the antiemetic efficacy of three different anaesthetic regimens: (i) propofol anaesthesia compared with another anaesthetic (control); (ii) anaesthesia without nitrous oxide compared with the same anaesthetic with nitrous oxide (control); (iii) propofol anaesthesia without nitrous oxide (TIVA) compared with another anaesthetic with nitrous oxide (control). Efficacy (prevention of postoperative nausea and vomiting compared with control) was estimated using odds ratio and number-needed-to-treat methods, and compared within a range of 20-60% control event rates for early efficacy (0-6 h) and 40-80% for late efficacy (0-48 h). Propofol anaesthesia or omitting nitrous oxide had similar effects on vomiting, both early and late. ⋯ TIVA studies were documented poorly; appropriate comparison with other interventions were not possible. Efficacy of treatments should be compared within a setting-specific range of control event rates. There is insufficient evidence that TIVA with propofol is an anaesthetic technique with a low emetogenic potency.
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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 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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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.