British journal of anaesthesia
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We have studied midlatency auditory evoked potentials (MLAEP) and motor signs of wakefulness during anaesthesia with midazolam in 10 patients undergoing elective laparotomy under continuous extradural analgesia. Anaesthesia was induced with midazolam 0.3 mg kg-1 and maintained with midazolam 0.3-0.9 mg kg-1 h-1. Motor signs of wakefulness were documented as spontaneous movements and movements after simple commands (open eyes or move arms). ⋯ Latencies of the MLAEP peaks Pa, Nb and P1 increased slightly during anaesthesia. Amplitudes for Na/Pa, Pa/Nb and Nb/P1 did not change significantly. The high incidence of motor signs of wakefulness associated with preserved MLAEP indicated a high level of cortical neural activity and none of the MLAEP variables predicted movement during anaesthesia with midazolam.
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In common with halogenated anaesthetics, nicorandil, a new KATP channel opener, has been shown to have cardioprotective and vasodilator effects. Recent studies have also suggested that the vasodilator and protective effects of halogenated anaesthetics are mediated partly via KATP channel opening. This study examined the effects of concurrent administration of nicorandil and isoflurane on haemodynamic state and ventricular function before, during and after 15 min of ischaemia. ⋯ Group IN showed better recovery compared with all other groups when ventricular contractility was assessed by PRWA normalized to pre-occlusion values (mean 99.3 (SEM 10.5)% vs 73.4 (7.5)%, 50.2 (5.8)% and 52.4 (3.7)% at 120 min reperfusion in groups FN, I and F, respectively). Tissue ATP and lactate contents did not differ between groups. We conclude that concurrent administration of nicorandil and isoflurane enhanced post-ischaemic recovery compared with isoflurane anaesthesia or nicorandil and fentanyl administration.
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Randomized Controlled Trial Clinical Trial
Administration of magnesium sulphate before rocuronium: effects on speed of onset and duration of neuromuscular block.
The speeds of onset of pancuronium, atracurium and vecuronium are increased by prior administration of magnesium sulphate. A prospective, randomized, double-blind, controlled, clinical study was performed to examine the effects of prior i.v. administration of magnesium sulphate 60 mg kg-1 on the neuromuscular blocking effects of rocuronium 0.6 mg kg-1 during isoflurane anaesthesia. ⋯ Administration of magnesium sulphate was not associated with adverse haemodynamic effects. Prior administration of magnesium sulphate, under the study conditions described, prolonged rocuronium-induced neuromuscular block but did not increase speed of onset.
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Randomized Controlled Trial Clinical Trial
Quantitative study of Lowe's square-root-of-time method of closed-system anaesthesia.
Intermittent injection of liquid anaesthetic into a closed breathing system is particularly suitable in countries with limited resources. A method of calculating appropriate times and magnitudes of the injected doses was described by Lowe but the method has never been assessed rigorously. Such an assessment was the purpose of this study. ⋯ However, end-tidal partial pressure (just before each dose) stabilized at a steady level of only 0.97, 0.42 and 0.77 MAC for halothane, enflurane and isoflurane, respectively. Recovery from enflurane was much more rapid than that from the other agents but no patient admitted to any dreams. We conclude that the rate of uptake of anaesthetic declines more slowly than predicted and that the patients receiving enflurane were less deeply anaesthetized because the greater hypotensive effect of enflurane led to the use of smaller doses.
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Comparative Study Clinical Trial Controlled Clinical Trial
Intradermal compared with prick testing in the diagnosis of anaesthetic allergy.
We have tested the hypothesis that intradermal testing is a more effective method for determining the drug responsible for anaesthetic anaphylactic reactions than prick testing in 212 consecutive patients, aged more than 10 yr, referred to an anaesthetic allergy clinic over a 4-yr period. The study was a prospective, non-randomized design. Intradermal testing was conducted using a previously described method and diluted drugs, and prick testing using undiluted drugs (with the exception of opioid analgesics which were diluted 1:10). ⋯ Intradermal testing may be easier for the infrequent user. Skin testing is valuable in the investigation of anaesthetic anaphylaxis whichever test is chosen. When there is doubt both tests should be performed.