Canadian journal of anaesthesia = Journal canadien d'anesthésie
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Randomized Controlled Trial Comparative Study Clinical Trial
Propofol or midazolam for short-term alterations in sedation.
It is often necessary to adjust a patient's sedation level while they are in the intensive care unit. The purpose of this study was to compare propofol with midazolam for controlling short-term alterations in sedation. Twenty-three patients undergoing an interactive procedure, physiotherapy, during mechanical ventilation of the lungs were studied. ⋯ After physiotherapy, those patients sedated with propofol re-awakened to level 3 faster (8.3 +/- 2.3 min, mean +/- SE) than those receiving midazolam (92.8 +/- 35.0 min, P < 0.05). After physiotherapy, a further 1.8 +/- 0.5 dose adjustments were required to the midazolam infusion while only 0.4 +/- 0.2 adjustments were required to the propofol infusion (P < 0.05). During physiotherapy 3.0 +/- 0.5 dose adjustments to the propofol dose were required compared with 3.6 +/- 0.5 adjustments to the midazolam dose (NS).(ABSTRACT TRUNCATED AT 250 WORDS)
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Randomized Controlled Trial Clinical Trial
Effects of benzodiazepines on mid-latency auditory evoked potentials.
Midlatency auditory evoked potentials (MLAEP) reflect primary cortical processing of auditory stimuli. The effects of benzodiazepines on MLAEP have not yet been studied. We examined the effects of intravenous induction of general anaesthesia using the benzodiazepines midazolam, diazepam and flunitrazepam on MLAEP in 30 patients scheduled for minor gynaecological procedures. ⋯ The MLAEPs do not change markedly in amplitude or latency during induction of general anaesthesia with benzodiazepines. Primary cortical processing of auditory stimuli seems to be preserved under benzodiazepines. This may be seen in connection with cases of intraoperative awareness and especially the perception of auditory stimuli during anaesthetic regimens where benzodiazepines are used to suppress consciousness.
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This study was undertaken to examine the effect of sevoflurane on right ventricular function, the safety of sevoflurane for one-lung ventilation and the effects of PEEP (positive end-expiratory pressure) to the dependent lung in this model using 12 open-chest sheep. Haemodynamic variables, including cardiac output, mean arterial blood pressure, right ventricular pressure and pulmonary arterial pressure, and right ventricular segment shortening (sonomicrometry) were measured. First, animals received 2.0, 3.0 or 4.0% sevoflurane for 20 min each, respectively, during two-lung ventilation to measure the dose-dependent haemodynamic effects of sevoflurane. ⋯ During one-lung ventilation the PaO2 was greater with 5 cm H2O PEEP 198 mmHg (+/- 25 SEM) than with ZEEP 138 mmHg (+/- 22) or with 10 cm H2O PEEP 153 mmHg (+/- 23) (P < 0.05). No differences in haemodynamic variables or segment shortening between ZEEP and PEEPs during one-lung ventilation were observed. We conclude that although sevoflurane causes a dose-dependent depression of right ventricular function, sevoflurane anaesthesia can be safely applied to one-lung ventilation, and that 5 cm H2O PEEP to the dependent lung can improve arterial oxygenation without causing changes in right ventricular function.
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Shortly after elicitation of a muscle response by supramaximal stimulation of its motor nerve, there exists a period of refractoriness of neuromuscular transmission when a second stimulation elicits only a submaximal response or no response at all. Many anaesthetics and neuromuscular blocking and facilitatory drugs change the refractoriness of neuromuscular transmission. ⋯ Based on an existing technique of digitization and time expansion of the neurally evoked compound electromyogram (ncEMG), we developed a computer programme of waveform subtraction, and determined in nine normal awake volunteers the various interstimulus intervals when neuromuscular transmission was refractory (RP0), 3/4 refractory (RP.25), half refractory (RP.5), 1/4 refractory (RP.75) or non-refractory (RP1). We confirmed our hypotheses that computer-based waveform subtraction of the digitized ncEMG is a feasible and necessary technique for the accurate determination of the RPs of neuromuscular transmission, and report that the normal values in humans are: RP0 = 1.0 +/- 0.1, RP.25 = 1.3 +/- 0.3, RP.5 = 1.9 +/- 0.3, RP.75 = 2.9 +/- 0.5, and RP1 = 6.6 +/- 1.9 ms (mean +/- SD), respectively, in the ulnar nerve-first dorsal interosseous muscle model.
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Letter Case Reports
The Combitube oesophageal-tracheal double lumen airway for difficult intubation.