British journal of anaesthesia
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Comparative Study
Calculated vs measured pharyngeal mucosal pressures with the laryngeal mask airway during cuff inflation: assessment of four locations.
We have compared calculated with measured pharyngeal mucosal pressures at four different locations on the surface of the laryngeal mask airway (LMA) during cuff inflation in 10 anaesthetized, paralysed adult patients. Microchip sensors were attached to a size 5 LMA at the following locations: the anterior and lateral side, tip and backplate. Pressures were recorded during inflation of the cuff from 0 to 40 ml in 5-ml increments. ⋯ Calculated pressures were greater than measured pressures at cuff volumes of 5 ml or greater at all locations (P < or = 0.003). The greatest mean calculated the measured pressures were 118 and 14 cm H2O, respectively. We conclude that measured mucosal pressures at the four locations tested were less than calculated pressures and less than capillary perfusion pressure.
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Clinical Trial
Patient-maintained propofol sedation as premedication in day-case surgery: assessment of a target-controlled system.
We have assessed the efficacy and safety of a system which allowed 20 patients undergoing day-case anaesthesia to operate a target-controlled infusion of propofol to provide anxiolytic premedication. A target-controlled infusion of propofol was started with a target blood concentration of 1 microgram ml-1, and the patient was allowed to increase the target by 0.2 microgram ml-1 by operating a control button. There was a lockout time of 2 min and a maximum target concentration of 3 micrograms ml-1. ⋯ No patient became oversedated and all remained cardiovascularly stable. Two individuals required low-dose supplementary oxygen for mild arterial oxygen desaturation but there were no instances of airway obstruction. Patient satisfaction with the system was high.
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Auditory evoked potentials (AEP) were used to monitor central nervous system effects during induction and recovery from anaesthesia produced by infusion of propofol 30 mg kg-1 h-1 in 22 healthy male patients. Non-parametric and parametric modelling techniques were used successfully to calculate the parameter keo which linked pharmacokinetic with pharmacodynamic aspects of drug action in only 15 of the study patients. ⋯ There were no significant differences between keo values calculated by non-parametric and individual parametric modelling techniques. During recovery, 50% of patients demonstrated evidence of waking at an effect-site concentration of 2.28 micrograms ml-1.
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Randomized Controlled Trial Comparative Study Clinical Trial
Neuropeptide Y response to tracheal intubation in anaesthetized children: effects of clonidine vs midazolam as premedication.
We have determined if tracheal intubation causes an increase in neuropeptide Y (NPY), a marker of major adrenergic activation, and investigated if rectal premedication with clonidine 2.5 micrograms kg-1 might be capable of attenuating the stress response to tracheal intubation compared with midazolam 300 micrograms kg-1, in 20 paediatric patients (1-9 yr). Prospective randomization was performed in a double-blind manner. ⋯ There was no significant difference between the two groups. We conclude that the adrenergic stress reaction in response to tracheal intubation in children was short-lived and of limited magnitude, as indicated by the lack of NPY release.
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Randomized Controlled Trial Comparative Study Clinical Trial
Recovery after anaesthesia for pulmonary surgery: desflurane, sevoflurane and isoflurane.
We have studied maintenance and recovery profiles after general anaesthesia with sevoflurane, desflurane and isoflurane in 100 patients undergoing pulmonary surgery. End-tidal concentrations of anaesthetic required to maintain mean arterial pressure and heart rate within 20% of baseline values were 1.4 +/- 0.6% for sevoflurane, 3.4 +/- 0.9% for desflurane and 0.7 +/- 0.3% for isoflurane. ⋯ Early recovery (Aldrete score, cognitive and psychomotor functions) was also more rapid after desflurane. In pulmonary surgery, desflurane, but not sevoflurane, allowed more rapid emergence and earlier recovery than isoflurane.