British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Effects of propofol, propofol-nitrous oxide and midazolam on cortical somatosensory evoked potentials during sufentanil anaesthesia for major spinal surgery.
Recording of cortical somatosensory evoked potentials (CSEP) enables monitoring of spinal cord function. We studied the effects of propofol, propofol-nitrous oxide or midazolam during sufentanil anaesthesia on CSEP monitoring during major spinal surgery. Thirty patients with normal preoperative CSEP were allocated randomly to one of the following anaesthesia regimens: propofol (2.5 mg kg-1 followed by 10-6 mg kg-1 h-1) with or without nitrous oxide, or midazolam (0.3 mg kg-1 followed by 0.15 mg kg-1 h-1) combined with sufentanil 0.5 microgram kg-1 h-1 in the propofol and midazolam groups, or 0.25 microgram kg-1 h-1 in the propofol-nitrous oxide group. ⋯ CSEP amplitude decreased significantly in the propofol-nitrous oxide group (from mean 2.0 (SEM 0.3) to 0.6 (0.1) microV; P < 0.05) but not in the propofol (from 1.8 (0.6) to 2.2 (0.3) microV) or midazolam (1.7 (0.5) to 1.6 (0.5) microV) groups. The time to the first postoperative voluntary motor response (recovery) delay was significantly greater in the midazolam group (115 (19) min) compared with the propofol and propofol-nitrous oxide groups (43 (8) and 41 (3) min, respectively). Consequently, the use of propofol without nitrous oxide can be recommended during spinal surgery when CSEP monitoring is required.
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Clinical Trial Controlled Clinical Trial
Electromyographic assessment of neuromuscular block at the gastrocnemius muscle.
We have assessed neuromuscular block electromyographically at the gastrocnemius muscle and compared it with that at the abductor digiti minimi muscle in 60 adult patients undergoing cervical spine surgery under general anaesthesia. All patients were in the prone position. ⋯ Times to return of the first response of the train-of-four (TOF) at the gastrocnemius and abductor digiti minimi muscles were 41.0 (9.1) and 49.9 (8.7) min, respectively (P = 0.01). Recovery of PTC, T1/T0 and TOF ratio at the gastrocnemius muscle were significantly faster than at the abductor digiti minimi muscle.
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Clinical Trial Controlled Clinical Trial
Cuffed oropharyngeal airway (COPA) as an adjunct to fibreoptic tracheal intubation.
The cuffed oropharyngeal airway (COPA) was evaluated as an adjunct to oral and nasal fibreoptic tracheal intubation in 40 adult patients during general anaesthesia. Time from start to completion of intubation decreased rapidly with experience (median time 138 s). We conclude that the COPA may be a useful adjunct to fibreoptic tracheal intubation, allowing control and support of the airway during the procedure, using various anaesthetic techniques, in an acceptable amount of time. The ability to perform fibreoptic tracheal intubation while effectively supporting the airway using the COPA may be advantageous in managing the difficult airway and in trainee education.
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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.