British journal of anaesthesia
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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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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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Propofol may cause profound bradycardia and asystole, which are mediated indirectly via cardiac innervation but could involve direct effects on the sino-atrial (SA) node and the conducting system of the heart. To test the hypothesis that propofol may also activate Bezold-Jarisch reflexes to cause bradycardia, 5-hydroxytryptamine (5-HT), veratridine and propofol were injected into the left ventricle of the heart in both intact and vagotomized rabbits. 5-HT and veratridine produced an acute, rapid, dose-dependent decrease in mean heart rate (delta HR) and a decrease in mean arterial pressure (delta MAP) together with transient but severe depression and abolition of renal sympathetic nerve activity (RSNA). ⋯ Propofol depressed but did not abolish RSNA, and bilateral vagotomy had no effect on any of these responses. These results indicate that the cause of acute bradycardia after administration of propofol does not involve the Bezold-Jarisch reflex.