British journal of anaesthesia
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We have studied plasma protein binding of alfentanil in 10 patients given a mean total dose of 949 micrograms kg-1 as the principal anaesthetic agent for coronary artery bypass grafting. The mean unbound fraction of plasma alfentanil increased from 0.09 to 0.16 after administration of heparin and to 0.26 after beginning cardiopulmonary bypass (CPB). ⋯ Within the first 1 min of CPB, total alfentanil concentration had decreased by more than the unbound concentration and the decrease observed in the latter disappeared rapidly. From induction of anaesthesia until awakening of the patient, plasma protein binding of alfentanil was related significantly (P = 0.0166) to the serum concentration of orosomucoid (alpha 1-acid glyco-protein).
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Comment Letter Comparative Study
Comparison of the Belscope with the Macintosh laryngoscope.
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We have described the design and design considerations of the desflurane Tec 6 "vaporizer" and have tested its performance characteristics. The vaporizer differs from previous vaporizers designed for anaesthesia in that electromechanical rather than mechanical controls accommodate the different physical characteristics of desflurane. This design, while offering perhaps an increased risk of failure (owing to sophisticated electronic components and circuitry), on the other hand offers the decreased likelihood of accidental delivery of very large concentrations of liquid anaesthetic resulting from tilting or overfilling and alarms and warnings not previously incorporated into the design of anaesthetic vaporizers. The output characteristics of the vaporizer are as expected, based on the design: desflurane concentration output in oxygen has accuracy (+/- 15%) which is similar to that of the mechanical vaporizers; output decreases when nitrous oxide is added owing to the lower viscosity, but remains within 20% of the dial setting or 0.5% absolute.
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A late development model of the Tec 6 vaporizer for the administration of desflurane vapour has been evaluated. It is heated electrically and has both electronic monitors of vaporizer function and alarms. The new filling system is a significant improvement over previous Tec filling systems. The vaporizer requires a warm-up period before it may be used, but when activated it provides an output that is approximately linear between 1 and 18% vapour concentrations, at flow rates between 200 ml min-1 and 10 litre min-1.
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Randomized Controlled Trial Comparative Study Clinical Trial
Tracheal intubation without neuromuscular block in children.
We have studied 80 healthy children, aged 2-14 yr, undergoing adenotonsillectomy in a double-blind, randomized design. Tracheal intubation facilitated by either suxamethonium 1.5 mg kg-1 or alfentanil 15 micrograms kg-1 was compared after induction of anaesthesia with propofol 3-4 mg kg-1. ⋯ Fewer patients coughed (P < 0.014) and limb movement was less common (P < 0.007) after tracheal intubation facilitated by suxamethonium. Alfentanil attenuated the haemodynamic responses to tracheal intubation.