The desflurane (Tec 6) vaporizer: design, design considerations and performance evaluation

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.