• W A Tweed, R Amatya, and W E Spoerel.
• Department of Anaesthesia, University of Western, Ontario, London, Canada.
• Can J Anaesth. 1990 Nov 1;37(8):928-31.

AbstractThis is a report of our experience with a portable anaesthesia system that was developed for use under field conditions, when compressed gas supplies are limited. We first assembled and bench-tested a low-pressure plenum system, based upon the Farman entrainer. The entrainer required a low flow of compressed gas, O2 at 1-2 L.min-1, and generated a low-pressure mixture of O2 and air which was directed through an Oxford miniature vaporizer, a non-return valve, and a widebore T-piece circuit. With this system we anaesthetized 24 patients with intermittent positive pressure ventilation (IPPV) and nine patients breathing spontaneously. During IPPV, the circuit resembled a T-piece and provided effective gas exchange with a FGF of 1.2 times minute ventilation. Inspiratory and expiratory valves were arranged so that the spontaneous mode was non-rebreathing, and FGF was adjusted to equal minute ventilation. The system was very economical, using 1-2 L.min-1 O2 and 20-25 ml.hr-1 liquid halothane to produce a FGF of 6-10 L.min-1, an FIO2 of 0.33, and FIhal of 1-1.5 per cent. We have demonstrated that this is a versatile, safe, and economical system, compatible with the practice of modern inhalational anaesthesia under field conditions. It can be readily assembled from commercially available components.

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