Description

Introduction

Contrary to what appears to be the general impression, the first ether anaesthetics were administered using apparatuses, or vaporizers, not by the more primitive ‘open’ or ‘rag and bottle’ method which soon displaced them. All these early inhalers were based on apparatus, generally chemical, already in existence. Thus Morton’s was essentially a retort fitted with valves. Robinson’s inhaler, and Squire’s, in the UK, were adaptations of the lower vessel of a Nooth’s apparatus, which had originally been designed for the domestic production of soda-water. In France, Charri??re’s was on the Nooth principle, while Dieffenbach’s in Germany followed Morton’s design.¹ Everyone was in a hurry, and designed his own, so they were one-offs, made by the local instrument maker, and of material that a craftsman could readily adapt, which meant glass. The limitations of these early vaporizers are apparent in the number of contemporary accounts of failure to anaesthetise patients adequately or at all; and the problems faced by the earliest practitioners will be familiar also to all anaesthetists over a certain age. Those whose experience extends to before the 1950s will be well acquainted with the difficulty of achieving an adequate depth of anaesthesia when ether was being vaporized in the glass bottle of a Boyle’s machine. They would have observed the condensation of water vapour from the air onto the surface of the bottle, and even ice formation. They would have attempted to raise the ether concentration by the application of warmth, either from the hand, or the warm water can which hooked on to the back bar. So here already we see some of the important physical principles which influenced the design of vaporizers. These were first put into effect by John Snow, who, by the end of January 1847, had designed a metal vaporizer which allowed him, by controlling the ambient temperature, to determine the ether concentration.