The development of inhalation anaesthesia : with special reference to the years 1846-1900... / [Barbara M. Duncum].

Duncum, Barbara M.

Date:: 1947

Credit: The development of inhalation anaesthesia : with special reference to the years 1846-1900... / [Barbara M. Duncum]. Source: Wellcome Collection.

496/664 page 476

$resort to it as a measure for securing a longer anaesthesia, or for successfully terminating an administration when the supply of nitrous oxide had unexpectedly fallen short. There was no apparatus which would allow of two valves being in action for the earlier or middle stages of the administration and would subsequently permit re-breathing. I therefore devised and used a face-piece with thin rubber valves which could,' he wrote, ' at the will of the administrator, be thrown out of action, and allow of the gas-bag being used very much as Clover's supplemental bag [see Fig. 71] was used, i.e. for to-and-fro breathing. Sub- sequently I placed these rubber valves in a little box between the stopcock and the face-piece, so that plain valveless face-pieces could be attached- The valves were thrown into and out of action at will by turning a small handle surmounting the valve-box. A short trial of this apparatus led to my placing the valves and the two-way stopcock in one chamber.' 1 In the first edition of his book, Anaesthetics and their administra- tion (London. 1893), Hewitt described and illustrated the final form which this apparatus took : [Fig. 124] ' From the single union (su) the tube (t) passes to join the bag (B). A little stopcock (s) is useful in case it should be wished to disconnect a full bag from the rest of the apparatus. The bag (B) has a capacity of from 2 to o.\ gallons. There is certainly an advantage in having the bag as near as possible to the face-piece ; for not only can its movements be readily watched, but the patient can take the most forcible inspirations without any of that impediment which is likely to be experienced when a tube exists between the bag and the face-piece. The valved stopcock (VS), which is the most important part of the apparatus, connects the gas-bag (B) to the face-piece (F). This stopcock [see Fig. 125] . . . contains two thin valves of sheet india-rubber, which may be thrown into or out of action by turning the tap T. The handle H determines whether air or gas is admitted to the face- piece. When T and H are arranged as in . . . [the diagram on the left, Fig. 125] air enters the stopcock and is breathed out through valves in the direction shown by the arrows. [Fig. 125, diagram on right] . . . shows in diagrammatic section the mechan- ism of the valved stopcock. It has two slots cut out of its circum- ference, an upper slot (US) and a lower slot (LS). There are two inner cylinders which revolve immediately inside the outer casing of the stopcock. The upper inner cylinder (UIC) is worked by T, the lower (LIC) by H. The upper cylinder carries the 1 Hewitt, F. W. 1893. Anaesthetics and their administration. London. 94-5 ; see also Lancet, 1885, i, 840-1 ; J. Brit. dent. Ass., 1886, 7, 86-91 ; Brit. med. J., 1887, ii, 452-4-$