Three Paediatric face masks, all with metal hooks, made by William Warne and Co. Ltd.; British Oxygen Company Limited, 1940-1999

During a surgical operation, a face mask covers a patient’s nose and mouth. The mask delivers anaesthetic gases and oxygen and is connected to an anaesthetic machine. Before, during and after a surgery, breathing is closely monitored by the anaesthetist. The delivery of gases is also careful watched.

The metal rings are an addition to a triangular piece of rubber with 3 straps known as a Clausen Harness. These were designed in the 1930s to help keep the face mask in place, freeing the anaesthetist’s hands and allowing them to concentrate on monitoring their patient. The metal hook was a modification, one that the original developer Raymond J Clausen (1890-1966) did not necessarily approve of. Anaesthetic masks are still supplied with a now plastic hook, but are not always used.