Ergonomics and Anaesthesia: Auditory Alarm Signals in the Operating Room

Abstract

Anaesthetists must interact with apparatus to obtain information upon which much decision-making during clinical anaesthesia is based. The “anaesthetic machine” is such an apparatus, this term referring to a movable table to which are customarily attached gas and vapour delivery system, mechanical ventilator, scavenging and fluid suction systems, and monitors. In a previous study it was found that the relative positions of patient, anaesthetic machine, and anaesthetist adopted for a specific surgical procedure varied widely (Mclntyre 1982). Often the anaesthetist faced the surgical site and the anaesthesia apparatus was behind him, an arrangement also described by Boquet et al. (1980). An implication is that under such circumstances the anaesthetist relied on an infallible ability to decide when it was necessary to turn and obtain information visually, or relied on auditory signals specified as alarms. These alarms are delivered from diverse equipment items made by different manufacturers and in the presence of environmental sounds. In this institution it was obvious that in the presence of certain hostile environmental sounds certain currently employed alarm signals could not be heard even if they were deliberately listened for. Thus it seemed important to study certain aspects of auditory alarm signals in the operating room with a view to improving our understanding and our arrangements. These aspects were their relative sites, origin and reception, their auditory characteristics and their interaction with certain other sounds in the operating room. This project involved a Boyle anaesthesia apparatus (Medishield) upon which were mounted an oxygen monitor (Ohio 200), blood pressure monitor (Dinamap 845, Critikon), transcutaneous PO2 monitor (Kontron Medical 820) and airway pressure monitor (Ventilarm 5520, Ventronics).