This review examines the basic concepts of workload and methods of measuring them. The components of anaesthetists' operating room activities, and the factors contributing to workload, are analysed using an ergonomic-based model for technological environments. The available evidence on the relationship between workload and training and supervision is presented and the effect of workload on the quality and safety of anaesthetic care is reviewed. There is, as yet, only a small body of work examining workload and its effects in anaesthesia. While studies have identified the general pattern of workload in relation to the different stages of the perioperative period, measurement, particularly of overlapping tasks, is still evolving. It is clear, however, that induction and emergence are the most intense periods of both practical and 'non-technical' aspects of work. Allocation of attention to a range of tasks simultaneously is a key characteristic of anaesthetic practice. Experienced staff appear to show 'spare capacity' in performance during routine cases, which, we suggest, allows them an attentional 'safety margin' should adverse events occur. The effects of production pressure and mental 'overload' remain speculative and so practical recommendations for anaesthetic staffing, both in terms of numbers and matching skills to surgical demand, cannot be made. The potential for delegation of tasks, for instance to non-physician anaesthetists, can also not be made on evidence-based grounds. Strategies for active management of workload may be useful in practice.
