Background
Studies in operating rooms (OR) show that minor disruptions tend to group together to result in serious adverse events such as surgical errors. Understanding the characteristics of these minor flow disruptions (FD) that impact major events is important in order to proactively design safer systems

Objective
The purpose of this study is to use a systems approach to investigate the aetiology of minor and major FDs in ORs in terms of the people involved, tasks performed and OR traffic, as well as the location of FDs and other environmental characteristics of the OR that may contribute to these disruptions.

Methods
Using direct observation and classification of FDs via video recordings of 28 surgical procedures, this study modelled the impact of a range of system factorslocation of minor FDs, roles of staff members involved in FDs, type of staff activities as well as OR traffic-related factors-on major FDs in the OR.

Results
The rate of major FDs increases as the rate of minor FDs increases, especially in the context of equipment-related FDs, and specific physical locations in the OR. Circulating nurse-related minor FDs and minor FDs that took place in the transitional zone 2, near the foot of the surgical table, were also related to an increase in the rate of major FDs. This study also found that more major and minor FDs took place in the anaesthesia zone compared with all other OR zones. Layout-related disruptions comprised more than half of all observed FDs.

Conclusion
Room design and layout issues may create barriers to task performance, potentially contributing to the escalation of FDs in the OR.