Dynamic simulation on impact of surgeon bending movement on bacteria-carrying particles distribution in operating theatre

Bacteria-carrying particles (BCPs) released from surgical team are the major source causing surgical site infections (SSIs). Ultraclean ventilation (UCV) system has been widely applied to reduce the risk of SSIs in operating theatre (OT). Whether the surgeon movement when performing operation can influence BCPs distribution within the surgical zone has been rarely investigated. This paper presents a study of the influence of periodic bending movement of a surgeon on the airflow field and the BCPs distribution, by applying the Eulerian RANS model for the airflow, the modified drift-flux model for the phase of BCPs and the dynamic mesh model for the bending body of surgeon. It is found that when all surgical staff stands upright without movement, the UCV system can generally keep the concentration of BCPs to less than 1 cfu/m3 within the surgical critical zone. But in the scenario considering the periodic bending movement of a surgeon, two movement sessions i.e. 45° bending posture for performing operation and bending back movement of surgeon can cause the concentration of BCPs within the surgical critical zone exceeding the recommended 10 cfu/m3, among which the 2-s bending back movement of surgeon poses the highest risk.