Background: Transmission of airborne bacteria is one of these main factors causing surgical site infection (SSI), which is harmful to patient's health and even life, and would cause great economic burden. Many earlier studies have provided evidence of relationships between ventilation of operating room and incidence of SSI. Method: This paper focuses on the airborne transmission of bacteria under mixing ventilation in hospital operating room by using CFD simulation, which is carried out to calculate the bacteria trajectories using the large eddy simulation (LES) coupling with Lagrangian method. Under operating conditions, one patient, two surgeons and three nurses were simulated by relatively realistic three-dimensional thermal manikins. In the simulation, the bacteria are produced from the skin and nose breathing. Field measurements were conducted at St. Olavs hospital to validate the simulation. The influence of other parameters on the bacteria distribution in the wound zone are analyzed, including ventilation rate, supply air velocity and supply vent area. Results: The numerical simulation results of wound zone are analyzed by using velocity vector diagram, temperature contour diagram and bacteria distribution. The results indicate that the interaction of thermal plumes from patient and surgeon, the use of surgical light and the downward airflow may dominate the operating microenvironment and influence the bacteria distribution. Conclusions: The bacteria distribution in the wound zone may be influenced by both the surgical facility and the presence of medical staff. Simply increasing supply air velocity and supply airflow area may reduce bacteria deposition on wound surface, but its effect may be less evident than increasing clean air supply directly to the operating microenvironment.
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