Conflicting effects of a portable ultra-clean airflow unit on the sterility of operating rooms: a numerical investigation

The onset of post-operatory surgical-site infections is significantly correlated with the concentration of viable airborne bacteria that are shed from the surgical team or entering the operating room during door openings and are deposited directly on the patient’s wound or on surgical instruments. The ultra-clean vertical laminar airflow ventilation system is often used to protect the main surgical area of operating rooms. The clean zone provided by the laminar airflow system is crowded with staff and furniture. As a result, some surgical instruments might remain outside the protected area. We use a numerical simulation to investigate the capability of a portable ultra-clean airflow unit to reduce the contamination of the principal instrumentation table by airborne bacteria, during a sham operation. The numerical model is thoroughly validated against the experimental data available for a test room. The portable air-cleaning device maintains sterile conditions on the principal instrumentation table over a range of flow rates of the general ventilation, although it induces higher levels of bacterial contamination in other zones of the room at the same time.