On field ventilation performance in operating theaters against airborne contamination: a comparison of unidirectional and mixed airflow systems

Controversy exists between engineers and clinicians over the beneficial effects of Uni-Directional Flow (laminar airflow) adoption in the ventilation in the OR in order to further minimize airborne Surgical Site Infections (SSIs). This paper presents the results obtained during environmental monitoring campaign on 31 operating theaters (OTs), 18 OTs equipped with unidirectional air flow systems and 13 OTs adopted a mixing (turbulent) airflow ventilation system. Inert and viable airborne particle concentration have been measured in “at rest” and “operational condition” in different places within the OTs under evaluation. Number of persons present during operations, type of technical clothing system adopted, thermo-hygrometric conditions have been acquired as well as airflow rate, air velocity and type of filtration system. Results have shown how OTs equipped with unidirectional airflow diffusion system have generally lower inert and viable airborne particle concentration within the OT than those with mixed airflow, and therefore lower risk of SSIs.