Systematic Characterization of Air and Aerosol Dispersion in Operating Rooms

TERRENCE GARCIA, Benjamin Alvarez, Crystal Butler, Daniel Winker, Erika Yu, Stephanie Ku, Kira Loshin, Michael Morrison, Shirley Klimkiewicz, Sarah Ton, Mika Helfers, Tim O'Hanlon, Megan Toms, Christopher Stiles, Ryan Darragh, Anurupa Bhonsale, Christopher Bradburne, Sarah Grady, Carlos Barajas, Sarah Harrison, Mayalen Brock, Greta Kintzley, Lucy Carruth, Brian Damit, et al., Johns Hopkins University Applied Physics Laboratory

     Abstract Number: 744
     Working Group: Health-Related Aerosols

Abstract
Within operating room (OR) settings, the movement of pathogenic droplets and aerosols are of critical concern, particularly in the occurrence of surgical site infections (SSIs). Owing to the highly complex nature of OR environments, new approaches are needed to systematically characterize these spaces and develop evidence-based improvements to infection prevention and control (IPC) practice and the built environment. To address this gap, this study developed a multimodal sensor system comprised of a suite of low size, weight, and power sensors for measuring a range of OR properties including airflow, aerosols, human activity, equipment position, ambient temperature, humidity, door openings, 3D room geometry, and biological burden (proteomic and genomic content). Embedded inconspicuously in an OR, this system can autonomously gather rich spatiotemporally-resolved datasets for characterization of aerosol-generating procedures (AGPs) and droplet and aerosol dispersion in the OR linked to specific events (e.g., door openings and clinician movements) in the context of SSIs.
Following development, an active OR at a large public hospital was sensorized for data collection over a three-month period. In sensorizing the OR, computational fluid dynamics (CFD) modeling informed the placement and distribution of aerosol sensors (Alphasense) and environmental samplers (Button samplers) throughout the space. The research team also completed in-person surgical observations to further contextualize surgical events. The results show a size-dependent propagation of aerosols throughout the space during surgical patient care, with absolute aerosol concentrations dependent on the activity, e.g., cautery, fan output from workstation, etc. Early data science-based interpretations indicate that several factors are indeed correlated to air and aerosols being directed toward the patient (and perhaps SSIs), namely, the number of clinical staff in the room, degree of human activity, air velocity at vents, and others. Ongoing data analysis will continue to quantify and generalize these relationships for translation into IPC guidance toward reducing SSIs.