Reducing Infectious Disease Transmission in Operating Rooms

Reza Daneshazarian, JEFFREY SIEGEL, University of Toronto

     Abstract Number: 356
     Working Group: Indoor Aerosols

Abstract
Operating rooms (ORs) are typically designed and operated to reduce the occurrence of surgical site infections (SSIs). Because of SSIs, hospital operating rooms (ORs) are typically maintained at positive pressure which can increase the risk of disease transmission within and to spaces outside of the OR when an infected patient is present. We conducted experiments and simulations in an OR with both a continuous source and an episodic source (a cough box) of simulated respiratory aerosol. The independent experimental parameters included pressurization status (positive vs. negative), healthcare worker (HCW) presence and activities, and anteroom presence or absence. The experimental results demonstrated the value of negative pressure for both reducing exposure to HCW as well as transmission to the sterile corridor outside of the OR (concentration reductions ranged from 1.2 – 63%, depending on location and experimental parameters). Positive pressurization was also associated with higher variability in respiratory aerosol concentrations in the operating table area. In general, negative pressure did not increase particle concentrations in the surgical site area. HCW activities impacted respiratory aerosol concentrations in the operating table area, but this impact was similar under both positive and negative concentrations. Independent of operating room pressure, an uncontrolled anteroom did not impact aerosol concentrations in the operating table area. The simulation results (validated with experimental results) demonstrated the value of controlling the anteroom pressure to minimize the transport of aerosols both into and out of the OR as well as reinforcing the similarity between positive and negative pressure for protection of the surgical site. Collectively, the results suggest that negative pressure should be considered for ORs, especially when operating on patients with known or suspected airborne infectious diseases.