Pressurization and HVAC Configuration of Hospital Operating Rooms with an Airborne Disease Infected Patient

REZA DANESHAZARIAN, Jeffrey Siegel, University of Toronto

     Abstract Number: 124
     Working Group: Identifying and Addressing Disparate Health and Social Impacts of Exposure to Aerosols and Other Contaminants across Continents, Communities, and Microenvironments

Abstract
Surgical-site infections (SSIs) are a major concern in the field of surgery, and various factors need to be considered in order to reduce their occurrence, including pressurization, air exchange rate, and the presence of an anteroom. Hospital operating rooms (ORs) are typically maintained at positive pressure, and the addition of an anteroom can help to prevent the transmission of airborne infectious diseases. The anteroom is kept at a lower pressure than the OR to act as a barrier against contamination from the OR. In response to the emergence of SARS-CoV-2 in 2020, temporary anterooms were sometimes used to reduce the risk of transmission. The objective of the current study is to design an optimal OR ventilation system that reduces the transmission of airborne infectious diseases. To achieve this goal, a wide range of monitoring systems were deployed to characterize the size distributions and spatial variations in concentrations of particles in the OR. Sensors and monitors were placed at different heights to account for the location of the operating table and healthcare workers. Air properties such as temperature, relative humidity, air velocity, and pressure were measured at every step of the process. Artificial saliva was prepared and characterized to simulate human saliva (pH=6.78). Aerosol solution was released from a nebulizer positioned at the patient's head (lying horizontally on the operating table) to simulate continuous breathing aerosol, and a cough box was constructed to study sudden particle generation during OR procedures such as extubating. Computational fluid dynamics (CFD) and experimental results showed that the presence of an anteroom can reduce ventilation contamination and prevent the migration of particles from the OR into clean corridors. The results also confirmed that the type of air ventilation has a significant impact on particle transmission, and the use of mixed turbulent airflow can increase contamination.