Performance investigation of a novel positively or negatively pressurized operating room for infection control

Abstract

Operating rooms are often positively pressurized and maintained at a higher pressure than adjacent areas, preventing contaminated air from entering the sterile surgical environment. However, the COVID-19 outbreak has necessitated the construction of negatively pressurized operating rooms for contagious patients, preventing contaminated air from escaping into adjacent spaces. Therefore, this study developed a heating, ventilation, and air-conditioning (HVAC) system that can have a dual function pressurization, positively or negatively pressurized. High-efficiency particulate air (HEPA) filters were used for filtration. Then, a variable-speed driven (VSD) HVAC system modulates the pressure in response to environmental conditions when changing the pressure from positive to negative or while the door opens. At the same time, the air change rate (ACR) for dilution was implemented through the separated HVAC systems control schemes. Field measurements were performed to validate the results of a computational fluid dynamics (CFD) simulation, which was conducted to compare air particle distributions in a positively and negatively pressurized operating room and the effects of air curtains. The results showed that the positive pressurized operating room has a better airflow pattern and dilutes contaminants faster. In contrast, the negative pressurized system is the best solution for reducing the chance of airborne infection, particularly for contagious patients. Furthermore, utilizing air curtains can provide a better barrier against airborne contaminants, increasing the efficiency of contaminant control measures. The ventilation efficiency could be increased by approximately 10 % by applying an air curtain with a velocity of 0.5 m/s under both types of pressurization.