Optimization of Ventilation Design for the Hospital Post-Anesthesia Care Unit
ASHRAE Journal, Vol. 66, no. 10, October 2024
Author:
Kishor Khankari
Abstract:
The postoperative patients in the Post Anesthesia Care Unit (PACU) of a hospital are the sources of
waste anesthetic gases (WAGs). The healthcare workers in the PACU can potentially be exposed to
hazardous WAGs. To protect these workers, it's important to design a ventilation system that effectively
removes these gases and reduces exposure. By improving airflow patterns, the concentration of WAGs
in the breathing zone of occupants can be reduced. To evaluate the impact of various HVAC layouts on
the ventilation performance of the PACU, a study was conducted using non-isothermal computational
fluid dynamics (CFD) simulations. The study employed a Spread Index metric to compare the spread of
sevoflurane, a commonly used anesthetic gas, for various HVAC layouts.
The traditional HVAC layout with four-way supply diffusers and ceiling returns was found to create
mixing airflow patterns. These patterns can potentially distribute WAGs throughout the entire PACU,
increasing the risk of exposure for healthcare workers. Similarly, the low wall and ceiling returns layouts
with ceiling laminar diffusers also create recirculating airflow patterns, which can bring sevoflurane
plumes from the patient’s face into the breathing zone of occupants.
The HVAC layout with laminar diffusers and headwall returns showed the most promise in reducing the
concentration of WAGs in the breathing zone. This layout utilizes horizontal movement of a sevoflurane
plume below the breathing zone of occupants combined with immediate exit of the contaminated air
through the headwall returns. This significantly reduces the concentration of sevoflurane in the
breathing zone and limits the spread of WAGs in the PACU.
The study also indicates that the PACU with such an optimized HVAC layout can be operated at reduced
dilution airflow rates without significantly affecting the ventilation performance. This confirms that it's
not the air change rates but the airflow patterns that play a crucial role in improving ventilation
effectiveness. By using CFD to analyze and optimize airflow patterns in indoor spaces, it's possible to
limit the spread of contaminants and reduce the exposure of occupants. Such optimized ventilation
designs can further reduce energy consumption, first costs, and the operating costs of the HVAC system.
Fill the following form to download
About the author
Dr. Kishor Khankari
ASHRAE Fellow, ASHRAE Distinguished Lecturer
Dr Kishor Khankari is the founder of AnSight LLC. As a specialist in Computational Fluid Dynamics (CFD), his passion for solving engineering problems and providing sound scientific solutions has led to innovations and optimized designs in the industry.
A noted expert in his field, he has a Ph.D. from the University of Minnesota and has published in several technical journals and trade magazines. As a well sought-after speaker Dr. Khankari makes regular presentations in various technical conferences and professional meetings worldwide.
