©2024 This excerpt taken from the article of the same name which appeared in ASHRAE Journal, vol. 66, No. 10, October 2024.
Optimization of Ventilation Design for the Hospital Post-Anesthesia Care Unit
By Kishor Khankari, Ph.D.; Alberto Garcia; Leonid Turkevich, Ph.D.; Kevin H. Dunn, CIH
About the Author
Kishor Khankari is the president at AnSight LLC in Ann Arbor, Mich. Alberto Garcia is a mechanical engineer, Leonid Turkevich, Ph.D., is senior service fellow and Kevin H. Dunn, CIH, is research mechanical engineer at the National Institute for Occupational Safety and Health (NIOSH) in Cincinnati.
Perianesthesia nurses and other health-care providers who primarily work in post-anesthesia care units (PACUs) are at risk of exposure to hazardous waste anesthetic gases (WAGs) released by patients who have been brought into the PACU for recovery immediately following surgery. These can cause potential health effects. The airflow patterns in the PACU play a crucial role in determining the spread and concentration of WAGs in the breathing zone of occupants. A computational fluid dynamics (CFD) study was conducted to evaluate PACU ventilation performance.
It evaluates the impact of various HVAC layouts including supply and return locations on the airflow patterns, temperature distribution and the concentration of sevoflurane in the breathing zone of occupants. In addition, the impact of the supply airflow rate is also evaluated. A newly developed metric of the Spread Index is used to compare the spread of sevoflurane under different HVAC layouts and supply airflow rates.
The waste anesthetic gases (WAGs) include nitrous oxide (N2O) and halogenated agents (vapors) such as halothane, sevoflurane, enflurane, isoflurane and desflurane. Exposure to waste anesthetic gases can potentially cause nausea, dizziness, headaches, fatigue and irritability, as well as sterility, miscarriages, birth defects, cancer and liver and kidney disease.1,2
The National Institute for Occupational Safety and Health (NIOSH) recommends that workers should not be exposed to halogenated agent concentrations of more than 2 ppm when used alone or more than 0.5 ppm when used in combination with N2O over a sampling period of less than 1 hour.3,4 Currently, NIOSH does not have specific recommended exposure limits (RELs) for the three most used anesthetics (isoflurane, desflurane and sevoflurane).
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