Development and efficacy testing of a portable negative pressure enclosure for airborne infection containment.

Objectives: To overcome the shortage of personal protective equipment and airborne infection isolation rooms (AIIRs) in the COVID-19 pandemic, a collaborative team of research engineers and clinical physicians worked to build a novel negative pressure environment in the hopes of improving healthcare worker and patient safety. The team then sought to test the device's efficacy in generating and maintaining negative pressure. The goal proved prescient as the US Food and Drug Administration (FDA) later recommended that all barrier devices use negative pressure.

Methods: Initially, engineers observed simulations of various aerosol- and droplet-generating procedures using hospital beds and stretchers to determine the optimal working dimensions of the containment device. Several prototypes were made based on these dimensions which were combined with filters and various flow-generating devices. Then, the airflow generated and the pressure differential within the device during simulated patient care were measured, specifically assessing its ability to create a negative pressure environment consistent with standards published by the Centers for Disease Control and Prevention (CDC).

Results: The portable fans were unable to generate any airflow and were dropped from further testing. The vacuums tested were all able to generate a negative pressure environment with the magnitude of pressure differential increasing with the vacuum horsepower. Only the 3.5-horsepower Shop-Vac, however, generated a -3.0 pascal (Pa) pressure gradient, exceeding the CDC-recommended minimum of -2.5 Pa for AIIRs.

Conclusion: A collaborative team of physicians and engineers demonstrated the efficacy of a prototype portable negative pressure environment, surpassing the negative pressure differential recommended by the CDC.