Containment effectiveness of expedient patient isolation units

It is generally recognized that the health care system does not have adequate isolation capacity to meet the surge in demand during a major outbreak of airborne infectious disease. Alternatives to engineered isolation rooms undoubtedly will be required as surge isolation requirements exceed the available resources. The purpose of this work was to estimate containment efficiency of expedient airborne infectious isolation units with and without anterooms in the absence and presence of care provider traffic.

Fluorescent 2-microm aerosol particles were released into the interior of expedient-construction isolation modules exhausted with a high-efficiency particulate air (HEPA)-filtered fan unit. Particle concentrations inside and outside the enclosure were measured with and without provider traffic simulated with a mannequin. Measurements were obtained on modules constructed with and without an anteroom, which was not separately ventilated.

Containment estimates were excellent for all isolation configurations evaluated, generally exceeding 99.7%. Particle escape was statistically significantly higher with simulated traffic than without; however, there was no statistically significant difference in particle escape with and without an anteroom.

Our findings demonstrate that effective isolation may be possible using low-technology, low-cost, easily built structures that can be readily constructed within hospital and other environments in emergency response situations.