Different Types of Door-Opening Motions as Contributing Factors to Containment Failures in Hospital Isolation Rooms

Abstract

Hospital isolation rooms are vital for the containment (when under negative pressure) of patients with, or the protection (when under positive pressure) of patients, from airborne infectious agents. Such facilities were essential for the management of highly contagious patients during the 2003 severe acute respiratory syndrome (SARS) outbreaks and the more recent 2009 A/H1N1 influenza pandemic. Many different types of door designs are used in the construction of such isolation rooms, which may be related to the space available and affordability. Using colored food dye as a tracer, the qualitative effects of door-opening motions on the dissemination of potentially contaminated air into and out of a single isolation room were visualized and filmed using Reynolds-number-equivalent, small-scale, water-tank models fitted with programmable door-opening and moving human figure motions. Careful scaling considerations involved in the design and construction of these water-tank models enabled these results to be accurately extrapolated to the full-scale situation. Four simple types of door design were tested: variable speed single and double, sliding and hinged doors, in combination with the moving human figure. The resulting video footage was edited, synchronized and presented in a series of split-screen formats. From these experiments, it is clear that double-hinged doors pose the greatest risk of leakage into or out of the room, followed by (in order of decreasing risk) single-hinged, double-sliding and single-sliding doors. The relative effect of the moving human figure on spreading any potential contamination was greatest with the sliding doors, as the bulk airflows induced were large relative to those resulting from these door-opening motions. However, with the hinged doors, the airflows induced by these door-opening motions were significantly greater. Further experiments involving a simulated ventilated environment are required, but from these findings alone, it appears that sliding-doors are far more effective for hospital isolation room containment.

Effectiveness of a personalized ventilation system in reducing personal exposure against directly released simulated cough droplets

“…In some cases when supply flow rate is increased, total volume systems can generate airflow patterns that will increase exposure of occupants to the expiratory droplets aerosolized by breathing (Bolashikov et al., ) or coughing (Pantelic and Tham, ). A moving person can also entrap infectious droplets in the wake generated behind the back, which can increase exposure of some occupants in the space (Tang et al., ). The results from these studies suggest that advanced air delivery systems such as DPV should be given a priority in the design of indoor spaces where airborne infection transmission is a concern because of its ability to supply clean air effectively in the user's breathing zone.…”

Ventilation Rates and Airflow Pathways in Patient Rooms: A Case Study of Bioaerosol Containment and Removal

“…A neutral air pressure relationship between the general patient room and corridor, and, the isolation patient room and anteroom, was found to be effective in containing both <1.0 and >1.0 μm particles when the door separating these spaces was closed. Door motion, however, was found to cause a transient breakdown in aerosol containment, allowing the intermittent release of both <1.0 and >1.0 μm particles from the general patient (Tang et al, 2005;Eames et al, 2009;Tang et al, 2013). Together, as much as 5% of the isolation room volume can be transported to the corridor by a healthcare worker entering or exiting a patient room despite a −2.5 Pa pressure difference (Eames et al, 2009).…”

Airflow patterns through single hinged and sliding doors in hospital isolation rooms – Effect of ventilation, flow differential and passage

“…Enhanced usage has led to increased interest in containment testing and to door operation induced air and contaminant transport [19e34]. A wide variety of different methods have been used to study the issue, including: computational fluid dynamics (CFD) [23,26,30e32,34], small-scale models [19,22,24,29], full-scale models [20] and field studies [21,25,27,28,32,33].…”