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.
Highlights
Isolation rooms to contain infectious patients or to protect vulnerable patients from infection are an important facility to protect patients and staff against the risk of infection by airborne pathogens [1,2]
All the dimensions of the one-tenth scale models were taken from full-scale models that were being constructed at the same time by collaborators at the Finnish Institute of Occupational Health (FIOH) and their collaborators Oy Halton Group (Finland)
For the hinged-doors, both slow (Table 1, Videos S3–S4) and fast (Table 2, Figures 5 and 6) angular velocities were investigated. This was done because the effect of these door-opening motions on the movements of the food dye were much more dramatic and it was of interest to capture these flows at these two speeds, with the fast parameters being approximately twice those of the slow parameters
Summary
Isolation rooms to contain infectious patients or to protect vulnerable (e.g. immunocompromised) patients from infection are an important facility to protect patients and staff against the risk of infection by airborne pathogens [1,2]. In the aftermath of the severe acute respiratory syndrome outbreaks of 2003, the demand for such rooms increased, dramatically [7,8,9,10]. Many of these were eventually utilized in the management of patients infected with the 2009 pandemic influenza A/H1N1 virus [11,12,13,14]. At least one analytical case report has demonstrated that containment failure may result from opening isolation room doors [23]
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