The ventilation of multiple-bed hospital wards: Review and analysis

Background: Although the merits of ventilating operating theatres and isolation rooms are well known, the clinical benefits derived from ventilating hospital wards and patient rooms are unclear. This is because relatively little research work has been done in the ventilation of these areas compared with that done in operating theatres and isolation rooms. Consequently, there is a paucity of good quality data from which to make important decisions regarding hospital infrastructure. This review evaluates the role of general ward ventilation to assess whether or not it affects the transmission of infection. Methods: A critical review was undertaken of guidelines in the United Kingdom and United States governing the design of ventilation systems for hospital wards and other multibed rooms. in addition, an analytical computational fluid dynamics (CFD) study was performed to evaluate the effectiveness of various ventilation strategies in removing airborne pathogens from ward spaces. Results: The CFD simulation showed the bioaerosol concentration in the study room to be substantially lower (2467 cfu/m(3)) when air was supplied and extracted through the ceiling compared with other simulated ventilations strategies, which achieved bioaerosol concentrations of 12487 and 10601 cfu/m(3), respectively. Conclusions: There is a growing body of evidence that the aerial dispersion of some nosocomial pathogens can seed widespread environmental contamination, and that this may be contributing to the spread infection in hospital wards. Acinetobacter spp in particular appear to conform to this model, with numerous outbreaks attributed to aerial dissemination. This suggests that the clinical role of general ward ventilation may have been underestimated and that through improved ward ventilation, it may be possible to reduce environmental contamination and thus reduce nosocomial infection rates.