Hospital and community acquired infection and the built environment – design and testing of infection control rooms

Abstract

Negative-pressure isolation rooms are required to house patients infected with agents transmissible by the aerosol route in order to minimise exposure of healthcare workers and other patients. Housing patients in a separate room provides a barrier which minimises any physical contact with other patients. An isolation room held at negative pressure to reduce aerosol escape and a high air-change rate to allow rapid removal of aerosols can eliminate transmission of infectious aerosols to those outside the room. However, badly designed and/or incorrectly operating isolation rooms have been shown to place healthcare workers and other patients at risk from airborne diseases such as tuberculosis. Few standards are available for the design of isolation rooms and no pressure differential or air-change rates are specified. Techniques such as aerosol particle tracer sampling and computational fluid dynamics can be applied to study the performance of negative-pressure rooms and to assess how design variables can affect their performance. This should allow cost-effective designs for isolation rooms to be developed. Healthcare staff should be trained to understand how these rooms operate and there should be systems in place to ensure they are functioning correctly.

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

“…To reduce both the concentration and time patients and healthcare workers are exposed to pathogenic microorganisms, ASHRAE Standard 170 and several other guidelines recommend 6-12 ACH for infectious isolations rooms (AIA, 2006;Siegel et al, 2007;ASHRAE, 2008;Atkinson et al, 2009). Although higher air change rates can better dilute contaminant concentrations within a patient room, air changes alone have not proven to reduce the risk of airborne cross infection (Marshall et al, 1996;Novoselac and Srebric, 2003;Walker et al, 2007;Johnson et al, 2009;Memarzadeh and Xu, 2011). For this, new research has begun to look beyond air change rates to examine the effects that other factors such as supply and exhaust location, door position and motion, spatial orientation, surface composition, temperature, humidity, and air distribution patterns have on particle migration in clinical spaces.…”

Airborne bacterial dispersal during and after dressing and bed changes on burns patients

“…When a burns patient is at rest in bed, the dispersal of bacteria from their wounds is likely to be negligible. On the instigation of activity however, a proliferation of bacteria are released into the air, and onto surrounding surfaces, after travelling a distance of up to two metres from whence they came [2]. Certain events have been identified as high-risk periods of bacterial liberation.…”

Experimental Investigation of Ventilation Efficiency in a Dentistry Surgical Room

“…The mean operative temperature and humidity were used to evaluate Equations (3) to (6). The results of dimensionless ventilation efficiency for heat and moisture removal are presented in Table 2.…”

“…In health care buildings, ventilation systems are expected to preventing cross infection risks in addition to maintaining adequate thermal comfort to the patients, the caregivers and visitors. On the contrary, despite the high energy requirements [1,2], the HVAC contributes to making building unhealthy [3] as several cases of nosocomial or hospital acquired illness (HAI) had been previously reported [4][5][6]. These problems, amongst others, had hitherto led to the emergence of building performance diagnostics.…”