![]() ![]() These lamps (nonlouvered GL-188 Lumalier, Memphis, TN) were installed near the door in each stairwell internal to the ward at a height of 2.1 m. One solution to ensure any escaping particles are disinfected was to install upper room germicidal UV lamps. Negative-air machine flow rates were set such that the anteroom pressure was highly negative relative to the MMH, yet not as negatively pressurized as the isolation ward, to direct air flow toward the isolation ward.ĭuring planning visits, pressure measurements collected from the stairwells indicated that they were positively pressurized relative to the ward, limiting the possibility of infectious particles escaping through these spaces except when stairwell doors were opened. Two HEPA-filtered negative-air machines (MICROCON MAP800 Biological Controls, Eatontown, NJ) were operated at 1,104 m 3/h to establish negative pressure in the ANT and were exhausted into the MHH. This ventilation scheme generated −29 Pa of pressure across closed fire doors in the MHH, while limiting nuisance noise on the ward produced by the AHU. All return and exhaust air was directly released through on-roof stacks with no mixing or recirculation. The AHU was an air-to-air, constant-air-volume system, set to 100% outside air and 100% exhaust manually for this study. ![]() Data collected included the following: pressure differentials at the isolation ward's outer envelope, internal variability of pressure on the ward, performance of the temporary anteroom (ANT), pressure fluctuations when ingress or egress events occurred, flow rates and AERs in bedrooms, and ultraviolet (UV)-C fluxes in stairwells.ĭuring the demonstration, the AHU was operated with supply airflow reduced to 60% of its normal operating speed and exhaust airflow operating at capacity. 17 The purpose of this project was to demonstrate and test whether a functional hospital wing could be operated effectively as a negative-pressure isolation ward for an entire day. 16 Containment was estimated using fluorescent tracer particles, and very high levels of containment were achieved (>99%) with AERs of 15 ACHs.Īlthough it is recognized that increased surge capacity is an important component of hospital preparedness, more knowledge and field experience are needed to guide decisions about increasing airborne surge capacity. 15 In another demonstration, a 3-unit temporary patient shelter was constructed out of plastic sheeting and ventilated using negative-air machines. Rosenbaum et al demonstrated during a hospital disaster preparedness drill that multiple high-efficiency particulate air (HEPA)–filtered negative air machines placed in a physical therapy gymnasium produced the recommended pressure and AER for negative-pressure isolation. To date, there are few studies detailing the effectiveness of temporary isolation wards to be used during a surge. 5, 6, 11, 12, 13, 14 One option to meet capacity needs would be to implement a temporary negative-pressure isolation ward that could house a large number of patients. Guidance for intensive care unit capacity has been published, ranging from a 20%-300% increase in bed numbers, depending on the type of incident. There are no regulations stipulating surge capacity requirements for U.S. 10 The number of patients needing health care services may rapidly exceed such a small AIIR capacity during an airborne transmissible pandemic or bioterror event. 2, 8 In approximately one-half of urban hospitals, only 2%-4% of rooms are equipped with negative pressure. 8, 9 It is also recommended to have an air exchange rate (AER) of 12 air changes per hour (ACH), of which 2 ACHs must be outside air in an AIIR. The pressure difference between an AIIR and the hospital corridor is recommended to be −2.5 Pa in the United States. hospitals use negative-pressure airborne infection isolation rooms (AIIRs) to house patients with suspected or confirmed airborne transmissible infections. 6 Hospitals need to respond rapidly if they are among the first impacted by a highly contagious outbreak. 1, 4, 5 Hospital pandemic preparedness plans typically include protocols for handling a surge of infectious patients. 1, 2, 3 A robust response to a large-scale infectious disease outbreak is predicated, in part, on coordination between public health and health care delivery systems. Infectious disease epidemics, such as severe acute respiratory syndrome in 2003, H1N1 influenza in 2009, and the outbreak of Middle East respiratory syndrome starting in 2012, are public health threats that are best mitigated by deliberate planning at the health system level. ![]()
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