A collaborative model by a group of scientists and architects has demonstrated how any large open function halls or buildings can be converted into covid-special ICU-equivalent wards, with a focus to reduce cross-contamination, within a week using limited funds. This model has can be utilized for pockets with severe shortage of hospital beds, said Indian developmental biologist LS Shashidhara.
Shashidhara, along with architect CS Raghuram and University of Cambridge researchers professor Andrew Woods and professor Alan Short, Department of Architecture at the Cambridge University has designed the module to help protect healthcare workers while treating patients with severe symptoms. The proposal has been shared with health officials and government authorities two weeks ago.
Healthcare authorities are attempting to add additional bed spaces by temporarily adapting any available large open halls.However, large air-conditioned halls tend to have top-down air-conditioning, which creates turbulent flows that can mix and spread droplets containing the virus widely. It may take over 20 minutes to dilute the concentration of smaller droplets produced in a cough to below a tenth of their original density.This, say the researchers, is plenty of time for droplets to travel beyond 20m, putting healthcare professionals in particular at risk. Presently, there is no data quantifying the effects or mortality caused by cross-infection, said Dr Shashidhara, also the dean of research at Delhi-based Ashoka University, adding that studies on this have begun.
Given the danger of rapid escalation of number of cases post lockdown, this could be adopted as a contingency plan for governments. The module involves rapid interior remodelling of halls to pipe in filtered air and evacuate corrupted air from the patient’s bed to reduce air borne pathogens. Such a facility would have airlock lobbies and chimneys to cut down flow of pathogens. “What we are planning is to have tent like removable structures, each for 10-12 patients, in a hall that typically accommodate 1000 people. Here, we can set up 100 beds positioned in squares. The idea is to extract exhaled air, and inject fresh air from bottom to top so that no droplet will circulate horizontally. PPE protects health-workers, but all surfaces can get contaminated. This can reduce the chances of cross-contamination,” Dr Shahidhara told the Indian Express.
The model involves series of solutions to reduce the concentration of airborne virus experienced by patients and healthcare workers in buildings converted into makeshift wards.“Effective ventilation is critically important in helping to suppress cross-infection, and nowhere more so than in an infectious diseases ward. Patients coughing or being ventilated will project droplets, some containing the virus, as an aerosol. They are so small that they may take tens of minutes to fall to the floor as the droplet evaporates in still air,” the researchers said in a statement.
The module has been designed to ensure that the exhaust air does not permeate the rest of the hall. In a completely open space, ventilation air moves down to the ground and spreads out over the patient beds, leading to a highly mixed environment. When a patient coughs or releases aerosols, the flow pattern of the aerosols can extend across the space to other patient beds, even to patients across the corridor. The design showcases subdivision of beds into patient bays, where the ventilation flow still comes down from the ceiling and moves into the patient bed-spaces and mixes, but a good proportion of this air is removed through exhaust ducts located behind the beds. When a patient produces aerosols within a bay, the aerosol concentration remains high in the bay and as air is drawn out through the exhaust duct this limits the aerosol transport into the main space.
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