Preparing for the Next Outbreak: Engineering Out the Risk

Background: When new diseases emerge, the mode of transmission  is uncertain, and there are invariably fears about airborne transmission, especially with diseases that manifest with respiratory symptoms. The SARS outbreak in 2003 raised questions about airborne transmission that have never been fully answered. With Influenza AH1N1, initial recommendations called for patients to be isolated in negative pressure rooms. The number of such rooms will clearly be inadequate for a surge, nor are they likely to be built on time. When there are no outbreaks, the cost of building and maintainence of such rooms would be difficult to justify.

Objective: Our objective was to take the lessons learnt from SARS to prepare for the next outbreak, and to have a plan for rapid conversion of private rooms into negative pressure ones.

Methods: As the designated hospital for SARS in 2003, we did not have sufficient negative-pressure rooms. The decision was made to convert air-conditioned rooms with attached bathrooms located on the highest floor into isolation rooms. Both the nursing station and patient rooms in these wards were supplied by a central air-conditioning unit, with recirculation of air in normal times. Industrial fans (Fig 1) were installed to exhaust air from patient rooms resulting in positive pressure of air from the nursing station to the patient rooms

Results: We converted 4 wards of private rooms (total 52) on the top floor of the hospital into negative pressure rooms. Directional air flow was confirmed with smoke tests. When these rooms were filled, we moved down the floors, doing the same for successive wards, some of which then had 2 to 4 beds in one room.

When the outbreak was over, the fans were removed, and the rooms converted into “normal” status. Since 2003 however, we have been preparing for possible outbreaks of new diseases. We were most concerned about Avian influenza  H5N1 as we are in a region where there are ongoing cases. In the advent of a new outbreak, where the number of patients requiring isolation exceeds our existing capacity,  we will again convert existing rooms to “negative pressure”. Similar industrial fans have been kept wrapped in plastic, in storage, and engineers can rapidly deploy them within days

Conclusions: The rapidly evolving A Influenza H1N1 has again highlighted the difficulties with surge response especially with regards to infrastructure capacity, and supplies. These engineering modifications may be an option for other institutions in resource-limited countries with mild climate conditions.