Protecting healthcare workers from SARS

Introduction

There are only limited data from which to estimate the risk to ICU healthcare workers of acquiring SARS. We describe our experience of infection of healthcare workers in our SARS ICU.

Methods

The study was a retrospective audit of the outcome of measures to prevent SARS infection among ICU staff. During the study period (13 March–31 May) only patients with SARS or suspected to have SARS were admitted to our ICU. Data extraction was carried out by a trained research nurse. The following data were collected: patient demographic data, duration of invasive mechanical ventilation, place of intubation, ICU length of stay, number of days with diarrhea and days from symptom onset to ICU admission. Duration of exposure to SARS patients was obtained from nursing and medical rosters. Infection control procedures evolved during the first few weeks of the epidemic. In brief, the final protocol consisted of the following. All staff entering the ICU were required to clean their hands and don a gown, gloves, hat, face shield and fit-tested N95 or N100 mask. Initial fit-testing involved a qualitative fit-test, with a subsequent quantitative test for those who failed the qualitative test. Those staff for whom an adequate fit could not be achieved with a N95 or N100 mask were issued with powered air purifying respirators.

Results

Sixty-seven patients with SARS were admitted, with eight patients being admitted twice. The median (interquartile range [IQR]) length of ICU stay was 13 (6–24) days. The mean (standard deviation) number of days between symptom onset and ICU admission was 9.5 (4.7) days. The median (IQR) age was 47 (36–59) years and median (IQR) APACHE II score 10 (8–13). Thirty-two patients were ventilated for a median (IQR) of 14.5 (7–25) days. Total number of ventilated patient-days was 525 days. No patients received non-invasive ventilation. All patients who were ventilated were intubated by ICU doctors, 28 in the ICU and four in other areas of the hospital. Diarrhoea occurred in 55% of patients. Thirty-five doctors worked in the ICU for a median (IQR) of 284 (97–376) hours. One hundred and fifty-two nurses and healthcare assistants worked for a median (IQR) of 119 (57–166) hours. Five ICU healthcare workers developed SARS (2.67%, 95% confidence intervals 1.15–6.11). Four of these were nurses and the fourth was a healthcare assistant. Three became symptomatic in the first 10 days of exposure to patients with SARS, strongly suggesting that they were infected in the first few days of exposure. Three of the five were subsequently underwent quantitative fit-testing of the N95 mask that they were using at the time of infection. In all cases the fit was adequate.

Conclusion

The incidence of SARS among healthcare workers in our ICU was low despite a prolonged period of exposure to patients with SARS. Three of five infections occurred when the protective strategies were being developed and vigilance in the correct use of protective equipment was probably lowest.