Epidemiology, clinical characteristics and resource implications of pandemic (H1N1) 2009 in intensive care units in Ireland.

Objective: To describe the incidence, clinical characteristics and outcomes of critically ill patients in Ireland with pandemic (H1N1) 2009 infection, and to provide a dynamic assessment of the burden of such cases on Irish intensive care units.

Design, Setting And Participants: Multicentre prospective observational study of all adult patients admitted to any of the 30 ICUs in the Republic of Ireland between 15 July 2009 and 30 May 2010.

Main Outcome Measures: Patient demographics, clinical characteristics and ICU mortality; ICU admissions, bed-days, bed occupancy rates and distribution.

Results: Seventy-seven adult patients with pandemic (H1N1) 2009 infection were admitted to 27 of 30 Irish ICUs. The median age was 43 years (IQR, 30-56 years); 67 patients (88%) were aged under 65; 39 (51%) were male. Sixty-two patients (82%) had comorbid conditions, including obesity (36%), respiratory disease (34%) and malignancy or immunosuppression (20%). Eight (11%) were pregnant, and 27 (36%) were smokers. Sixty-seven patients were mechanically ventilated, 24 (32%) required renal replacement therapy, 39 (51%) received vasopressors and four (5%) received extracorporeal membrane oxygenation. Of 14 patients (18%) who died in the ICU, two had no pre-existing comorbidities. The ICU admission rate of patients with pandemic (H1N1) 2009 infection was 22.5/million population. A total of 1882 ICU bed-days (557.5 bed-days/million adult population) were consumed, equating to a 3.9% bed occupancy rate, with a peak of 14.0% in October 2009. Median length of stay was 12 days (IQR, 7-34 days).

Conclusion: The 2009 influenza A (H1N1) pandemic was a significant burden on Irish ICUs, predominantly affecting the tertiary centres. The demographics and clinical characteristics were similar to those described in the southern hemisphere, suggesting such data may inform future resource planning for similar threats.