Impact of pandemic (H1N1) 2009 on Australasian critical care units.

Objective: To identify the resource usage by patients with influenza A H1N1 admitted to Australian and New Zealand intensive care units during the first wave of the pandemic in June, July and August 2009.

Design, Setting And Participants: Data were collected in two separate surveys: the 2007-08 resource and activity survey and the 2009 influenza pandemic survey. Participants comprised 143 of the 189 Australian and New Zealand critical care units identified by the Australian and New Zealand Intensive Care Society Centre for Outcome and Resource Evaluation (ANZICS CORE). Mean length of stay (LOS) and ventilation data for H1N1 patients were reported by the ANZIC Influenza Investigators study from the same units over the same time period. Mean LOS for all ICU admissions was obtained from the ANZICS CORE adult patient database 10-year study.

Main Outcome Measures: H1N1 patient admissions as a proportion of all ICU admissions; H1N1 patient bed-days as a proportion of total bed-days; ventilation resource usage by H1N1 patients; changes in ICU admissions for elective surgery during the H1N1 pandemic.

Results: Over the period June-August 2009, among 30 222 ICU admissions to 133 ICUs contributing data, 704 patients (2.3%) had H1N1 influenza A. Twenty-eight units had no H1N1 patient admissions. The peak of the pandemic in Australia and New Zealand occurred in July 2009, when H1N1 patients represented 3.7% of all ICU admissions for July and 53.5% of all H1N1 patient admissions in the period June-August 2009. We estimate that H1N1 cases required approximately 12.4% of the ventilator resources and used 8.1% of total patient bed-days. During the pandemic, there was a 3.2 percentage-point reduction in elective admissions to public hospitals (from 32.5% to 29.3%).

Conclusion: Low rates of admission of H1N1 patients to ICUs during the 2009 pandemic enabled the intensive care system to cope with the large demand when analysed at a jurisdictional level.