Clinical characteristics of critically ill patients with suspected influenza during the 2009-10 and 2013-14 outbreaks.

Purpose: Pandemic influenza A pdm09 (pH1N1) virus was the predominant isolate identified during the 2009-10 and 2013-14 influenza outbreaks, causing significant morbidity and mortality. We describe clinical characteristics of critically ill patients during 2 pH1N1 outbreaks.

Methods: Single-center, retrospective cohort study of patients admitted to the intensive care unit receiving oseltamivir for suspected influenza during 2 outbreak periods. Demographics and comorbidities were collected from the medical record. Outcomes included use of adjunct oxygenation therapies and oseltamivir dosing.

Results: One hundred twenty-four patients were included (2009, n=53; 2013, n=71). Demographics were as follows: mean (SD) age, 52.3 (14.2) years; mean (SD) Acute Physiology and Chronic Health Evaluation II score, 19.4 (9.2); 71% had greater than or equal to 2 comorbidities; and mortality was 27%. Inhaled nitric oxide was administered more commonly in 2009 (P=.01), whereas neuromuscular blockade (P=.02) and epoprostenol were administered more commonly in 2013 (P=.01). Patients in 2009 were more likely to receive high-dose oseltamivir (P=.02; odds ratio, 1.8; 95% confidence interval, 1.18-6.62). No differences in clinical outcomes were observed between 2009 and 2013.

Conclusions: Use of adjunct oxygenation therapies and nontraditional antiviral dosing has changed significantly since the 2009 pandemic, although this has not resulted in a measurable impact on clinical outcomes.