The critically ill child with novel H1N1 influenza A: a case series.

OBJECTIVE To describe the presentation, course, and outcome of critically ill children with novel H1N1 influenza disease. DESIGN Retrospective case series. SETTING Pediatric intensive care unit in an urban tertiary academic center. PATIENTS Thirteen consecutive patients admitted between June 2009 and August 2009 and known or subsequently found to be infected with novel H1N1 influenza A. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Clinical, laboratory, and radiographic data were reviewed. The patients were predominantly male (62%), aged 5 months to 21 yrs, and most (92%) had known risk factors for severe disease. Direct fluorescent antibody testing had a high false-negative rate (62%) and delayed treatment in some cases. The respiratory illness presented clinically with both bronchoconstriction and alveolar consolidation to varying degrees. Bacterial superinfection occurred frequently (23%). Forty-six percent of patients required mechanical ventilation and 23% required inotropic support for hypotension. None of the patients in this series required extracorporeal membrane oxygenation. Intensive care unit length of stay did not differ between an early (within 48 hrs) oseltamivir treatment group (length of stay, 4.2 +/- 4.4 days) vs. a late treatment group (length of stay, 6.8 +/- 8.8 days). All patients survived to hospital discharge. CONCLUSIONS Underlying chronic illness (especially respiratory illness) seems associated with critical novel H1N1 influenza disease in children. Respiratory manifestations are highly variable among patients and within a single patient involving both bronchoconstriction and alveolar disease. Therapies must be individualized and rapidly adjusted. The duration of critical illness was not different between early and late treatment groups. Whether this is reflective of sample size or indicative of the importance of therapeutic intervention at any time early during infection in critically ill patients is unclear. Bacterial superinfection was more common than previously reported for seasonal influenza A. Moderate novel H1N1 influenza disease, including respiratory failure and hypotension, had 100% survival in our series.