Critically ill patients with 2009 influenza A(H1N1) infection in Canada.


CONTEXT Between March and July 2009, the largest number of confirmed cases of 2009 influenza A(H1N1) infection occurred in North America. OBJECTIVE To describe characteristics, treatment, and outcomes of critically ill patients in Canada with 2009 influenza A(H1N1) infection. DESIGN, SETTING, AND PATIENTS A prospective observational study of 168 critically ill patients with 2009 influenza A(H1N1) infection in 38 adult and pediatric intensive care units (ICUs) in Canada between April 16 and August 12, 2009. MAIN OUTCOME MEASURES The primary outcome measures were 28-day and 90-day mortality. Secondary outcomes included frequency and duration of mechanical ventilation and duration of ICU stay. RESULTS Critical illness occurred in 215 patients with confirmed (n = 162), probable (n = 6), or suspected (n = 47) community-acquired 2009 influenza A(H1N1) infection. Among the 168 patients with confirmed or probable 2009 influenza A(H1N1), the mean (SD) age was 32.3 (21.4) years; 113 were female (67.3%) and 50 were children (29.8%). Overall mortality among critically ill patients at 28 days was 14.3% (95% confidence interval, 9.5%-20.7%). There were 43 patients who were aboriginal Canadians (25.6%). The median time from symptom onset to hospital admission was 4 days (interquartile range [IQR], 2-7 days) and from hospitalization to ICU admission was 1 day (IQR, 0-2 days). Shock and nonpulmonary acute organ dysfunction was common (Sequential Organ Failure Assessment mean [SD] score of 6.8 [3.6] on day 1). Neuraminidase inhibitors were administered to 152 patients (90.5%). All patients were severely hypoxemic (mean [SD] ratio of Pao(2) to fraction of inspired oxygen [Fio(2)] of 147 [128] mm Hg) at ICU admission. Mechanical ventilation was received by 136 patients (81.0%). The median duration of ventilation was 12 days (IQR, 6-20 days) and ICU stay was 12 days (IQR, 5-20 days). Lung rescue therapies included neuromuscular blockade (28% of patients), inhaled nitric oxide (13.7%), high-frequency oscillatory ventilation (11.9%), extracorporeal membrane oxygenation (4.2%), and prone positioning ventilation (3.0%). Overall mortality among critically ill patients at 90 days was 17.3% (95% confidence interval, 12.0%-24.0%; n = 29). CONCLUSION Critical illness due to 2009 influenza A(H1N1) in Canada occurred rapidly after hospital admission, often in young adults, and was associated with severe hypoxemia, multisystem organ failure, a requirement for prolonged mechanical ventilation, and the frequent use of rescue therapies.

DOI: 10.1001/jama.2009.1496

8 Figures and Tables

Citations per Year

4,524 Citations

Semantic Scholar estimates that this publication has 4,524 citations based on the available data.

See our FAQ for additional information.

Cite this paper

@article{Kumar2009CriticallyIP, title={Critically ill patients with 2009 influenza A(H1N1) infection in Canada.}, author={Anand Kumar and Ryan Zarychanski and Ruxandra Pinto and Deborah J Cook and John Marshall and Jacques Lacroix and Tom Stelfox and Sean Bagshaw and Karen Choong and Francois Lamontagne and Alexis F Turgeon and Stephen Lapinsky and St{\'e}phane P Ahern and Orla Smith and Faisal Siddiqui and Philippe Jouvet and Kosar Khwaja and Lauralyn McIntyre and Kusum Menon and Jamie Hutchison and David Hornstein and Ari Joffe and Francois Lauzier and Jeffrey Singh and Tim Karachi and Kim Wiebe and Kendiss Olafson and Clare Ramsey and Sat Sharma and Peter Dodek and Maureen Meade and Richard Hall and Robert A Fowler}, journal={JAMA}, year={2009}, volume={302 17}, pages={1872-9} }