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VOLUME 19 , ISSUE 11 ( 2015 ) > List of Articles


Critical illness associated with 2013-2014 influenza A (H1N1): Postpandemic characteristics, presentation and outcomes

Dhruv Joshi, Jonathan Wiesen, Jorge A. Guzman, Abhijit Duggal

Keywords : Acute respiratory distress syndrome, influenza A, mechanical ventilation

Citation Information : Joshi D, Wiesen J, Guzman JA, Duggal A. Critical illness associated with 2013-2014 influenza A (H1N1): Postpandemic characteristics, presentation and outcomes. Indian J Crit Care Med 2015; 19 (11):636-641.

DOI: 10.4103/0972-5229.169328

License: CC BY-ND 3.0

Published Online: 01-06-2018

Copyright Statement:  Copyright © 2015; The Author(s).


Introduction: The United States experienced a postpandemic outbreak of H1N1 influenza in 2013-2014. Unlike the pandemic in 2009 clinical course and outcomes associated with critical illness in this postpandemic outbreak has been only sparsely described. Methods: We conducted a retrospective analysis of all patients admitted to the Medical Intensive Care Unit with H1N1 influenza infection in 2009-2010 (pandemic) and 2013-2014 (postpandemic). Results: Patients admitted in the postpandemic period were older (55 ± 13 vs. 45 ± 12, P = 0.002), and had a higher incidence of underlying pulmonary (17 vs. 7, P = 0.0007) and cardiac (16 vs. 8, P = 0.005) disease. Mechanical ventilation was initiated in most patients in both groups (27 vs. 21, P = 1.00). The PaO 2 /FiO 2 ratio was significantly higher in the pandemic group on days 1 (216 vs. 81, P = 0.0009), 3 (202 ± 99 vs. 100 ± 46, P = 0.002) and 7 (199 ± 103 vs. 113 ± 44, P = 0.019) but by day 14 no difference was seen between the groups. Rescue therapies were used in more patients in the postpandemic period (48% vs. 20%, P = 0.028), including more frequent use of prone ventilation (10 vs. 3, P = 0.015), inhaled vasodilator therapy (11 vs. 4, P = 0.015) and extracorporeal membrane oxygenation (ECMO) (4 vs. 2, P = NS). No significant differences in mortality were seen between the two cohorts. Conclusions: Compared to the 2009-2010 pandemic, the 2013-2014 H1N1 strain affected older patients with more underlying co-morbid cardio-pulmonary diseases. The patients had worse oxygenation indices and rescue modalities such as prone ventilation, inhaled epoprostenol and ECMO, were used more consistently as compared to the 2009 pandemic.

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