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Should lower respiratory tract secretions from intensive care patients be systematically screened for influenza virus during the influenza season
Critical Care, 06/21/2012
Giannella M et al. – During the influenza season, almost one–third of critical patients with suspected lower respiratory tract infection had influenza, and in 48.4% the influenza was unsuspected. Lower respiratory samples from adult intensive care units (ICU) should be systematically screened for influenza during seasonal epidemics.
Methods- The authors performed a prospective study of patients admitted to 3 adult ICUs of the hospital from December 2010 to February 2011.
- All tracheal aspirate (TA) samples sent to the microbiology department were systematically screened for influenza.
- They defined influenza as unsuspected if testing was not requested and the patient was not on empirical antiviral therapy after sample collection.
- The authors received TA samples from 105 patients.
- Influenza was detected in 31 patients and was classified as unsuspected in 15 patients (48.4%) and as hospital–acquired in 13 (42%) patients.
- Suspected and unsuspected cases were compared, and significant differences were found for age (53 vs. 69 median years), severe respiratory failure (68.8% vs. 20%), surgery (6.3% vs. 60%), median days of ICU stay before diagnosis (1 vs. 4), nosocomial infection (18.8% vs. 66.7%), cough (93.8% vs. 53.3%), localized infiltrate on chest x–ray (6.3% vs. 40%), median days to antiviral treatment (2 vs. 9), pneumonia (93.8% vs. 53.3%), and acute respiratory distress syndrome (75% vs. 26.7%).
- Multivariate analysis showed admission to the surgical ICU (OR 37.1, 95%CI 2.1 – 666.6, p=0.01) and localized infiltrate on chest x–ray (OR 27.8, 95%CI 1.3–584.1, p=0.03) to be independent risk factors for unsuspected influenza.
- Overall mortality at 30days was 29%.
- ICU admission for severe respiratory failure was an independent risk factor for poor outcome.