Risk factors associated to noninvasive ventilation failure in primary influenza A pneumonia in the critical care setting.

OBJECTIVE

To evaluate the risk factors associated to noninvasive mechanical ventilation (NIV) failure in patients with primary pneumonia due to influenza A (H1N1)pdm09 virus admitted to the intensive care unit (ICU), and to demonstrate the association of NIV failure to increased mortality and longer stays.

DESIGN

A cohort study was carried out.

SCOPE

A mixed ICU (16 beds) in a teaching hospital.

PATIENTS

Adult patients admitted to the ICU with a diagnosis of pneumonia due to influenza A (H1N1)pdm09 virus requiring mechanical ventilation.

MEASUREMENTS

Age, sex, severity scores, administration of corticosteroids, oseltamivir within 72h of symptoms onset, days of symptoms prior to admission, affected quadrants, hemodynamic parameters, renal failure, laboratory test data on admission, mortality and stay in ICU and in hospital.

RESULTS

A total of 54 patients were admitted to the ICU and 49 were ventilated; 29 were females (59.2%), and the mean age±standard deviation was 66.77±14.77 years. Forty-three patients (87.75%) were ventilated with NIV, and 18 (41.9%) of them failed. Patients with NIV failure were younger (63 vs. 74 years; p=0.04), with a higher SOFA score (7 vs. 4; p=0.01) and greater early hemodynamic failure (61.1 vs. 8%; p=0.01). In addition, they presented longer ICU (26.28 vs. 6.88 days; p=0.01) and hospital stay (32.78 vs. 18.8 days; p=0.01). The ICU mortality rate was also higher in the NIV failure group (38.9 vs. 0%; p=0.02). In the multivariate analysis, corticosteroid therapy (OR 7.08; 95% CI 1.23-40.50) and early hemodynamic failure (OR 14.77; 95% CI 2.34-92.97) were identified as independent risk factors for NIV failure.

CONCLUSIONS

Treatment with corticosteroids and early hemodynamic failure were associated to NIV failure in patients with primary pneumonia due to influenza A (H1N1)pdm09 virus infection admitted to the ICU. The failure of NIV was associated to increased mortality.