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Acute respiratory failure from pandemic influenza A (H1N1) in an intensive care unit in southern Brazil


In the winter of 2009 the influenza A (H1N1) pandemic reached Brazil, affecting severely its southern states. A total 68,806 cases of suspected pandemic influenza A infection had been reported in Brazil and 91% of the specimens tested were positive. Incidence of pandemic influenza A in southern Brazil was 137/100,000. In the southern Brazilian state of Santa Catarina, Nereu Ramos Hospital is the referral center for the treatment of infectious diseases, and it provided eight intensive care beds for the management of acute respiratory failure from suspected cases of influenza A during the 2009 pandemic.


We collected retrospective data on the epidemiological features, clinical course and ventilatory characteristics of patients with laboratory-confirmed influenza A (H1N1) infection who were admitted to our ICU during the winter of 2009.


Thirty-four adult patients were admitted to our ICU with acute respiratory failure and suspected pandemic influenza A infection. Of these, 14 cases tested positive for influenza A (H1N1). The majority of the patients were male (61.5%) with median age of 27.5 years and interquartile range (IR) of 26.5 to 48.5. The APACHE II median was 14.5 (IR 10.0 to 18.25) with median predicted mortality of 20.0 (IR 10.73 to 27.7). Risk factors were: obesity (23.1%), obstructive respiratory diseases (15.4%); pregnancy, immunosuppressive and neuromuscular disorders were present in one patient each. All 14 patients presented severe respiratory failure, with a median lowest PaO2/IOF of 113.3 (IR 83.53 to 159.55) and 92.3% of them requiring mechanical ventilation. The patients in mechanical ventilation were all ventilated in pressured-controlled mode, demanded high PEEP levels (mean of 18.5 ± 5.16 cmH2O), presented high peak inspiratory pressure (mean of 37.83 ± 7.35 cmH2O) and required elevated IOF (81.15 ± 20.83%). A total of 57.1% of the patients were submitted to lung recruitment, while the prone position was used in 42.8% of them. The median ICU stay was 13.0 days (IR 4.75 to 23.50) and the median hospital stay was 16.5 days (IR 9.75 to 25.0). The ventilatory-associated pneumonia (VAP) rate was unusually high (69.2%) as well as the mortality rate during the intensive care stay (38.5%).


Patients admitted to our ICU with confirmed pandemic influenza A infection presented severe acute respiratory failure and an unusually high incidence of VAP and mortality rates.


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    Perez-Padilla R, et al: Pneumonia and respiratory failure from swine-origin influenza A (H1N1) in Mexico. N Engl J Med. 2009, 361: 680-689. 10.1056/NEJMoa0904252.

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Correspondence to S Beduschi Filho.

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Filho, S.B., Siqueira, D., Flores, S.C. et al. Acute respiratory failure from pandemic influenza A (H1N1) in an intensive care unit in southern Brazil. Crit Care 14, P91 (2010).

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  • Influenza
  • Interquartile Range
  • Acute Respiratory Failure
  • Pandemic Influenza
  • Peak Inspiratory Pressure