Outcome of influenza A (H1N1) patients admitted to intensive care units in the Paraná state, Brazil.

Objective: This study aimed to analyze outcome, clinical and epidemiological characteristics and severity factors in adult patients admitted with a diagnosis of infection by virus A (H1N1) to public and private intensive care units, in Paraná, Brazil.

Methods: Cohort study of medical charts of patients older than 12 years admitted to 11 intensive care units in 6 cities in the state of Parana, Brazil, during a period of 45 days, with diagnosis of swine influenza. The diagnosis of infection with A (H1N1) was made by real time polymerase chain reaction (RT-PCR) of nasopharyngeal secretion, or strong clinical suspicion when other causes had been ruled out (even with negative RT-PCR). Descriptive statistics were performed, analysis by the Chi square test was used to compare percentages and the Student's t test for continuous variables with univariate analysis, assuming a significance level of p <0.05.

Results: There were 63 adult patients admitted with a diagnosis of H1N1, 37 (58.7%) being RT-PCR positive. Most patients were young adults (65% under 40 years of age) with no gender predominance and high incidence of obesity (27.0% with Body Mass Index > 30). Mean of the Acute Physiologic Chronic Health Evaluation II (APACHE II) score was 15.0 + 8.1. Mortality in the intensive care unit was 39.7%. The main factors associated with mortality were: positive RT-PCR, low levels of initial PaO2/FiO2, high initial levels of urea and lactate dehydrogenase, required level of positive end expiratory pressure, need for the prone position and vasopressors.

Conclusions: Adult patients with A (H1N1) virus infection admitted to intensive care units had a high risk of death, particularly due to respiratory impairment. Positive RT-PCR, urea and lactic dehydrogenase, low initial PaO2/FiO2 and high levels of PEEP were correlated with higher mortality.