The development of acute respiratory distress syndrome (ARDS) as a complication of mechanical ventilation in individuals with community-acquired pneumonia (CAP) may not be related to the etiology or mortality, according to a study published by the European Respiratory Journal.

Researchers conducted a prospective single-center observational cohort study of 125 individuals hospitalized during the course of 20 years (1996-2016) diagnosed with CAP, who underwent mechanical ventilation, and who met the Berlin criteria for ARDS. The purpose of the study was to determine the 30-day mortality, etiology, clinical characteristics, incidence, and risk factors in patients who underwent mechanical ventilation in the intensive care unit (ICU) and had severe CAP and ARDS compared with individuals who underwent mechanical ventilation and did not have ARDS.

Researchers hypothesized that there would be a higher mortality in individuals with severe CAP and ARDS compared with individuals without ARDS who required mechanical ventilation.

The results showed, and confirmed by propensity-adjusted multivariate analysis, that the 30-day mortality rate was similar in patients with and without ARDS (25% vs 30%, P =.25), even after adjusting for potential confounders (area under the curve, 0.79; 95% CI, 0.75-0.84). 

Based on the baseline arterial oxygen tension to inspired oxygen fraction ratios, patients’ clinical severity of ARDS was classified as mild (n=60; 48%), moderate (n=49; 40%), or severe (n=15; 12%), with 30-day mortality rates of 32%, 33%, and 60%, respectively. The most frequent pathogen identified was Streptococcus pneumoniae, with no significant difference in etiology noted among the severity groups. The variables associated with a higher risk for ARDS were a higher Sepsis-related Organ Failure Assessment score and previous antibiotic treatment. The only variable associated with a lower risk for ARDS was prior treatment with inhaled corticosteroids.

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Overall mortality and hospital length of stay was not significantly different between groups; however, ICU mortality was higher in individuals with pneumococcal CAP and ARDS (P =.026). It is important to note that a previous episode of pneumonia and receipt of the pneumococcal vaccine were independently associated with reducing 30-day mortality rates.

Researchers concluded that ARDS occurs in individuals who undergo mechanical ventilation and have CAP as a complication, but that it is not related to the etiology, and there was no difference in 30-day mortality rates between individuals with or without ARDS who underwent mechanical ventilation and had CAP. Clinicians should continue to provide appropriate respiratory support and encourage individuals of appropriate age to receive the pneumococcal vaccine because it was independently associated with reducing 30-day mortality rates.

Reference

Cilloniz C, Ferrer M, Liapikou A, et al. Acute respiratory distress syndrome in mechanically-ventilated patients with community-acquired pneumonia. Eur Respir J. 2018;51:1702481.