Markers of poor outcome in patients with acute hypoxemic respiratory failure

Abstract

Purpose: This study described the acute hypoxemic respiratory failure (AHRF) population and identified potential modifiable markers of outcome.

Methods: A prospective, multicenter study was performed in 22 intensive care units (ICUs). The clinical outcomes of patients with acute respiratory distress syndrome (ARDS) were compared to the outcomes in patients with non-ARDS AHRF, and a propensity score matched analysis was performed.

Results: A total 837 patients with an arterial oxygen tension/fraction of inspired oxygen ratio (Pao2/Fio2) less than 300 mm Hg on ICU admission were included. Of these, 163 patients met the criteria defining ARDS, whereas the remaining 674 patients who had unilateral or no pulmonary opacities were classified as non-ARDS AHRF. Baseline Pao2/Fio2 ratio, thrombocytopenia, increased positive end-expiratory pressure (PEEP) were significantly associated with the 60-day mortality in hypoxemic respiratory failure after multivariate analysis. However, ARDS was not associated with increased 60-day mortality when independent predictors for the 60-day mortality and propensity score were controlled. In the case-control study, the 60-day mortality rate was 38.6% in the ARDS group and 32.3% in the non-ARDS AHRF group. In both patients with ARDS and non-ARDS AHRF, the mortality rate increased proportionally to a lower baseline Pao2/Fio2.

Conclusion: Lower baseline oxygenation (Pao2/Fio2) is a poor prognostic marker in acute hypoxemic respiratory failure.

Keywords: ARDS; Acute respiratory failure; Hypoxemia.