Prognostic evaluation by oxygenation with positive end-expiratory pressure in acute exacerbation of idiopathic pulmonary fibrosis: A retrospective cohort study.

INTRODUCTION: Acute exacerbation (AE) is a severe complication of idiopathic pulmonary fibrosis (IPF), which shares some common pathological features with acute respiratory distress syndrome (ARDS). The new definition of ARDS requires positive end-expiratory pressure (PEEP) to assess gas exchange and has better predictive validity for short-term mortality compared with the previous definition.

OBJECTIVES: The aim of this study was to evaluate the prognostic utility of oxygenation with PEEP in AE-IPF.

METHODS: We performed a retrospective cohort study using the data of AE-IPF patients between 2007 and 2015. At the time of diagnosis, PaO2 /FiO2 was evaluated before and 30 minutes after PEEP. We evaluated the prognostic utility of PaO2 /FiO2 with PEEP after including other candidate prognostic factors. Considering the definition of ARDS, patients with AE-IPF were classified into a severe group (PaO2 /FiO2  ≤ 300 with PEEP) and a non-severe group (PaO2 /FiO2  > 300 with PEEP).

RESULTS: We identified 62 consecutive patients with AE-IPF. All patients were treated with mechanical ventilation on the first day. The median PaO2 /FiO2 before and 30 minutes after PEEP was significantly increased (237.5-425.5, P < .001). In multivariate Cox proportional analysis, Krebs von den Lungen-6 (KL-6) (HR 1.239; 95%CI 1.050-1.461; P = .011), D-dimer (HR 1.039; 95%CI 1.015-1.064; P = .001), % neutrophils in bronchoalveolar lavage fluid (HR 1.015; 95%CI 1.003-1.027; P = .017), and being in the severe group (HR 3.233; 95%CI 1.503-6.957; P = .003) had significant impacts on survival up to 90 days.

CONCLUSION: Evaluation of oxygenation with PEEP may provide useful information for predicting short-term mortality in patients with AE-IPF.