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.