Physiological effects of lung protective ventilation in patients with lung fibrosis and usual interstitial pneumonia pattern versus primary ARDS: a matched-control study

Abstract Background Although patients with AE-ILD and UIP pattern may experience severe acute respiratory failure requiring invasive MV, physiological data on lung mechanics during these events are lacking. We aimed to describe the physiological effect of lung protective ventilation in patients with AE-ILD-UIP and to compare it with primary ARDS. Methods Partitioned lung and chest wall mechanics were compared between patients AE-ILD-UIP and 1:1 matched primary ARDS (based on BMI and PaO 2 /FiO 2 ratio) within a PEEP trial performed within 24 h from intubation and comprising three levels of PEEP [(ZEEP), 4–8 cmH 2 O (PEEP LOW ) and PEEP titrated to achieve positive end-expiratory transpulmonary pressure (P L,EE ) (PEEP TITRATED )] Results Ten patients with AE-ILD-UIP and 10 matched with primary ARDS were included. In AE-ILD-UIP median P L,EE at ZEEP was − 4.3 [-7.6 – -2.3] cmH 2 O and lung elastance (E L ) 44 [40–51] cmH 2 O/L. At PEEP LOW , P L,EE remained negative and E L did not change (p = 0.995) versus ZEEP. At PEEP TITRATED , P L,EE increased to 0.8 [0.3–1.5] cmH 2 O and E L to 49 [59–43] (p = 0.004 and p < 0.001 compared to ZEEP and PEEP LOW , respectively). ΔP L decreased at PEEP LOW (p = 0.018) and increased at PEEP TITRATED (p = 0.003). Differently than AE-ILD-UIP, in ARDS matched controls PEEP titration to obtain a positive P L,EE did not result in changes in E L and ΔP L . Conclusions In mechanically ventilated AE-ILD-UIP, lower PEEP levels did not impact on E L and ΔP L whereas, differently than in patients with primary ARDS, PEEP titrated to obtain a positive P L,EE worsened E L and ΔP L .