Physiological effects of lung-protective ventilation in patients with lung fibrosis and usual interstitial pneumonia...

Although patients with interstitial pneumonia pattern (ILD-UIP) and acute exacerbation (AE) leading to severe acute respiratory failure may require invasive mechanical ventilation (MV), physiological data on lung mechanics during MV are lacking. We aimed at describing the physiological effect of lung-protective ventilation in patients with AE-ILD-UIP compared with primary ARDS.

Partitioned lung and chest wall mechanics were assessed in a series of AE-ILD-UIP patients matched 1:1 with primary ARDS as controls (based on BMI and PaO₂/FiO₂ ratio). Three PEEP levels (zero = ZEEP, 4-8 cmH₂O = PEEP_LOW, and titrated to achieve positive end-expiratory transpulmonary pressure P_L,EE = PEEP_TITRATED) were used for measurements.

Ten AE-ILD-UIP patients and 10 matched ARDS were included. In AE-ILD-UIP median P_L,EE at ZEEP was - 4.3 [- 7.6- - 2.3] cmH₂O and lung elastance (E_L) 44 [40-51] cmH₂O/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] cmH₂O and E_L to 49 [43-59] (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). In matched ARDS control PEEP titration to obtain a positive P_L,EE did not result in significant changes in E_L and ΔP_L.

In mechanically ventilated AE-ILD-UIP patients, differently than in patients with primary ARDS, PEEP titrated to obtain a positive P_L,EE significantly worsened lung mechanics.