Rationale: Acute exacerbation of interstitial lung diseases (AE-ILD) could be at high risk of developing P-SILI (patient self-inflicted lung injury).

Objective:To design a model for AE-ILD and assess conditions that favor volo- and atelec-trauma.

Methods: Based on our model of ventilation in patients with mild, moderate and severe ILD on a 2-compartment (A1 and A2) artificial mechanical lung simulator, we simulated AE-ILD and its worsening by increasing the proportion of altered alveoli. The model consisted of a proportion (X) of alveoli with basal compliance (C1) based on the ILD profile and a proportion (Y) of alveoli with altered compliance (C2), with X+Y= 100%. Tidal volume (TV), end-expiratory lung volume (EELV), driving pressure (?P), driving transpulmonary pressure (?P_tp), dynamic alveolar strain (Strain_alv), mechanical power (MP), time lag between inspiratory flow in A1 and A2 (?t _(Q1-Q2)) were measured.

Results: Regardless of the ILD profile, similar significative results were observed. For exemple, during the worsening of AE-ILD in a moderate ILD profile,TV remained stable but was higher in the compartment with the highest C, while EELV decreased (min value of 129 ml) particularly in the compartment with the lowest C, ?P increased (9.3 to 10.5 cmH2O), ?P_tp increased (6.3 to 10.8 cmH2O), Strain_alv increased (0.6 to 0.9), and MP increased (18.3 to 27.7 J/min). ?t _(Q1-Q2) was correlated with the difference in C between A1 and A2 (r=0.99, CI_95% (0,96;0,99), p=0.0002).     

Conclusion: This physiological bench study designed for the first time a mechanical ventilation model that can reproduce the heterogeneity of the lungs and mechanisms of volo- and atelec-trauma in AE-ILD.