Impact of mechanical ventilation in acute exacerbation of interstitial lung disease: a bench study

<bold>Rationale:</bold> Patients with acute exacerbation of interstitial lung disease (AE-ILD) have poor prognosis during mechanical ventilation (MV) despite the use of protective ventilatory settings. To evaluate protective ventilation in AE-ILD, we modeled various MV conditions on a bench test. <bold>Methods:</bold> We simulated conditions of breathing pattern in AE-ILD in a two-compartment lung simulator with a global compliance of 27.5 ml/cmH₂O connected to an intubated high-fidelity manikin. We first tested incremental tidal volume (TV) (3, 4, 5, 6, 7 and 8 ml/kg) with a constant positive end-expiratory pressure (PEEP) of 4 cmH₂O and then incremental PEEP levels (0, 4, 5, 6 ,7 and 8 cmH₂O) in assist-control ventilation with a TV of 6 ml/kg. <bold>Results:</bold> During TV titration, at more than 5 ml/kg, we observed a significant decrease of dynamic compliance, and of end-expiratory lung volume (EELV), while plateau pressure (PPlat), driving pressure (ΔP), mechanical power (MP), end-expiratory, end-inspiratory and driving transpulmonary pressure (TPend-expi, TPend-inspi, ΔPTP), and alveolar strain (Strainalv) increased. During PEEP titration, at more than 4 cmH₂O, we observed in global lung, a significant decrease of dynamic compliance, and EELV, while PPlat, ΔP, MP, TPend-expi, TPend-inspi, ΔPtp and Strainalv increased. We observed a significant difference of dynamic compliance for thresholds of ΔP at 14 cmH₂O, of PPlat at 30 cmH₂O, and of TPend-inspi at 20 cmH₂O (p<0.01). <bold>Conclusion:</bold> This bench study supports the previously suspected deleterious effect of PEEP and could provide an overview of the most relevant protective ventilatory settings in mechanically ventilated patients with AE-ILD.