Ventilatory support and mechanical properties of the fibrotic lung acting as a “squishy ball”

Annals of Intensive Care

Table 1 Lung mechanical properties of three patients experiencing acute exacerbation of interstitial lung disease (AE-ILD)

Measurement	Patient 1 (CHP)		Patient 2 (IPF)		Patient 3 (CHP)
PEEP titration strategy	Lung resting strategy	Open lung approach	Lung resting strategy	Open lung approach	Lung resting strategy	Open lung approach
Set PEEP (cmH₂O)	4	12	4	12	4	12
Driving pressure (cmH₂O)	17.0	18.0	14.5	18.0	12.0	16.0
Transpulmonary pressure (cmH₂O)
End-inspiratory	14.0	16.7	9.9	16.0	10.0	13.9
End-expiratory	− 2.2	0.2	− 4.0	0.3	− 1.0	1.6
Driving pressure	16.2	16.5	14.0	16.3	11.0	12.3
Elastance (cmH₂O/L)
Respiratory system	44.6	51.6	34	47	40	43
Pulmonary	42.5	47.0	33.0	45.0	35.0	37.9
Chest wall	2.1	4.6	1.0	2.0	5.0	5.8
Blood arterial PaO₂/FiO₂ (mmHg)	92	78	113	110	85	79

Patient 1 and 3 presented chronic hypersensitivity pneumonitis (CHF) while patient 2 presented idiopathic pulmonary fibrosis (IPF) In each patient, two PEEP setting strategies were tested: a “lung resting strategy” aimed at minimizing PEEP while maintaining sufficient oxygenation (SpO₂ > 88–92%) and an “open lung approach” titrating PEEP aiming at avoiding negative end-expiratory transpulmonary pressure. The negative end-expiratory transpulmonary pressure values achieved at 4 cmH₂O PEEP suggest that low levels of PEEP do not prevent tidal alveolar de-recruitment. Nevertheless, higher levels of PEEP determined mild-to-critical increase in lung elastance and non-clinically relevant worsening of gas exchange
PEEP positive end-expiratory pressure