Idiopathic pulmonary fibrosis is a life-threatening lung disease characterized by progressive deterioration of lung function and a median survival time of 3-5 years from diagnosis. The onset of an acute deterioration (AE) of respiratory function, the so called acute exacerbation of IPF (AE-IPF), may lead to severe hypoxemia, further worsening prognosis. During these events, the typical usual interstitial pneumonia pattern (UIP) - the radiologic and histologic hallmark of IPF- is overlapped with diffuse alveolar damage (DAD), sharing similarities with the acute respiratory distress syndrome (ARDS) and often requiring respiratory assistance. Several studies show that the need for mechanical ventilation (MV) is associated with high mortality in IPF patients, probably due to the pathophysiological properties of UIP-like fibrotic lung (i.e. collapse induration areas, elevated lung elastance, high inhomogeneity) that make it more susceptible to ventilatory-induced lung injury (VILI). It has been theorized that the application of PEEP on a UIP-like lung pattern can determine the protrusion of the most distensible areas through a dense anelastic fibrotic tissue circles, causing increased rigidity, worsening compliance, and thus enabling tissue breakdown. In this scenario, non-invasive mechanical ventilation (NIV) may therefore represent an alternative option to assist these patients, although no specific recommendations have been made so far. In patients with ARDS, the efficacy of NIV in reducing the patient's inspiratory effort early after its application has been related to a favorable clinical outcome. Indeed, the mitigation of respiratory drive might have resulted in a lower risk for the self-inflicted lung injury (SILI) during spontaneous breathing, whose onset is very likely to worse outcomes of patients undergoing acute respiratory failure (ARF).

To date no data available on the inspiratory effort and the lung mechanics in patients with AE-IPF either during unassisted of assisted spontaneous breathing. Aim of this study was then to compare respiratory mechanics, at baseline and 2-h following NIV application, in AE-IPF and ARDS patients matched for severity.

Inclusion Criteria:

previously established diagnosis of IPF; occurring acute exacerbation of IPF as defined by an acute, clinically significant respiratory deterioration characterized by evidence of new widespread alveolar abnormality on chest CT scan (12); age >18 years; presence of ARF with PaO2/FiO2 ratio <200 mmHg despite HFNC (set with at least 60 L/min and FiO2 higher than 0.6); suitability for a NIV trial according to the attending staff; consent to measure esophageal pressure.

Exclusion Criteria:

• acute cardiogenic pulmonary edema,
• concomitant hypercapnic respiratory failure (PaCO2 >45 mmHg) of any etiology,
• neuromuscular disease or chest wall deformities,
• home long-term oxygen therapy,
• intolerance or contraindication to NIV, such as the need for immediate endotracheal intubation

Patients with IPF developing AE consecutively admitted to the Respiratory Intensive Care Unit and the Intensive Care Unit of the University Hospital of Modena over the period August 1st, 2016 to January 1th, 2022 were prospectively considered eligible for enrollment.