Characteristics and Outcomes of Diffuse Interstitial Pneumonias Discovered in ICU. A Retrospective Monocentric Study, the “IPIC” (Interstitial Pneumonia in Intensive Care) Study

Background. Interstitial lung disease (ILD) is a heterogenous group of disorders char-acterized by an association of inflammatory and fibrotic abnormalities of the lung. An acute respiratory failure (ARF) may represent the initial picture of the disease. This study aims to highlight the diagnosis of ILD in intensive care unit (ICU) and describe the epidemiologic, prognosis, and imaging features of patients with ILD diagnosed in our ICU department. We conducted a single-center retrospective study. We screened all the 2,459 patients admitted to our ICU from October 2017 to February 2020. The inclusion criteria consisted of the ILD diagnosis criteria. For each patient, clinical data and lung computed tomog-raphy scan patterns were analyzed. The selected cases were then reviewed by an expert team in the tertiary care teaching hospital of Marseille (Hôpital Nord, Marseille, France). Results During the study period, 26 ICU patients were diagnosed with ILD and 20 cases were confirmed by the expert team. The most frequent diagnoses were idiopathic ILD (n = 7, 35%), auto-immune disease related ILD (n = 7, 35%), exposure-related ILD (n = 3, 15%) and carcinomatous lymphangitis (n = 3, 15%). Fifteen patients were men (75%), with a mean age of 70 [62 – 72] years. Median SOFA score was 4 [3-7]and 16 (80%) received invasive mechanical ventilation. The mean ratio of the partial ratio of oxygen to the fraction of inspired oxygen was 174 [148 – 198] mmHg. The ICU mortality rate of our cohort was significantly higher than in the average ICU mortality (65% vs 26%, p< 0.003). The mortality rate was lower among the subgroup of auto-immune disease related ILD (57%). Conclusions We conducted a single-center cohort of patients diagnosed with ILD in the ICU. This rare cause of ARF was associated with poor outcome in ICU, but auto-immune disease related ILD seemed to have a better prognosis. Lung high-resolution CT and identifi-cation of lesion patterns are the cornerstone of the diagnosis. Improved knowledge of ILD and multidisciplinary discussion involving radiologists, pneumologists and intensivists may result in an earlier diagnosis and eventually im-proved treatments.