Retrospective immunohistological study of autopsied lungs in patients with acute exacerbation of interstitial pneumonia managed with extracorporeal membrane oxygenation

Background: Acute exacerbation of interstitial pneumonia (AE-IP) is a life-threatening pulmonary condition that involves various pathogeneses. In patients with AE-IP who need mechanical ventilation with high driving pressure and oxygen concentration, veno-venous extracorporeal membrane oxygenation (V-V ECMO) may diminish alveolar epithelial damage by decreasing ventilator settings. The pathophysiological benefit of this therapeutic option is not well investigated. Methods: We retrospectively collected 15 autopsied patients with AE-IP who were treated with mechanical ventilation in the intensive care unit (ICU) at Hiroshima University Hospital (Hiroshima, Japan) between 2010 and 2016. The patients were grouped by whether they were managed with mechanical ventilation only (the ventilator group, n=6) or with mechanical ventilation and V-V ECMO (the ECMO group, n=9). Results: The median age of the ventilator and ECMO group patients were similar (65 and 64 years, respectively). The severity score APACHE II in the ECMO group (35.0) is significantly higher than that of ventilator group (14.5) (P=0.006). Ventilator days were significantly shorter in the ventilator group (17.5 days) than in the ECMO group (30.0 days) (P=0.04). Compared with the ECMO group, the ventilator group had a stronger Masson-trichrome stain grade (4 vs . 6, P=0.04) and higher immunoreactivity grades for Krebs von den Lungen-6 (4 vs . 6, P=0.04) and IL-8 (3 vs . 6, P=0.02). Between the ventilator and ECMO groups, the immunoreactivity grades of angiopoietin 2 (4 vs . 1, P=0.08) and receptor for advanced glycation end products (2 vs . 1, P=0.52) did not differ. Conclusions: The lungs of mechanically ventilated AE-IP patients treated with V-V ECMO had decreased fibrosis, endothelial injury, and inflammation. This finding suggests the lung-protective efficacy of adjunctive V-V ECMO therapy.