Introduction

Pulmonary fibrosis (PF) after COVID-19 ARDS is a well-recognized entity. Unless usually stable, the course of this PF is variable. Viral-induced alveolar epithelial lung injury leads to fibroblast activation and PF. Alveolar epithelial cells type 2 hyperplasia expresses high levels of Krebs von den Lungen 6 (KL-6), a factor associated with poor prognosis in idiopathic PF.

Aim

The aim of the present study was to correlate ARDS sequelae and KL-6 levels in ICU-COVID-19 survivors.

Methods

ICU-COVID-19 survivors were assessed one-year post-ICU discharge by Chest CT Scanner, pulmonary function test and KL-6 dosage. Correlations between Chest CT sequelae (number of affected segments, type of sequelae), DLCO, FEV1, TLC and KL-6 levels were performed.

Results

21 patients (67% women, mean age: 57+11, 43% obese, 48% hypertension) have been assessed. In ICU, 57% required mechanical ventilation, 53% received dexamethasone, 29% tocilizumab and 14% remdesivir. Initial Chest CT showed a mean involved segments of 17/20 (ground glass opacities). One year later, decreased DLCO<80% and FEV1<80% were respectively present in 52% and 29% of included patients. Pathologic segments decreased to 9/20 on Chest CT (fibrotic lesions). Mean KL-6 was 524 U/mL and was increased in all but 4 patients (cut-off>275 U/mL).A positive correlation was observed between KL-6 and number of affected segments on Chest CT at one year (p=0.003).

Conclusion

High KL-6, a marker of PF, is still increased in most of ICU-COVID-19 survivors one year after ICU discharge and is associated with Chest CT sequelae. These results offer perspectives for further research focused on these severely disabled patients.