O. Danilevskaya*a (Dr), A. Averyanova (Prof), E. Popovaa (Dr), D. Sazonovb (Dr), T. Klypab (Dr), F. Zabozlaevb (Prof), V. Lesnyakb (Dr), E. Ilyushnikovc (Dr), D. Panchenkovc (Prof), M. Bychininb (Dr)

a FSBI Pulmonology Scientific Research Institute under Federal Medical Biological Agency of Russia, Moscow, RUSSIAN FEDERATION ; b FSBI Federal Research and Clinical Center for Specialized Types of Medical Care and Medical Technologies of the Federal Medical Biological Agency of Russia, Moscow, RUSSIAN FEDERATION ; c A I Yevdokimov Moscow State University of Medicine and Dentistry of the Ministry of Healthcare of the Russian Federation, Moscow, RUSSIAN FEDERATION

* danless@mail.ru

Background. Probe-based confocal laser endomicroscopy (pCLE) is a minimally invasive technique for in vivo real-time microscopic imaging of proximal and distal airways during bronchoscopy [1]. The role of pCLE or alveoloscopy, has not yet been clearly established in covid-19 patients, especially correlating with HRCT data, BAL and traditional histopathology.

Methods. 15 COVID-19 positive patients were examined by HRCT,pCLEand BAL the next dayafter intubation. pCLE has been done in several right andleft lung segments to assess tissue microstructures, in the most and the least affected zones according to HRCT. 113 bronchopulmonary zones were examined by pCLE in total.

Results. In alveolar spaces in 27% of examined zones, pCLE showed large highly fluorescent floating structures 50-240 μm. Alveolar structure exhibited increased elastin fiber thickening in 58% of the zones were alveoloscopy was done, dystelectatic abnormalities were found in 34% of zones. Disorganized microvessel growth was also observed in 18% of zones. 7 patients died. On autopsy in 5 patients, protein agglomerates with increased expression of surfactant-associated protein A, macrophages and desquamated alveolocytes were found in the corresponding zones with floating structures detected by pCLE. BAL was predominantely lymphocytic in 67% of patients and neutrophilic in 33%.

Conclusions. pCLE is a useful diagnostic tool and could be useful in better understanding of the phase of acute respiratory distress syndrome observed in covid-19 [2] and in making a decision about potentially therapy with inhaled surfactant.

1. Thiberville L, Salaün M, Lachkar S, et al. Human in vivo fluorescence microimaging of the alveolar ducts and sacs during bronchoscopy. J Eur Respir. 2009;33:974-985.

2. Lesur O, Chagnon F, Lebel R, Lepage M. In vivo endomicroscopy of lung injury and repair in ARDS: potential added value to current imaging. J Clin Med 2019 Aug 11;8(8):1197.

Disclosure of funding source(s): none