BACKGROUND: The primary objective of the study is to describe the cellular characteristics of bronchoalveolar lavage fluid (BALF) of COVID-19 patients requiring invasive mechanical ventilation; the secondary outcome is to describe BALF findings between survivors vs non-survivors . MATERIALS AND
METHODS: Patients positive for SARS-CoV-2 RT PCR, admitted to ICU between March and April 2020 were enrolled . At ICU admission, BALF were analyzed by flow cytometry . Univariate, multivariate and Spearman correlation analyses were performed .
RESULTS: Sixty-four patients were enrolled, median age of 64 years (IQR 58-69). The majority cells in the BALF were neutrophils (70%, IQR 37.5-90.5) and macrophages (27%, IQR 7-49) while a minority were lymphocytes , 1%, TCD3+ 92% (IQR 82-95). The ICU mortality was 32.8% . Non-survivors had a significantly older age (p = 0.033) and peripheral lymphocytes (p = 0.012) were lower compared to the survivors . At multivariate analysis the percentage of macrophages in the BALF correlated with poor outcome (OR 1.336, CI95% 1.014-1.759, p = 0.039).
CONCLUSIONS: In critically ill patients, BALF cellularity is mainly composed of neutrophils and macrophages . The macrophages percentage in the BALF at ICU admittance correlated with higher ICU mortality . The lack of lymphocytes in BALF could partly explain a reduced anti-viral response.