Bronchoalveolar lavage fluid characteristics and outcomes of invasively mechanically ventilated patients with COVID-19 pneumonia in Genoa, Italy

Chiara Dentone,Nicolò Patroniti,Antonio Vena,Lucia Taramasso,Emanuela Barisione,Elisabetta Tedone,Andrea Orsi,Martina Bavastro,Matteo Cerchiaro,Federica Grillo,Emanuele Delfino,Maurizio Loconte,Sara Mora,Chiara Sepulcri,Rachele Pincino,Rosa Mangerini,Laura Magnasco,Giancarlo Icardi,Antonio Di Biagio,Andrea De Maria,Paolo Pelosi,Lorenzo Ball,Iole Brunetti,Paolo Frisoni,Małgorzata Mikulska ,Laura Ambra Nicolini ,Bianca Bruzzone,Angelo Gratarola,Daniele Roberto Giacobbe,Luca Mastracci,Matteo Bassetti

doi:10.1186/s12879-021-06015-9

Abstract

BackgroundThe 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 methodsPatients 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.ResultsSixty-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).ConclusionsIn 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.

Highlights

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
At multivariate analysis the percentage of macrophages in the BALF correlated with poor outcome
In critically ill patients, BALF cellularity is mainly composed of neutrophils and macrophages

Summary

Introduction

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. In December 2019, in China emerged a new coronavirus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the new disease caused by this virus is named coronavirus disease 2019 (COVID-19). The spectrum of clinical manifestations of SARS-CoV-2 infection is vast, ranging from asymptomatic or patients with few symptoms to complication of severe viral pneumonia with the acute respiratory distress syndrome (ARDS) [1,2,3,4]. An excessive inflammatory response to SARS-CoV-2 is a major cause of disease severity and death and is associated with high levels of circulating cytokines, severe lymphopenia and mononuclear cell lung infiltration [5]. In lungs with characteristic diffuse alveolar damage [1] and in the bronchoalveolar lavage fluid (BALF) [7, 8], monocytes and macrophages were prevalent, with a moderate numbers of multinucleated giant cells, and very few lymphocytes. Most of the infiltrating lymphocytes were CD4-positive T cells [1]

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