The role of electrical impedance tomography in predicting the failure of non-invasive ventilation in patients with COVID-19-associated hypoxemic acute respiratory failure: a prospective observational study

Abstract

INTRODUCTION: Data on prediction of the failure of non-invasive lung ventilation (NIV) in patients with respiratory failure associated with COVID-19, based on electrical impedance tomography (EIT) patterns are limited. OBJECTIVE: To identify predictors of non-invasive lung ventilation failure in patients with respiratory insufficiency associated with COVID-19, using electrical impedance tomography data. MATERIALS AND METHODS: A monocenter prospective cohort observational study was conducted in patients with moderate-to-severe COVID-19-associated acute respiratory failure, who underwent NIV in the ICU (n = 43). EIT was used to measure the actual ventilation area (SVENT), hyperinflation area (SHYPER), ventilation delay zone (SRVD), and calculate the proportion of ventilated lungs (AVENT), proportion of hyperinflation area (ZHYPER), proportion of RVD area (ZRVD), as well as the duration of hyperinflation during one respiratory cycle (THYPER), and the ratio of hyperinflation time to inhalation time. RESULTS: The study included 43 patients admitted 15 (10–22) days after the onset of COVID-19. Patients with NIV failure (n = 34) had higher ZHYPER values on the first day (19.5 (16.3–30.5) in the NIV success group and 35.2 (25.0–45.0) in the failure group, AUROC 0.80, p = 0.004, Cut-off 39.7, Se 85 %, Sp 89 %) and the last day (20.6 (10.4–28.5) in the success group and 32.7 (26.4–43.3) in the failure group, AUROC 0.92, p = 0.003, Cut-off 32.7, Se 50 %, Sp 100 %), as well as a higher THYPER/TINSP ratio on the last day of NIV (37.5 (31.0–47.9) in the success group and 65.3 (43.7–88.4) in the failure group, AUROC 0.87, p = 0.001, Cut-off 52.7, Se 71 %, Sp 100 %). AVENT, ZRVD, and inhalation time did not show prognostic significance. CONCLUSIONS: EIT can predict the NIV failure in moderate-to-severe ARDS associated with COVID-19, based on the assessment of alveolar overdistention zones. Further research are needed to investigate this theory.