Single‐breath counting test predicts non‐invasive respiratory support requirements in patients with covid‐19 pneumonia

Abstract

The use of non‐invasive respiratory strategies (NIRS) is crucial to improve oxygenation in COVID‐19 patients with hypoxemia refractory to conventional oxygen therapy. However, the absence of respiratory symptoms may delay the start of NIRS. The aim of this study was to determine whether a simple bedside test such as single‐breath counting test (SBCT) can predict the need for NIRS in the 24 h following the access to Emergency Department (ED). We performed a prospective observational study on 120 patients with COVID‐19 pneumonia. ROC curves were used to analyze factors which might predict NIRS requirement. We found that 36% of patients had normal respiratory rate and did not experience dyspnea at rest. 65% of study population required NIRS in the 24 h following the access to ED. NIRS‐requiring group presented lower PaO2/FiO2 (235.09 vs. 299.02), SpO2/FiO2 ratio (357.83 vs. 431.07), PaCO2 (35.12 vs. 40.08), and SBCT (24.46 vs. 30.36) and showed higher incidence of dyspnea at rest (57.7% vs. 28.6%). Furthermore, SBCT predicted NIRS requirement even in the subgroup of patients without respiratory symptoms (AUC = 0.882, cut‐off = 30). SBCT might be a valuable tool for bedside assessment of respiratory function in patients with COVID‐19 pneumonia and might be considered as an early clinical sign of impending respiratory deterioration.