ABSTRACT
Introduction: NIRS reduces intubation rate in COVID-19 pneumonia. Outcome is related to age, comorbidities, and baseline illness severity. Thoracic CT has prognostic value in COVID-19 pneumonia. Forced Oscillatory Technique (FOT) allows non-invasive assessment of respiratory reactance (Xrs) that is related to lung compliance. A pilot study showed FOT feasibility in patients with COVID-19 pneumonia receiving NIRS (1). Aim(s): Measuring Xrs in COVID19 patients receiving NIRS and correlate with CT. Method(s): The local ERB approved the study. 32 consecutive patients with moderate-severe COVID-19 ARDS were enrolled. Patients underwent non-invasive ventilation (NIV) alternated to High Flow Nasal Cannula (HFNC). In the first 24 hours of hospitalization triplicate FOT measurements were performed (Resmon ProFULL) according to current guidelines during HFNC. Within 1 week 28 patients underwent computed tomographic pulmonary angiography (CTPA) and collapsed, infiltrated and normally inflated areas were quantified (3D Slicer software). Result(s): 12 patients had altered Xrs-z score. Collapsed areas correlated with Xrs z-score (rho=0.37;p=0.046) and almost with inspiratory Xrs (rho=-0.36;p=0.055). Inflated areas correlated with inspiratory Xrs (rho=0.42;p=0.024) while infiltrated areas didn't. In our cohort CTPA and FOT parameters didn't discriminate outcomes but inflated areas were inversely related to hospitalization (rho=-0.43;p=0.04). Conclusion(s): FOT showed abnormal Xrs in a subset of patients. Xrs z-score is a noninvasive index of collapsed areas in COVID-19 pneumonia and could be useful in patients assessment and follow up.