Persistent radiological abnormalities in correlation to lung function in survivors of severe COVID-19 pneumonia

Abstract

Introduction: There is little data about the impact of radiological changes on lung function in patients recovered from COVID-19 pneumonia who underwent mechanical ventilation.

Aim: to show a correlation between radiologic pattern at thoracic CT scan (normal, ground glass opacities (GGO), air trapping, fibrotic changes and consolidation) and impairment in lung function.

Methods: We performed lung function in 38 patients (30 males, mean age 60) by self-assessment of dyspnea (mMRC), spirometry, DLCO-SB and CT scan at 3 months after discharge from hospital. 32 patients received inspiratory and expiratory HRCT as planned, 6 had CT scan done elsewhere.

Results: 15% showed normal CT scan, 44% GGO, 26% fibrotic changes, 10% air trapping and 2% consolidations.

All patients with no changes at CT presented normal lung function and no dyspnoea, (defined as FEV1, FVC, and DLCO <80% of normal range and mMRC >0).

The group with GGO showed dyspnoea in 35%, impaired DLCO and lung function (41% and 23% respectively) those with fibrotic changes dyspnoea in 90%, DLCO and lung function (100% and 60%), those with air trapping dyspnoea in 50%, DLCO and lung function (50% and 75%), those with consolidation (only 1 patient) dyspnoea in 100% and DLCO 100%

Conclusions: Normal CT scan correlates with normal lung function as an expression of full respiratory recovery. While the most impaired values on symptoms and lung function are found in patients who showed radiologic fibrotic changes.

The most sensitive parameter of persistent lung damage is DLCO, as this was pathological in 62% off all patients irrespective of radiologic pattern.