Decrease of exercise endurance in critically ill COVID-19 survivors: 4 case reports

Abstract Background: The Coronavirus Disease 2019 (COVID-19) already have been as a pandemic. However, knowledge about the sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection remains limited. Here we descirbe the pulmonary function test (PFT) and cardiopulmonary exercise test (CPET) of critically ill COVID-19 in four cases with sereve acute respiratory distress syndrome (ARDS) after discharge.Case presentation: We introduce four patients who complained of fever, cough, chest tightness and other symptoms, all of them were confirmed as SARS-CoV-2 infection by real-time reverse transcription polymerase chain reaction (RT-PCR). They were treated with mechanical ventilation because of severe ARDS. After respiratory support, antiviral and anti-infective treatment, they were weaned from mechanic ventilation with the improvement of hypoxemia. All patients were discharged from the hospital after completion of treatment and had no mortality. Around 1-month post-discharge, they were followed up for chest computed tomography (CT) scan, and performed PFT and CPET. Peak oxygen uptake of predicted (peakVO2% pred) decreased in all four cases, although spirometry were in the normal range, and only 2 cases had mild decline in carbon monoxide diffusion capacity of predicted (DLCO%pred).Conclusions: We found reduced exercise endurance in all four COVID-19 survivors, even parts of them with normal or slightly abnormal static lung function. We also believe that exercise endurance impairment of COVID-19 convalescents is more likely affected by extrapulmonary factors. Taken the above into consideration, our study highlights that the combination of PFT and CPET are important tests for tracking the development and recovery of COVID-19 survivors.