SARS-CoV-2 infection sequelae on exercise response: persistent or reversible? A 2-year perspective

Association of Pulmonary Involvement at Baseline with Exercise Intolerance and Worse Physical Functioning 8 Months Following COVID-19 Pneumonia

Objectives: We aimed to describe the cardiopulmonary function during exercise and the health-related quality of life (HRQoL) in patients with a history of COVID-19 pneumonia, stratified by chest computed tomography (CT) findings at baseline. Methods: Among 77 consecutive patients with COVID-19 who were discharged from the Pulmonology Ward between March 2020 and April 2021, 28 (mean age 54.3 ± 8.6 years, 8 females) agreed to participate to the current study. The participants were analyzed in two groups based on pulmonary involvement (PI) at baseline chest CT applying a threshold of 25%. A consequent artificial intelligence (AI)-guided total opacity score (TOS) was calculated in a subgroup of 22 patients. A cardiopulmonary exercise test (CPET) was conducted on average 8.4 (±1.9) months after discharge from the hospital. HRQoL was defined using the short-form (SF-36) questionnaire. The primary outcome was exercise intolerance that was defined as a peak oxygen uptake (V'O2peak) < 80% predicted. Secondary outcomes were ventilatory limitation, defined as breathing reserve < 15%, circulatory limitation, defined as oxygen pulse predicted below 80%, and deconditioning, defined as exercise intolerance in the absence of ventilatory and circulatory limitations. Other secondary outcomes included the SF-36 domains. Results: In all, 15 patients had at least 25% PI (53.6%) at baseline chest CT. Exercise intolerance was observed in ten patients (35.7%), six due to deconditioning and four due to circulatory limitation; none had ventilatory limitation. AI-guided TOS was 30.1 ± 24.4% vs. 6.1 ± 4.8% (p < 0.001) at baseline, and 1.7 ± 3.0% vs. 0.2 ± 0.7% (nonsignificant) at follow-up in high and low PI groups, respectively. The physical functioning (PF) domain score of the SF-36 questionnaire was 66.3 ± 19.4 vs. 85.0 ± 13.1 in high and low PI groups, respectively (p = 0.007). Other SF-36 domains did not differ significantly between the groups. A high PI at baseline was inversely correlated with V'O2peak (standardized β coefficient = -0.436; 95% CI -26.1; -0.7; p = 0.040) and with PF scores (standardized β coefficient -0.654; 95% CI -41.3; -7.6; p = 0.006) adjusted for age, sex, body mass index and lung diffusion capacity. Conclusions: One-third of participants experienced exercise intolerance eight months after COVID-19 pneumonia. A higher PI at baseline was significantly associated with exercise intolerance and PF. Notwithstanding, the radiological PI was resolved, and the exercise intolerance was mainly explained not by ventilatory limitation but by circulatory limitation and deconditioning.

Persistence of Diffusion Capacity Impairment and Its Relationship with Dyspnea 12 Months after Hospitalization for COVID-19

Background: Dyspnea is a common persistent symptom after acute coronavirus disease 2019 illness (COVID-19). One potential explanation for post-COVID-19 dyspnea is a reduction in diffusion capacity. This longitudinal study investigated diffusion capacity and its relationship with dyspnea on exertion in individuals previously hospitalized with COVID-19. Methods: Eligible participants had been hospitalized for the treatment of acute COVID-19 and were assessed at 6 weeks, 6 months, and 12 months after discharge. Pulmonary function testing, diffusion capacity of carbon monoxide (DLCO), blood gas analysis and the level of dyspnea (Borg scale; before and after a 6 min walk test [6 MWT]) were performed. Participants were divided into subgroups based on the presence or absence of dyspnea during the 6 MWT at 12 months after hospitalization. Results: Seventy-two participants (twenty-two female, mean age 59.8 ± 13.5 years) were included. At 12 months after discharge, 41/72 participants (57%) had DLCO below the lower limit of normal and 56/72 (78%) had DLCO < 80% of the predicted value. Individuals with exertional dyspnea had significantly lower DLCO than those without exertional dyspnea (p = 0.001). In participants with DLCO data being available at three timepoints over 12 months (baseline, 6 months, and 12 months) after discharge (n = 25), DLCO improved between 6 weeks and 6 months after hospital discharge, but not thereafter (p = 0.017). Conclusions: About 2/3 of the post-COVID individuals in this study had impaired diffusion capacity at 12 months after hospital discharge. There was an association between persisting dyspnea on exertion and significantly reduced DLCO. Impaired diffusion capacity improved over the first 6 months after hospitalization but not thereafter.

Post-exertional malaise in daily life and experimental exercise models in patients with myalgic encephalomyelitis/chronic fatigue syndrome

Post-exertional malaise (PEM) is commonly recognized as a hallmark of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and is often used as one of several criteria for diagnosing ME/CFS. In this perspective paper we want to reflect on how PEM is understood, assessed, and evaluated in scientific literature, and to identify topics to be addressed in future research. Studies show that patients use a wide variety of words and concepts to label their experience of PEM in everyday life, and they report physical or mental exertions as triggers of PEM. They also report that PEM may have an immediate or delayed onset and may last from a few days to several months. When standardized exercise tests are used to trigger PEM experimentally, the exacerbation of symptoms has a more immediate onset but still shows a wide variability in duration. There are indications of altered muscular metabolism and autonomic nervous responses if exercise is repeated on successive days in patients with ME/CFS. The decreased muscular capacity appears to be maintained over several days following such controlled exercise bouts. These responses may correspond to patients' experiences of increased exertion. Based on this background we argue that there is a need to look more closely into the processes occurring in the restitution period following exercise, as PEM reaches the peak in this phase.