Unraveling pathophysiologic mechanisms contributing to symptoms in patients with post-acute sequelae of COVID-19 (PASC): A retrospective study

Personalized pulmonary rehabilitation program for patients with post-acute sequelae of COVID-19: A proof-of-concept retrospective study

Long-COVID patients present with a decline in physical fitness. The aim of this study is to reveal the impact of pulmonary rehabilitation (PR) on physical fitness, quality of life (QoL), and parameters of quantified thorax CT. Long-COVID patients enrolled in a 3-month PR program were retrospectively studied. PR included endurance and resistance training three times a week. Assessments pre- and post-rehabilitation included quantified chest CT, pulmonary function tests (PFT), six-minute walk test (6MWT), cardiopulmonary exercise test, and questionnaires: Hospital Anxiety and Depression Scale, post-COVID-19 Functional Status scale, Borg score, and EuroQol. Seventeen subjects (5M/12F), mean age 42 ± 13 years, were included. PR improved all questionnaires' results significantly. Only significant difference in PFT parameters was correlation between baseline total lung capacity (TLC) and difference in TLC pre- and post-rehabilitation (p = 0.002). 6MWT increased from 329 to 365 m (p < 0.001), VO2max changed from 21 to 24 mL/kg/min (p = 0.007), peak load increased from 116 to 141 Watt (p < 0.001). Blood volume in small pulmonary vessels of 1.25 to 5 mm2 in cross-sectional area (BV5%) was higher than observed in patients with acute COVID-19 infection. After rehabilitation, BV5% decreased from 65% to 62% (p = 0.020). These changes correlated directly with changes in TLC (p = 0.039). Quantified CT airway volume increased after rehabilitation (p = 0.013). After rehabilitation, TLC tended to normalize due to (re)opening of small airways, with decline in air trapping and recruitment of alveoli. Furthermore, this study revealed that pulmonary rehabilitation can improve QoL and physical fitness in long-COVID patients.

Unraveling pathophysiologic mechanisms contributing to symptoms in patients with post-acute sequelae of COVID-19 (PASC): A retrospective study

Patients with post-acute sequelae of COVID-19 (PASC) present with a decrease in physical fitness. The aim of this paper is to reveal the relations between the remaining symptoms, blood volume distribution, exercise tolerance, static and dynamic lung volumes, and overall functioning. Patients with PASC were retrospectively studied. Pulmonary function tests (PFT), 6-minute walk test (6MWT), and cardiopulmonary exercise test were performed. Chest CT was taken and quantified. Patients were divided into two groups: minor functional limitations (MFL) and severe functional limitations (SFL) based on the completed Post-COVID-19 Functional Status scale (PCFS). Twenty one patients (3 M; 18 FM), mean age 44 (IQR 21) were studied. Eighteen completed the PCFS (8 MFL; 10 SFL). VO2 max was suboptimal in both groups (not significant). 6MWT was significantly higher in MFL-group (p = 0.043). Subjects with SFL, had significant lower TLC (p = 0.029). The MFL-group had more air trapping (p = 0.036). Throughout the sample, air trapping correlated significantly with residual volume (RV) in L (p < 0.001). An increase in air trapping was related to an increase in BV5 (p < 0.001). Mean BV5 was 65% (IQR 5%). BV5% in patients with PASC was higher than in patients with acute COVID-19 infection. This increase in BV5% in patients with PASC is thought to be driven by the air trapping in the lobes. This study reveals that symptoms are more driven by occlusion of the small airways. Patients with more physical complaints have significantly lower TLC. All subjects encounter physical limitations as indicated by suboptimal VO2 max. Treatment should focus on opening or re-opening of small airways by recruiting alveoli.