Lung pathophysiology in patients with long COVID-19: one size definitely does not fit all

Abstract

Despite reduced resting lung volumes and D LCO , patients with long COVID and dyspnoea have similar physiological response to exercise to healthy subjects. D LCO impairment can marginally explain heterogeneity of complex syndromes such as long COVID. https://bit.ly/40j4aX6

Reply to: Lung pathophysiology in patients with long COVID-19: one size definitely does not fit all

“…We were very pleased that our recent paper on long COVID [ 1 ] was found worthy to be accompanied by an editorial. We fully agree with R adovanovic and D ’ A ngelo [ 2 ] that, as for most medical conditions, one size does not fit all, but we think some of the issues they raised to our study deserve further clarification.…”

“…Second, R adovanovic and D ’ A ngelo [ 2 ] also question our interpretation of post-exercise recruitment of pulmonary capillary blood volume ( V C ) because we did not measure D LCO at different fractions of inspired oxygen. However, we used the simultaneous D LNO – D LCO technique, which has been proposed as an alternative to solve the Roughton–Forster equation without the need of measurements of CO uptake at different alveolar oxygen tensions [ 3 ], which would have been unfeasible over a short time after exercise.…”

“…Rather, our interpretation was that loss of alveolar volume ( V A ), using combined single-breath (4–6 s breath-hold time) D LNO – D LCO , was not the main reason for the reductions in D LNO and D LCO , though we made no causal inference with dyspnoea. R adovanovic and D ’ A ngelo [ 2 ] suggest uneven peripheral ventilation as the main putative mechanism underlying the decrement of V A . However, V A /total lung capacity ratio was close to unity (∼0.996) in our subjects, which makes poor mixing of the tracer gas unlikely.…”

Persistent alveolar bronchiolization, interstitial fibrosis and impaired lung function post-exercise are features of long-COVID in SARS-CoV-2-Delta variant infected aged hamsters

“…It is interesting to note that, both during the acute phase of the disease and long-COVID, patients often report dyspnea or coughing 50 . However, hamsters had very mild to moderate respiratory signs detectable by clinical scoring, limited only to the acute phase of the disease despite a marked alteration of lung function.…”

Effects of pulmonary rehabilitation on ventilation dynamics measured during exertion in patients with post-acute COVID-19 syndrome: A cross-sectional observational study

“…The lungs are the organ most affected by COVID-19, and respiratory symptoms and exercise intolerance are prevalent [7]. The persistence of dyspnea in patients who had pneumonia or milder forms of COVID-19 does not seem to be associated with the degree of disease severity or residual impairment of lung function [8]. Post-COVID-19 dyspnea and exercise intolerance are also potential contributors to small airway dysfunction and lung hyperinflation, which are demonstrated in these individuals [9][10][11][12].…”