Exertional intolerance and dyspnea with preserved lung function: an emerging long COVID phenotype?, 2021, Lam et al

Abstract

The COVID-19 pandemic has resulted in significant acute morbidity and mortality worldwide. There is now a growing recognition of the longer-term sequelae of this infection, termed “long COVID”. However, little is known about this condition. Here, we describe a distinct phenotype seen in a subset of patients with long COVID who have reduced exercise tolerance as measured by the 6 min walk test. They are associated with significant exertional dyspnea, reduced health-related quality of life and poor functional status. However, surprisingly, they do not appear to have any major pulmonary function abnormalities or increased burden of neurologic, musculoskeletal or fatigue symptoms.

Open access, https://respiratory-research.biomedcentral.com/articles/10.1186/s12931-021-01814-9

 

Sad that the 6 minute walking test was not repeated again on a day two, as this does not enable us to distinguish between increased fatiguability and PEM.

 

They appear oblivious that this is an old thing, but it's good that they recognized it organically with zero awareness. If only they could, I don't know, check? But how can you check something when you are unaware of it?

I assume it would take them several years to organically do repeat tests and notice the degradation of performance.

We are quite literally seeing medicine repeat the last several decades of early research, finding the exact same things, and being completely unaware of it. It's good that they are finally reaching the starting line but 16+ months in is a bit of an embarrassment, but I guess that's about the best that can be done.

 

The 6 minute walking test is not maximal (or reliant on a ramped workrate protocol), so it is fairly meaningless.

They are claiming these people are suffering from dyspnea, but without fatigue or pulmonary impairment - but the latter claim is not based on prospective data and is therefore uncontrolled.

A single CPET test won't be useful either, unless we happen to know the individuals pre-COVID test results. I guess they could do a prospective study, if some of the participants happen to recover and are compared to those who don't.