Use of Cardiopulmonary Stress Testing for Patients With Unexplained Dyspnea Post–Coronavirus Disease, 2021, Mancini et al

Abstract
Objectives
The authors used cardiopulmonary exercise testing (CPET) to define unexplained dyspnea in patients with post-acute sequelae of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection (PASC). We assessed participants for criteria to diagnose myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).

Background
Approximately 20% of patients who recover from coronavirus disease (COVID) remain symptomatic. This syndrome is named PASC. Its etiology is unclear. Dyspnea is a frequent symptom.

Methods
The authors performed CPET and symptom assessment for ME/CFS in 41 patients with PASC 8.9 ± 3.3 months after COVID. All patients had normal pulmonary function tests, chest X-ray, and chest computed tomography scans. Peak oxygen consumption (peak VO2), slope of minute ventilation to CO2 production (VE/VCO2 slope), and end tidal pressure of CO2 (PetCO2) were measured. Ventilatory patterns were reviewed with dysfunctional breathing defined as rapid erratic breathing.

Results
Eighteen men and 23 women (average age: 45 ± 13 years) were studied. Left ventricular ejection fraction was 59% ± 9%. Peak VO2 averaged 20.3 ± 7 mL/kg/min (77% ± 21% predicted VO2). VE/VCO2 slope was 30 ± 7. PetCO2 at rest was 33.5 ± 4.5 mm Hg. Twenty-four patients (58.5%) had a peak VO2 <80% predicted. All patients with peak VO2 <80% had a circulatory limitation to exercise. Fifteen of 17 patients with normal peak VO2 had ventilatory abnormalities including peak respiratory rate >55 (n = 3) or dysfunctional breathing (n = 12). For the whole cohort, 88% of patients (n = 36) had ventilatory abnormalities with dysfunctional breathing (n = 26), increased VE/VCO2 (n = 17), and/or hypocapnia PetCO2 <35 (n = 25). Nineteen patients (46%) met criteria for ME/CFS.

Conclusions
Circulatory impairment, abnormal ventilatory pattern, and ME/CFS are common in patients with PASC. The dysfunctional breathing, resting hypocapnia, and ME/CFS may contribute to symptoms. CPET is a valuable tool to assess these patients.

https://www.sciencedirect.com/science/article/abs/pii/S2213177921004807

 

article on the study
https://newatlas.com/health-wellbeing/long-covid-chronic-fatigue-syndrome-shortness-breath-fatigue/

eta: another article
https://www.crtonline.org/news-detail/chronic-fatigue-syndrome-common-in-covid-long-haul

eta2: and another
https://scitechdaily.com/covid-long...ormal-breathing-and-chronic-fatigue-syndrome/

https://inews.co.uk/news/science/long-covid-patients-chronic-fatigue-syndrome-1325934

 

This is nearly half. If half of all LC patients have ME this is a game changer. We need more studies urgently.

For example, if 11 million Americans are already known to have something like LC, then are there 5 million more Americans with ME? We need an answer to that question.

 

Disappointing that they seem to think that it is all down to poor breathing techniques which can be cured by retraining. There may well be a physiological/biological reason for that breathing pattern and retraining won't cure that.

 

Its a shame that the COVID gravy train seems to be open to all. I can't see much evidence here that these researchers understand this field, they've just jumped on the band wagon and came to the same naive & convenient conclusions about hyperventilation that other researchers did decades ago.

If they did a proper literature review they might've noticed that there's been a decade of specific research on dyspnea in dysautonomia/POTS that disproves their conclusion, assuming many of these patients also meet that diagnostic criteria, which they very likely would. I've not read the full-text but if they're not even aware of this it says it all really.

This and all the prior work it discusses would've been a good start:
Postural orthostatic tachycardia syndrome: A respiratory disorder?
https://www.sciencedirect.com/science/article/pii/S266594412100002X

 

perhaps a software tech could create an app to cross reference known research so those new to the field can save themselves from redoing the same research poorly . or is it just about easy money ?

 

Miriam Tucker for Medscape: In Long COVID, CPET Finds Abnormalities Other Tests Don't

quotes:

These data align completely with prior work in patients with both PASC and ME/CFS by David M. Systrom, MD, director of the Advanced CPET program and Dyspnea Clinic at Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, and colleagues.

...

Systrom and colleagues are now collaborating with the National Institutes of Health to develop plasma biomarkers that could be used in combination with CPET to either avoid or minimize the invasiveness, yet still allow for obtaining gas exchange and VO2 peak estimates for use in both ME/CFS and PASC patients. "We have some emerging evidence that there are distinct metabolomic, proteomic, and cytokine profiles or signatures in plasma, elicited by a brief bout of exercise in the blood that are very different from normal," he said, noting that it's possible these markers can be obtained via a small catheter in an antecubital vein rather than directly into the radial and pulmonary arteries.

...

19 patients (46%) met the 1994 "chronic fatigue syndrome" criteria. Mancini said that she didn't think the results would differ significantly had they used the more recent Institute (now Academy) of Medicine criteria published in 2015.

...

On the bright side, she noted that this dysfunctional breathing isn't associated with a high mortality. For now, she advises patients to consider yoga and, to the best of their ability, "breath slow and deep."

 

The full text is available for free here:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8629098/