CHEST Guidelines-Insights-From-Invasive-Cardiopulmonary-Exercise-Te

Insights-From-Invasive-Cardiopulmonary-Exercise-Te

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This study investigates the pathophysiology of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) using invasive cardiopulmonary exercise testing (iCPET) and skin biopsies, particularly looking into potential links to small fiber neuropathy (SFN). ME/CFS, affecting up to 2.5 million Americans, overlaps with syndromic conditions like postural orthostatic tachycardia syndrome (POTS) and fibromyalgia, and evidence suggests SFN involvement in these disorders. <br /><br />The research analyzed 1,516 iCPETs on patients with exertional intolerance, focusing on 160 patients diagnosed with ME/CFS and under 36 control subjects. Results showed that ME/CFS patients had significantly lower right atrial pressures and peak oxygen uptake during exercise. Patients fell into either a low, normal, or high pulmonary blood flow group based on cardiac output and oxygen uptake changes during exercise. The low-flow group had lower peak cardiac output, while the high-flow group's systemic oxygen extraction was impaired, suggesting microvascular shunting.<br /><br />Findings revealed two types of neurovascular dysregulation: reduced cardiac output due to impaired venous return and decreased peripheral oxygen extraction efficiency. Moreover, 31% of the ME/CFS patients had biopsy-confirmed SFN, although nerve denervation severity did not correlate with exercise test variables.<br /><br />The study suggests that peripheral neurovascular dysregulation could be a contributor to exertional intolerance in ME/CFS, with SFN possibly causing neuropathic dysregulation, leading to inadequate oxygenation during exertion. While the research adds to understanding ME/CFS, further investigations are necessary to clarify SFN's role in this condition fully. Such insights could facilitate better diagnoses and treatment options, potentially important given post-COVID-19 syndrome developments showing similar characteristics.

Keywords

myalgic encephalomyelitis

chronic fatigue syndrome

invasive cardiopulmonary exercise testing

small fiber neuropathy

postural orthostatic tachycardia syndrome

fibromyalgia

neurovascular dysregulation

peripheral oxygen extraction

microvascular shunting

post-COVID-19 syndrome