Journal Article

Deconditioning does not explain orthostatic intolerance in ME/CFS (myalgic encephalomyelitis/chronic fatigue syndrome)

Visser, Frans C., Rowe, Peter C., van Campen, C. (Linda) M. C.

2021

Overview

Background Orthostatic intolerance (OI) is a frequent finding in individuals with myalgic encephalomyelitis /chronic fatigue syndrome (ME/CFS). Published studies have proposed that deconditioning is an important pathophysiological mechanism in various forms of OI, including postural orthostatic tachycardia syndrome (POTS), however conflicting opinions exist. Deconditioning can be classified objectively using the predicted peak oxygen consumption (VO 2 ) values from cardiopulmonary exercise testing (CPET). Therefore, if deconditioning is an important contributor to OI symptomatology, one would expect a relation between the degree of reduction in peak VO 2 during CPET and the degree of reduction in CBF during head-up tilt testing (HUT). Methods and results In 22 healthy controls and 199 ME/CFS patients were included. Deconditioning was classified by the CPET response as follows: %peak VO 2  ≥ 85% = no deconditioning, %peak VO 2 65–85% = mild deconditioning, and %peak VO 2  < 65% = severe deconditioning. HC had higher oxygen consumption at the ventilatory threshold and at peak exercise as compared to ME/CFS patients (p ranging between 0.001 and < 0.0001). Although ME/CFS patients had significantly greater CBF reduction than HC (p < 0.0001), there were no differences in CBF reduction among ME/CFS patients with no, mild, or severe deconditioning. We classified the hemodynamic response to HUT into three categories: those with a normal heart rate and blood pressure response, postural orthostatic tachycardia syndrome, or orthostatic hypotension. No difference in the degree of CBF reduction was shown in those three groups. Conclusion This study shows that in ME/CFS patients orthostatic intolerance is not caused by deconditioning as defined on cardiopulmonary exercise testing. An abnormal high decline in cerebral blood flow during orthostatic stress was present in all ME/CFS patients regardless of their %peak VO 2 results on cardiopulmonary exercise testing.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Anaerobic threshold / Biomedical and Life Sciences / Biomedicine / Blood flow / Blood pressure / Cardiopulmonary exercise test / Cerebral blood flow / Cerebral circulation / Chronic fatigue syndrome / Complications and side effects / Deconditioning / Development and progression / Diagnosis / Dysautonomia / Encephalomyelitis / Exercise / Fatigue / Fatigue Syndrome, Chronic / Flow velocity / Health aspects / Heart Rate / Humans / Hypotension / Illnesses of Unknown Etiology / Intolerance / Medicine/Public Health / Myalgic encephalomyelitis / Orthostatic hypotension / Orthostatic Intolerance / Oxygen consumption / Patients / Peak oxygen consumption / Physical training / Physiological aspects / Postural Orthostatic Tachycardia Syndrome / Posture / Pulmonary ventilation / Risk factors / Software / Tachycardia / Veins & arteries