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Environ Anal Health Toxicol > Volume 37:2022 > Article
Environmental Analysis Health and Toxicology 2022;37(4):e2022033-0. doi: https://doi.org/10.5620/eaht.2022033
A 2-day cardiopulmonary exercise test in chronic fatigue syndrome patients who were exposed to humidifier disinfectants
Jong-Han Leem1 , Hyoung-Eun Jeon2 , Hun Nam2 , Hwan-Cheol Kim1 , Kyung-Lim Joa2
1Department of Occupational and Environmental Medicine, College of Medicine, Inha University, Incheon, Republic of Korea
2Department of Physical & Rehabilitation Medicine, College of Medicine, Inha University, Incheon, Republic of Korea
Corresponding Author: Kyung-Lim Joa ,Email: drjoakl@gmail.com
Received: August 30, 2022;  Accepted: October 19, 2022.
Some survivors of humidifier disinfectants (HDs) complain of chronic, inexplicable fatigue, and post-exertional malaise (PEM). Two-day cardiopulmonary exercise tests (CPETs) performed 24 hours apart (2-day CPET protocol) are increasingly employed to evaluate PEM and related disabilities among individuals with chronic fatigue syndrome (CFS). The purpose of this study was to assess the reproducibility of CPET variables in individuals who had been exposed to HD and to show that 2-day CPET is an objective means of differentiating between fatigue conditions in people with CFS symptoms who have been exposed to HDs. Twenty-nine HD survivors with CFS symptoms were enrolled in this study. To document and assess PEM in CFS, a 2-day CPET was conducted to measure baseline functional capacity (CPET1) and provoke PEM. Twenty-four hours later, a second CPET assessed changes in related variables, focusing on PEM effects on functional capacity. This CPET also measured changes in energy production and physiological function, objectively documenting PEM effects. In the 2-day CPET, the peak oxygen consumption (VO2peak), VO2 at ventilatory threshold (VO2@VT), time to reach VO2peak, and time to reach VO2@VT were significantly decreased (p<0.001). The peak O2 pulse and O2 pulse at VT also decreased significantly (p<0.001). A 6-minute walk test revealed significantly decreased distance (p<0.01). This is the first study to conduct a 2-day consecutive CPET in previously exposed HD participants with CFS symptoms. Our results confirm previous work that demonstrated abnormal responses to PEM in CFS patients. Therefore, a 2-day CPET is an objective measure to differentiate fatigue conditions in people with CFS symptoms who have been exposed to HDs.
Keywords: Chronic fatigue syndrome, post-exertional malaise, 2-day cardiopulmonary exercise test, Peak oxygen consumption, Ventilatory threshold
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