End-tidal CO2 in patients with panic, stress-related or persistent somatic symptoms versus healthy controls

Abstract

Introduction A dysregulated autonomic stress physiology is hypothesized to play an important role in the etiology and perpetuation of somatic symptoms that cannot be (fully) medically explained1,2,3.

Methods The aim of this study was to focus on the role of the respiratory system. We examined end-tidal CO2 concentration (PetCO2) in healthy controls (HC; n=30), and in patient groups experiencing panic (n=36), stress-related (overstrain; n=35, burnout; n=44) or persistent somatic symptoms in daily life [fibromyalgia (FM) and/or chronic fatigue syndrome (CFS); n=36]. Further, we explored perfectionism, experiential avoidance, and self-reported trauma in the different groups. Participants filled out questionnaires and went through a rest period and a respiratory challenge with recovery, whilst PetCO2 was continuously monitored.

Results Our results suggest: 1) an overactive respiratory system to be a transdiagnostic underlying factor of panic disorder, overstrain, and burnout, and 2) the presence of a more active fight-flight response in less chronic and severe disorders (overstrain), which gradually becomes more passive as symptoms become more chronic and severe (FM/CFS). Finally, our data show higher perfectionism and experiential avoidance in all patients, and higher self-reported trauma in FM/CFS patients compared to HC.

Discussion Although respiratory dysfunctions are often seen as a specific characteristic of panic disorder, the present study found evidence for an overactive respiratory system be a transdiagnostic underlying factor of both panic and stress-related disorders.

Process evaluation A limitation is that we only studied one respiratory parameter. Research including multiple psychophysiological parameters is needed to confirm the specificity of the current findings.

References 1. Martinez-Martinez L, Mora T, Vargas A, et al. Sympathetic nervous system dysfunction in fibromyalgia, chronic fatigue syndrome, irritable bowel syndrome, and interstitial cystitis: a review of case-control studies. Journal of Clinical Rheumatology; 2014; 20(3): 146-150. 2. May R, Seibert G, Sanchez-Gonzalez M, et al. Physiology of school burnout in medical students: Hemodynamic and autonomic functioning. Burnout Research; 2016; 3(3): 63-68. 3. Meeus M, Goubert D, De Backer F, et al. Heart rate variability in patients with fibromyalgia and patients with chronic fatigue syndrome: a systematic review. Seminars in Arthritis and Rheumatism; 2013; 43(2): 279-287.