Rumination syndrome: Assessment of vagal tone during and after meals and during diaphragmatic breathing.

Background: Pathophysiology of rumination syndrome (RS) is not well understood. Treatment with diaphragmatic breathing improves rumination syndrome. The aim of the study was to characterize vagal tone in patients with rumination syndrome during and after meals and during diaphragmatic breathing.
Methods: We prospectively recruited 10 healthy volunteers (HV) and 10 patients with RS. Subjects underwent measurement of vagal tone using heart rate variability. Vagal tone was measured during baseline, test meal and intervention (diaphragmatic (DiaB), slow deep (SlowDB), and normal breathing). Vagal tone was assessed using mean values of root mean square of successive differences (RMSSD), and area under curves (AUC) were calculated for each period. We compared baseline RMSSD, the AUC and meal-induced discomfort scores between HV and RS. Furthermore, we assessed the effect of respiratory exercises on symptom scores, and number of rumination episodes.
Key Results: There was no significant difference in baseline vagal tone between HV and RS. During the postprandial period, there was a trend to higher vagal tone in RS, but not significantly (P > .2 for all). RS had the higher total symptom scores than HV (P < .011). In RS, only DiaB decreased the number of rumination episodes during the intervention period (P = .028), while both DiaB and SlowDB increased vagal tone (P < .05 for both). The symptom scores with the 3 breathing exercises showed very similar trends.
Conclusions and Inferences: Patients with RS do not have decreased vagal tone related to meals. DiaB reduced number of rumination events by a mechanism not related to changes in vagal tone.
(© 2020 John Wiley & Sons Ltd.)