The effects of slow deep breathing on microvascular and autonomic function and symptoms in adults with irritable bowel syndrome: A pilot study

Background:
Irritable bowel syndrome (IBS) is linked to disruptions in sympathovagal balance, which could impair vascular homeostasis and cause IBS symptoms. Studies have shown reductions in sympathetic activity following a single slow, deep breathing (SDB) bout in healthy adults; however, no studies have investigated its chronic effects in IBS. The purpose of this study was to evaluate the feasibility and impact of a SDB intervention on microvascular and autonomic function and symptoms in adults with IBS.

Methods:
Fourteen participants (ages 18-65 years) with IBS were randomly assigned to 4-week SDB or control conditions. The SDB group completed a 20-min video 5 times weekly while the control group maintained their normal activities. Microvascular endothelial function was measured using laser Doppler in response to thermal provocation and expressed as cutaneous vascular conductance at 39°C relative to a maximum response at 43.5°C (%CVCmax ). Heart rate variability (HRV) and post-exercise heart rate recovery (HRR) were employed as surrogate measures of autonomic function. IBS symptoms were assessed using the IBS-Severity Scale (IBS-SS).

Key results:
Thirteen participants (6 controls and 7 SDB) completed the study. Age (p = 0.541) and body mass index (p = 0.157) were similar between groups. In the SDB group, %CVCmax increased from 45% to 59% (p < 0.00001) after the 4-week intervention. HRV, HRR, and IBS-SS scores were unaltered.

Conclusions:
and Inferences. These results demonstrate the feasibility of a SDB intervention in adults with IBS and suggest improvements in microvascular function in the absence of changes in symptoms or autonomic function in this population.

Keywords: diaphragmatic breathing; irritable bowel syndrome; microvascular function.

PMID: 34595801 DOI: 10.1111/nmo.14275