Background. Abdominal distention in patients with functional gut disorders is produced by abdominophrenic dyssynergia (blockade of the diaphragm), which can be corrected by electromyography-guided biofeedback, but the technique is complex and unpractical.

Aims & Methods. Our aim was to validate an original, simple biofeedback treatment for abdominal distension. In a randomized, parallel, placebo-controlled trial, 42 consecutive patients (36 women, 6 men; 17-64 yr age range) complaining of visible abdominal distension triggered by identified offending meals, who fulfilled the Rome IV criteria for functional intestinal disorders were recruited. Intervention: recordings of abdominal and thoracic wall motion were performed by pletismography, using adaptable belts; patients in the biofeedback group were shown the signal and instructed to mobilize the diaphragm, alternating thoracic inspirations (chest up, abdomen in) with diaphragmatic inspirations (chest down, abdomen out); patients in the placebo received no instructions and were given oral simethicone. Each patient underwent 3 sessions over a 4-wk treatment period with instructions to perform exercises (biofeedback group) or to take simethicone (control group) before meals. Outcomes: a) tolerance of an offending meal, measured as changes in abdominothoracic muscular activity (intercostal and anterior wall muscles by electromyography; primary outcome) and in girth (by tape measure); b) clinical symptoms, measured by daily 0-6 scales for 7 days.

Results. Patients on biofeedback, but not on placebo (n=19 analyzed per group), effectively learned to correct abdominophrenic dyssynergia triggered by the offending meal: patients learned to reduce intercostal activity (by 19±6% vs 0±2% on placebo; p<0.001) and to increase anterior wall activity (internal oblique increased by 74±7% vs 4±4% on placebo; p<0.001), and thereby prevented the increase in girth (objective distension improved by 66±5 % vs 9±3 % on placebo; p<0.001). Improvement of clinical symptoms was reported immediately after treatment (subjective sensation of abdominal distension improved by 66%±5% vs 8±3% on placebo; p<0.001), and further during follow-up (85±3% improvement at 1 mo and 94±1% at 6 mo).

Conclusion. Abdominophrenic dyssynergia and abdominal distention can be effectively corrected by biofeedback control of abdominothoracic wall motion guided by pletismography. ClincialTrials.gov no: NCT04043208.

Fernando Azpiroz

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