The Relationship between Cardiovascular Function and Decreased Intra-Abdominal Pressure Following Stool Evacuation

Abdominal organs, though less than one-tenth of body mass, receive about 30% of cardiac output, with two-thirds passing through the descending aorta. The abdominal cavity contents-including organs, adipose tissue, and stool-affect peripheral vascular resistance. This study evaluated the impact of stool evacuation exceeding routine daily volume on intra-abdominal vascular resistance and systemic blood pressure. We retrospectively reviewed records of 56 patients who underwent tap water enemas for bloating and constipation. Episodes with >400 g body weight reduction after evacuation were analyzed. Blood pressure, body weight, BMI, mean arterial pressure (MAP), and pulse pressure (PP) were measured before and after evacuation. In hypertensive patients (systolic BP ≥140 mmHg), MAP decreased significantly, with notable PP differences between groups (p<.05). Comparisons among normotensive (≤119 mmHg), prehypertensive (120-139 mmHg), and hypertensive (≥140 mmHg) groups revealed significant MAP changes (p<.001). These findings suggest that stool evacuation beyond routine volume is associated with changes in intra-abdominal vascular resistance and correlates with systemic circulation, particularly showing a reduction in blood pressure among hypertensive individuals.