Anthropometric correlates of intragastric pressure

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Abstract
Obesity may increase intra-abdominal pressure on the stomach leading to an increase in intragastric pressure, which in turn induces lower esophageal sphincter relaxation, with subsequent reflux. However, the association between anthropometric measures of total body as well as abdominal obesity and intragastric pressure has not been examined. This prospective cross-sectional study included consecutive patients undergoing manometry at an open access Reflux Center. Standardized measurements of body-weight, height, and waist and hip circumference were prospectively obtained. To assess the intragastric pressure, the perfusion port levels of the catheter were verified to be at the same vertical height (0 mmHg) inside the patient as they were outside the patient during calibration. Correlation between gastric pressure and anthropometric measures was calculated and adjusted for demographic features and presenting symptoms. A total of 322 patients (67% women) with a mean age of 52.5 years were enrolled. The mean values for weight, height, and body mass index (BMI) were 77.2 kg, 168 cm, and 27.5 kg/m2, respectively (range 16.0-52.0, median 27.0). The mean intragastric pressure was 2.9 cm H2O (SD: 1.7). There was a weak, positive correlation between gastric pressure and both BMI (r=0.11, p=0.05) and waist circumference (r=0.11, p=0.06). The associations between gastric pressure and both BMI and waist circumference were relatively unaffected by adjusting for several variables including age, indications for manometry, race, and gender in a multivariable linear regression model. For each unit increase in BMI, there was approximately a 10% increase in intragastric pressure. In this study of consecutive patients with wide-ranging BMI values, there was a weak, positive correlation between intragastric pressure and both BMI and waist circumference. This indicates that obesity operates to increase the risk of gastroesophageal reflux disease (GERD) at least partly by increasing intragastric pressure.