Effect of body position on lower esophageal sphincter pressure.

This study examined the effect of body position on lower esophageal sphincter (LES) pressure. In 36 healthy subjects and 31 patients with reflux esophagitis, LES and intragastric pressures were measured with subjects in the supine and sitting positions by the intraluminal microtransducer method. LES pressure was significantly lower in the sitting position than in the supine position in both healthy subjects and patients with reflux esophagitis. Intragastric pressure was significantly higher in the sitting position than in the supine position in both healthy subjects and patients with reflux esophagitis, but this increase was less marked than the decrease in LES pressure in the sitting position. The overlap of LES pressure values between healthy subjects and patients with reflux esophagitis was lower in the sitting position than in the supine position. We conclude that the measurement of LES pressure in the sitting position reflects LES function more accurately.