Yield pressure: a new concept in the evaluation of GERD?

This study evaluates the yield pressure at the gastroesophageal junction in a group of 73 patients undergoing diagnostic endoscopy and in another group of 82 patients during the course of manometry for suspected GERD. The group included 17 patients who had previously undergone a successful Nissen fundoplication and eight patients who had a failed Nissen fundoplication. Air is insufflated into the stomach, and a water perfused pressure transducer is used to detect intragastric pressure. The pressure at which the cardia was seen to open at endoscopy, or when a common cavity phenomenon was detected at manometry, was taken as the opening pressure. Yield pressure was calculated as the difference between the opening pressure of the cardia and the resting gastric pressure. Results indicated a significant decrease in yield pressure in 65 patients with esophagitis compared with 65 patients with no evidence of reflux or esophagitis. A significant inverse correlation was found between yield pressure and the size of the hiatus hernia noted in these patients. There was also a correlation between valvular appearance of the cardia at endoscopy and the yield pressure. A progressive decrease in yield pressure occurred with an increasing deterioration in the physical appearance of the valve. There was no significant relationship found between yield pressure and lower esophageal sphincter (LES) pressure or intra-abdominal length. A small but significant relationship was found between yield pressure and acid exposure of the lower esophagus. The 17 patients with a successful Nissen showed a significantly increased yield pressure to supranormal values. In contrast, the eight patients with a failed Nissen had yield pressures within the range of the patients with esophagitis. In eight patients, yield pressure was measured by both manometry and endoscopy and showed no significant differences between the two methods.