The Role of Transsphincteric Pressure and Proximal Gastric Volume in Acid Reflux Before and After Fundoplication

Background & Aims: This study was conducted to explore the role of proximal gastric volume and transsphincteric pressure on acid reflux during transient lower esophageal sphincter relaxation (TLESR) in patients with gastroesophageal reflux disease (GERD) both before and after laparoscopic fundoplication. Methods: Twenty GERD patients were studied before and after fundoplication along with 20 healthy controls. High-resolution manometry and pH recording was performed for 1 hour before and 2 hours following meal ingestion (500 mL/300 kcal). Three-dimensional ultrasonographic images of the stomach were acquired before and every 15 minutes after meal ingestion. Results: Postprandial proximal to total gastric volume distribution ratios were significantly larger in GERD patients before fundoplication (0.57 ± 0.01; P < .05) and smaller following fundoplication (0.37 ± 0.01; P < .001) compared with controls (0.46 ± 0.01). The percentage of TLESRs associated with acid reflux did not relate to proximal gastric volume in any subject group. The transsphincteric pressure profile was different for TLESRs with and without reflux in GERD patients as well as in healthy controls. The pressure gradient across the esophagogastric junction (EGJ) (ΔEGJp) was greater for TLESRs with acid reflux compared with TLESRs without acid reflux in both GERD patients (11.4 ± 0.8 vs 8.0 ± 0.5 mm Hg, respectively; P < .01) and controls (10.6 ± 0.7 vs 7.1 ± 0.8 mm Hg, respectively; P < .05). After fundoplication, ΔEGJp during TLESRs was 7.9 ± 0.9 mm Hg, and the transsphincteric pressure profile markedly changed. Conclusions: Although proximal gastric volume plays a key role in eliciting TLESRs, it is not related to the incidence of acid reflux during TLESRs. The transsphincteric pressure gradient is greater in TLESRs associated with acid gastroesophageal reflux.