Physiology of intra-abdominal and intrathoracic Nissen fundoplications in a porcine model

Background: The physiologic competency of intrathoracic fundoplications rem ains controversial. This study compared the physiologic qualities of intra- abdominal Nissen fundoplications (LAF) with those of intrathoracic Nissen f undoplications (ITF) in a porcine model. Methods: The lower esophageal sphincter (LES) length (cm), LES resting pres sure (mm Hg), and intragastric pressure (mm Hg) necessary to produce reflux or wrap distribution were manometrically assessed before and after IAF and ITF in 10 pigs. Mean +/- SD were compared using analysis of variance. Results: There was no difference in LES length before and after IAF or ITF, but there was a significant increase in resting LES pressure after either IAF or ITF (P < 0.0001). In every fundoplication, physiologic intragastric pressures (<65 mm Hg) could not induce reflux, whereas supraphysiologic int ragastric pressures resulted in wrap disruption of the most distal suture i n every fundoplication, producing a full-thickness tear in the gastric wall . The amount of intragastric pressure necessary to disrupt either IAF or IT F was significantly greater than the intragastric pressures that produced r eflux before fundoplication (P < 0.0001). However, there was no difference in intragastric pressures producing wrap disruption of IAF and ITF. Conclusions: Nissen fundoplications remain physiologically competent regard less of intra-abdominal or intrathoracic position.