Clinical Significance of Esophageal Outflow Resistance Imposed by a Nissen Fundoplication
BACKGROUND: Attention has been focused on the amplitude of esophageal body contraction to avoid persistent dysphagia after a Nissen fundoplication. The current recommended level is a contraction amplitude in the distal third of esophagus above the fifth percentile. We hypothesized that a more physiologic approach is to measure outflow resistance imposed by a fundoplication, which needs to be overcome by the esophageal contraction amplitude. STUDY DESIGN: The esophageal outflow resistance, as reflected by the intra-bolus pressure (iBP) measured 5 cm above the lower esophageal sphincter (LES), was measured in 53 normal subjects and 37 reflux patients with normal esophageal contraction amplitude, before and after a standardized Nissen fundoplication. All were free of postoperative dysphagia. A test population of 100 patients who had a Nissen fundoplication was used to validate the threshold of outflow resistance to avoid persistent postoperative dysphagia. RESULTS: The mean (SD) amplitude of the iBP in normal subjects was 6.8 (3.7) mmHg and in patients before fundoplication was 3.6 (7.0) mmHg (p = 0.003). After Nissen fundoplication, the mean (SD) amplitude of the iBP increased to 12.0 (3.2) mmHg (p < 0.0001 vs normal subjects or preoperative values). The 95th percentile value for iBP after a Nissen fundoplication was 20.0 mmHg and was exceeded by esophageal contraction in all patients in the validation population, and 97% of these patients were free of persistent postoperative dysphagia at a median 50-month follow-up. CONCLUSIONS: Nissen fundoplication increases the outflow resistance of the esophagus and should be constructed to avoid an iBP > 20 mmHg. Patients whose distal third esophageal contraction amplitude is >20 mmHg have a minimal risk of dysphagia after a tension-free Nissen fundoplication.