Clinical Significance of Esophageal Outflow Resistance Imposed by a Nissen Fundoplication

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.

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.

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.

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.