Susceptibility to dysphagia after fundoplication revealed by novel automated impedance manometry analysis

Background Conventional measures of esophageal pressures or bolus transport fail to identify patients at risk of dysphagia after laparoscopic fundoplication. Methods Liquid and viscous swallows were evaluated with impedance/manometry in 19 patients with reflux disease before and after surgery. A new method of automated impedance manometry (AIM) analysis correlated esophageal pressure with impedance data and automatically calculated a range of pressure and bolus movement variables. An iterative analysis determined whether any variables were altered in relation to dysphagia. Standard measures of esophago-gastric junction pressure, bolus presence time, and total bolus transit time were also evaluated. Key Results At 5months postop, 15 patients reported some dysphagia, including 7 with new-onset dysphagia. For viscous boluses, three AIM-derived pressure-flow variables recorded preoperatively varied significantly in relation to postoperative dysphagia. These were: time from nadir esophageal impedance to peak esophageal pressure (TNadImp-PeakP), median intra-bolus pressure (IBP, mmHg), and the rate of bolus pressure rise (IBP slope, mmHgs^-1). These variables were combined to form a dysphagia risk index (DRI=IBP×IBP_slope/TNadImp-PeakP). DRI values derived from preoperative measurements were significantly elevated in those with postoperative dysphagia (DRI=58, IQR=21-408 vs no dysphagia DRI=9, IQR=2-19, P<0.02). A DRI >14 was optimally predictive of dysphagia (sensitivity 75% and specificity 93%). Conclusions & Inferences Before surgery, a greater and faster compression of a swallowed viscous bolus with less bolus flow time relates to postoperative dysphagia. Thus, susceptibility to postfundoplication dysphagia is related to a pre-existing sub-clinical variation of esophageal function.