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

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Background: To evaluate dysphagia in relation to bolus movement in patients undergoing 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 & bolus movement variables. An iterative analysis determined if any variables were altered in relation to dysphagia. Standard measures of esophago-gastric junction (EGJ) pressure, bolus presence time (BPT) and total bolus transit time (TBTT) were also evaluated. Key Results: At 5 months post-op, 15 patients had some dysphagia, including 7 with new-onset dysphagia. For viscous boluses, three AIM-derived pressure-flow variables recorded pre-operatively varied significantly in relation to post-operative 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, mmHg s-1). These variables were combined to form a dysphagia risk index (DRI) of esophageal dysfunction (DRI = IBP*IBP_slope/TNadImp-PeakP). DRI values derived from pre-operative measurements were significantly elevated in those with post-operative dysphagia (DRI 58, IQR 21-408 vs no dysphagia DRI 9, IQR -2-19, p 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 post-operative dysphagia. Thus susceptibility to post-fundoplication dysphagia is related to a pre-existing sub-clinical variation of esophageal function.