USING A FUNCTIONAL LUMEN IMAGING PROBE TO EVALUATE ADEQUACY OF INTERVENTION AND PREDICT PATIENT OUTCOMES IN THE SURGICAL TREATMENT OF ACHALASIA
Bailey Su*1,2, Zachary M. Callahan2, Stephanie M. Novak2, Kristine Kuchta2, JoAnn Carbray2, Michael Ujiki2
1University of Chicago, Chicago, IL; 2General Surgery, Northshore University HealthSystem, Evanston, IL
Introduction
The functional lumen imaging probe (FLIP) is an innovative tool that uses impedance planimetry to assess esophageal geometry in real time. It can be used in the operating room to evaluate the adequacy of myotomy after laparoscopic Heller myotomy (LHM) and peroral endoscopic myotomy (POEM) for the treatment of achalasia. Its correlation with patient outcomes has not been well defined, particularly long-term outcomes. We hypothesize that impedance planimetry can be utilized intra-operatively to assess adequacy of myotomy and assist in predicting and improving patient outcomes.
Methods
This is a retrospective review of a prospectively maintained patient database at a single center. Seventy-five patients with achalasia underwent POEM or LHM by a single surgeon. The FLIP was used to measure minimum diameter (Dmin), balloon pressure and distensibility index (DI) of the lower esophageal sphincter (LES) before and after the procedure. The measurements were used immediately to evaluate the adequacy of myotomy. Clinical and objective outcomes were measured up to one year after treatment. Post-operative Eckardt, Reflux Severity Index (RSI), Gastroesophageal Reflux Disease-Health Related Quality of Life (GERD-HRQL) and Dysphagia Scores were compared to post-operative FLIP measurements using Fisher's exact test and Spearman's rank correlation coefficients.
Results
Post-operative Dmin, balloon pressure and DI values were all significantly different from pre-operative values (p < .001). The Dmin increased from 6.1 mm to 10.9 mm, balloon pressure decreased from 32.1 mmHg to 26.0 mmHg and DI increased from 1.2 mm2/mmHg to 4.0 mm2/mmHg. Although there was no correlation between final DI and outcome at one year, patients with increased percent change of distensibility reported significantly less dysphagia at one year (rs = -0.532, p < 0.05). Patients with a larger percent change of Dmin also trended towards having less dysphagia at one year (rs = -0.404, p = 0.054). Lastly, patients with a larger Dmin had more reflux, with a final Dmin >11.5 mm being associated with a 2.5-times higher risk of antacid use at one year (66.7% vs 26.3%, p = 0.026).
Conclusion
Impedance planimetry using the FLIP is a novel way to provide real-time feedback about the geometry of the LES, which allows a surgeon to make adjustments during myotomy for achalasia. The most useful parameters in predicting patient outcomes have yet to be clearly defined. While a greater percentage change in DI and Dmin were associated with less dysphagia at one year, there was also an increased risk of antacid use, specifically at Dmin > 11.5 mm. These findings suggest that proportional changes in FLIP measurements should be taken into consideration as they may contribute towards predicting symptom resolution.
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