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Moustafa Moussally*, Halim Bou Daher, Ala I. Sharara, Hani Tamim, Ramzi Alami
Internal Medicine, Gastroenterology Division, American University of Beirut Medical Center, Beirut, Lebanon

Introduction: Gastroesophageal reflux disease (GERD) is a common occurrence after laparoscopic sleeve gastrectomy (LSG). The pathophysiology of post-operative GERD is not well understood but is thought to be related to anatomic changes inflicted by sleeve gastrectomy. The aim of this study is to identify factors associated with post-operative GERD by measuring the trans-diaphragmatic pressure gradient and identify its effect on development of GERD.

Methods: A total of 59 LSG patients were followed for 3 years as part of prospective observational study. Patients were assessed for symptoms of GERD using the validated Gastroesophageal Reflux Disease Questionnaire (GERDQ). Cut-off scores of 8 or above were considered as positive for GERD. The trans-diaphragmatic pressure gradient was calculated using a formula derived from Bernouilli's principle ΔP α [1 -( re4/ rS4)] where ΔP (change in pressure) is P Stomach –P esophagus, re is radius of esophagus at the gastroesophageal junction and rs is the radius of stomach at incisura. Post-operative Gastrografin swallow studies were used to obtain the measurements. Analysis was done using SPSS version 23.0, Receiving Operator Characteristic (ROC) Curve, and Youden Index.

Results: There was no association between GERDQ score at 3 years and preoperative BMI or weight (p-value 0.97 and 0.5 respectively), percentage weight loss 3 years after LSG (p-value 0.9), Helicobacter pylori positive serology (p-value 0.89), or preoperative proton pump inhibitor use (p-value 0.97). There was a significant association between GERDQ score at 3 years and the ratio of radii which reflects trans-diaphragmatic pressure gradient (p-value 0.023) and preoperative GERDQ score (p value 0.009). For the ratio of radii, which is inversely proportional to the pressure gradient, we used the ROC curve and Younden Index to choose the cut-off value of 7.25. The mean GERDQ score was 8.1 among patients with a ratio <7.25 compared to 6.1 among those with a ratio ≥7.25 (p-value <0.001). PPI use was greater among those with a ratio <7.25 (66%) compared to those with a ratio ≥7.25 (42%). Among patients with a ratio <7.25, 20 of 35 patients (57%) had a GERDQ score >8. None of the 24 patients with a ratio ≥7.25 had a GERDQ score >8.

Conclusion: Development of GERD after LSG is multifactorial. Our study highlights that the resulting altered trans-diaphragmatic pressure gradient is an important determinant of GERD development. The measurement of the trans-diaphragmatic pressure gradient using our formula enables prediction of the development of GERD with high specificity (100%) and modest sensitivity (61%).

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