TRANSDIAPHRAGMATIC PRESSURE GRADIENT (TPG) HAS A CENTRAL ROLE IN THE PATHOPHYSIOLOGY OF GASTROESOPHAGEAL REFLUX DISEASE (GERD) IN THE OBESE AND IT CORRELATES WITH ABDOMINAL CIRCUMFERENCE BUT NOT WITH BODY MASS INDEX (BMI)
Leonardo M. Del Grande1, Fernando A. M. Herbella*1, Rafael C. Katayama1, William G. Lima1, Marco G. Patti2
1Department of Surgery, Federal University of Sao Paulo, Sao Paulo - SP, Sao Paulo, Brazil; 2Department of Surgery and Medicine, University of North Carolina @ Chapel Hill, Chapel Hill, NC
Introduction: Pathophysiology of gastroesophageal reflux disease (GERD) is multifactorial. An increased transdiaphragmatic pressure gradient (TPG) may be a main element for GERD in the obese patient. This study aims to evaluate the role of TGP in obese individuals.
Methods: We studied 47 unselected consecutive candidates for bariatric operations (body mass index - BMI > 35). All patients underwent high resolution manometry and esophageal pH monitoring. Individuals were grouped as GERD + or GERD - based on DeMeester Score. Abdominal (AP) and thoracic pressures (TP), transdiaphragmatic pressure gradient (AP-TP) and lower esophageal sphincter (LES) retention pressure (LES basal pressure - TPG) were determined. Manometric variables were compared to a group of 20 lean healthy individuals (BMI <25).
Results: There were 27 (57%) GERD + patients and 20 (43%) GERD - patients. TPG, waist circumference, LES retention pressure and AP were higher in GERD + group as compared to GERD - individuals. GERD - group had manometric parameters similar to controls except for AP. GERD + patients had higher AP and TGP; and lower LES retention pressure compared to controls and GERD - patients. TPG and LES retention pressure correlated with waist circumference and DeMeester Score. BMI correlated with AP but not with waist circumference or DeMeester score. Waist circumference >=150 cm has 100% specificity for GERD diagnosis. AP>=21mmHg has 95% specificity for GERD.
Conclusion: GERD - obeses patients and lean volunteers have a similar pressure pattern. GERD presence and severity were associated to a high TPG due to increase AP that correlates with waist circumference but not with BMI in GERD + patients.
Pressures patterns for GERD + and GERD - patients
| GERD + | GERD - | p | confidence interval | |
| Abdominal pressure (mmHg) | 22.63±6.03 | 15.65±3.52 | <0.01 | 3.9 - 10.0 |
| Thoracic pressure (mmHg) | 9.42±4.43 | 11.0±4.17 | 0.2 | -1.1 - 4.3 |
| transdiaphragmatic pressure gradient (mmHg) | 13.14±6.20 | 4.72±4.69 | <0.01 | 5.5-11.7 |
| lower esophageal sphincter resting pressure (mmHg) | 16.50±8.61 | 18.62±7.58 | 0.4 | -7.2 -2.7 |
| lower esophageal sphincter retention pressure (mmHg) | 2.76±8.35 | 13.9±9.79 | <0.01 | 5.5 - 16.5 |
GERD = Gastroesophageal reflux disease
Demographic and anthropometric data for GERD + and GERD - patients
| GERD + | GERD - | p | confidence interval | |
| Age | 40.96±10.67 | 47.35±13.57 | 0.08 | -13.5 - 7.5 |
| Gender (% females) | 75 | 86 | 0.5 | - |
| Body Mass Index (kg/cm2) | 45.88±6.98 | 43.8±7.05 | 0.3 | -2.1 - 6.2 |
| waist circumference (cm) | 135.22±14.8 | 125.45±10.71 | 0.01 | -14.4 - -2.2 |
| DeMeester score | 46.16±40.15 | 7.29±4.35 | <0.01 | -56.4 - -20.1 |
GERD = gastroesophageal reflux disease
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