Bariatric Surgery and Gastroesophageal Reflux

Introduction

The epidemic of morbid obesity in the United States has reached dramatic proportions. Because of the associated comorbidities and because life style changes and exercise have limited effect, bariatric surgery has been used more often during the last 10 years as it has been shown to be safe and effective in decreasing weight and resolving comorbidities.

Gastroesophageal reflux disease (GERD) is a common comorbidity in patients who have severe obesity. It has been shown that a high body mass index (BMI) increases the risk of GERD symptoms, erosive esophagitis, Barrett's esophagus, and adenocarcinoma, and that there is a dose–response relationship between increasing BMI and prevalence of GERD and its complications.^1,2

GERD in Obese Patients

The pathophysiology of GERD in these patients is multifactorial, but different from individuals who are not obese. Herbella et al. reviewed the esophageal manometry and the ambulatory pH monitoring studies of 599 consecutive patients with GERD, specifically looking at the lower esophageal sphincter (LES) profile, esophageal peristalsis, and the esophageal acid exposure. ³ Patients were divided into two groups based on the BMI: 520 patients with a BMI <35 and 79 patients with a BMI ≥35. A linear regression model showed that BMI, LES pressure, LES abdominal length, and distal esophageal amplitude were independently associated with the reflux score. After adjusting for these variables as well as age and gender, BMI remained independently associated with the reflux score. For each five point increase in the BMI, the reflux score increased by three points. ³ This finding is, in part, explained by the presence in obese patients of an increased pressure gradient between the abdomen and the chest (transdiaphragmatic pressure gradient [TDPG]). ⁴ In obese individuals, the intra-abdominal pressure is increased, correlating with the BMI and the waist circumference. In addition, about 70% of patients have obstructive sleep apnea, which determines a more negative intrathoracic pressure, therefore, increasing the TDPG and promoting reflux. ⁵ The increased intra-abdominal pressure also disrupts the integrity of the gastroesophageal junction, determining the presence of a hiatal hernia—present in about 40% of morbidly obese patients—which contributes to the presence of abnormal reflux.^6,7 Considering the low sensitivity and specificity of reflux symptoms in the diagnosis of GERD, and because the presence of abnormal reflux is very high in morbidly obese patients, the preoperative work-up should include an upper endoscopy and an ambulatory pH to determine whether abnormal reflux is present, and tailor the procedure accordingly.

Bariatric Procedures

Many bariatric operations have been designed over the past three decades. Some of them, like the gastric banding (GB), have been slowly abandoned so that today two procedures are mainly used for the treatment of morbid obese patients: the Roux-en-Y gastric bypass (RYGB) and the sleeve gastrectomy (SG). In 2016, the ASMBS Bariatric Numbers taskforce reported on the use of the more common bariatric operations between 2011 and 2015 in the United States ⁸ :

The percentage of laparoscopic GB decreased from 35.4% to 5.7%.

These numbers clearly show that between 2011 and 2015 there was a major shift in the surgical approach to morbid obesity, with the almost complete abandonment of the GB, a 30% decrease in the use of the RYGB, and a threefold increase in the use of the gastric sleeve. Therefore, we have witnessed a major change in thinking, moving away from an operation that was based on a restrictive and mala-absorptive component (RYGB) to an operation, which is exclusively restrictive in nature (SG). Varela and Nguyen also observed a similar shift, with an increased utilization of the SG in academic medical centers between 2011 and 2014 from 23.7% of all bariatric operations to 60.7%. During the same time period, the utilization of the RYGB decreased from 62.2% to 37.0%. ⁹

There are many reasons for this shift. The laparoscopic SG was initially used as the first step of a duodenal switch in super obese patients. Subsequently, however, many studies reported on the effectiveness of the SG as a solo procedure.^10,11 The operation is easier to perform than a RYGB as it does not require anastomoses, is faster, staple line leaks are rare, there is no risk of internal hernias, and it does not preclude the endoscopic exploration of the duodenum, or of the biliary tree in case of choledocholithiasis.

Bariatric Surgery and GERD

Recently two European prospective and randomized multicenter trials with 5 year follow-up have confirmed that the RYGB and the SG are equivalent in terms of weight loss.^12,13 Both trials highlighted that although the most common reason for an operation after RYGB was for the treatment of internal hernias, after SG it was for severe reflux refractory to medical treatment, with conversion to a RYGB.^12,13

These studies highlighted the major difference between these two procedures in terms of inducing or worsening GERD:

Independently of its effectiveness in determining weight loss, the RYGB is indeed an ideal operation for patients with GERD because of its anatomic configuration. In the small gastric pouch based on the lesser curvature of the stomach, there are in fact few parietal cells, therefore, minimizing the acid reflux. In addition, the long Roux loop prevents the reflux of duodenal contents. A subtotal gastrectomy with Roux-en-Y reconstructions has been used to stop reflux after failed fundoplications in patients with GERD. ¹⁴

Possible factors that play a role in the incidence of GERD after SG include ¹⁷ : (1)

A change in the angle of His during the creation of the sleeve.

Based on these findings, it is imperative to carefully screen patients before bariatric surgery to exclude the presence of abnormal reflux. ¹⁸ In patients in whom GERD is present, a RYGB should be the procedure of choice. ¹⁹ In addition, as the SG is becoming more popular for the treatment of severely obese adolescents, proper follow-up should be standard even in asymptomatic patients as reflux can still occur and a lifelong exposure to gastric contents can determine the occurrence of Barrett's esophagus and even adenocarcinoma. ²⁰