Intragastric balloons for weight loss: Not just occupying space in the stomach.

Abstract

Intragastric balloon therapy for weight loss has been recently reintroduced in the United States as a treatment option for patients with obesity. Both the ReShape Integrated Dual Balloon System and the Orbera Intragastric Balloon System were approved for use by the FDA last summer based on randomized trials which demonstrated weight loss benefit over control groups even 6 months after device removal. The currently approved intragastric balloons overcome the issues of the first generation of intragastric balloons, including a lack of weight loss in randomized sham controlled trials (1). The mechanism of action of intragastric balloon therapy has also been studied. Research has demonstrated that at least 400 mL of volume is needed in an intragastric balloon in order to produce weight loss over control (2). The ineffective Garren-Edwards Bubble only had a volume of 220 mL, suggesting that at least one mechanism for weight loss with the intragastric balloon is occupation of space in the stomach. However, evidence of other mechanisms causing weight loss with intragastric balloon therapy were also considered early on. Patients have significant retention of food in the stomach on intragastric balloon removal and are instructed to consume a liquid diet for several days before removal in order to reduce the risk of aspiration. This is similar to what is seen in patients with gastroparesis, a disease of delayed gastric emptying resulting in weight loss (3); and the finding led several investigators to measure gastric emptying in patients before, during, and after intragastric balloon implantation in small uncontrolled studies (4, 5). These demonstrated that there was a significant increase in gastric retention of solids with intragastric balloons implanted in the stomach but were limited by the lack of a control group. The study by Gómez et al. (6) in this issue of Obesity reports the results of intragastric balloon therapy on gastric emptying in a randomized controlled trial. Not only did intragastric balloon therapy result in significantly increased gastric retention of food, but the amount of gastric retention correlated with weight loss both at balloon removal and 6 months after balloon removal and was not seen in patients in the control group. This suggests that the physiologic changes which result in delayed gastric emptying during intragastric balloon implantation continue to exert some effect even after the device is removed. The results of this study may also help to explain the weight maintenance that is seen in the first 6 months after intragastric balloon removal (7) and is in contrast to the weight gain that is seen immediately after cessation of obesity medications (8). The mechanisms behind intragastric balloon-induced delayed gastric emptying are unclear. Emptying of gastric contents into the small bowel is a complex process that involves coordination of multiple organs and signaling from mechanical, chemical, and neurohormonal stimuli. Moreover, delayed gastric emptying did not explain all of the variance in weight loss with intragastric balloon therapy. Further research is needed to better understand the mechanisms responsible for delayed gastric emptying in patients treated with intragastric balloon therapy and other mechanisms that are also involved in intragastric balloon-induced weight loss. As with all obesity therapies, our ultimate goal is to understand how intragastric balloon therapy works to both identify patients who will be most likely to respond to the therapy before placing the intragastric balloon and to optimize therapy with the intragastric balloon in place.