[The characteristics of gastric electric rhythm in obese patients]

Objective: To investigate the characteristics of gastric electric rhythm in patients with obesity. Methods: Obese patients who were scheduled to undergo weight reduction surgery in Peking Union Medical College Hospital from January 2018 to February 2024 were prospectively included. According to body mass index (BMI), the patients were divided into mild-to-moderate obesity group (28 kg/m²≤BMI<40 kg/m²) and severe obesity group (BMI≥40 kg/m²). Patients who were going to complete electrogastrography (EGG) with normal BMI (18.5 kg/m²≤BMI<25 kg/m²), without upper gastrointestinal symptoms, gastrointestinal surgery history, and underlying diseases such as diabetes mellitus were included as normal BMI group. The clinical data was recorded and EGG examination and analysis were performed. The gastric electric rhythm characteristics of patients were compared among the three groups. The correlation between BMI and gastric electric rhythm parameters was analyzed. The differences of EGG parameters between obese patients with diabetes mellitus and obese patients without diabetes mellitus were compared. Results: A total of 60 obese patients were included, including 25 males and 35 females, whose age were 18.0-59.0 (27.6±6.9) years old and BMI were (41.0±7.1) kg/m². There were 30 patients in mild-to-moderate obesity group and 30 patients in severe obesity group. Twenty-four patients were included in normal BMI group, including 11 males and 13 females, whose age were 21.0-42.0 (30.7±6.8) years old, and BMI were (22.7±3.1) kg/m², with no difference in age and gender compared with mild-to-moderate and severe obesity groups (both P>0.05). EGG results showed that the percentage of normal slow wave before meal (43.2%±20.0%, 37.0%±16.9%, respectively, vs 74.6%±13.6%), and the percentage of normal slow wave after meal (31.6%±13.8%, 28.5%±11.3%, respectively, vs 68.5%±14.4%) in the mild-to-moderate obesity group and the severe obesity group were significantly lower than those in the normal BMI group (all P<0.001). In the mild-to-moderate obesity group, the percentage of preprandial bradycardia [M (Q₁, Q₃), 3.4% (0, 15.2%) vs 0 (0, 0), P<0.001], preprandial tachycardia [0 (0, 3.3%) vs 0 (0, 0), P=0.014], postprandial bradycardia [13.3% (3.3%, 20.4%) vs 0 (0, 5.2%), P<0.001] were higher than those in the normal BMI group. In severe obese group, the percentage of preprandial bradycardia [9.4% (3.1%, 13.8%) vs 0 (0, 0), P<0.001], preprandial tachycardia[0 (0, 3.7%) vs 0 (0, 0), P=0.011], postprandial bradycardia [16.7% (7.4%, 20.0%) vs 0 (0, 5.2%), P<0.001] were all higher than those in the normal BMI group. The dominant power before meal [(57.9±12.6), (65.8±9.6), respectively, vs (46.4±4.9) μv] and after meal [(63.5±13.7), (68.3±12.6), respectively, vs (50.6±6.3) μv] in mild-to-moderate obesity group and the severe obesity group were higher than those in the normal BMI group (all P<0.001). The dominant power before meal in severe obesity group was higher than that in mild-to-moderate obesity group (P=0.008), but there were no statistically significant differences in other parameters between the two groups (P>0.017, corrected significance level α=0.017). In obese patients, the dominant power was positively correlated with BMI before and after meal (r=0.47, 0.34, respectively, both P<0.05). There was no significant difference in gastric electric rhythm between obese patients with diabetes mellitus and obese patients without diabetes mellitus (P>0.05). Conclusions: Patients with obesity have lower percentage of normal slow waves before and after meal, but increased percentage of preprandial bradycardia, tachycardia and postprandial bradycardia. The dominant power of patients with obesity before and after meals were increased, which is positively correlated with BMI.