Sa1953 Delayed Gastric Emptying-Response to Temporary and Permanent GES With Effect on Symptoms and Gastric Emptying

Abstract

Introduction: Gastric electrical stimulation (GES) appears to have a beneficial effect in disorders of foregut dysfunction but the mechanisms are unknown. We have previously reported that different electrical energies may cause differing responses when measured during surgical implantation of GES devices. We now report on a large series of consecutive patients who were given different magnitudes of electrical stimulation intraoperatively. We aimed to investigate the types of response to better understand the mechanisms of GES. Patients: We intraoperatively evaluated 87 consecutive patients with drug-refractory gastroparesis (68 female, 19 male; aged 13-76 years, mean 43.4 years; 37 diabetic, 50 idiopathic etiologies) who had elected treatment by permanent GES. Methods: Four energy settings were studied sequentially by using previously standardized parameters: low (pulse width, 330 μs; amplitude, 5 mA; frequency, 14 Hz; cycle ON, 0.1 s; cycle OFF, 5.0 s), medium (pulse width of 330 μs; amplitude, 10 mA; frequency, 28 Hz; cycle ON: 1.0 s; cycle OFF, 4.0 s), and high (pulse width of 450 μs; amplitude, 20 mA; frequency, 55 Hz; cycle ON: 4.0 s; cycle OFF, 1.0 s) energy settings, along with a ‘super high' setting (pulse width of 450 μs: amplitude 20mA; frequency, 130 Hz; cycle ON: 4.0 s; cycle OFF, 1.0 s). Surgical incision exposed the stomach. One pair of leads (‘Lead 1') was attached to the gastric serosa at the cardia-body junction, another pair (‘Lead 2') attached to the serosa at the antrum, and an initial 10-minute EGG recording was obtained simultaneously from each pair (‘Baseline Lead 1'; ‘Baseline Lead 2'). The cardia-body leads were then connected to the stimulator and used to deliver current for the remainder of the study. EGG frequency and amplitude were recorded through the antral leads. Results: Overall, mean frequency did not show much change with incremental GES energy settings. However many patients showed changes at low setting and a few showed irregular frequency changes throughout study session.(figure1, 2). Baseline mean (25%Q, 75%) frequency was 3.97[3.74, 4.21]cpm which changed to 4.01 (3.75, 4.27)cpm with low energy stimulation (p=0.942). Conclusions: Intraoperative delivery of differing energies to the stomach reveals diverse patterns of response in patients with the symptoms of gastroparesis. For the majority of patients, the greatest change seemed to occur at the first energy level applied without much further change with the application of increasing energy. This finding creates the question of whether the effect is caused by the mere application of energy or the amount applied. Further analysis of this data may help us better understand the mechanism of the beneficial effect of GES.