IEGGS_7.doc
Gastric Myoelectrical Activity and Nausea Responses to the Water Load Test in Patients with
Chronic Unexplained Nausea.
GS Raymer, L Xu, KL Koch, Penn. State University, Milton S. Hershey
Medical Center, Hershey, PA.
Introduction: The pathophysiology of chronic, unexplained nausea remains poorly understood. Gastric distention, water loading and gastric dysrhythmias are associated with nausea symptoms in some but not all patients. The AIM of this study was to compare gastric myoelectrical activity and water load test (WLT) results in patients presenting with mild or severe baseline nausea scores on the day of study. Methods: 15 patients (4 men, 11 women, ages 16-80) were selected based on their severe nausea scores at baseline.
Nausea was scored on a visual analog scale (VAS) with 0 indicating no nausea and 300 indicating severe nausea. The mean baseline nausea score for these 15 patients was 206  16 (Group 1). 10 other patients with chronic nausea (10 women, ages 16-48) were selected based on their minimal nausea at baseline. The mean nausea score was 57  13 (Group 2). All patients underwent electrogastrography (EGG) and WLT using a standard protocol. Nausea was also assessed at 10 and 30 min. after ingestion of water. Based on EGG rhythm strips and computer analyses, the EGGs were interpreted as normal, tachygastria, bradygastria or mixed dysrhythmia. Results: In Group 1, the severe baseline nausea increased only 14% to 234  13 and 8% to 222  17 at 10 and 30 min. after the WLT (p’s>0.2). In contrast, in Group 2 the minimal baseline nausea increased 210% to 177  20 and 175% to 157  25 at 10 and 30 min. after the WLT (p’s<0.01). Group 1 had significantly higher nausea scores than Group 2 at all time points (P<0.04). Group 1 ingested smaller volumes of water compared with Group 2 (340  60 ml vs 464  64 ml, p =0.18). Baseline EGGs in Group 1 were: 9 normal (60%), 5 tachygastria (33%) and 1 mixed dysrhythmia (7%), whereas after the WLT the
EGGs were: 10 normal (67%) and 5 tachygastria (33%). Baseline EGGs in Group 2 were: 7 normal (70%) and 3 tachygastria (30%), but after the WLT the EGG diagnoses were normal in only 3 (30%) and tachygastria in 7 (70%). The number of gastric dysrhythmias after the WLT was significantly greater in
Group 2 compared with Group 1 ( p <0.05, Chi 2 ). Conclusions : 1) Patients with severe baseline nausea ingested less water, had continued severe nausea and more normal EGGs after the WLT, suggesting hypersensitivity to gastric distention. 2) Patients with minimal baseline nausea ingested more water, had significantly increased nausea and more gastric dysrhythmias, suggesting that gastric distention with water evoked the tachygastrias. The data suggest two distinct pathophysiological mechanisms of nausea in these patient groups.