Normal values and influence of anthropometric and demographic factors on ambulatory cutaneous electrogastrography in healthy volunteers.

INTRODUCTION: Cutaneous Electrogastrography (EGGc) is a technique used for recording the Gastric Electrical Activity by means of electrodes placed on the abdominal skin. The aim of the present study was to determine normal values in healthy volunteers as well as the influence of factors such as age, gender, Body Mass Index (BMI) and echographic location of the gastric antrum. METHODS: An abdominal echography was initially performed in 35 of the 44 healthy volunteers in order to locate the gastric antrum and to place along its axis the skin electrodes, whereas in the other 9, the electrodes were placed according to anatomical references. Afterwards, the echography was also performed in those 9 volunteers in order to have all the 44 baseline echographic records. In every case, a record of ambulatory EGGc over 60 minutes was obtained, along with other record over the same period after eating a standard meal. The analysis of data was conducted through visual inspection and combined computer analysis. RESULTS: Eighty per cent of the study subjects showed a dominant frequency ranging from 2 to 4 cpm during both periods. After the meal, the parameters showed a characteristic variation. A significant difference was found when comparing subjects under 40 years of age versus subjects between 40 and 60 years of age in terms of preprandial dominant frequency instability coefficient (DFIC) (p = 0.002) and bradygastria (p = 0.03). Subjects with BMI < 25 kg/m2 showed preprandially a smaller dominant power instability coefficient (DPIC) (p = 0.035) and a greater Dominant Power (DP) (p = 0.045). In subjects without echographic control, DFIC (p = 0.001), bradygastria (p = 0.016) and tachygastria (p = 0.02) were more frequent, with a shorter period of normogastria (p = 0.001) during the postprandial period. CONCLUSIONS: Normogastria is the predominant rhythm in healthy people, although brief dysarrhythmias can be recorded that do not have any pathological meaning. Age and BMI, but not sex, seem to influence the Gastric Electrical Activity. The percentage of gastric dysarrhythmias decreases when the electrodes are placed along the longitudinal axis of the gastric antrum through echographic control.