title: Factors responsible for computed electrogastrographic parameters in humans.
abstract: OBJECTIVE
  Clinical knowledge about myoelectrical frequency is well known, but the factors responsible for recorded myoelectrical amplitude remain less clear.
  
  
  METHODS
  We assembled an electrogastrographic system that could automatically compute the dominant myoelectrical frequency and power and power ratio. We enrolled 50 healthy volunteers (25 men and 25 women) to study their myoelectrical characteristics. Three surface electrodes were placed in the fundic, stomach body, and antral positions for two 30-min recordings in the fasting and postprandial states.
  
  
  RESULTS
  The three different electrodes recorded similar dominant frequencies of about 3 cpm before and after a meal. The fasting dominant powers from these electrodes were 52.9 +/- 14.7, 44.6 +/- 11.5, and 50.1 +/- 15.1 dB, respectively (p < 0.01), whereas the postprandial dominant powers were 61.6 +/- 28.8, 54.3 +/- 26.6, and 61.9 +/- 27.8 dB, respectively (p < 0.01). Meal ingestion did increase the power (p < 0.05). Women had a lower dominant power than men (p < 0.001). Moreover, the dominant powers of each electrode were significantly correlated with body mass index (r = 0.3-0.36, p < 0.05) regardless of meal ingestion. The postprandial power ratio was not influenced by electrode position, gender, or body mass index.
  
  
  CONCLUSIONS
  Myoelectrical dominant frequencies and power ratios are similar throughout the whole stomach area, whereas a lower power area exists on the stomach body. Gender-related variation in dominant power seems to be an effect of body size. The power ratio is the only reliable parameter for expressing myoelectrical amplitude.
authors.affiliation: Division of Gastroenterology, Veterans General Hospital-Taipei, Taiwan, Republic of China.
authors.forename: F Y
authors.initials: FY
authors.lastname: Chang
authors.forename: C L
authors.initials: CL
authors.lastname: Lu
authors.forename: C Y
authors.initials: CY
authors.lastname: Chen
authors.forename: S D
authors.initials: SD
authors.lastname: Lee
authors.forename: H C
authors.initials: HC
authors.lastname: Jang
authors.forename: S E
authors.initials: SE
authors.lastname: Fu
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D004566:Electrodes; D004568:Electrodiagnosis / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D005215:Fasting / Q000502:physiology; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D016065:Myoelectric Complex, Migrating; D019518:Postprandial Period / Q000502:physiology; D012016:Reference Values; D012727:Sex Characteristics; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation; D013270:Stomach / Q000502:physiology*