Electrogastrogram

1
Electrogastrogram

• Jayson
• Franky
• Dana

2
Discovery

• William Beaumont 1833
• First to notice gastric psychological changes
  induced by various emotions.
• Later noted emotion causes increased and
  decreased gastric acid formation
• Also causes reflux of bile into stomach causing
  the slowing of gastric emptying

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• October 14, 1921
• First recording of Electrogastrogram
• Scientists begin to discover changes due to
  specific stimuli such as stress and anxiety
• Use EEG to measure gastric emptying
• Recent research has shown that improving quality
  of life will improve gastrointestinal disease.

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What is EGG

• Like EKG and heart
• Measures muscle activity related to the stomach
  and abdominal region.
• Measured from a baseline reading containing a
  regular rhythm. In a normal subject a current
  increase is observed after a meal.
• Still an early experimental procedure because it
  has yet to become a standard medical procedure.

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Gastrointestinal Problems

• Nausea
• Gastric Reflux
• Peptic Ulcer
• Irritable Bowel Syndrome
• Cirrhosis

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Nausea

• Uneasy feeling feeling of vomiting
• Commonly associated with stomach but including
  all parts of the body
• Brought on by any and all physiological stimuli
• May cause dehydration or esophageal erosion and
  irritation

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Gastric Reflux

• Very common
• Reflux of stomach content into esophagus
• Causes damage to lining if occurring often
• Heartburn, burning pain
• Treatable with weight reduction, avoiding food
  and activities that cause reflux, avoiding
  situations that cause reflux, and some medication.

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Peptic Ulcers

• Break in surface of organ
• Excessive HCl formation, infection, some drugs
  (asprin, anti inflammatory)
• Indigestion, nausea, vomiting, bleeding
• Monitor pH levels in stomach
• Use biofeedback to maintain appropriate HCl
  amounts

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Irritable Bowel Syndrome

• Most common psychophysiological disease
• Caused by stress and anxiety and effects all
  parts of the digestive tract
• Stress increases corticotropin-releasing factors
  from brain inhibiting gastric emptying

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IBS (Cont)

• Causes various symptoms abdominal pain, altered
  bowel habit, bloating, bowel noises, indigestion,
  nausea, headaches, etc.
• Avoid problematic food, improve bowel function,
  antidepressant medication, relaxation therapy,
  psychological counseling

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Cirrhosis

• Extended liver damage
• Not directly caused by emotional stimuli
• Alcohol abuse, drug abuse (hepatitis), AIDs
• Generally found amoung older individuals
• Irreversible

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References

• Mai FM. 1988. Beaumonts Contribution to gastric
  psychophysiology a reappraisal. Can J
  Psychiatry. 33 650-653.
• Muth ER, Koch KL, Stern RM, Thayer JF. 1999.
  Effect of autonomic nervious system
  manipulations on gastric myoelectrical activity
  and emotional responses in healthy human
  subjects. Psychosom Med. 61 297-303.
• www.gastro.net.au/gastrodiseases/index.php3

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Electrogastrography (EGG)
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Electrogastrography

• How it works.
• Difficulties.
• Precautions.
• EGG setup.
• Data acquisition and analysis.
• Capabilities and limitations of EGG.
• Applications.

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How EGG Works

• Very similar to EKG.
• Recording of electrical signals produced by the
  muscles of the stomach that control constriction.
• Two forms.

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Difficulties

• The main difficulty is the human EGG signal.
• 3 cycles/min sinusoid.
• Data obtained is difficult to analyze and
  abnormalities difficult to define.
• Interference from the duodenum and from the
  transverse and descending colon.

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Precautions

• Optimal recording conditions.
• Electrodes produce noise to an extent.
• Noise must be reduced (0-0.5Hz).
• Electrodes should be recessed.
• Skin abrasion.
• Ideally impedance below 10 Kila-ohmes.

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EGG setup

• EGG signal is recorded by electrodes that are
  placed over the upper abdomen.

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EGG setup

• EGG sample amplitude is typically in the 50-100
  micro-Volt range.
• Must be filtered.
• Removes artifacts.
• Provides a low and high frequency cutoff (1cpm
  and 18cpm)

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Data acquisition and analysis

• Bradygastrias
• O-2.4cpm
• Tachygastrias
• 3.6-9.9cpm
• These Gastric Dysrhythmias have clinical
  relevance.

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Capabilities and Limitations (Frequency)

• Most reliable EGG parameter.
• Stable frequencies obtained over a population.
• Low standard deviation between measurements.
• Slight increase in gastric frequency obtained
  after feeding (only in some people).

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Capabilities and Limitations (Amplitude)

• With decrease between electrode distance mean
  power of the major EGG component decays.
• Bipolar channels yield stronger signals but are
  more sensitive to movement artifacts.
• Results over a population were surprisingly
  varied after having eaten.
• Poor correlation between amplitude of the EGG
  signal and the presence of gastric contractions.
• In dogs data was recorded for contractions that
  had been blocked by atropine and glucagon.

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Capabilities and Limitations (Time Shifts)

• Shifts during periods of greatest stability of
  EGG channel pairs near non existent regardless of
  relative difference.
• However simultaneous internal recordings from
  dogs and patients show well defined time shifts.

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Capabilities and Limitations (Waveform)

• Increased inter electrode distance in internal
  bipolar recordings results in a change of
  waveform. (biphasic to sinusoidal)
• Occasional changes in waveform will be found in
  any participant including those deemed normal.

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Capabilities and Limitations (Discussion)

• Frequency is most reliable parameter for clinical
  applications.
• Electrodes.
• Artifact filtering.
• Amplification techniques.
• Recorded deviations will be related to gastric
  electrical abnormalities.

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Applications

• Motion Sickness
• Gastric Emptying and Motility
• Nausea and Vomiting
• Gastric Dysrhythmias
• EGG in Children

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References

• Chen, J. A. McCallum, R. W. (1994).
  Electrogastrography Principles and Applications.
  Raven Press., New York.

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Current Research in Gastric Psychophysiology
29

• A lot of research has been done to investigate
  the effects of the mind, mood, and voluntary
  behaviors on the digestive system
• Gastric psychophysiology refers to the stomach or
  anything relating to it

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Psychophysiology of Nausea

• (A study conducted by R.M. Stern in 2002)
• Investigation Topic nausea (uncomfortable
  sensation usually associated with the stomach and
  occasionally followed by vomiting)
• Nausea (like emotional pain or motion sickness)
  is a private sensation, so little is known.
• Hypothesis each individual has a personal
  threshold for nausea dependant on interaction of
  inherent factors and changeable physiological
  factors.

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Results and Conclusions of Nausea Study

• Results subjects observed showed an increase in
  sympathetic nerve activity, decrease in
  parasympathetic nerve activity, increase in
  abnormal dysrhythmic gastric activity, increase
  in plasma vasopressin
• Conclusions beneficial selective reduction of
  nausea depends on a greater knowledge of its
  psychophysiological variables.

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Psycho-Physiological Aspects of Gastroesophageal
Reflux Disease

• (a review study by Kamolz, Bammer, Pasuit,
  Pointner in 2002)
• Investigation Topic confirmed the strong
  relationship between psychophysiological aspects
  and gastrointestinal diseases
• Additionally investigated interventions into
  these relationships and focused in on
  Gastroesophageal reflux disease (GERD).

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GERD study

• Gastroesophageal reflux disease (more commonly
  known as acid reflux) occurs when the liquid
  contents of the stomach are regurgitated into the
  esophagus, thus damaging the lining of the
  esophageal walls
• Occurs in as many as 10 of Americans per day, 44
  expressing symptoms at least once a month
• can be caused/contributed to by the lower
  esophageal sphincter, significant stressors,
  hiatal hernias, esophogeal contractions, and the
  emptying of the gastric chamber.

34
GERD

• Other physiological factors that may contribute
  to GERD
• Delayed clearance of physiological reflux by
  saliva
• Decreased bicarbonate secretion by esophageal
  submucosal glands
• Attenuated ability of cells lining esophagus to
  resist acid injury

35
GERD

• Treatments
• Prilosec (a proton pump inhibitor)
• Antacids
• Lifestyle changes
• Elevate head of bed 6inches, decrease fat intake,
  smoking cessation, weight reduction, avoiding
  large meals
• Endoscopy
• Ambulatory pH monitoring (a pH monitor is placed
  on the esophageal sphincter)

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Psychological and Sex Features of delayed gut
transit in functional gastrointestinal disorders

• Study by Bennett, et al. in 2000.
• Investigation Topic comparing psychosocial and
  demographic features of patients w/ functional
  gastrointestinal disorders and delayed transit in
  the gastrointestinal tract regions
• 110 subjects, 46 w/ delayed transit in region 1,
  32 delayed transit for region II, and 17 had
  normal transit

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Delayed Gut Transit Study

• Gut transit was assessed using a scintigraphic
  technique, psychometric measures were used to
  judge psychological status
• RESULTS delayed transit was increased in
  females, those with depressive mood states,
  increasing age, frequent control of anger, and
  severe gastric stasis, whereas Increased transit
  was found in males and hypochondriasis.
• CONCLUSIONS a distinct psycho physiological
  subgroup defined by delayed gut transit is
  indicative of gastrointestinal disorders.

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Effects of different psychophysiological
stressors on the cutaneous electrogastrogram in
healthy subjects.

• A study by Riezzo, Porcelli, Guerra, and Giorgio
  in 1996
• Investigation Topic following
  psychophysiological stress on gastric electrical
  activity
• Apparatus used a non invasive, cutaneous
  electrogastrography (EGG)

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Cutaneous EGG study

• 3 stressful tests (a cold pressor test,
  arithmetic test, and Stroop color-word test
• A non stressful tests (reading a booklet)
• EGG parameters were measured dominant
  frequency, coefficient variation of dominant
  frequency, and gastric power) and were recorded
  during baseline, task, and rest periods.

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Cutaneous EGG study

• RESULTS
• Non stressful task had no effects
• During stress (especially arithmetic test)
  gastric power significantly increased. Stroop
  test showed nearly significant trend to increases
  in gastric power.
• CONCLUSIONS increased individual susceptibility
  to psychological stress may influence the EGG
  responses and thus increase gastric electrical
  activity.

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Antidepressants Attenuate Increased
Susceptibility to Colitis in Murine Model of
Depression

• Varghese, et al. in 2005.
• Based on the theory that psychiatric factors
  determine gastrointestinal health
• Investigation Topic using a model of
  depression, attempted to find alterations in gut
  physiology and to assess association with
  increased sensitivity to experimental colitis in
  adulthood. (also investigated effects of
  antidepressants therapy)

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Depression Study

• Using mice some mouse pups were seperated from
  their mother, some werent.
• At 8 weeks, pups were evaluated on behavior
  changes, intestinal permeability, and sensitivity
  to colitis.
• RESULTS adult mice that had been seperated
  showed depressive behaviors and enhanced
  intestinal permeability with more severe colitis.
• CONCLUSIONS maternal seperation can lead to
  depression/increased responsiveness to stress,
  impaired intestinal function, and vulnerability
  to gastric inflammation.

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Peptic Ulcer Disease nothing but an infection?

• M. Gross C. Herrmann in 1999.
• Investigated duodenal and gastric ulcers and
  stressors
• RESULTS
• 73 of patients had gastric ulcers, 92 had
  duodenal ulcers. Relapse was 50 and 66,
  respectively after 1 year without eradication of
  the ulcer. After eradication, relapse rates
  reduced to 0 and 6, respectively, suggesting an
  infectious agent.

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Peptic Ulcer

• HOWEVER only a minority had the Helicobacter
  pylori infection!
• CONCLUDED chronic physiological stress is an
  ulcerogenic co-factor, interaction between stress
  and infection can cause ulcers, acute
  psychological stressors show increased risk of
  gastric ulcer formation.

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REFERENCES

• Bennett, E., Evans, P., Scott, A., Badcock, C,
  Shuter, B., Hoscle, R., Tennant, C., Kellow, J.
  (2000). Psychological and sex features of delayed
  gut transit in functional gastrointestinal
  disorders. GUT. 46(1) 83-87.
• Gross, M. Herrmann, C. (1999). Peptic Ulcer
  Disease- nothing but an infection? Zeitschrift
  Fur Psychosomatische Medizin Und Psychotherapie.
  45 (4) 390-400.
• Kamolz, T, Bammer, T., Pasuit, M., Pointner, R.
  (2002). Psycho-physiological aspects of
  gastroesophageal reflux disease. Psychotherapie
  Psychosomatik Medizinische Psychologie 52 (3-4)
  159-165.
• Riezzo, G., Porcelli, P., Guerra, V., Giorgio,
  I. (1996). Effects of different
  psychophysiological stressors on the cutaneous
  electrogastrogram in healthy subjects. Archives
  of Physiology and Biochemistry 104(3) 282-286.
• Stern, R.M. (2002). The psychophysiology of
  Nausea. Acta Biologica Hungarica 53(4) 589-599.
• Varghese, A., Verdu, E., Bercik, P., Khan, W.,
  Blennerhassett, P., Szectman, H., Collins, S.
  (2006) Gastroenterology 130(6) 1743-1753.