Gastric Motility

Question 1

What are important components of gastric motility?

Answer 1

Gastric pacemaker: ICC located in proximal body along greater curvature.
Gastric slow waves: internal rhythm at 3 per minute with contraction threshold and a maximum contraction frequency

Question 2

Describe mixing process in post-prandial phase

Answer 2

Food processing: mixing wave (contractions) and retropulsion

Food emptying via pyloric pump

Question 3

Describe the emptying process in post-prandial phase: Liquids vs. Solids

Answer 3

Liquid: antroduodenal pressure gradient. Dependent on liquid volume

Solids: broken down into chyme then emptying contractions of pyloric pump

Question 4

Rules of gastric emptying rate: volume, consistency and content

Answer 4

Large volume>smaller
Liquids>semiliquids>solids
Starch>protein>fat

Question 5

How does duodenum regulate gastric emptying?

What activates duodenal feedback? (4)

Answer 5

Inhibits pyloric pump via neuronal and hormonal feedback.

It is activated by too much gastric acid, high protein or fat, excessive chyme volume, hypertonic fluids

Question 6

What are the three feedback loops in the enterogastric nervous reflexes?

Answer 6

Inhibitor vagal efferent nerve
Enteric nerves connecting duodenum and stomach
Inhibitory sympathetic nerve fibers

Question 7

Which hormones are involved in duodenal feedback? (4)

Answer 7

CCK, SS, DA, secretin

Question 8

Describe the contraction pattern during the fasting phase

Answer 8

Full migrating motor complex (MMC) is 84-112minutes
Long phase I: no contractions
Shorter phase II: few irregular contractions
Brief phase III (5-10min): intense contractions– house keeping function and motilin

Question 9

What are the major causes of gastroparesis?

Answer 9

Idiopathic (1 in 3)
Post-surgical
Diabetic
Medication related (i.e narcotic)
Others: paraneoplastic, rheumatologic, neurologic, myopathic

Question 10

How common is diabetic gastropathy? In which type is it most prevalent

Answer 10

Observed in 50% of long-standing type I DM

Also occurs in Type II DM

Question 11

What are the consequences of diabetic gastropathy? (4)

Answer 11

Delayed emptying of solids but rapid emptying of liquids
Bezoar formation
Poor blood sugar control– tendency to hypoglycemia
Malnutrition/weight loss

Question 12

What are the clinical manifestations of gastroparesis?

Answer 12

Nausea 
Vomiting
Early satiety
Postprandial abdominal distention
Postprandial abdominal pain

Question 13

How is gastroparesis diagnosed?

Answer 13

Gastric emptying study: scintigraphy, radiolabeled eggbeaters with toast, jam and water

If retention>60% at 2hr or >10% at 4hr then you got it

Question 14

Other diagnostic tests for gastric emptying (2)

Answer 14

Breath test involving labeled spirulina

SmartPill

Question 15

How is gastroparesis managed? (4)

Answer 15

Lifestyle/dietary measures: small/frequent meals, low fat diet, glucose control in DM
Medications: prokinetic agents and antiemetics
Gastric electric stimulation
Surgery (2%)

Question 16

What are common prokinetic agents (3)

Answer 16

Metocloprimaide (DA antagonist)
Domperidone (DA antagonist)
Erytromycin (Motilin agonist)

Question 17

What are AE of common pro kinetics?

Answer 17

Metocloprimaide: prolactin, arrhythmia, extrapyramidal symptoms
Domperidone: prolactin, arrhythmia
Erythromycin: cramping, nausea, vomiting

Question 18

What are indications for enteral nutrition?

Answer 18

Surgical jejunostomy
Severe weight loss
Repeated admissions for IVF/IV meds
Inability to absorb meds due to vomiting
Need for gastric decompressions

Question 19

What is dumping syndrome? When is it seen?

Answer 19

Rapid gastric emptying of hypertonic liquids

Seen in gastrojejunostomy patients

Question 20

Compare the clinical presentation of early dumping vs. late dumpying

Answer 20

Early dumping: nausea, flushing, syncope due release of vasoactive factors
Late dumping: hypoglycemia due to release of insulin

Question 21

What is criteria for non-ulcer dyspepsia or functional dyspepsia?

Answer 21

Postprandial distress (early satiety, fullness from normal meal) or epigastric pain without structural disease

Question 22

Describe motility observed in patients with non-ulcer dyspepsia

Answer 22

45% have delayed gastric emptying
Poor gastric compliance
Gastric dysrhythmias
Ineffective contraction patterns

Question 23

How is NUD managed?

Answer 23

Meds: antisecretory therapy, prokinetics, gastric compliance enhancers, visceral perception blockers
Psychological approaches