SB Dysmotility

DEFINITION

Notes on a collection of various dysmotility issues.
In general, surgery should only be considered for patients with extreme symptoms when reasonable efforts at medical management have failed

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EPIDEMIOLOGY

As per individual conditions

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AETIOLOGY

See below

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BIOLOGICAL BEHAVIOUR

Roux Stasis Syndrome
Encountered after Roux-en-Y gastrojejunostomy.
- Roux-stasis, delayed gastric emptying, or both
- but pure Roux limb dysfunction is generally a late complication, onset over months to years.
--> difficult to investigate / work out what is the exact causative segment, could try scintigraphy or manometry
--> can assess vagal function via the pancreatic polypeptide response to insulin-induced hypoglycaemia test (PP test)
Encompasses symptoms of nausea, vomiting, early satiety, and abdominal pain; like gastroparesis
- seen in ~25-30% of patients
Risk factors:
- women
- Roux length >40cm

Post-Vagotomy Diarrhoea
Diarrhoea in 20% after truncal vagotomy, severe in 2-4%
- doesn't really occur with selective vagotomy; only truncal
May have up to 20 loose BMs per day.
May get malnutrition, weight loss, orthostatic hypovolaemia.
Unclear why it occurs.  Theories:
- impaired gastric relaxation
- bile acid malabsorption
- i.e. alters gastric tone, motility and also facilitates bacterial overgrowth.
- also hepatic and celiac denervation impairs contractility of gallbladder, fills up and then dumps out of sync, causing a large enteral load that overwhelms the enterohepatic circulation
--> direct action of bile salts in colon causes secretary and osmotic diarrhoea.
More likely in patients with past cholectystectomy, further implicating role of gallbladder and bile salts
Diagnosis
Difficult as features are non-specific
- Consider bacterial overgrowth, malabsorption, infection (c. diff), obstruction, IBD,
- Medications may cause diarrhoea (alter intestinal transit time, luminal osmolarity, ion transport, intestinal flora etc)

Post-Vagotomy Dumping
Up to 25-50% of pts with gastrectomy, gastroenterostomy, vagotomy or roux-en-Y bypass experience some form of dumping
- less than 5% of these have severe disabling symptoms that actually require management
Causes:
- loss of reservoir function
- loss of pyloric sphincter tone
- stomach cannot relax and accommodate; elevated intragastric pressure and common-cavity pressure gradient to duodenum
--> forces contents through more rapidly than should
- also after gastrojejunostomy, normal duodenal feedback on gastric emptying is lost
Rapid gastric emptying is accompanied by gut hormone release, e.g. glucagon-like-peptide 1 (GLP-1), eliciting sympathetic activation
Enteroglucagon = inhibits absorption of sodium and water --> diarrhoea
Severity is proportional to rapidity of gastric emptying

Early dumping

(classified this way, but quite difficult to distinguish the two in practice).
- most pts suffer early dumping or a combination
Early = within 60min of eating
- GI and vasomotor complaints
- Hyperosmolar food bolus causes osmotic fluid shifts into gut, distention, increases amplitude and frequency of bowel contraction
- variety of vasoactive transmitters are released
--> splanchnic and systemic vasodilation
--> relative hypovolaemia,
--> symptom complex = pain, bloating, vomiting, diarrhoea, palpitations, weakness, sweating, fainting, flushing

Late dumping
Late = 1-3h after meal
- Secondary to reactive hypoglycaemia
- Dump of carbs into gut causes GLP-1 release, and exaggerated insulin response.
- Pts become hypoglycaemic, surge of catecholamines
--> symptoms of lightheadedness, palpitations, diaphoresis, tremors and confusion.
Rapid weight loss and malnutrition may ensue from fear of eating from these problems.
Consider other causes, like insulinoma, noninsulinoma pancreatogenous hypoglycaemic syndrome.

Ileus
See ileus notes

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MANIFESTATIONS

See above

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INVESTIGATIONS

Included below
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MANAGEMENT

Surgery in Gastroparesis
Gastrectomy, pyloroplasty, and surgical drainage procedures may be offered as a last resort, though data demonstrating efficacy are limited.
Conversion from a Billroth I to a Billroth II, although tempting, is rarely an effective intervention.
Completion gastrectomy with preservation of a small cuff of gastric tissue may have some long-term benefits
- but up to 25% of patients still require some form of parenteral support.

Roux Stasis Syndrome
Exclude mechanical obstruction by OGD and small bowel series
Motility agents
Cisapride
provides long-lasting symptomatic relief from pain, fullness, nausea and vomiting
- improves transit in ~40%
Erythromycin improves gastric emptying
Bethanecol short term relief to gastric retention
Surgery
Up to 50% of patients may eventually need subtotal or total gastrectomy to relieve symptoms
Completion gastrectomy works in ~50%, less likely in more severe cases
Uncut Roux Procedure
Prevents dysfunction in the intestinal limb.
Antrectomy, Bilroth II reconstruction
Then side-side anastomosis between afferent and efferent ~40cm distal to gastrojejunostomy
Rho-shaped Roux-en-Y, & Noh's operation
No convincing evidence for these
- coils bowel up like spaghetti to "try to control ectopic pacemaking"; sounds like BS
 
Post-Vagotomy Diarrhoea
Most cases are self-limiting and resolve with time
1. Modify diet
- small, frequent, low-fat meals
- bulking agents
2. Loperamide (12-24mg) and codeine phosphate (60mg)
- codeine makes some people v. drowsy though
3. Cholestyramine binds diarrhoeal bile salts
- significantly reduces stool volume
- but poorly tolerated and unconfirmed long-term benefit.
Do not use ocreotide; not effective and may make things worse as messes with pancreatic exocrine fx.
4. Conservative approach should resolve symptoms by 18m after vagotomy
- if not effective, re-evaluate the entire GI tract and look for alternate causes again.
... Correcting rapid gastric emptying may help dumping symptoms but does not help diarrhoea.
5. More successful approach = slow transit through SB
- e.g. 10cm antiperistaltic duodenal segment 70-100cm from ligament of Treitz
... mixed results, short lived, risk of partial obstrucitons
- passive non-propulsive reversed ileal graft 30cm from ileocaecal junction.
--> last resorts in patients with disabling symptoms.

Post-Vagotomy Dumping
1. Provocation testing
To confirm diagnosis
Ingest a 50g oral glucose load at 30 min intervals over 3h
Measure plasma glucose for hypoglycaemia, hematocrit (increases >3%), HR (increases >10 bpm)
And reproduces patients' symptoms
2. Solid meal scintigraphy test for rapid gastric emptying
- 30% left after just 1 hr = rapid
3. Dietary modification
- Eat small meals
- Avoid fluid intake while eating solids and for 2h post-prandially to maintain gastric retention
- Minimise ingestion of simple carbohydrates
- Nonabsorbable polysaccharides such as pectin, guar gum, can alleviate dumping symptoms and reduce symptoms from reactive hypoglycaemia.
4. If dumping persists, pharmaceutical intervention
Acarbase = alpha-glucosidase inhibitor
- attenuates post-prandial increase in plasma glucose
- helps, but pay-off is unfermented carbs in system increasing flatulence and diarrhoea
Ocreotide = somatostatin analog
- use long-acting analog, sandostatin-LR depot injection; better QOL rating.
- effectively controls symptoms of dumping by slowing gastric emptying
- inhibits secretion of insulin and enteric peptides
- mitigates postprandial haemodynamic changes, by limiting hormonal release and splanchnic vasoconstriction.
--> reduces dumping 50% in short term, long term = limited benefit; also causes steatorrhoea and gallstones
5. Remedial surgery?
Not always very effective.
Reserved for refractory patients as a desperate measure.
Aim is to create a gastric reservoir, prevent uncontrolled delivery of food into the small intestine.
- anti-peristaltic jejunal interposition loops and conversion Roux-en-Y gastrojejunostomy are generally thought to provide best results.
If dumping after pyloroplasty, consider pyloric reconstruction
- convert Bilroth I or II to a Roux-en-Y gastrojejunostomy. Slows motility by interrupting MMC and creates retrograde jejunal contractions.
- could convert II to I but ineffective in 25%.
Jejunal interposition can be a meter or a reservoir;
- 10cm can serve as a 'valve' to delay transit
- 10-20cm will dilate over time and serve as a reservoir.
- can interpose the reversed segment into an efferent Billroth II limb.

Ileus
See ileus notes


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REFERENCES
Cameron 10th