Impact of Drugs and Surgery on Gut Function Flashcards
What does intrinsic factor do?
Promote absorption of Vitamin B12 in the terminal ileum.
What medical procedure can lead to a decrease in intrinsic factor production and what does this lead to?
Distal gastrectomy.
Can lead to vitamin B12 not being absorbed, thus causing pernicious anaemia.
What are the secretory functions of the stomach?
Secretes HCL
Mucins
Lipase
Intrinsic factor
Electrolytes
Neurocrine / Paracrine agents
For what reason would you have a partial gastrectomy?
Gastric cancer
What are the long term problems with having partial gastrectomy?
Diarrhoea
Small bowel overgrowth
Pancreatic exocrine dysfunction
Gastroparesis
Too rapid transit
Dumping
How does small bowel overgrowth occur?
Can occur due to a partial gastrectomy - less acid is secreted into the duodenum which can lead to small bowel bacterial overgrowth.
This can lead to diarrhoea.
How does pancreatic exocrine dysfunction occur due to a partial gastrectomy?
The pancreas will not put the enzymes into the gut at the right time - this leads to a reduction in lipase.
Causes steatorrhoea.
Gastroparesis
Gastroparesis is a disease in which the stomach cannot empty itself of food in a normal fashion.
- either does not empty well at all or empties to fast.
Why does partial gastrectomy cause gastroparesis?
The vagus nerve is likely damaged / affected during surgery.
What is ‘Dumping’?
After eating a large fatty meal patients suddenly feel very flushed, hypotensive and hypoglycaemic which can cause them to collapse.
A group of symptoms, including weakness, abdominal discomfort, flushing, hypotension, hypoglycemia and sometimes abnormally rapid bowel evacuation. Occurs after eating a fatty meal in some patients who have undergone gastric surgery.
Why does dumping syndrome occur?
Gastric emptying suddenly leads to a large dump of big osmotic food into the bowel - this causes a rush of fluid from the body into the intestine.
Billroth 2 Surgery
Billroth’s operation II, is an operation in which the greater curvature of the stomach is connected to the first part of the jejunum in end-to-side anastomosis.
What is a Billroth 2 surgery used to treat?
The Billroth II is often indicated in refractory peptic ulcer disease and gastric adenocarcinoma.
Billroth 1 surgery
Billroth I, more formally Billroth’s operation I, is an operation in which the pylorus is removed and the distal stomach is anastomosed directly to the duodenum.
What is a Billroth 1 surgery used to treat?
It may be performed in cases of stomach cancer, a malfunctioning pyloric valve, gastric obstruction, and peptic ulcers, and gastric cancer.
Understand
What are the complications associated with having a billroth surgery?
- why are they complications?
Diarrhoea due to:
– Small bowel bacterial overgrowth
– Pancreatic exocrine dysfunction
–Gastroparesis
– Too rapid transit
Dumping due to:
– Post prandial flushing, hypotension, diarrhoea and hypoglycaemia.
– Caused by dysregulated gastric emptying, osmotic load and peptide hormone release.
Who are the complications of diarrhoea and dumping due to Billroth surgery managed?
- Diet
- Antidiarroeals
- SSI - octreotide
What is the aim of Barriatric surgery?
Reduce weight in obese patients and treat type 2 diabetes.
What are the three different types of bariatric procedure?
Restrictive
Malabsorbative
Restrictive + Malasorbative
Summary of Bariatric surgery
What are the different bariatric procedures?
Gastric band
Laparascopic sleeve gastrectomy
Laparascopic gastric bypass
The biliopancreatic diversion with duodenal switch
Gastric band
The adjustable gastric banding is a purely restrictive procedure consisting of the placement of an inflatable prosthetic ring just below the gastroesophageal junction to create a small proximal gastric pouch.
- objective is to reduce food intake
Laparascopic sleeve gastrectomy
Sleeve gastrectomy is a restrictive operation that involves resection of the greater curve of the stomach, which is permanently removed.
What are the benefits of laparascopic sleeve gastrectomy?
It also avoids malabsorptive complications such as ‘dumping syndrome.’
The laparoscopic gastric bypass
The gastric bypass produces a restriction of food intake by creating a small gastric pouch and mild malabsorption by bypassing the duodenum and the proximal jejunum.
After the stomach has been divided, the distal jejunum is connected to the gastric pouch. Food will travel from the pouch through this new connection called a Roux limb, bypassing the gastric remnant, the duodenum and the proximal jejunum.
What are the complications of the laparascopic gastric bypass?
Complications of the gastric bypass include anastomotic leaks, internal hernias, and pernicious anaemia. Weight loss is rapid in the first year and maximum weight loss is achieved at 18 months to 2 years.
The biliopancreatic diversion with duodenal switch
The biliopancreatic diversion with duodenal switch is a malabsorptive procedure consisting of a vertical subtotal gastrectomy (sleeve gastrectomy) associated with a consistent reduction of the absorbing intestine
The bile and pancreatic juice mix with the food in the distal small bowel segment called the common limb. The length of this common limb (usually between 50 and 100 cm) is critical in the absorption of sufficient protein, fat and fat-soluble vitamins.
What are the complications the biliopancreatic diversion with duodenal switch?
Complications include anastomotic leaks and malnutrition, with diarrhoea and foul-smelling stools as frequent side-effects.
This procedure has the highest mortality of bariatric surgeries.
What type of surgery is shown here?
Laparascopic gastric bypass
What type of surgery is shown here?
Sleeve gastrectomy
What type of surgery is shown here?
Adjustable gastric band
What type of surgery is shown here?
Biliopancreatic diversion with duodenal switch
What are the general complications of bariatric surgery?
Restriction of intake can lead to reduced fibre and fluid intake, causing constipation.
Reduced gastric capacity can result in reflux, vomiting, dyphagia and dysmotility.
Nutritional deficincies - B12, calcium, folate, vitamin D
Dumping syndrome
Malabsorption of fat causing steatorrhoea
What procedure is shown here?
Right Hemi-Colectomy
What is the impact of a right hemi-colectomy on gut function?
Ileocaecal resection results in limited absorption of sodium against and electrochemical gradient
Terminal ileal resection results in a permanent reduction in Vitamin B12 absorption and reduced bile reabsorption.
Bacterial overgrowth
What do prostaglandins play in the stomach?
Prostaglandins stimulate gastrric protection through mucus, bicarbonate and phospholipid secretion.
Prostaglandins also sitmulate mucosal bloodflow.
How do asprin and NSAID’s relate to H.pylori?
Asprin and NSAID’s are synergistic with H.pylori exacerbating it’s effects.
Why are NSAID’s synergistic with H.pylori?
(explain the mechanism)
NSAID’s inhibit COX1 and COX2 enzymes which are essential to prostaglandin synthesis.
COX1 is expressed in the stomach and it’s inhibtion results in decreased mucosal bloodflow and reduced mucosal defence.
What is the treatment for peptic ulcer disease?
Eradicated H.pylori (infection is diagnosed by a gastric biopsy).
Stop NSAID’s and Asprin medication.
Use antacids and H2 receptor antagonists.
PPI’s
What bacteria is associated with diarrhoea following a course of antibiotics and why?
C.dificile - C.dif is present in normal gut flora however antibiotics can kill other gut flora allowing overgrowth of C.dif.
Explain one possible cause of pseudomembranous collitis regarding medication.
Antibiotic course resulting in a C.dif infection.
