Week 7: Gastroenterology (2) (abdominal X-ray and nutrition) Flashcards
abdominal x-rays basics
- Check:
- Patient details
- Orientation
- Look at the x-ray- do you see anything obvious
- Then work through the GI tract in order
- Rectum (is air visible in the rectum)
- Large bowel and small bowel
- Stomach
- Kidneys, ureter and bladder
- Organs (liver and spleen
- bones
normal abdominal x-ray
- Should be able to see some air in the stomach and almost always in the sigmoid and rectum, and there should be one or two air filled small bowel loops
- Large bowel- peripherally placed with haustral markings that do not extend wall to wall
- Small bowel- more centrally placed with valvulae that extend the whole way across the lumen
large bowel on x-ray
peripherally placed with haustral amrkins that do not extend wall to waal
small bowel on x-ray
more centrally places with valvulae that extend the whole way across the lume
valvulae
plicae circulares or just small bowel folds, are the mucosal folds of the small intestine
hallmarks of intestinal obstruction
is dilated loops of bowel and absence of gas distal to the obstruction (e.g. in the rectum)
small bowel obstruction on x-ray
- Central position
- Often don’t see (need gas in the bowel to see)
- Plica/circulares/ permanent folds/ Valvulae conniventes
- Cross the entire wall
- Thin
- No gas in rectum
Causes of small bowel obstruction
- Adhesions (scar tissue) which form after surgery
- Hernias
- Colon cancer
- Strictures from an inflamed intestine caused by IBD
Large bowel obstruction on X-ray (369 rule)
Depends on the level of obstruction and ileo-caecal valve
- Peripheral position
- Haustra- sacculation’s formed by outer longitudinal muscles
- Lines only extend partially along the bowel wall
- Remember
- Transverse colon hangs down to the pelvic
- Sigmoid colon can loop and be long
In the presence of competent ileo-caecal valve…
- there is distension of the large bowel and caecum with normal looking small bowel (high risk of colonic perforation as the colon acts as a closed loop with no mechanism to decrease the luminal pressure
If ileo-caecal valve is incompetent …
there is dilation of both the large and small bowel and the risk of perforation reduced
UC and X-ray
- X-ray important for assessing flare up
- Looking for toxic mega-colin (med and surg emergency)
- lead pipe colon
classic findins of UC on x-ray
- Thickening of the colonic wall consistent with mucosal oedema secondary to active UC
signs of colititis constipation
-
- the normal colon acts to absorb water with liquid faeces entering the ascending colon from the small bowel. This gradually becomes more solid as it progresses through the colon
- E.g. in patients with left sided colitis constipation can occur in the right side of the colon due to distal inflammation important to look for on x-ray as proximal constipation cannot be diagnosed by PR exam
Toxic megacolon
‘segmental or total colonic diameter of greater than 6cm radiologically with signs of systemic upset (toxic)’
- Pan-colonic dilation that is worse in the transverse colon
- Mucosal oedema and dilated small bowel
- Urgent surgical input and colectomy with formation of an ileostomy
Volvulus
- Complete twisting of a loop of intestine around its mesenteric attachment site
- Can happen at various GI sites, however most commonly affects the sigmoid colon
risk factors for volvulus
- Chronic constipation
- Mega-colon
- Excessively mobile colon
- Elderly patients
symptoms of volvulus
- Abdominal distension
- Absolute constipation
- Abdominal pain
- X-ray findings are diagnostic
typical x-ray finding of volvulus: sigmoidal volvulus
- Coffee-bean appearance
- Caused by dilation proximal to the twist
- treatment placement of flatus tube or endoscopic decompression
x-ray caecal volvulus
- Rare
- Embryo sign
- Usually point of torsion is located in the ascending colonn
- Requires urgent surgical intervention
causes of large bowel obstruction
- Abdominal adhesions (scar tissue) from surgeries.
- Diverticulitis.
- Hernias.
- Inflammatory bowel disease (IBD).
- Radiation therapy to the abdomen or pelvis.
- Twisted intestine (rare in adults)
perforation on x-ray
- Erect chest x-ray AP
- Perotisnim is very painful
- Heart enlarged
- Perforation will cause air within the peritoneal cavity which rises when the patient is upright
Pneumoperitoneum- need erect chest X-ray
- An erect chest x-ray can show even a very small volume of abdominal gas- free air in the diaphragm
- Reference to the clinical setting is required to determine if this a life threating perforation
pneumoperitoneum and recent laparoscopic surgery
- Patient might have undergone laparoscopic surgery earlier in the day→ free gas under diaphragm is insufflated CO2- an acceptable post surgery finding
- To expand visible field for surgeon
Causes of pneumoperitoneum
- Peptic ulcer
- Diverticular
- Tumour
- Obstruction
- Trauma
- Iatrogenic
Stones and calcification
Any stones are radio-opaque and therefor visible on plain abdominal x-rays
e.g. in chronic pancreatitis
foreign bodies
What is food?
- Energy
- Macronutrients
- Protein
- Carbohydrate (CHO)
- Fat
- Micronutrients
- Vitamins
- Trace elements
Energy
- Measured in kilocalories
- 1kcal is the amount of energy required to heat 1kg of water by 1oC at sea level
- 1kcal= 4.2kj
- Not all macronutrients provide the same energy
- Fat is most energy dense- 9kcal/gram of substrate
- CHO and protein= 4kcal/gram
Fat
- Highest density energy storage
- Broken down to fatty acids and glycerol
- Converted to glucose and ketones in starvation state
Vitamins
- Cannot be synthesised in the body and need to be included in the diet
- Can be fat or water soluble
- Fat: Always do eat KitKat
- Non fat: vit B1, B2, B3, B5, B6 etc
nutuitonal assessment of malnutitions
The Malnutrition Universal Screening Tool (MUST) is a simple validated bedside tool.
Simple questions such as asking your patient about their appetite, diet history, changes in oral intake and changes in weight are key.
intravenous fluid regimine
what is in PN
how is PN given
- Prolonged infusion over 12-24 hours via central venous catheter
- Can be given via. PICC line or Hickman line (pts can have both)
- Red- PICC
- Right – Hickman
Why use a central venous catheter
- CVC is a long flexible cannula that sits with its tip in a large vein
- This stops thrombosis and damage to vessel wall that might be caused by infusing PN into a small peripheral vein
How many calories in a bag of PN?
- Grams of nitrogen X 25= protein calories
- Add this to glucose and lipid calories= total calories in bag
refeeding is a biochemical triad of
- Hypophosphatemia (biochemical marker)
- Hypokalaemia
- Hypomagnesaemia
outline how refeeding syndrome occurs
- When carbohydrate is reintroduced in starvation, the insulin levels quickly rise to accommodate the glucose load to facilitate the production of glycogen, muscle and fat.
- This process requires ATP( which uses up phosphate) and drives phosphate, potassium, magnesium and water into cells and sodium out.
- As a result the phosphate stores become further depleted and the corresponding fluid shift causes oedema.
- The hypophosphataemia reduces the production of ATP and impairs function of cardiac muscle.
- In addition 2,3-DGP is reduced in red cells and this decreases the ability of red cells to deliver oxygen to tissues.
- The combined effect of fluid shifts, reduced tissue oxygenation and impaired cardiac function is potentially catastrophic.
who is at risk of refeeding syndrome
During starvation
- During prolonged starvation insulin levels drop activating hormone-sensitive lipase which results in the breakdown of fat.
- This results in the production of fatty acids and glycerol.
- The fatty acids are converted to ketone bodies which are used as an alternative fuel to glucose, and the glycerol is used for gluconeogenesis.
- In addition muscle is also broken down to amino acids which are used for gluconeogenesis.
- During starvation state phosphate stores become depleted
clinical signs of anorexia
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complications of anorexia
