Surgical Nutrition Flashcards
What is the motto of surgical nutrition?
“If the gut works, use it”
What is the normal adult daily requirement of protein?
1 g/kg/day
What is the normal adult daily requirement of calories?
30 kcal/kg/day
How is basal energy expenditure changed after a severe head injury?
Increased 1.7 fold
How is basal energy expenditure changed after a severe burn?
Increased 2-3 fold
What is the calorie content of fat?
9 kcal/g
What is the calorie content of protein?
4 kcal/g
What is the calorie content of carbohydrate?
4 kcal/g
What is the formula for converting nitrogen requirement/loss to protein requirement/loss?
Nitrogen X 6.25 = protein
What is RQ?
Respiratory Quotient:
Ratio of CO2 produced to O2 consumed
What is the normal RQ?
0.8
What can be done to decrease the RQ?
More fat, less carbohydrates
What dietary change can be made to decrease CO2 production in a patient in whom CO2 retention is a concern?
Decrease carbohydrate calories and increase fat calories
What lab tests are used to monitor nutritional status?
Prealbumin (acute change determination); transferrin; albumin (more chronic determination); total lymphocyte count; anergy; retinol-binding protein
Where is iron absorbed?
Duodenum (some in proximal jejunum)
Where is vitamin B12 absorbed?
Terminal ileum
What are the surgical causes of vitamin B12 deficiency?
Gastrectomy, excision of terminal ileum, blind loop syndrome
Where are bile salts absorbed?
Terminal ileum
Where are fat-soluble vitamins absorbed?
Terminal ileum
Which vitamins are fat-soluble?
K, A, D, E
What are the signs of vitamin A deficiency?
Poor wound healing
What are the signs of vitamin B12/folate deficiency?
Megaloblastic anemia
What are the signs of vitamin C deficiency?
Poor wound healing, bleeding gums
What are the signs of vitamin K deficiency?
Decrease in the vitamin K-dependent clotting factors (II, VII, IX, X), bleeding, elevated PT
What are the signs of chromium deficiency?
Diabetic state
What are the signs of zinc deficiency?
Poor wound healing, alopecia, dermatitis, taste disorder
What vitamin increases the PO absorption of iron?
PO vitamin C (ascorbic acid)
What vitamin lessens the deleterious effects of steroids on wound healing?
Vitamin A
What are the common indications for TPN?
NPO > 7 days; enterocutaneous fistula; short bowel syndrome; prolonged ileus
What is TPN?
Total Parenteral Nutrition
What is in TPN?
Protein, carbohydrates, lipids, (H2O, electrolytes, minerals, vitamins, +/- insulin, +/- H2 blocker)
What percentage of calories in TPN comes from lipids?
20-30%
What percentage of calories in TPN comes from protein?
10-20%
What percentage of calories in TPN comes from carbohydrates?
50-60%
What are the possible complications of TPN?
Line infection, fatty infiltration of the liver, electrolyte or glucose problems, PTX during placement of central line, loss of gut barrier, acalculus cholecystitis, refeeding syndrome, hyperosmolality
What are the advantages of enteral feeding?
Keeps gut barrier healthy, thought to lessen translocation of bacteria, not associated with complications of line placement, associated with fewer electrolyte or glucose problems
What is the major nutrient of the small bowel?
Glutamine
What is refeeding syndrome?
Decreased serum potassium, magnesium, and phosphate after refeeding (via TPN or enterally) a starving patient
What is an elemental tube feed?
Very low residue tube feed in which almost all the tube feed is absorbed
Where is calcium absorbed?
Duodenum (actively), jejunum (passively)
What is the major nutrient of the colon?
Butyrate (and other short-chain fatty acids)
What must bind B12 for absorption?
Intrinsic factor from the gastric parietal cells
What sedative medication has caloric value?
Propofol delivers 1 kcal/cc in the form of lipid
Why may all the insulin placed in a TPN bag not get to the patient?
Insulin will bind to the IV tubing
What is the best way to determine the caloric requirements of a patient on the ventilator?
Metabolic chart
How can serum bicarbonate be increased in patients on TPN?
Increase acetate (which is metabolized into bicarbonate)
What are trophic tube feeds?
Very low rate of tube feeds (usually 10-25 cc/hr), which are thought to deep mucosa alive and healthy
When should PO feedings be started after a laparotomy?
Classically after flatus or stool PR (usally POD #3-5)
What is the best parameter to check adequacy of nutritional status?
Prealbumin
