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Give me important MCQ and value points from these pages so I don't have to study them separately.
Here is a high-yield MCQ and value point summary of Chapter 19 - Surgical Nutrition (pages 140-146):
🏥 Surgical Nutrition - High Yield MCQ & Value Points
ENTERAL FEEDING
Key Concept
- Enteral nutrition is suitable when spontaneous oral intake is inadequate
- For enteral feeding to work: small intestine must be functioning adequately
Indications (MCQ favorite)
| Indication | Key Detail |
|---|---|
| Protein-energy malnutrition | Inadequate oral intake |
| Dysphagia for solids | |
| Unconsciousness | |
| Enterocutaneous fistula | Distal, low output (<200ml) |
| Post massive enterectomy | For enhancing adaptation |
Contraindications
- Small bowel obstruction
- Paralytic ileus
- Severe diarrhoea
- Proximal high output small intestinal fistula (relative contraindication)
- Severe pancreatitis
ROUTES OF ENTERAL FEEDING
| Route | Duration / Key Detail |
|---|---|
| Nasogastric/Nasojejunal tube | < 6 weeks; Narrow bore 7-9F |
| Tube Gastrostomy/Enterostomy | > 4-6 weeks (prolonged feeding) |
| Methods of gastrostomy | Open surgical / PEG / PEJ |
MCQ: Tube should NOT be left in the stomach if gastric emptying is inadequate or gag reflex is impaired - advance to duodenum or jejunum to prevent aspiration.
ORAL SUPPLEMENTS - Value Numbers
- Provide 200 kcal and 2g of Nitrogen per each 200ml of feed
- Used in patients who can drink but have impaired appetite
NASOGASTRIC FEEDING PROTOCOL (MCQ Numbers)
| Step | Value |
|---|---|
| Head elevation | 30° |
| Starting rate | 40 ml/hour |
| Advancement | 10-20 ml increments every 8-12 hours |
| Tube flush | Every 4 hours with 20ml sterile water |
| Residual volume threshold | >150ml → discontinue for 2 hours |
| After 2 hours, if residual still >150ml | Do NOT restart until physician notified |
NUTRIENT FORMULATIONS
| Type | Key Feature |
|---|---|
| Polymeric / Blenderized | Short peptides, MCT, polysaccharides, vitamins, trace elements; require digestion |
| Elemental diets | Pre-digested; L-amino acids + monosaccharides; expensive, unpalatable; high osmolarity → diarrhoea |
- Standard formulas: 1-2 kcal/ml and 0.6g protein/ml
ADVANTAGES OF ENTERAL FEEDING (MCQ)
- Prevents intestinal mucosal atrophy
- Maintains gut barrier function
- Decreases post-operative infectious complications
- Luminal availability of glutamine is important for normal small bowel mucosa
- Supports gut-associated immunological shield
- Cheaper than TPN and has fewer complications
- No IV access needed
SIDE EFFECTS OF GASTROSTOMY
- Necrotizing fasciitis
- Intra-abdominal wall abscess
- Sepsis
- Persistent gastric fistula
COMPLICATIONS OF ENTERAL FEEDING
Tube-related
- Malposition, breakage, dislodgement, aspiration, erosion, peritonitis, intestinal obstruction, tube blockage
Regimen-related (MCQ)
- Feed intolerance diarrhoea - most common complication (>30% of patients)
- Hyperglycemia - reduce rate + insulin therapy
- Enteric infection - discard container after 12-24 hours; rule out C. difficile for persistent diarrhoea
- Electrolyte disorders, drug interactions, vitamin/mineral deficiency
TOTAL PARENTERAL NUTRITION (TPN)
Definition
Provision of ALL nutritional requirements without use of the GI tract - used when there is intestinal failure
Indications ("Gut 5S") - MCQ
- Gut is Obstructed
- Gut is Short
- Gut is Fistulated (high output ECF)
- Gut is Inflamed
- Gut Cannot cope (ileus)
Contraindications
- Congestive cardiac failure
- Blood dyscrasias
- Uncontrolled diabetes mellitus
- Fat metabolism disturbance
TPN ROUTES & KEY NUMBERS
| Parameter | Value |
|---|---|
| Volume per day | 2-4 liters |
| Calories provided | 1500-3200 kcal/day |
| Peripheral glucose max | 20% |
| Central glucose | up to 50% |
| Peripheral chief calorie source | Lipid (20% fat emulsion, 500ml daily) |
| TPN rate slow | <3L/day to prevent thrombophlebitis |
| Heparin (if required) | 900 units added to regimen |
Rate of Administration
- Day 1: 40 ml/hour
- Day 2: 80 ml/hour
- Day 3 onwards: 100-125 ml/hour
MCQ: Peripheral TPN solutions are hyperosmolar and low in pH → cause thrombophlebitis and venous thrombosis if given peripherally
CATHETER CARE (MCQ)
- Use smallest possible caliber catheters
- Single lumen catheters wherever possible
- Catheters must be tunneled subcutaneously to minimize infection
- Chest X-ray post-insertion to confirm no pneumothorax
- Catheter tip screened under radiological guidance to distal SVC
SPECIAL DIETARY CONSIDERATIONS (High MCQ Yield)
| Condition | Key Point |
|---|---|
| Respiratory failure | Avoid large amounts of glucose (produces excess CO₂); Glucose should NOT be chief energy source in sepsis (insulin resistance) |
| Renal failure | Glucose = chief energy source; 70% dextrose water (500ml) + essential amino acids only; limited Na, K, Mg, Phosphate |
| Hepatic failure | Use Branched Chain Amino Acids (BCAA) - metabolized by skeletal muscle, not liver |
MONITORING OF TPN
| Frequency | Parameters |
|---|---|
| Daily | Sodium, Potassium, Urea, Creatinine, Glucose |
| Weekly | FBC, LFTs, Calcium, Phosphate, Magnesium |
| Monthly | Selenium, Zinc, Copper, Urinary electrolytes |
- 5% of patients on TPN develop metabolic derangement
- Blood cultures on any sign of sepsis
COMPLICATIONS OF TPN
Catheter Insertion Problems
- Failure to cannulate, Pneumothorax, Haemothorax, Cardiac perforation/tamponade
- Pleural effusion, Arterial puncture, Brachial plexus injury, Mediastinal hematoma, Thoracic duct injury
Catheter Care Problems
- Catheter related infection (most common - 3-14%)
- Infective endocarditis, Air embolus, CVT
- >90% infections caused by Staph aureus from catheter hub
Catheter Infection Features
- Unexplained hyperglycemia, fever, rigors, leukocytosis
- Treatment: IV antibiotics + remove/exchange catheter
- Failure to resolve after 48 hours → echocardiography to rule out infective endocarditis
Metabolic Complications (MCQ)
| Complication | Key Detail |
|---|---|
| Hyperglycemia | Most common |
| Hypoglycemia | Caused by sudden stoppage of TPN (high insulin levels); must taper gradually |
| Hyperchloremic acidosis | Due to excessive NaCl administration |
| Hyperosmolar dehydration | |
| Hepatic steatosis | |
| Zinc deficiency | Rash, alopecia, impaired wound healing |
| Chromium deficiency | Diabetes-like state |
| Copper deficiency | Anemia |
| Essential fatty acid deficiency | Within 4-6 weeks if no lipids given |
REFEEDING SYNDROME (Very High Yield MCQ)
| Feature | Detail |
|---|---|
| Also called | Severe hypophosphatemia |
| Occurs in | Severely malnourished patients |
| Caused by | High caloric, high carbohydrate diet suddenly |
| More common in | Parenteral nutrition (can occur in both) |
| Metabolic shift | Catabolic → Anabolic; Fat → Glucose metabolism |
| Mechanism | Phosphorylated intermediates of glycolysis trap phosphates → hypophosphatemia → ↓ATP → ↓ventricular stroke volume → severe congestive cardiomyopathy |
| Electrolyte changes | Hypophosphatemia, Hypocalcemia, Hypomagnesemia |
| Clinical features | Arrhythmias, liver dysfunction, seizure, coma, tetani, abdominal pain, vomiting, constipation, deteriorating respiratory function |
| Prevention/Treatment | Gradual initiation of TPN + phosphorus supplementation |
NUTRITIONAL CONSEQUENCES OF INTESTINAL RESECTION
Small Intestine Anatomy (Value Numbers - MCQ)
- Total small intestine: ~400 cm
- Duodenum: 25-30 cm
- Jejunum: 160-200 cm
- Ileum: remainder
Absorption Sites
| Site | Absorbs |
|---|---|
| Duodenum + Jejunum | Carbohydrates, Proteins |
| Ileum | Fats bound to bile salts, fat-soluble vitamins, Vitamin B12 (bound to intrinsic factor) |
| Ileum + Large intestine | Most fluids and electrolytes |
MCQ: Resection of only 100cm of terminal ileum → severe diarrhoea, malabsorption, malnutrition
Deficiencies After Intestinal Resection
- Dehydration, Electrolyte imbalances
- Zinc deficiency
- Vitamin B12 deficiency
- Malabsorption of fat, carbohydrates, proteins
- Late: Cholelithiasis, Renal stones, D-lactic acidosis
🎯 Top MCQ Traps to Remember
- Nasogastric tube duration = <6 weeks (narrow bore 7-9F)
- Gastrostomy/enterostomy = >4-6 weeks
- Residual >150ml → stop feeding for 2 hours
- Most common complication of enteral feeding = feed intolerance diarrhoea (>30%)
- Hypoglycemia from TPN = sudden stoppage → taper gradually
- Refeeding syndrome = hypophosphatemia = high carb diet in malnourished patient
- Hepatic failure = BCAA (not regular amino acids)
- Respiratory failure = avoid glucose (→ CO₂)
- Renal failure = glucose is the chief energy source
- Catheter infection organism = Staph aureus (>90%)
- Terminal ileum resection 100cm = severe consequences
- Vitamin B12 absorbed in ileum (bound to intrinsic factor from stomach)
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