6.2 GI Management & Nutrition Support

Nasogastric Tubes and Enteral Feeding

Nasogastric (NG) tubes are used for decompression, feeding, and medication administration. Placement verification is a core safety competency:

• Radiographic (X-ray) confirmation is the gold standard before the first use for feeding or medications.
• At the bedside, measure and document the exit length at the naris and re-check it before each use; a change suggests migration.
• Aspirate gastric contents and test pH — gastric aspirate is typically 5.5 or lower (many protocols use 5.0 or 5.5 as the cutoff), whereas respiratory and intestinal aspirates read higher. Note that acid-suppressing medications can raise gastric pH.
• Never rely on the air bolus auscultation (whoosh) test. Injecting air and listening over the epigastrium is unreliable — a tube coiled in the esophagus or sitting in the lung can produce a similar sound. It must never be the sole method.
• Stop insertion and remove the tube if the patient develops coughing, cyanosis, respiratory distress, or desaturation.

For enteral (tube) feeding, aspiration prevention is the priority: keep the head of bed at 30 to 45 degrees during feeding and for 30 to 60 minutes after intermittent feedings. Flush the tube with 15 to 30 mL of water before and after medications and feedings (and every 4 hours with continuous feeding), and never add medications directly to the formula.

Gastric residual volume practices vary: older teaching held feedings for residuals over 250 to 500 mL, while current ASPEN guidelines discourage routine residual checks in stable patients; follow facility protocol and never discard large residuals — return them to prevent electrolyte loss. Diarrhea is the most common enteral complication; culprits include sorbitol-containing liquid medications, antibiotics (consider Clostridioides difficile), hyperosmolar formulas, and contaminated formula. Evaluate the cause rather than automatically stopping the feeding. Limit hang time of open-system formula (commonly 4 to 8 hours) and change bags and tubing every 24 hours.

Total Parenteral Nutrition

Total parenteral nutrition (TPN) delivers concentrated dextrose (typically 20 to 25%), amino acids, lipids, electrolytes, vitamins, and trace elements. Because of its high osmolarity, TPN requires a central venous catheter (peripheral parenteral nutrition is limited to about 10% dextrose and short-term use).

Key nursing actions:

• Use a dedicated central line lumen, strict aseptic technique, an in-line filter, and change IV tubing every 24 hours per protocol.
• Monitor blood glucose every 6 hours (or per protocol); hyperglycemia is common and often requires an insulin infusion or sliding-scale coverage.
• Never abruptly stop TPN. If the next bag is unavailable, hang 10% dextrose (D10W) at the same rate to prevent rebound hypoglycemia from circulating endogenous insulin. Likewise, never increase the rate to catch up a delayed bag — rapid shifts in glucose and volume are dangerous.
• TPN solutions are generally good for 24 hours once hung; inspect for separation or precipitate and never add medications to the bag.

Refeeding syndrome is a life-threatening complication of starting nutrition in chronically malnourished patients. As carbohydrate intake stimulates insulin, phosphorus, potassium, and magnesium shift into cells, causing hypophosphatemia (the hallmark), hypokalemia, and hypomagnesemia, plus fluid retention — resulting in cardiac dysrhythmias, respiratory failure, and weakness. Prevention: start nutrition low and slow, check electrolytes frequently, aggressively replace phosphorus, potassium, and magnesium, and give thiamine (especially with alcohol use disorder) before glucose to prevent Wernicke encephalopathy.

Ostomy Care

Stoma output depends on location. An ileostomy drains continuous liquid to semi-liquid effluent rich in digestive enzymes — expect high output (initially up to 1 to 2 liters per day), risk of dehydration and electrolyte loss, and aggressive skin protection because enzymes excoriate peristomal skin. A colostomy output becomes more formed as you move distally: ascending colostomies are semi-liquid, transverse semi-formed, and descending/sigmoid colostomies produce near-formed stool and may be regulated with irrigation.

A healthy stoma is beefy red to pink and moist. A dusky, pale, blue, or black stoma indicates ischemia — report immediately. Cut the pouch wafer opening only about 1/16 to 1/8 inch larger than the stoma, change the appliance every 3 to 7 days, and empty the pouch when it is one-third to one-half full.

Liver Disease: Cirrhosis Complications

Cirrhosis produces portal hypertension, which drives its major complications.

• Ascites: manage with sodium restriction (about 2 g/day), fluid restriction if hyponatremic, and diuretics — spironolactone (potassium-sparing, first-line) often combined with furosemide in a 100:40 ratio. Monitor daily weights, abdominal girth, electrolytes, and renal function.
• Paracentesis: have the patient void first to avoid bladder puncture, position upright or in high Fowler, and monitor blood pressure throughout. For large-volume paracentesis (more than 5 liters removed), give IV albumin — 6 to 8 grams per liter removed — to prevent post-paracentesis circulatory dysfunction.
• Esophageal varices: fragile, distended veins that can bleed catastrophically. Teach the patient to avoid straining, heavy lifting, and NSAIDs. Nonselective beta-blockers (propranolol, nadolol) reduce portal pressure; endoscopic band ligation treats high-risk varices. For acute hemorrhage, the airway is the priority; expect octreotide (or vasopressin), blood products, urgent endoscopy, balloon tamponade as a temporizing measure, and possibly transjugular intrahepatic portosystemic shunt (TIPS).
• Hepatic encephalopathy: ammonia accumulates as the liver fails to detoxify it. Watch for subtle mental status changes, asterixis (flapping hand tremor), constructional apraxia, and fetor hepaticus (musty breath). Lactulose is titrated to 2 to 3 soft stools per day — it acidifies the colon, converting absorbable ammonia (NH3) to nonabsorbable ammonium (NH4+) that is excreted in stool; rifaximin is a common adjunct. Avoid sedatives and benzodiazepines, and institute bleeding and fall precautions (thrombocytopenia, prolonged prothrombin time, confusion).

Post-Op Diets and Malnutrition Screening

The classic postoperative diet progression is NPO to clear liquids to full liquids to soft/mechanical soft to regular diet, advanced as tolerated once bowel function returns (bowel sounds, flatus). Clear liquids include broth, gelatin, pulp-free juice, tea, and popsicles — they leave minimal residue but are nutritionally inadequate beyond a few days. Current enhanced-recovery practice favors early enteral feeding whenever the gut works.

Malnutrition screening matters because malnutrition worsens surgical outcomes and healing. Red flags: unintentional weight loss of more than 5% in 1 month or more than 10% in 6 months, BMI under 18.5, poor intake, and chronic illness. Serum albumin (normal 3.5 to 5.0 g/dL, half-life about 20 days) reflects chronic status and inflammation rather than acute intake; prealbumin (normal 15 to 36 mg/dL, half-life 2 to 3 days) better reflects recent nutritional changes. Screen with a validated tool (such as the Malnutrition Screening Tool or MUST) and consult a dietitian early.