Clinical Management
Clinical Management is the largest CNSC domain and tests whether you can choose, initiate, advance, monitor, and troubleshoot enteral nutrition (EN) and parenteral nutrition (PN) safely.
EN first, PN only with an indication
EN is preferred when the gut works. In critical illness, start EN within 24–48 hours once resuscitation is complete; trophic feeding at 10–20 mL/h may be used initially in hemodynamically stable patients with intolerance. PN is indicated when EN is contraindicated-bowel obstruction, ischemia, high-output fistula, severe malabsorption-or when EN provides <60% of target after 7–10 days in a high-risk patient. Gastric access is usual; postpyloric access is considered for gastroparesis or aspiration risk. PEG is for longer-term use; NG/NJ for short term.
Prevent refeeding syndrome
High risk: BMI <16, weight loss >15% in 3–6 months, negligible intake >10 days, or low potassium, magnesium, or phosphate. Start at 10–15 kcal/kg/day, give thiamine 200–300 mg before feeding, replete electrolytes, and monitor phosphate, potassium, and magnesium daily. Advance over 4–7 days.
Worked example
A 50 kg woman has BMI 15.5, 18% weight loss over 4 months, and 12 days of negligible intake; phosphate is 0.8 mmol/L. She is high risk. Start 10–15 kcal/kg = 500–750 kcal/day, protein 1.2–1.5 g/kg = 60–75 g/day, thiamine 200 mg IV before feed, and daily phosphate. Do not start at 25–30 kcal/kg. Advance only after electrolytes are stable.
Monitor and avoid overfeeding
Check glucose, electrolytes, triglycerides, liver enzymes, and fluid balance. Keep glucose infusion rate generally ≤4–5 mg/kg/min. Account for propofol calories (1.1 kcal/mL) and dextrose in medications. Do not check gastric residual volumes routinely; check for vomiting, distention, or aspiration.
Traps
Starting full-target feeds in a high-risk patient, omitting thiamine, using PN when EN is feasible, and missing non-nutritional calories are common failures. Also avoid stopping EN for high residuals alone without clinical signs.