Total Parenteral Nutrition (TPN)
TPN for NCHDs in Irish hospitals: indications, access, refeeding risk, monitoring, complications, and when to escalate to dietetics and pharmacy.
🧠 Definition
- Parenteral nutrition (PN) delivers nutrition intravenously, bypassing the GI tract.
- Total PN (TPN): nutrition needs met entirely IV. Supplementary PN (SPN): IV nutrition on top of some enteral/oral intake.
- Use oral or enteral feeding whenever the gut works. PN is support when the gut cannot be used safely or adequately.
- Regimens, bag types, and ordering systems are hospital-specific. Always follow local PN PPPG and involve dietetics and pharmacy.
🚨 Red flags / escalate
- Suspected catheter-related bloodstream infection (fever, rigors, line erythema) on PN: escalate early; do not ignore.
- Severe electrolyte shifts after starting or increasing feed (especially phosphate, potassium, magnesium): treat, slow/stop feed per local protocol, call senior and dietetics.
- Line disconnection, damage, or extravasation of PN: stop infusion, senior/vascular access review.
- Hypoglycaemia or marked hyperglycaemia on PN: check rate, bag, and concurrent insulin/fluids; escalate if unstable.
- PN bag not ordered, not delivered, or about to run out: escalate to ward, pharmacy, and dietetics before the bag finishes.
🧾 Indications (examples)
- Prolonged ileus or obstruction where enteral route is not usable
- High-output enterocutaneous fistula, short bowel, or major GI resection with inadequate absorption
- Severe mucositis or other inability to use the gut for a clinically important period
- Failed or inadequate enteral nutrition despite optimisation, with ongoing malnutrition risk
- Decision to start PN is MDT (consultant, dietetics, pharmacy). NCHDs do not initiate PN alone.
🚫 Prefer enteral first
- If the gut works, use it: oral intake, oral nutritional supplements, NG/NJ, or other enteral access.
- See NG tube for enteral access; involve SALT if swallow is unsafe.
- PN has higher infection and metabolic risk than enteral feeding. Document why enteral is not possible or not enough.
🔌 Access
- Most adult TPN needs dedicated central venous access (PICC, tunnelled CVC, or port). Confirm local policy.
- Peripheral PN (if used at all) is short-term only and limited by osmolarity. Do not invent a peripheral regimen.
- Use a dedicated lumen for PN where possible. Do not mix incompatible drugs into the PN bag or Y-site without pharmacy advice.
- Strict asepsis and line care bundles reduce catheter infection risk.
📋 Starting and prescribing (Irish hospital practice)
- Refer dietetics urgently. Pharmacy usually compounds or supplies the bag and advises on additives and stability.
- Baseline: weight, U&E, LFTs, bone profile, Mg²⁺, phosphate, glucose, FBC, triglycerides/lipids as per local protocol; ECG if high refeeding risk.
- Screen for refeeding risk (IrSPEN / HSE nutrition policy). Start slowly if at risk (often ~10 kcal/kg/day, or lower in extreme risk; confirm dietetics plan).
- Give thiamine and multivitamins before and during early feeding in refeeding risk, per local protocol.
- Correct critical electrolyte deficits before or as feed starts. Do not chase “perfect” labs at the cost of delayed safe feeding without senior/dietetic input.
- Order bags in time for pharmacy cut-offs. Document indication, access, rate, start time, and monitoring plan.
🔄 Refeeding syndrome
- Highest risk: prolonged poor intake, low BMI, recent weight loss, alcohol misuse, already low K⁺/Mg²⁺/phosphate.
- Watch for falling phosphate, potassium, and magnesium in the first days of feeding; arrhythmias and respiratory failure can follow.
- IrSPEN-style approach: daily electrolytes for ~5 days then thrice weekly until stable if high risk; ECG/telemetry if severe deficits or clinical concern.
- Replace electrolytes promptly (see hypophosphataemia, hypokalaemia, hypomagnesaemia). Do not accelerate feed until safe.
🔍 Monitoring on PN
- Until stable: fluid balance, weight trend, capillary glucose (often QDS initially), U&E, Mg²⁺, phosphate, calcium.
- Also trend LFTs, FBC, and lipids/triglycerides per local PN protocol (frequency falls once stable).
- Review line site each shift; escalate early for infection or mechanical problems.
- Reassess whether enteral progress allows weaning or stopping PN. Stop when gut use is adequate.
⚠️ Complications
- Catheter-related bloodstream infection (most serious avoidable harm)
- Metabolic: refeeding, hyper/hypoglycaemia, electrolyte imbalance, hypertriglyceridaemia
- Hepatic: PN-associated liver dysfunction with prolonged use
- Fluid overload or dehydration if rate and other IV fluids are not reconciled
- Line thrombosis, occlusion, or mechanical failure
🛠️ On-call troubleshooting
- Bag almost empty / next bag missing: contact pharmacy and dietetics; do not improvise a substitute bag. Temporary dextrose-containing fluids may be needed to avoid rebound hypoglycaemia if PN stops abruptly. Confirm local protocol.
- Fever on PN: full septic work-up including line cultures per sepsis pathway; senior review regarding line removal vs salvage.
- High glucose: check for steroids/infection/rate errors; consider insulin per local protocol; do not arbitrarily change the PN bag overnight without pharmacy/dietetics.
- Low phosphate/K⁺/Mg²⁺: replace, consider slowing feed, inform dietetics for next bag adjustment.
- Blocked line: follow local line protocol; never force flush against resistance.
📄 Documentation
- Indication and why enteral is not sufficient
- Access type and lumen used
- Bag identity, rate, start/stop times
- Refeeding risk and vitamin/electrolyte plan
- Monitoring results and MDT contacts (dietetics, pharmacy, consultant)
Based on
HSEFood, Nutrition and Hydration Policy for Adult Patients in Acute HospitalsGuidelineIrSPEN — Prevention and Treatment of Refeeding Syndrome in the Acute Care Setting (Guideline Document No. 1, 2013)GuidelineState Claims Agency / IrSPEN — Reducing patient safety incidents associated with parenteral nutrition
Note Template
Ready-to-use clinical note structure
🕒 30 / 10 / 2026 — 00:15 ATRP re: parenteral nutrition / TPN Patient: [age] [sex] Admission Dx: [reason for admission] PMHx: [GI surgery, short bowel, fistula, ileus, malnutrition] 🧾 Hx: • Indication for PN vs enteral: [gut not usable / inadequate enteral] • Current access: [PICC / CVC / port / other] • Current bag/rate and start date: [ ] • Symptoms: [fever, line issues, hypoglycaemia, overload] • Refeeding risk factors: [poor intake, low BMI, weight loss, alcohol, low electrolytes] 🩺 Exam: • Vitals: HR __ BP __ Temp __ SpO₂ __ • Line site: [clean / erythema / discharge] • Fluid status and glucose: [ ] 📋 Impression: [Issue on PN: infection concern / electrolyte shift / bag/logistics / metabolic / other] 📌 Plan: • Bloods: U&E, Mg²⁺, phosphate, Ca²⁺, LFTs, FBC, glucose [± lipids] • Electrolyte replacement / feed rate as per dietetics and local protocol • Pharmacy / dietetics contacted: [yes/no] • Line cultures / sepsis pathway if indicated • Escalated to senior: [yes/no] 👤 [Your Name], [Role] IMC: _______
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