Total Parenteral Nutrition (TPN)

• 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.
• Prefer 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.

• 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.

• 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.

• If the gut works, use it: oral intake, oral nutritional supplements, NG/NJ, or other enteral access.
• See NG tube topic 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.

• 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.

• 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.

• 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 topics). Do not accelerate feed until safe.

• 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.

• 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

• 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.

• 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)

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