Synopsis
Use parenteral nutrition only for a defined gastrointestinal failure, prescribe a complete individual admixture safely, and prevent catheter, metabolic, hepatic and refeeding complications through specialist monitoring.
- Parenteral nutrition is indicated when oral and enteral routes are unsafe, inadequate or impossible because the gastrointestinal tract cannot absorb or be accessed sufficiently; it is not a shortcut around feeding difficulties.
- Define the intestinal problem, expected duration, treatment goal and exit strategy before insertion of vascular access, involving the nutrition-support team early.
- A complete prescription accounts for energy, amino acids, glucose, lipid, electrolytes, vitamins, trace elements and fluid, with daily individualisation during unstable illness.
- Central venous access permits more concentrated long-term delivery; peripheral PN is limited by venous tolerance, composition and duration and remains subject to the same metabolic safeguards.
- Use a dedicated lumen and strict aseptic technique, minimising manipulation; never connect incompatible medicines or sample blood routinely through a PN line outside the agreed policy.
- Identify refeeding risk before the first bag, give vitamin support, initiate energy cautiously and monitor phosphate, potassium, magnesium, glucose and fluid balance.
- Suspected catheter-related bloodstream infection requires paired appropriately labelled cultures and early microbiology or intestinal-failure advice; shock needs immediate treatment, while line removal depends on organism and clinical context.
- Return to oral or enteral intake whenever useful gut function recovers, reducing PN in a controlled manner rather than maintaining intravenous calories through clinical inertia.
Key red flags
Rigors with hypotension, confusion, mottling or lactate elevation in a patient with central access requires immediate sepsis treatment after cultures when safe and must not await proof of line infection.
Sudden chest pain, dyspnoea, arrhythmia or cardiovascular collapse during line insertion or manipulation suggests pneumothorax, embolic or malposition complications requiring emergency response.
Rapid oedema, heart failure, respiratory weakness, delirium or arrhythmia after nutrition begins may indicate severe refeeding physiology and demands urgent correction.
Painful swollen limb or face with catheter dysfunction suggests central venous thrombosis; preserve future access by seeking specialist imaging and anticoagulation advice promptly.
Marked hyperglycaemia with ketones, hyperosmolar symptoms or reduced consciousness is a medical emergency, not simply a reason to discard the current PN bag.
Investigation priorities
Confirm indication, estimate requirements and identify a feasible route transition.
Management branches
Nutrition goals cannot be met safely through oral or enteral routes because gut function or access is inadequate.
- Define the gastrointestinal mechanism, predicted duration, prior route optimisation, refeeding category and patient-centred objective.
- Refer to the multidisciplinary nutrition-support team to estimate requirements and choose peripheral or central access with a documented rationale.
- Establish baseline biochemistry, fluid balance, vascular-access plan and aseptic responsibilities before ordering the tailored formulation.
- Set review criteria for progression, complication surveillance and transition back toward gastrointestinal feeding.