01Principles and purposeThe professional or clinical skill and the decisions it supports.
Malnutrition is a state in which deficient or imbalanced intake causes measurable harm to body composition, function or clinical outcome. It can be concealed by obesity, oedema or rapid fluid shifts. Screening identifies risk; it does not diagnose the cause or dictate a feed. Record actual weight, previous weight, timeframe, BMI, recent intake and the acute disease effect. Then investigate swallowing, dentition, gastrointestinal symptoms, inflammation, cognition, mood, poverty, ability to shop and prepare food, and help available at home.
The route follows physiology and goals. Food-first measures, assistance, texture modification and oral supplements preserve normal eating when swallowing is safe. Enteral feeding uses a functioning gastrointestinal tract when intake is insufficient or unsafe. Parenteral nutrition bypasses the gut and requires specialist vascular-access, metabolic and infection management when oral and enteral routes are inadequate or impossible. A tube or line is an intervention with burdens; capacity, consent, prognosis and the intended duration must be discussed.
Refeeding after depletion increases cellular uptake of phosphate, potassium and magnesium; fluid retention and thiamine demand can contribute to organ dysfunction. NICE defines high risk by any one of: BMI below 16 kg/m², unintentional loss exceeding 15% over 3–6 months, little or no intake for more than 10 days, or low potassium, phosphate or magnesium before feeding. Alternatively, two or more qualify: BMI below 18.5, unintentional loss above 10% over 3–6 months, little or no intake for more than 5 days, or alcohol misuse/drug risk including insulin, chemotherapy, antacids or diuretics. Start at a maximum of 10 kcal/kg/day, building towards full needs over 4–7 days. Extreme depletion, such as BMI below 14 or negligible intake over 15 days, calls for 5 kcal/kg/day and continuous rhythm monitoring; that monitoring also applies to existing or newly developing arrhythmias. Suspected Wernicke encephalopathy needs urgent treatment beyond preventive support.
Nasogastric feeding has a specific catastrophic hazard: feeding or flushing into the respiratory tract. Nothing, including water, medicine or feed, is put down a newly placed tube before position is confirmed. Gastric aspirate in the established safe range pH 1–5.5 can confirm gastric placement when obtained and tested correctly; otherwise use the defined X-ray pathway with competent interpretation and documentation of the full tube course and tip. Difficulty aspirating, coughing or absence of respiratory symptoms cannot confirm placement. Recheck after possible displacement.
Monitoring asks whether the plan is delivered, tolerated, safe and useful. Record intake versus prescription, weight under comparable conditions, fluid balance, bowel function, nausea, aspiration risk, glucose and relevant electrolytes. Review line or tube complications and functional outcomes. Adjust for renal, hepatic and cardiac disease, and avoid chasing short-term weight distorted by fluid. Discharge requires access to supplies, training, community follow-up and an explicit plan for pending blood results or tube problems.
Key points
- Screen all relevant patients for malnutrition using current weight, recent unintentional loss and acute intake history; repeat screening when clinical state changes.
- Nutrition assessment adds trajectory, intake, swallowing, gastrointestinal function, inflammation, function, social barriers and patient goals to the screening score.
- Use the oral route when safe and sufficient, enteral tube feeding when the gastrointestinal tract works but oral intake is unsafe or inadequate, and parenteral support when it does not.
- Before feeding, identify refeeding risk from low BMI, major weight loss, minimal intake, electrolyte depletion, alcohol use and relevant medicines or comorbidity.
- For high refeeding risk, start at no more than 10 kcal/kg/day and progress over 4–7 days with vitamin and electrolyte support. Extreme cases need 5 kcal/kg/day; monitor rhythm continuously in extreme cases and whenever arrhythmias are present or develop.
- Nasogastric position must be confirmed by an approved method before use and after displacement concern; never rely on auscultation or an undocumented assumption.
- Define success beyond calories: intake achieved, weight and function trajectory, wound healing, tolerance, metabolic safety and alignment with the person’s goals.
02Situations and prioritiesThe context, relevant information and actions that matter most.
Percentage loss over a defined period is more informative than a single weight and may be clinically important at any starting BMI.
Eating little or nothing because of dysphagia, nausea, pain, delirium, depression or access barriers can rapidly compound disease-related catabolism.
Weakness, reduced grip, inability to prepare meals, poor wound healing and repeated falls may reveal nutritional impact.
Low BMI, substantial recent loss, prolonged minimal intake, low phosphate, potassium or magnesium, alcohol use and certain medicines raise risk.
Coughing, wet voice, recurrent chest infection, neurological disease or reduced consciousness requires formal swallowing assessment rather than bedside guesswork.
Vomiting, diarrhoea, aspiration, hyperglycaemia, electrolyte shifts, fluid overload, tube displacement and line infection require active surveillance.
03Assessment and interpretationHow to gather information, assess the situation and recognise uncertainty.
Consider the information, its meaning and its limitations before deciding what follows.
- 01
Validated malnutrition screen - Why
- Apply the organisation’s validated tool with measured or best-supported anthropometry and intake history.
- Interpretation and limitations
- A risk category triggers assessment and action; oedema, amputations and unavailable weights require documented clinical judgment.
- 02
Dietetic and swallowing assessment - Why
- Quantify usual and current intake, requirements, feeding ability and swallow safety.
- Interpretation and limitations
- The outcome defines achievable oral modification, supplementation, enteral route or need for specialist alternatives.
- 03
Refeeding risk assessment - Why
- Review BMI, weight loss, duration of little intake, electrolytes, alcohol and relevant treatments before feeding.
- Interpretation and limitations
- High risk changes the starting prescription, supplementation, fluid plan and monitoring frequency; normal baseline electrolytes do not remove risk.
- 04
Baseline metabolic profile - Why
- Check clinically appropriate glucose, renal function, phosphate, magnesium, potassium and fluid status.
- Interpretation and limitations
- Results identify deficits and organ constraints but must be interpreted with total-body depletion and recent treatment.
- 05
Tube position verification - Why
- Use the approved national and local process before nasogastric use and after displacement concern.
- Interpretation and limitations
- Correctly obtained gastric aspirate at pH 1–5.5 or an appropriately requested, interpreted and documented X-ray can establish position in the national pathway. Never flush, feed or give medicine through an unconfirmed tube.
- 06
Outcome review - Why
- Track delivered intake, tolerance, weight trajectory, function, wounds and patient-defined goals.
- Interpretation and limitations
- Escalate or change route when the plan cannot be delivered, complications outweigh benefit or goals change.
04Worked approachesCases with ordered reasoning, an action and a check of the outcome.
01Worked caseHigh refeeding riskA 52-year-old, 1.75 m tall and weighing 50 kg (BMI 16.3 kg/m²), has negligible intake for nine days and low baseline phosphate. They have no alcohol dependence, are alert, swallow safely and have a functioning gastrointestinal tract with no features of Wernicke encephalopathy.+
- 1Recognise high refeeding risk before prescribing unrestricted meals or feed, assess ABCDE and fluid status, and escalate to senior, dietetic and pharmacy support.
- 2Choose supervised oral food plus oral supplements because swallowing and gut function are safe. At the NICE high-risk ceiling, calculate 10 kcal/kg/day × 50 kg = 500 kcal in the first 24 hours, then increase toward assessed full needs over 4–7 days if clinical and biochemical monitoring remains stable.
- 3Give NICE preventive vitamin support immediately before and during the first 10 feeding days: oral thiamine 200–300 mg daily, vitamin B compound strong 1–2 tablets three times daily and a balanced multivitamin/trace-element supplement once daily; use an appropriate intravenous B-vitamin preparation only when necessary. Low phosphate is supplemented while feeding under pharmacy-supported product and route selection; the NICE likely requirement is 0.3–0.6 mmol/kg/day, calculated here as 15–30 mmol/day. Calculate potassium and magnesium requirements from weight, route, renal function and serial results rather than automatically giving the top of each range.
- 4Review fluid balance and clinical status at least daily; check glucose once or twice daily until stable, and sodium, potassium, urea, creatinine, magnesium and phosphate daily initially because refeeding risk is present. Slow progression and escalate for oedema, arrhythmia, respiratory deterioration or worsening electrolyte disturbance, and verify delivered intake and function rather than prescribed calories alone.
02Applied approachChoosing a feeding routeA person after stroke cannot swallow safely but has a functioning gastrointestinal tract and a potentially reversible deficit.+
- 1Clarify prognosis, capacity, preferences and the intended goal and duration of support with the patient or appropriate decision-making process.
- 2Use specialist swallow and dietetic assessment to establish that oral intake is unsafe and requirements cannot be met.
- 3Prefer an enteral plan while the gut functions, with an approved tube-placement and aspiration-risk protocol.
- 4Review tolerance, delivered intake and recovery of swallow; remove or change the route when the indication changes.
03Safety processNasogastric tube before first feedA newly inserted nasogastric tube yields no clearly interpretable aspirate and the patient is awaiting medication and feed.+
- 1Do not use the tube; bedside auscultation, tube length alone and absence of cough do not confirm gastric placement.
- 2Follow the current algorithm for further aspiration attempts and X-ray indication. Never put water, feed or medicine down the tube to obtain aspirate or test tolerance before placement is confirmed.
- 3Ensure a trained clinician interprets and documents the complete tube course and tip position on X-ray before authorising use.
- 4Communicate the confirmed status at handover and repeat verification after any displacement concern.
05Feedback, follow-up and evidenceReview outcomes, seek feedback and identify what to improve.
- Measure intake against the agreed prescription and record reasons for missed feed, rather than assuming a prescribed volume was delivered.
- In refeeding risk, monitor clinical status, fluid balance, glucose and specified electrolytes at the frequency in the individual plan.
- Use comparable weights and interpret them with oedema, diuresis and fluid balance; rapid gain may represent water rather than tissue.
- Review tube position and external markings according to policy and whenever coughing, vomiting, transfer or handling suggests displacement.
- For parenteral support, monitor vascular access, infection, metabolic complications and liver tests through the specialist nutrition team.
- Review goals, burdens and route regularly, particularly after recovery, deterioration or a change in capacity or expressed preferences.
06Special situationsVariants, exceptions and circumstances that change the usual approach.
Screening is a trigger
A screening score identifies risk and need for action; only fuller assessment explains mechanism, requirements, route and goals.
Obesity does not exclude depletion
Muscle loss and micronutrient deficiency can coexist with high BMI, and oedema can conceal loss of dry weight.
Refeeding is systemic
Phosphate is prominent, but potassium, magnesium, thiamine, glucose and sodium-water balance also determine harm.
Route follows gut and swallow
An unsafe swallow does not automatically require parenteral nutrition if enteral feeding is feasible and consistent with goals.
Tube safety is evidential
A tube may be misplaced without dramatic symptoms; each use depends on documented approved confirmation, not confidence or habit.
Function validates nutrition
Improved intake, strength, wound healing and participation may be more meaningful than a short-term weight altered by fluid.
Inflammation alters response
Catabolic illness can limit tissue restoration despite delivered calories, so treat the underlying process and interpret weight carefully.
Discharge tests the plan
A regimen is not feasible until supplies, training, access and community clinical ownership are confirmed.
07Common pitfallsFrequent interpretation and management errors.
- 01
Relying on appearance or BMI alone and missing recent severe unintentional loss.
- 02
Starting unrestricted feeding before assessing refeeding risk and planning monitoring.
- 03
Using auscultation, absence of cough or external length alone to confirm nasogastric position.
- 04
Choosing parenteral nutrition before considering a safe usable gastrointestinal route.
- 05
Counting prescribed feed instead of checking the amount actually received and tolerated.
- 06
Continuing an invasive route without reviewing goals, burdens, recovery and the patient’s preferences.