Surgical Fluids, Electrolytes & Nutrition
Separate resuscitation, maintenance and loss replacement while protecting nutrition and monitoring the effects of treatment.
Quick revision ↓ Medical Dictionary
01Define the fluid problem
Decide whether the patient needs resuscitation, routine maintenance, replacement of abnormal losses or redistribution management. These are different tasks. Review intake, urine, vomiting, nasogastric output, drains, weight and examination. A postoperative patient can have oedema and still have complex perfusion needs, so neither swelling nor oliguria alone dictates a fluid prescription. Reassess after any therapeutic trial.
02Replace what is being lost
Gastric, intestinal and stoma losses differ in volume and electrolyte content. Persistent vomiting can produce chloride and potassium depletion with metabolic alkalosis; diarrhoeal losses can reduce bicarbonate. Measure ongoing output and monitor sodium, potassium, renal function and acid-base status. Replacing every loss with the same fixed fluid can worsen an imbalance, particularly when kidney function or cardiac reserve is limited.
03Use monitoring to change the plan
A fluid balance chart needs accurate timing and measured values. Daily weight can reveal cumulative retention that a single observation misses. Rising oxygen requirements, crepitations or oedema should prompt review for overload, while poor perfusion needs assessment of cause. Urinary catheter blockage can mimic oliguria. Avoid treating the chart without checking the patient and equipment.
04Protect nutritional recovery
Screen for weight loss, reduced intake and disease-related catabolism. Use the gut when it is functional and feeding is safe, with an individual plan after the specific operation. Parenteral support has a role when enteral feeding is unsuitable or inadequate, but needs specialist monitoring. Albumin is influenced by inflammation and fluid status and should not be treated as a standalone measure of nutritional adequacy.
05Recognise refeeding risk
A severely undernourished patient may develop dangerous phosphate, potassium and magnesium shifts when nutrition restarts. Identify risk before feeding, provide indicated vitamin support and use a monitored graded plan. Increasing calories rapidly without electrolyte review can cause cardiac or neurological complications. Coordinate dietetic and clinical teams and define how intake, tolerance, electrolytes and functional recovery will be reassessed.
High-Yield Revision
- Resuscitation, maintenance and replacement are separate prescriptions.
- Measure abnormal losses and review their composition.
- Identify refeeding risk before restarting nutrition.
Common Pitfalls
- Do not treat all oliguria with repeated fluid boluses.
- Do not use albumin alone to diagnose malnutrition.
References & Further Reading
Read the relevant guideline sections alongside these original clinical teaching cases. Local pathways, available services and individual patient factors determine care.
Reference review: 27 September 2026. Consult current local protocols for prescribing, procedures and escalation.