Synopsis
Assess adult fluid status, choose resuscitation, routine maintenance or replacement prescriptions, calculate transparent inputs and reassess response while recognising patients outside general guidance.
- Prescribe IV fluid only when oral or enteral intake cannot meet a defined need, and state whether the purpose is resuscitation, maintenance, replacement or redistribution.
- For non-sepsis adult resuscitation within NICE CG174 scope, use crystalloid containing sodium 130–154 mmol/L as a 500 mL bolus over less than 15 minutes, then reassess immediately.
- For an adult at high risk of severe illness or death from suspected sepsis under NICE NG253, start 250 mL isotonic electrolyte crystalloid, preferably balanced, ideally over 10–15 minutes and reassess after each bolus.
Reasoning priorities
Identify immediate circulatory compromise and its cause before choosing fluid.
If shocked, treat the cause and use a time-limited resuscitation trial; if not shocked, distinguish deficit, maintenance need and redistribution.
Worked reasoning
A 70 kg adult cannot drink for 24 hours, is haemodynamically stable, has no abnormal losses and has normal renal and cardiac function.
- Classify the indication as routine maintenance after confirming there is no resuscitation need, deficit requiring separate correction, abnormal loss or redistribution problem.
- Calculate water at 25–30 mL/kg/day: 70 × 25 = 1,750 mL and 70 × 30 = 2,100 mL over 24 hours; document the range and select within it using clinical context.
- Calculate approximate daily electrolytes at 1 mmol/kg each: about 70 mmol sodium, 70 mmol potassium and 70 mmol chloride, and account for 50–100 g glucose plus every non-IV-fluid input.
- Prescribe available fluids through the local safe system, then verify cumulative balance, weight, examination, urine output, renal function and electrolytes at the planned review; stop when enteral intake resumes.
A stable patient receives maintenance fluid but develops increasing measured stoma output and falling weight.
Key medicines
Adult resuscitation crystalloidGive 500 mL of crystalloid containing sodium 130 to 154 mmol/L over less than 15 minutes, then reassess.Applies only to adults within NICE CG174 scope and not suspected sepsis or another condition with a dedicated regimen. Reassess after every bolus; use the current condition-specific pathway for excluded groups, overload risk or complex shock.
Initial adult routine maintenance fluidSupply 25 to 30 mL/kg/day water, approximately 1 mmol/kg/day each sodium, potassium and chloride, and 50 to 100 g/day glucose.Adjust for every other input, loss and comorbidity; consider 20 to 25 mL/kg/day in older, frail, renal-impaired or cardiac-failure patients and follow local potassium safeguards.