Fluids, Electrolytes & Acid-Base Assessment
Separate resuscitation from maintenance and interpret biochemical changes in clinical context.
Quick revision ↓ Medical Dictionary
01Define the purpose
Distinguish resuscitation, routine maintenance and replacement of ongoing losses. Assess perfusion, intake, losses, weight and comorbidity before prescribing. A bag of fluid is a treatment with benefits and risks, not a default response to every low blood pressure reading.
02Reassess response
When a fluid challenge is indicated, review circulation, respiratory status and evidence of benefit afterward. Excess fluid can worsen pulmonary or tissue oedema. A patient can have peripheral swelling and inadequate effective circulation, so appearance alone is not a reliable guide to intravascular volume.
03Electrolytes
Potassium and sodium disturbances can cause cardiac or neurological harm. Check the result’s reliability, clinical context, renal function and ECG where appropriate. Severe abnormalities require urgent senior management; correction rates and routes are diagnosis-specific and should not be improvised from a single number.
04Acid-base reasoning
Interpret pH with carbon dioxide, bicarbonate and the clinical situation. Consider whether respiratory or metabolic disturbance predominates and whether compensation is appropriate. Mixed disorders occur, and a near-normal pH can conceal major opposing abnormalities.
05Ongoing prescription
Record the indication, fluid type, amount, rate and monitoring plan. Review oral intake and stop unnecessary intravenous therapy. Include glucose and electrolyte needs where relevant, but avoid assuming a maintenance prescription also treats shock or replaces every ongoing loss.
High-Yield Revision
- Resuscitation, maintenance and replacement have different purposes.
- Reassess after a fluid intervention.
- A normal pH can conceal a mixed disorder.
Common Pitfalls
- Giving repeated fluid without assessing benefit or overload.
- Correcting electrolytes without considering cause and safe rate.
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: 29 September 2026. Consult current local protocols for prescribing, procedures and escalation.