Fluid Review

Exam Cram

• Fluid assessment reviews the amount of fluid in the cells, blood vessels and everywhere else

• The assessment involves reviewing oral solid & liquid inputs + intravenous fluids, bowel & urine outputs, weight, skin turgor, heart rate, creatinine and electrolytes

• Diagnosis is usually either euvolaemic, hypovolaemic or hypervolaemic

• Interventions include IV fluids and IV furosemide

Outline

Background

• Fluid assessment can be difficult due to the differences between the three fluid compartments, which are related but independent: intracellular, intravascular and extracellular-extravascular

• Fluid overload & dehydration are key causes of deterioation in hospital and are commonly preventable with effective fluid management

Assessment

History

• Intake: oral solids, liquids and intravenous fluids

• Output: urine volume, bowel movements (number & consistency)

• PMH: heart failure, liver failure, kidney failure

Examination

• Peripheral fluid (extracellular): pulmonary oedema, pretibial oedema, ascites

• Blood pressure: good measure of intravascular hydration

• Mucous membranes, skin turgor, heart rate

Investigations

• Creatinine: good marker of renal perfusion & intracellular hydration

• Weight & comparison with trend

• CXR: ?fluid on lung

Diagnosis

Diagnostic Criteria: clinical. 

Often I find trajectory the most important detail. For example an individual with heart failure will have extravascular overload however if they have come in with diarrhoea will likely be dehydrated but if they've come in with worsening leg oedema they likely require diuresis. 

Classification (aetiology)

• Hypervolaemia- exacerbation of heart, liver or kidney failure; malignancy

• Euvolaemia- normal

• Hypovolaemia

  • Reduce intake: generally unwell- nausea, sepsis, 

  • Increased output: 

    • Polyuria: diabetes mellitus/ insipidus, hypercalcaemia, hypoaldrenalism, Haemochromatosis 

    • Diarrhoea: gastroenteritis/ colitis/ high output stoma, sweating- hyperthermia/ sepsis

Management

Acute

• Hypervolaemia- duiresis (e.g. furosemide) with daily weights, input/ output balance, assess underlying cause (ECHO, AUSS, creatinine, consider CTCAP)

• Euvolaemia- nil

• Hypovolaemia - fluids oral vs IV, if septic often 2 litres is reasonable fluid challenge

Written in 2025

References and Resources

Scope

• Body systems: cardiovascular, urinary, gastrointestinal

• Specialties: particularly Cardiology, Renal and Gastroenterology