Fluid Replacement 💧
Clinical guide for fluid replacement and IV fluid therapy. NICE CG174 guidelines, fluid calculator, resuscitation, maintenance fluids, and electrolyte management.
🎯 The 5 Rs of IV Fluid Therapy
- Resuscitation: Emergency fluid for shock/hypovolaemia
- Routine maintenance: Daily fluid and electrolyte needs
- Replacement: Address existing deficits or ongoing losses
- Redistribution: Correct abnormal fluid distribution
- Reassessment: Regular review and adjustment of therapy
- Key Principle: Only use IV when oral/enteral routes inadequate
- Stop IV fluids as soon as possible
🚨 Immediate Assessment - ABCDE Approach
- A: Airway - Ensure patent airway, consider intubation if compromised
- B: Breathing - Respiratory rate, oxygen saturation, breath sounds
- C: Circulation - BP, HR, capillary refill time, JVP, peripheral pulses
- D: Disability - GCS, pupil response, blood glucose
- E: Exposure - Look for signs of dehydration, fluid overload, bleeding
- Shock indicators: SBP <100mmHg, HR >90bpm, CRT >2s, RR >20/min
- NEWS score ≥5: Indicates need for urgent fluid resuscitation
🔍 Clinical Assessment of Fluid Status
- History: Fluid intake/output, vomiting, diarrhoea, bleeding, medications (diuretics, ACEi/ARBs)
- Examination:
- - Hypovolaemia: Dry mucous membranes, reduced skin turgor, sunken eyes, postural hypotension
- - Fluid overload: Peripheral oedema, pulmonary oedema (crackles), raised JVP, ascites
- Vital signs: BP, HR, temperature, respiratory rate, NEWS score
- Urine output: <0.5ml/kg/hr suggests hypovolaemia
- Capillary refill: >2 seconds indicates poor perfusion
- Weight: Recent weight loss suggests fluid deficit
- Passive leg raising: Bedside test for fluid responsiveness
📊 Laboratory Investigations
- Essential: FBC, U&E, creatinine, glucose
- FBC: Haemoglobin, haematocrit (elevated in dehydration)
- U&E: Na⁺, K⁺, urea, creatinine (elevated urea:creatinine ratio)
- Glucose: Check for DKA or hyperglycaemic states
- Lactate: Elevated in shock states (if signs of hypoperfusion)
- Blood gas: pH, bicarbonate, base excess (if acid-base disturbance)
- Urinary sodium: Consider in high-volume GI losses (<30mmol/L indicates sodium depletion)
- Additional: CRP, coagulation, LFTs, cardiac enzymes if indicated
🚑 Fluid Resuscitation
- Indication: Signs of hypovolaemic shock (SBP <100mmHg, HR >90bpm, CRT >2s)
- Fluid choice: Crystalloids containing sodium 130-154 mmol/L
- Bolus: 500ml over less than 15 minutes
- First choice: 0.9% NaCl (Normal Saline)
- Alternative: Hartmann's solution (if no contraindications)
- Reassessment: After each bolus - BP, HR, UO, mental state, NEWS score
- Maximum: Up to 1.5-2L before senior review
- Do NOT use: Tetrastarch for fluid resuscitation
- Consider: Human albumin 4-5% only in severe sepsis
- Escalate: If no response after 1.5L, consider vasopressors, ICU referral
💧 Maintenance Fluid Requirements
- Indication: Patients unable to take oral fluids for >12-24 hours
- Water: 25-30ml/kg/day (2-2.5L for 70kg adult)
- Sodium: 1mmol/kg/day (70-100mmol/day)
- Potassium: 1mmol/kg/day (if normal renal function)
- Chloride: 1mmol/kg/day
- Glucose: 50-100g/day to limit starvation ketosis
- Obese patients: Use ideal body weight for calculations
- Maximum: 3L/day total fluid
- Expert help: Required if BMI >40 kg/m²
- Review: Daily U&E, weight, fluid balance
- Weight-based K⁺: Round to nearest common fluids available
- Do NOT add K⁺: To IV fluid bags (dangerous)
⚠️ Special Considerations
- Elderly (>65): Reduce maintenance by 20-25%, increased risk of overload
- Heart failure: Restrict sodium, monitor for pulmonary oedema
- Renal impairment: Adjust potassium, monitor U&E closely, consider fluid restriction
- Liver disease: Consider albumin if <20g/L, risk of ascites
- DKA: 0.9% NaCl initially, add K⁺ when K⁺ <5.5
- Hypernatraemia: 0.45% NaCl or 5% dextrose, correct slowly
- Hyponatraemia: 0.9% NaCl, correct slowly (<0.5mmol/L/hr)
- Malnutrition: Risk of refeeding syndrome, monitor electrolytes
- Diabetes: Monitor blood glucose with dextrose-containing fluids
📋 Fluid Prescription Template
- Patient details: Name, DOB, hospital number
- Fluid type: 0.9% NaCl / Hartmann's / 5% dextrose
- Volume: Based on 25-30ml/kg/day water requirement
- Rate: ml/hr (calculate: total volume ÷ 24)
- Electrolytes: 1mmol/kg/day Na⁺, K⁺, Cl⁻
- Glucose: 50-100g/day to limit ketosis
- Duration: 24 hours or as specified
- Review: Daily U&E, weight, clinical assessment
- Include: Type, rate, and volume in prescription
- Example: "1L 0.9% NaCl + 20mmol KCl at 83ml/hr over 12 hours"
🔬 Monitoring Protocol
- Initial monitoring: Daily clinical fluid status, U&E, fluid balance charts
- Weight: Twice weekly measurement (same time, same scales)
- U&E: Daily for first 48hrs, then as clinically indicated
- Chloride monitoring: Daily if using fluids with Cl⁻ >120mmol/L
- Urinary sodium: Consider in high-volume GI losses (<30mmol/L indicates depletion)
- Signs of overload: Oedema, crackles, raised JVP, SOB
- Signs of under-resuscitation: Persistent hypotension, poor UO
- Document: Response to fluid therapy, any complications
- Report: Critical incidents of fluid mismanagement
- Reassessment: After each fluid bolus, daily for maintenance
🚫 Contraindications & Cautions
- Absolute: Anaphylaxis to fluid type
- Relative: Heart failure, renal failure, liver failure
- Caution: Elderly, frail patients, electrolyte imbalances
- Avoid: Rapid correction of chronic hyponatraemia
- Stop if: Signs of fluid overload develop
- Escalate: No response to 1.5L crystalloid
- Consider: Alternative diagnoses if no improvement
- Do NOT use: Tetrastarch for fluid resuscitation
- Monitor closely: Patients with BMI >40 kg/m²
📞 Escalation Criteria
- No response: To 1.5L crystalloid resuscitation
- Fluid overload: Oedema, crackles, raised JVP, SOB
- Deteriorating: Vital signs despite fluid therapy
- Severe electrolyte disturbances: Hyponatraemia, hyperkalaemia
- Suspected sepsis: Or other serious pathology
- Elderly patients: With multiple comorbidities
- BMI >40 kg/m²: Seek expert help
- Contact: Senior medical team, ICU if indicated
- Report: Critical incidents of fluid mismanagement
✅ Documentation Requirements
- IV fluid management plan: 24-hour prescription and monitoring
- Clinical assessment: Fluid status, vital signs, NEWS score
- Fluid prescription: Type, volume, rate, additives
- Monitoring plan: Frequency of obs, investigations
- Response to therapy: Improvement or deterioration
- Review plan: When to reassess, who to contact
- Patient information: Explain treatment, monitor for complications
- Critical incidents: Report fluid mismanagement
- Daily review: By expert initially, less frequent if stable
Fluid Maintenance Calculator
NICE CG174 Guidelines for maintenance fluid requirements
Instructions
Enter the patient's weight to calculate maintenance fluid requirements according to NICE CG174 guidelines. Always check for contraindications (heart failure, renal impairment) and adjust for ongoing losses.