IV Fluids Setup

Amplified
Checklist

IV Fluids - Amplified

Fluid Physiology

Body Fluid Compartments

  • Total body water: 60% body weight
  • Intracellular: 40% (2/3 of TBW)
  • Extracellular: 20% (1/3 of TBW)
    • Interstitial: 15%
    • Intravascular: 5%

Fluid Distribution

  • Crystalloid: distributes across entire ECF
  • Only 25% stays intravascular
  • Colloid: stays intravascular longer

Fluid Types

Crystalloids

Normal Saline (0.9% NaCl)

  • Na 154, Cl 154 mmol/L
  • Slightly hyperchloraemic
  • Risk: hyperchloraemic acidosis with large volumes

Hartmann's (Lactated Ringer's)

  • Na 131, K 5, Ca 2, Cl 111, Lactate 29 mmol/L
  • More physiological
  • Avoid in renal failure (K content)

Glucose Solutions

  • 5% dextrose: 50g/L, no electrolytes
  • Distributes to TBW (not useful for volume)
  • Use: free water replacement, hypoglycaemia

Colloids

  • Albumin 4%: human albumin
  • Gelofusine: gelatin-based
  • Stay intravascular longer but more expensive
  • No proven mortality benefit over crystalloids

Clinical Applications

Resuscitation

  • Initial: 20mL/kg crystalloid bolus
  • Reassess and repeat if needed
  • Consider blood products in haemorrhage

Maintenance Fluids

  • 4-2-1 rule: 4mL/kg for first 10kg + 2mL/kg for next 10kg + 1mL/kg thereafter
  • Example 70kg: 40+20+50 = 110mL/hr

Monitoring

  • Urine output (target >0.5mL/kg/hr)
  • Blood pressure, heart rate
  • Lactate clearance
  • Clinical signs of perfusion