Fluid requirements

See separate topic on 'Stress response' for post-operative ebb/flow

• Factors that increase fluid requirements:
  • After surgery and during critical illness
  • Epidural anaesthesia
  • Fever
  • Tachypnoea
  • Oxygen supplementation
• Factors that decrease fluid requirements:
  • Age
  • Cardiac disease
  • Renal disease

Fluid losses per 24 hours:

• Lungs - 400mL. Increased in dry atmospheres or those with tracheostomy.
• Skin - 600-1000mL
• Faeces - 60-150mL (in normal bowel function)
• Urine - 1500mL
  • Minimum of 400mL/24 hours to excrete end products of protein catabolism

Maintenance fluid requirements

• Estimated at 30-40mL/kg/day

For assessment of fluid status, see separate topic 'assessment' under 'critically ill patient'

• Check perfusion of skin, kidneys, brain
• Use fluid balance chart
• Use biochemical data too

Approach to fluid/electrolyte prescription:

• Basal requirements
• Current fluid/electrolyte deficit or excess
• Continuing abnormal losses