Fluid management

plasma interstitial intracellularCationsNa 140 146 12K 4 4 150Ca 5 3 10Mg 2 1 7AnionsCl 103 104 3HCO 24 27 10SO4 1 1 -HPO4 2 2 116Protein 16 5 40

• Potassium ~50 - 60 meq (1meq/kg/day)• Magnesium – 8-20 meq• Sodium – ~100-120 meq (2meq/kg/day)

Fluid requirements per day

Fluid requirements per hour

First 10kg 100 ml/kg 4 ml/kg

Second 10kg 50 ml/kg 2 ml/kg

Subsequent kgs 20 ml/kg 1 ml/kg

Adults ~ 1.5ml/kg per hour

Maintenace fluids in post operative patients.

• 1st post op day – only 5% D• 2nd post op day – add Na+• 3rd post op day – add K+

Daily requirements = Normal maintenance + Abnormal losses + Pre-existing deficits

Secretions Sodium (mmol/L)

Potassium(mmol/L)

Chloride (mmol/L)

Bicarbonate (mmol/L)

Salivary 50 20 40 50

Gastric 50 15 120 20

Duodenal 140 5 80 -

Biliary 140 10 100 40

Pancreatic 140 10 80 80

Jejuno-ileal 130 20 105 30

Faeces 80 10 100 25

Diarrhoea 100 30 50 60

Approximate electrolyte concentrations

• On going GI loss• CORRECT WITH 0.9% NS and 20 meq K+

(1g=13 mEq)

• What will be the maintainance IV fluid order for a 70 kg man. POD1. Ng=500ml.