Fluid Therapy

Question 1

Daily requirement of fluid and electrolytes

Answer 1

• 1.5 ml/kg/hr. fluid >>> for a 80kg man around 2-3 litres/day
• 70-150mmol sodium (Na)
• 40-70mmol potassium (K)

Question 2

Based on daily requirements of fluid-electrolytes >>> typical fluid regimens are - ?

Answer 2

• 1 litre 5% dextrose with 20mmol potassium over 8 hours
• 1 litre 0.9% normal saline with 20mmol potassium over 8 hours
• 1 litre 5% dextrose with 20mmol potassium over 8 hours

​These are usual/typical fluid regime prescribed for patients

Question 3

Do all patients require same amount of fluids?

Answer 3

NO

It obviously varies according to their recent and past medical history.

• For example:
  
  • A patient who is post-op + having significant losses from drains > requires more fluid
  • A patient with heart failure > should be given less fluid > to avoid precipitating pulmonary oedema

Question 4

Normal plasma levels of Na, K, Ca, HCO₃, and Cl

Answer 4

• Na: 135 to 145mmol/L
• K: 3.5 to 5.5mmol/L
• Ca: 2.2. to 2.6mmol/L
• HCO₃: 22 to 28mmol/L
• Cl: 98 to 105mmol/L

Ref: Magrabi

Question 5

Electrolytes level in 0.9% normal saline

Answer 5

• Na: 150mmol/L
• Cl: 150mmol/L
• Others are absent

Question 6

Electrolytes level in 5% dextrose

Answer 6

No electrolyte

Question 7

Electrolytes level in Hartman solution (Ringer’s lactate)

Answer 7

• Na: 131mmol/L
• K: 5mmol/L
• Ca; 2mmol/L
• Cl: 111mmol/L
• HCO₃: 29mmol/L

Question 8

If a patient is on maintenance IV fluid >>> which electrolyte requirement is imporant to understand?

Answer 8

Na requirements

Question 9

Daily requirements for maintenance IV fluid for a 70kg male

Answer 9

• 2.5-3.0L water
• 120-140 mmol sodium (~2 mmol/kg) (But daily body Na requirement is 70-150mmol)
  
  • Hartmann’s solution contains 131 mmol/L Na
  • Normal saline has 150 mmol/L
  • Dextrose saline has 30 mmol/L
• 70 mmol potassium (~1 mmol/kg)

Question 10

Na (sodium) conc. in different types of solution

Answer 10

• Hartmann’s solution contains 131 mmol/L
• Normal saline has 150 mmol/L
• Dextrose saline has 30 mmol/L

Question 11

Daily requirment of salt

Answer 11

6g/day

Question 12

Daily requirement of Na (sodium)

Answer 12

70-150mmol/L

• We can convert this to mg by multiplying by 58.5 (molecular weight of sodium is approximately 23, chloride is 35.5)
  So, 70-150mmol = 4095 - 8775mg = 4 - 8.5g. The avaerage roughly is 6g.
  Also, the governments recommended oral salt intake of 6g/day.