IV fluids

Question 1

What is the main clinical use of crystalloid fluids?

Answer 1

Resuscitation and maintenance of fluid balance.

Question 2

Name 3 crystalloid fluids which are P drugs.

Answer 2

1) 0.9% Sodium chloride (with or without KCl)
2) 5% glucose (with or without KCl)
3) Compound sodium lactate (Hartmann’s)

Question 3

1) What is the maintenance fluid requirement of ‘water’ per adult per 24 hours?
2) What is the requirement of Sodium per 24 hours?
3) What is the requirement of Potassium per 24 hours?

Answer 3

1) 30ml/kg/ 24 hours.
2) 1mmol/kg/24 hours (approx 1 x 0.9% NaCl).
3) 1mmol/kg/ 24 hours (give 20mmol/ 500ml bag). The rate should not exceed 20mmol/ hour.

Question 4

Name 3 groups of people who may need smaller volumes of maintenance fluids, such as 20-25ml/kg/hr.

Answer 4

1) Frail, elderly people.
2) Patients with renal or cardiac failure
3) Patients who are malnourished or at risk of referring syndrome.

Question 5

1) Why is compound sodium lactate best avoided in those with severe liver disease?
2) Why does compound sodium lactate offer less flexibility with options for potassium replacement?

Answer 5

1) Because the liver may not have sufficient capacity to metabolise the lactate.
2) Because in Hartmann’s, the potassium is fixed at 5mmol/ L. In sodium chloride or glucose, you can add in the concentration of potassium required (e.g. 20mmol/ 500ml bag).

Question 6

1) How might oedema be caused when giving a patient IV fluids?
2) Why should fluid challenge volumes be reduced in the with heart failure?
3) What is the main advantage of Hartmann’s over 0.9% sodium chloride?

Answer 6

1) By providing sodium more rapidly than the patient can excrete it.
2) Because excess volumes can cause a fall in CO by increasing LV filling beyond the point of maximum contractility on the Starling curve, which can worsen heart failure.
3) The lower chloride content, meaning that Hartmann’s is less likely to cause hyperchloraemic acidosis.

Question 7

What is an important adverse effect limited to Sodium chloride use?

Answer 7

Hyperchloraemia that can result from large-volume infusion can generate acidosis, due to increased urinary losses of bicarbonate.