Compound sodium lactate (Hartmann’s solution)

Question 1

Compound sodium lactate (Hartmann’s solution)

Clinical pharmacology

Common indications

Answer 1

• To provide sodium and water intravenously in patients unable to take enough orally.
• To expand circulating volume in states of circulatory compromise (including shock).
• This may be done as a ‘fluid challenge’, where a selected volume of fluid (e.g. 500 mL) is infused rapidly. Sodium chloride 0.9% and colloids are

Question 2

Mechanisms of action?

Answer 2

• Compound sodium lactate (more commonly known by its eponymous name, Hartmann’s solution) is a ‘balanced salt solution’.
• Its constituents are designed to mimic serum, at least in terms of electrolytes. One litre contains Na+ 131 mmol, Cl− 111 mmol, K+ 5 mmol, Ca2+ 2 mmol, and lactate 29 mmol.
• In the presence of adequate liver function, the lactate is metabolised to pyruvate and then either to glucose or carbon dioxide and water, with the release of bicarbonate in both cases.
• The sodium content means it may be used to provide sodium and water intravenously, and also for the expansion of circulating volume (see Sodium chloride)

Question 3

Warnings?

Answer 3

• Fluid challenge volume should be reduced in patients with heart failure, due to the risk of worsening myocardial contractility.
• In renal impairment, it is vital to monitor fluid balance closely to avoid overload.
• Moreover, although the potassium content is low, you should monitor the serum potassium concentration if it is used in this context.
• Compound sodium lactate is best avoided in severe liver disease because there may not be sufficient capacity to metabolise lactate.

Question 4

Practical prescribing?

Prescription

Answer 4

• Compound sodium lactate is prescribed in the ‘infusions’ section of the drug chart.
• You need to specify the volume to be infused and the rate at which it is to be given.
• The rate may be described either in mL per hour or as the intended duration for infusion of the total volume.
• For example, in providing sodium intravenously, you might prescribe 500 mL of compound sodium lactate for administration over 4 hours (equivalent to 125 mL/hr).
• This would provide 66 mmol of sodium, covering their daily ‘maintenance’ requirement.
• You would probably also prescribe glucose 5% to provide their remaining water requirement (about 2 L/day). To expand circulating volume, you might prescribe 500 mL of compound sodium lactate to be given over 15 minutes (equivalent to 2000 mL/hr).