Hartmann's Solution (Compound Sodium Lactate)

Hartmann's Solution (Compound Sodium Lactate)

Hartmann's solution (also called Compound Sodium Lactate in the UK or Lactated Ringer's solution in North America) is a balanced isotonic crystalloid used for intravenous fluid resuscitation and replacement. It closely resembles the electrolyte composition of extracellular fluid and is preferred over normal saline in many clinical situations because it produces less hyperchloraemic metabolic acidosis.

Composition (per litre)

Component	Concentration
Sodium (Na⁺)	131 mmol/L
Chloride (Cl⁻)	111 mmol/L
Potassium (K⁺)	5 mmol/L
Calcium (Ca²⁺)	2 mmol/L
Lactate	29 mmol/L

Osmolarity: ~278 mOsm/L

pH: Approximately 5.0–7.0 (varies by manufacturer)

Why is lactate added?

The lactate is not intended to treat lactic acidosis.

Instead:

• Sodium lactate is metabolised mainly in the liver (also kidneys and skeletal muscle).

• It is converted into bicarbonate (HCO₃⁻).

• This helps buffer hydrogen ions and reduce metabolic acidosis.

Reaction (simplified):

Lactate → Pyruvate → CO₂ + H₂O → HCO₃⁻

Thus Hartmann's has an alkalinising effect.

Indications

Fluid resuscitation

• Septic shock

• Trauma

• Burns

• Major haemorrhage (initial resuscitation)

• Peri-operative fluid replacement

Replacement of extracellular losses

• Vomiting

• Diarrhoea

• Surgical drains

• GI losses

Maintenance (selected patients)

Not ideal as the sole maintenance fluid because it contains insufficient glucose.

Advantages over Normal Saline

Hartmann's	Normal saline
Balanced electrolyte composition	High chloride content
Less hyperchloraemia	Hyperchloraemia common
Less metabolic acidosis	Can cause hyperchloraemic metabolic acidosis
Better renal perfusion	Associated with renal vasoconstriction in some studies
More physiological	Less physiological

Contraindications / Use with Caution

Severe hyperkalaemia

Contains 5 mmol/L potassium.

Although the potassium concentration is low, caution is advised in patients with significant hyperkalaemia or severe renal failure.

Severe liver failure

Because lactate metabolism may be impaired.

However, many patients with stable chronic liver disease can still receive Hartmann's safely.

Severe metabolic alkalosis

Since lactate generates bicarbonate.

Hypercalcaemia

Contains calcium.

Blood transfusion (important exam point)

Do NOT run through the same infusion line as stored blood.

Reason:

The calcium may overcome citrate anticoagulation, potentially promoting clot formation in the infusion line.

(Current practice in many centres allows sequential administration with appropriate flushing, but simultaneous infusion through the same line is generally avoided.)

Drug compatibility

Calcium present in Hartmann's makes it incompatible with some drugs.

Examples:

• Ceftriaxone (especially in neonates)

• Some phosphate-containing solutions

Always check compatibility before co-administration.

Hartmann's vs Normal Saline

Feature	Hartmann's	0.9% Saline
Sodium	131	154
Chloride	111	154
Potassium	5	0
Calcium	2	0
Buffer	Lactate	None
Acid-base effect	Alkalinising	Acidifying
Balanced solution	Yes	No

Hartmann's vs Plasma

Electrolyte	Plasma	Hartmann's
Sodium	135–145	131
Potassium	3.5–5	5
Chloride	98–106	111
Calcium	~2.2	2
Bicarbonate	24	Generated from lactate

Hartmann's therefore approximates plasma much more closely than normal saline.

FRCPath Part 2 Viva Pearls

Examiner: Why does Hartmann's not worsen lactic acidosis despite containing lactate?

Model answer:

The lactate in Hartmann's is sodium lactate rather than lactic acid. It is metabolised mainly by the liver to bicarbonate, producing an alkalinising effect. It does not significantly contribute to pathological hyperlactataemia.

Examiner: Why is Hartmann's often preferred in sepsis?

Model answer:

Balanced crystalloids reduce chloride load, minimise hyperchloraemic metabolic acidosis, and may better preserve renal perfusion compared with 0.9% saline. Many sepsis guidelines therefore favour balanced crystalloids for initial resuscitation.

Examiner: Does the potassium in Hartmann's cause hyperkalaemia?

Model answer:

Usually not. Hartmann's contains only 5 mmol/L potassium, close to physiological extracellular concentrations. Correction of acidosis with Hartmann's may actually reduce serum potassium by shifting potassium intracellularly. Nevertheless, caution is warranted in severe hyperkalaemia or advanced renal failure.

💎 FRCPath Key Points Summary

• Hartmann's is a balanced isotonic crystalloid.

• Also known as Compound Sodium Lactate or Lactated Ringer's.

• Contains Na 131, Cl 111, K 5, Ca 2, lactate 29 mmol/L.

• Lactate is metabolised to bicarbonate, providing an alkalinising effect.

• Preferred over normal saline in many resuscitation scenarios because it reduces the risk of hyperchloraemic metabolic acidosis.

• Widely used in sepsis, trauma, burns, and peri-operative fluid therapy.

• Contains calcium, so avoid simultaneous administration with citrated blood products through the same line.

• Use cautiously in severe liver failure, hyperkalaemia, hypercalcaemia, and metabolic alkalosis.

• Not suitable as the sole maintenance fluid due to the absence of glucose.

• Balanced crystalloids are increasingly favoured in critically ill patients because of their more physiological electrolyte composition.