Ringer's lactate solution

Ringer's lactate solution

A bottle of Ringer's lactate solution
Clinical data
AHFS/Drugs.com	FDA Professional Drug Information
Routes of administration	intravenous, topical
ATC code	B05BB01 (WHO)
Identifiers
Synonyms	compound sodium lactate, sodium lactate solution, Hartmann's solution, Ringer-Locke's solution, Ringer-lactate, lactated Ringer's solution (LRS)

Ringer's lactate solution (RL), also known as sodium lactate solution and Hartmann's solution, is a mixture of sodium chloride, sodium lactate, potassium chloride, and calcium chloride in water.^[1] It is used for replacing fluids and electrolytes in those who have low blood volume or low blood pressure.^[2] It may also be used to treat metabolic acidosis in cases other than those caused by lactic acidosis and to wash the eye following a chemical burn. It is given by injection into a vein or applied to the affected area.^[2][3]

Side effects may include allergic reactions, high blood potassium, volume overload, and high blood calcium.^[2] It may not be suitable for mixing with certain medications and some recommend against use in the same infusion as a blood transfusion.^[4] Ringer's lactate solution has a lower rate of acidosis as compared with normal saline.^[1][4] Use is generally safe in pregnancy and breastfeeding.^[2] Ringer's lactate solution is in the crystalloid family of medication.^[5] It is the same tonicity as the blood.^[2]

Ringer's solution was invented in the 1880 with lactate being added in the 1930s.^[4] It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system.^[6] Lactated Ringer's is available as a generic medication.^[1] The wholesale cost in the developing world is about 0.60 to 2.30 USD per liter.^[7] For people with poor liver function, Ringer's acetate may be a better alternative with the lactate replaced by acetate.^[8] In Scandinavia Ringer's acetate is typically used.^[9]

Medical uses

Ringer's lactate solution is very often used for fluid resuscitation after a blood loss due to trauma, surgery, or a burn injury. Ringer's lactate solution is used because the by-products of lactate metabolism in the liver counteract acidosis, which is a chemical imbalance that occurs with acute fluid loss or renal failure.^[10]

The IV dose of Ringer's lactate solution is usually calculated by estimated fluid loss and presumed fluid deficit. For fluid resuscitation the usual rate of administration is 20 to 30 ml/kg body weight/hour. RL is not suitable for maintenance therapy (i.e., maintenance fluids) because the sodium content (130 mEq/L) is considered too low, particularly for children, and the potassium content (4 mEq/L) is too low, in view of electrolyte daily requirement. Moreover, since the lactate is converted into bicarbonate, longterm use will cause patients to become alkalotic.^[11] Ringer's lactate and other crystalloids are also used as vehicles for the IV delivery of drugs.

In a large-volume resuscitation over several hours, LRS maintains a more stable blood pH than normal saline.^[4]

Chemistry

One liter of Ringer's lactate solution contains:

• 130–131 mEq of sodium ion = 130 mmol/L
• 109–111 mEq of chloride ion = 109 mmol/L
• 28–29 mEq of lactate = 28 mmol/L
• 4–5 mEq of potassium ion = 4 mmol/L
• 2–3 mEq of calcium ion = 1.5 mmol/L

Ringer's lactate has an osmolarity of 273 mOsm/L.^[12] The lactate is metabolized into bicarbonate by the liver, which can help correct metabolic acidosis. Ringer's lactate solution alkalinizes via its consumption in the citric acid cycle, the generation of a molecule of carbon dioxide which is then excreted by the lungs. They increase the strong ion difference in solution, leading to proton consumption and an overall alkalinizing effect.^[13]

The solution is formulated to have concentrations of potassium and calcium that are similar to the ionized concentrations found in normal blood plasma. To maintain electrical neutrality, the solution has a lower level of sodium than that found in blood plasma or normal saline.^[4]

Generally, the sodium, chloride, potassium and lactate come from NaCl (sodium chloride), NaC₃H₅O₃ (sodium lactate), CaCl₂ (calcium chloride), and KCl (potassium chloride).

There are slight variations for the composition for Ringer's as supplied by different manufacturers. As such, the term Ringer's lactate should not be equated with one precise formulation.^[14]

Although its pH is 6.5, it is an alkalizing solution.

History

Ringer's saline solution was invented in the early 1880s by Sydney Ringer,^[4] a British physician and physiologist. Ringer was studying the beating of an isolated frog heart outside of the body. He hoped to identify the substances in blood that would allow the isolated heart to beat normally for a time.^[15] The use of Ringer's original solution of inorganic salts slowly became more popular.^[4] In the 1930s, the original solution was further modified by American pediatrician Alexis Hartmann for the purpose of treating acidosis. Hartmann added lactate, which mitigates changes in pH by acting as a buffer for acid. Thus the solution became known as "Ringer's lactate solution" or "Hartmann's solution".^[4][16]

Formulations

Ringer's solution technically refers only to the saline component, without lactate. Some countries instead use a Ringer's acetate solution or Ringer-acetate, which has similar properties and the added benefit of not deranging the blood-lactate level. This may be helpful when analyzing blood-lactate for signs of anaerobic metabolism (e.g. present with septic shock, hypovolemic shock).^[17]

Veterinary use

It is used for the treatment or palliative care of chronic renal failure in small animals. The solution can be administered both by IV and subcutaneously. Administering the fluids subcutaneously allows the solution to be readily given to the animal by a trained layperson, as it is not required that a vein be located. The solution is slowly absorbed from beneath the skin into the bloodstream of the animal.

See also

• Intravenous therapy
• Oral rehydration therapy
• Phosphate buffered saline (cell culture)
• Tyrode's solution

References