Lactated Ringer's solution is a solution that is isotonic with blood and intended for intravenous administration. It may also be given subcutaneously.
It is grouped with intravenous fluids that are known as "crystalloids" - which include saline and dextrose solutions (compared to the "colloids" which contain larger molecules such as starch or gelatine).
Lactated Ringer's solution is abbreviated as "LR", "RL" or "LRS". It is also known as Ringer's lactate solution (although Ringer's solution technically refers only to the saline component, without lactate). It is very similar, though not identical to, Hartmann's Solution, which is more commonly found in British hospitals and has slightly different ionic concentrations.
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One litre of lactated Ringer's solution contains:
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.[1]
Although its pH is 6.5, it is an alkalizing solution.
Ringer's saline solution was invented in the early 1880s by Sydney Ringer,[2] 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.[3] The original solution of inorganic salts was further modified by Alexis Hartmann for the purpose of treating acidosis in children. Hartmann added lactate, which mitigates changes in pH by acting as a buffer for acid. Thus the solution became known as 'Lactated Ringer's Solution' or 'Hartmann's solution'.[4]
Lactated Ringer's solution is often used for fluid resuscitation after a blood loss due to trauma, surgery, or a burn injury. Previously, it was used to induce urine output in patients with renal failure.
Another common use is the treatment of renal failure in small animals, where the solution is administered subcutaneously instead of through an IV. Administering the fluids in this way allows the solution to be given to the animal quickly and does not require a vein to be located. The fluid is then slowly absorbed from under the skin into the bloodstream of the animal.[5]
Lactated Ringer's 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.[6]
The IV dose of lactated Ringer's 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. Lactated Ringer's solution is not suitable for maintenance therapy because the sodium content (130 mEq/L) is considered too high, particularly for children, and the potassium content (4 mEq/L) is too low, in view of electrolyte daily requirement.
Other commonly used intravenous fluids include normal saline and Hydroxyethyl starch solutions (used in hypovolemic shock). Lactated Ringer's and other crystalloids are also used as vehicles for the IV delivery of drugs. Lactated Ringer's is usually given intravenously, but if a suitable vein is not found, it can be taken orally (although it has an unpleasant taste).
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