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 kidney failure. 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 because the sodium content is considered too low, particularly for children, and the potassium content is too low, in view of electrolyte daily requirement. Moreover, since the lactate is converted into bicarbonate, long-term use will cause patients to become alkalotic. Ringer's lactate and other crystalloids are also used as vehicles for the IV delivery of medications. In a large-volume resuscitation over several hours, LRS maintains a more stable blood pH than normal saline.
Ringer's lactate has an osmolarity of 273 mOsm L−1 and a pH of 6.5.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. 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. Generally, the source of the constituent ions is a mixture of sodium chloride, sodium lactate, calcium chloride, and potassium chloride, dissolved into distilled water. Ringer's solution has the same constituents without the sodium lactate, though sometimes it may also include magnesium 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.
History
Ringer's saline solution was invented in the early 1880s by Sydney Ringer, 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. The use of Ringer's original solution of inorganic salts slowly became more popular. 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".
Formulations
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. This was thought to be helpful when analyzing blood-lactate for signs of anaerobic metabolism. Subsequently it has been shown that lactate is metabolized much faster than infused. Ringers lactate should not cause an elevated blood-lactate level except possibly in the most severe presentations of liver failure.
Veterinary use
It is used for the treatment or palliative care of chronic kidney 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.
