Ringer's lactate solution (RL)

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. It is used for replacing fluids and electrolytes in those who have low blood volume or low blood pressure. It may also be used to treat metabolic acidosis and to wash the eye following a chemical burn. It is given by injection into a vein or applied to the affected area.

Side effects may include allergic reactions, high blood potassium, volume overload, and high blood calcium. 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. Use is generally safe in pregnancy and breastfeeding. Ringer's lactate solution is in the crystalloid family of medication. It has the same tonicity as blood.

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 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 (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, 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.

According to an April 2019 US NRC Medical Generic Communication, Medical use licensees that use Strontium-82/Rubidium-82 (Sr-82/Rb-82) generators to produce Rb-82 for cardiac imaging [be advised] there have been two incidents in different states since December 2018 with patients injected with Rb-82 contaminated with Sr-82 and Sr-85 from generators eluted with Ringer’s lactate solution instead of sterile saline. Ringer's lactate solution is a mixture of sodium chloride, sodium lactate, potassium chloride, and calcium chloride in water. The calcium in the Ringer’s lactate solution replaces the strontium on the generator column. This results in the strontium being washed off the column when it is eluted. Ringers lactate should never be used to elute an Rb-82/Sr-82 generator for this reason

Chemistry

One liter of Ringer's lactate solution contains:

130–131 mEq of sodium ion = 130 mmol L−1
109–111 mEq of chloride ion = 109 mmol L−1
28–29 mEq of lactate ion = 28 mmol L−1
4–5 mEq of potassium ion = 4 mmol L−1
2–3 mEq of calcium ion = 1.5 mmol L−1

Ringer's lactate has an osmolarity of 273 mOsm L−1[12] 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 (NaCl), sodium lactate (CH3CH(OH)CO2Na), calcium chloride (CaCl2), and potassium chloride (KCl), dissolved into distilled water. Ringer's solution has the same constituents without the sodium lactate, though sometimes it may also include magnesium chloride (MgCl2).

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.

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