Magnesium Compatibility with Lactated Ringer's Solution

Composition and Compatibility

• Lactated Ringer's (LR) solution contains sodium (130 mmol/L), potassium (4 mmol/L), chloride (109 mmol/L), calcium (1.4 mmol/L), and lactate (28 mmol/L), according to the British Medical Journal 1
• LR has an osmolarity of approximately 273-277 mOsm/L, making it slightly hypotonic compared to plasma (275-295 mOsm/L), as reported by Anaesthesia 3
• The presence of calcium (1.4 mmol/L) in LR is important to consider when evaluating compatibility with other electrolytes, such as magnesium, as noted by the British Medical Journal 1
• LR is considered a balanced crystalloid solution with an electrolyte composition closer to plasma than normal saline, making it physiologically advantageous in many clinical scenarios, according to Anaesthesia 3
• The American Society of Anesthesiologists recommends considering the electrolyte composition of LR when administering magnesium, due to the potential interaction between calcium and magnesium, as reported by Anaesthesia 4
• Patients with renal impairment should be carefully monitored when administering magnesium in LR, as the solution already contains potassium (4 mmol/L), which can affect total electrolyte administration, as noted by Anaesthesia 3
• The British Medical Journal recommends monitoring for signs of magnesium toxicity (hyporeflexia, respiratory depression, hypotension) when administering magnesium in LR, regardless of the diluent used 1