Ringer's lactate
Summary
Balanced isotonic crystalloid containing sodium, chloride, potassium, calcium, and lactate; used for volume resuscitation in trauma, sepsis, burns, and surgery. Preferred over normal saline in large-volume resuscitation to avoid hyperchloremic non-anion-gap metabolic acidosis.
Detail
Typical composition: Na+ ~130 mEq/L, Cl- ~109 mEq/L, K+ ~4 mEq/L, Ca2+ ~3 mEq/L, lactate ~28 mEq/L, osmolarity ~273 mOsm/L. Lactate is metabolized by the liver to bicarbonate, providing a buffer and helping correct metabolic acidosis. Compared to 0.9% NaCl, LR has less chloride and so does not cause hyperchloremic acidosis with large volumes. Cautions: relative contraindications include severe liver failure (impaired lactate metabolism), hyperkalemia (contains potassium), and co-infusion with blood products through the same line because calcium can overcome citrate anticoagulation and cause clotting. Often the resuscitation fluid of choice for burns (Parkland formula).
Sources
- First Aid for USMLE Step 2 CK
- Harrison's Principles of Internal Medicine
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