II. Preparations: Hypotonic Solutions
- Dextrose in Water (D5W)
- Half Normal Saline (0.45 NaCl or 1/2NS)
- Osmolality: 154 mOsm/L
- Sodium: 77 mEq/L (with equivalent chloride)
- Equivalent of administering half free water and half Isotonic Saline
- Consider in Hypernatremia with volume depletion
- Risk of Hyponatremia
III. Preparations: Isotonic Solutions
- See Crystalloid Isotonic Solution
-
General
- NS or LR is the typical replacement in most volume depleted cases
- LR may be preferred as more physiologic (pH neutral) compared with the acidic NS
- Hypovolemia due to Hemorrhage should be replaced with blood (as indicated)
-
Normal Saline (0.9% NaCl or NS)
- Osmolality: 308 mOsm/L
- Sodium: 154 mEq/L (with equivalent chloride)
- pH: 5-6
- Lactated Ringers (LR)
IV. Preparations: Hypertonic Solutions
- Hypertonic Saline (3% NaCl)
- Osmolality: 1026 mOsm/L
- Sodium: 513 mEq/L (with equivalent chloride)
- pH: 5
- Exercise caution and dose very carefully (risk of Central Pontine Myelinolysis)
- Five fold greater effect of expanding extracellular space than Isotonic Solutions given the same fluid volume
- However, no survival benefit over Isotonic Solutions (with the added risk)
- Indications
- Severe symptomatic Hyponatremia
- Severe cerebral edema with risk of Herniation (Traumatic Brain Injury)
V. References
- Loflin (2015) Crit Dec Emerg Med 29(9): 11-18
- Marino (2014) The ICU Book, Wolters Kluwer, Philadelphia, p. 217-37
- Preston (2011) Acid-Base, Fluids and Electrolytes, Medmaster, Miami, p. 30-4