Category: Critical Care
Keywords: Sodium, ICP, neurocritical care, sodium bicarbonate, bicarb, hyperosmolar (PubMed Search)
Posted: 2/17/2026 by Zachary Wynne, MD
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Bottom Line: Hypertonic sodium bicarbonate (8.4%) can be used judiciously as an alternative hyperosmolar therapy in the setting of increased intracranial pressure (ICP) or cerebral edema with impending herniation, particularly in setting of concomitant metabolic acidosis. Two 50 mL ampules of hypertonic sodium bicarbonate is the equivalent of approximately 200 mL of 3% sodium chloride (hypertonic saline).
Scenario:
The CT scan on your patient presenting with altered mental status shows a large intraparenchymal hemorrhage with 8 mm of midline shift. Suddenly, the patient becomes bradycardic with irregular respirations. Examination shows aniscoria with a non reactive right pupil. You call for 3% sodium chloride (hypertonic saline) and mannitol but neither will arrive from pharmacy for the next 10 minutes. What can you do in the meantime?
Background:
Sodium bicarbonate (commonly known as baking soda, NaHCO3) is a salt that acts as a weak base when dissolved in water. Clinically, it comes in two forms: hypertonic sodium bicarbonate (8.4% in 50 mL ampules) and isotonic sodium bicarbonate (1.3%, made with 3 ampules of hypertonic bicarbonate in one liter of D5 water).
Hyperosmolar therapy is often used to temporize patients in the setting of cerebral edema/increased ICP with concern for herniation syndrome (Cushing triad, aniscoria with non reactive pupil, posturing). This therapy will temporize patients for CT imaging and definitive management. Usual choices include 3% hypertonic saline or mannitol. The administration of these agents increases intravascular osmolality and theoretically causes solute drag to pull water out of organs, such as the brain, decreasing edema.
Hypertonic sodium bicarbonate can also function in this manner. To compare osmolality:
Hypertonic sodium bicarbonate can be given by two 50 mL ampules given in rapid succession in the setting of elevated ICP. This is the osmotic equivalent to giving approximately 200 mL of 3% hypertonic saline. Hypertonic sodium bicarbonate is often found in code carts in the emergency department and can sometimes be easier to access quickly in case of an acute clinical change like our above scenario. Hypertonic sodium bicarbonate can also be considered in patients that have received multiple rounds of hypertonic saline and thus have developed a hyperchloremic metabolic acidosis. There is limited data from the Neurocritical Care literature that has shown decreased ICP in the setting of TBI with hypertonic sodium bicarbonate administration (references below).
Hypertonic sodium bicarbonate side effects include metabolic alkalosis which can be detrimental in the patient with elevated ICP; normocapnea/normocarbia is critical to maintain cerebral blood flow and excess sodium bicarbonate administration should be avoided in patients that already have a metabolic alkalosis. Additionally, the metabolic alkalosis from sodium bicarbonate can also precipitate hypocalcemia if a patient is at risk. Additionally, hypertonic sodium bicarbonate can also cause some irritation to peripheral veins.
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