Hypertonic Saline 3% (Sodium Chloride 3%)

• Core dose: Cerebral edema/herniation: 150–250 mL (23.4%: 30 mL) IV over 10–20 min; Symptomatic hyponatremia: 100–150 mL 3% bolus, may repeat x2
• Onset/duration: Osmotic effect within minutes; ICP reduction peaks 15–30 min; duration 2–6 hr depending on dose and pathology
• Key danger: Central pontine myelinolysis if Na corrected >10–12 mEq/L/24hr; fluid overload; hypernatremia; requires central line for 23.4%
• Special: 3% = 513 mEq/L Na⁺; osmolar agent for ICP crisis and severe symptomatic hyponatremia; monitor Na q2–4h during correction; goal Na rise 4–6 mEq/L initially

Hypertonic crystalloid (osmotic agent; electrolyte replenisher)

Mechanism of Action (Pharmacodynamics):

• Hypertonic saline increases plasma osmolality, drawing water from the intracellular to the extracellular compartment
• Expands intravascular volume and reduces cerebral edema
• Raises serum sodium and tonicity
• High chloride load can lower the strong ion difference → hyperchloremic metabolic acidosis with large doses

Disposition (Pharmacokinetics/Physiology):

• Distributes within extracellular fluid; immediate osmotic effect
• Sodium and chloride handled renally under hormonal control
• No discrete drug half-life; clinical effect depends on ongoing fluid/solute shifts and renal function

• Severe symptomatic hyponatremia (e.g., seizure, obtundation, impending herniation)
• Intracranial hypertension / cerebral edema (e.g., TBI, ICH, SAH) — bolus for ICP crisis and/or continuous infusion targeting serum Na⁺
• Acute neurologic deterioration from hyponatremia with risk of herniation (emergent bolus therapy)

Absolute Contraindications:

• None when clinically indicated in life-threatening hyponatremia/ICP crisis

Relative Contraindications:

• Hypernatremia
• Hyperchloremia/metabolic acidosis
• Severe congestive heart failure
• Significant renal impairment/oliguria
• Uncontrolled active bleeding where hyperosmolarity may worsen coagulopathy

Special Risk:

• Risk of osmotic demyelination from overly rapid correction of chronic hyponatremia — identify high-risk states (alcohol use disorder, malnutrition, liver disease, severe hypokalemia)

Local:

• Pain at infusion site
• Phlebitis
• Infiltration/extravasation (tissue injury rare but possible)

Systemic:

• Hypernatremia
• Hyperchloremic metabolic acidosis
• Hypokalemia (shift)
• Volume overload
• AKI signal with very high chloride loads

Neurologic:

• Osmotic demyelination syndrome (from over-rapid Na⁺ correction)

Critical Labs:

• Serum sodium every 2–4 hours during active correction
• Stop or slow infusion if Na⁺ rises >8 mEq/L in 24 h (stricter in high-risk)
• Urine output, urine osmolality/Na⁺ if available

Electrolytes/Acid-Base:

• Serum chloride, bicarbonate/base excess
• Blood gas if acid-base concerns
• Serum osmolality if severe hypernatremia or neuro symptoms

Renal Function:

• SCr, BUN
• Cumulative fluid balance and signs of pulmonary edema

For Neuro Indications:

• Neuro exam / ICP (when monitored)
• Serum Na⁺ goal adherence
• Avoid hypotonic co-infusions

• Generic/Official: Sodium Chloride Injection, USP — 3% (hypertonic)
• Common Names: 3% hypertonic saline ("3% HTS")

• May be given via well-placed peripheral IV when central access is not immediately available
• Monitor site closely for infiltration/phlebitis
• Use infusion pump for continuous therapy; dedicated line preferred
• Avoid co-infusion with hypotonic solutions
• Avoid sterile water dilution (hemolysis risk)

Adults — Severe Symptomatic Hyponatremia:

• Bolus strategy (U.S. practice): 100 mL of 3% NaCl IV over 10 minutes; may repeat up to 2 additional times based on symptoms and Na⁺ (goal early rise 4–6 mEq/L)
• Bolus strategy (European guidance): 150 mL of 3% NaCl IV over 20 minutes; may repeat 1–2 times with close monitoring
• Continuous strategy (moderate symptoms): 0.5–2 mL/kg/h of 3% NaCl IV with Na⁺ checks q2–4 h; adjust to avoid over-correction

Adults — Intracranial Hypertension / Cerebral Edema:

• Bolus for ICP crisis: 3% NaCl 2 mL/kg (commonly over 10–15 min). Alternative: fixed 250 mL bolus per institutional protocol
• Continuous infusion: Titrate 3% NaCl to achieve target serum Na⁺ 145–155 mEq/L (institutional range varies) with frequent labs and neuro checks

Pediatrics:

• Hyponatremic seizure: 3% NaCl 1–2 mL/kg IV bolus (commonly 2 mL/kg) over 10–20 minutes; repeat until symptoms improve or initial rise achieved
• Intracranial hypertension: 3% NaCl 2–5 mL/kg IV bolus for ICP spikes (institutional), or continuous infusion with target Na⁺ per PICU protocol

Desmopressin (DDAVP):

• Used therapeutically to control free-water diuresis and prevent over-correction ("DDAVP clamp")

Loop Diuretics:

• May be paired to enhance free-water clearance in hypervolemic hyponatremia

Compatibility:

• Avoid co-infusion with hypotonic fluids or bicarbonate/phosphate admixtures without compatibility data

• DailyMed. (2024). 3% Sodium Chloride Injection, USP — Prescribing Information (electrolyte content, pH, osmolarity).
• Medscape. (2025). Hyponatremia: Treatment & Management. https://emedicine.medscape.com/article/242166-treatment
• Medscape. (2025). Pediatric Hyponatremia: Treatment & Management. https://emedicine.medscape.com/article/907841-treatment