Buffer · Hyperkalemia treatment · Antidote
Sodium bicarbonate
Also called bicarb
Indications
- Severe metabolic acidosis; with pH 7.20 or less and stage 2–3 AKI it reduced dialysis but not 90-day mortality (BICAR-ICU-2, 2025)
- Tricyclic and other sodium channel blocker poisoning with a wide QRS or ventricular arrhythmias (AHA 2023)
- Urine alkalinization for salicylate poisoning (label)
- Hyperkalemia with metabolic acidosis, as an add-on (off-label)
- Bicarbonate loss from severe diarrhea (label)
Dosing
Sodium bicarbonate drip card and mL/h converterStart: Sodium channel blocker toxicity (TCA, QRS 100 ms or more): 50–150 mEq (1–2 mEq/kg) of 8.4% IV push, repeated until the QRS narrows, then an infusion if needed (AHA 2023). Salicylates: bolus, then the 150 mEq/L bag at 1.5–2 times maintenance. Hyperkalemia with acidosis: an add-on only
| Where | Dose |
|---|---|
| Cardiac arrest | Sodium bicarbonate: 1 mEq/kg for hyperkalemia or TCA overdose; not routine |
| Metabolic and electrolyte boluses | Sodium bicarbonate: 50 mEq if acidotic |
| Metabolic and electrolyte boluses | Sodium bicarbonate 8.4%: 1 mEq/kg; 1 ampule is 50 mEq in 50 mL |
| Unit conversions | Sodium bicarbonate 8.4%: 1 mEq/mL |
| Hypertonic and concentrated fluids | Sodium bicarbonate 8.4%: 1 mEq/mL (50 mEq in 50 mL); 2,000 mOsm/L. Vesicant: large or central vein; flush; never in a line with calcium, norepinephrine or dobutamine |
| Hypertonic and concentrated fluids | Sodium bicarbonate 150 mEq/L: Isotonic drip: premixed bag (about 300 mOsm/L), or 150 mEq added by pharmacy to 1 L of sterile water or D5W; a peripheral IV is fine |
On the quick cards
- Metabolic and electrolyte bolusesPush and Emergency Meds: Hyperkalemia, glucose, calcium, magnesium, thiamine
- Hypertonic and concentrated fluidsIV Fluids: Strength per mL, osmolarity and which line
Mechanism of action
HCO₃⁻ is the base of the body's main buffer: it takes up H⁺ to form carbonic acid, which carbonic anhydrase splits into CO₂ and water for the lungs to exhale. pH rises only if ventilation clears that CO₂; otherwise PaCO₂ climbs, and CO₂, which crosses membranes faster than bicarbonate, briefly lowers intracellular and CSF pH. In sodium channel blocker poisoning the sodium load steepens the gradient through blocked channels and alkalemia leaves less ionized drug to bind them, narrowing the QRS; alkaline urine traps ionized salicylate for excretion.
Pharmacology
- Metabolic: raises HCO₃⁻ and pH; moves K⁺ into cells (a small effect alone), lowers ionized Ca²⁺ and shifts the oxyhemoglobin curve left
- Respiratory: each mEq that buffers acid makes 1 mmol of CO₂ (over 1 L per 50 mEq), so ventilation must rise
- Cardiovascular: narrows the QRS and raises BP in tricyclic toxicity; in plain acidemia, trials show little hemodynamic benefit
- CNS: paradoxical CSF acidosis; linked to cerebral edema in pediatric DKA
- Renal: alkalinizes urine once plasma HCO₃⁻ passes the reabsorption threshold, unless K⁺ is low
Pharmacokinetics
| Onset | Minutes IV; the QRS narrows within minutes in tricyclic toxicity |
|---|---|
| Duration | Set by ongoing acid production and by lung and kidney excretion |
| Distribution | Extracellular at first; the apparent bicarbonate space is about 50% of body weight and grows in severe acidosis |
| Protein binding | None |
| Metabolism | None; it equilibrates with CO₂ through carbonic anhydrase |
| Elimination | CO₂ by the lungs; HCO₃⁻ in urine above about 24–26 mEq/L, less when volume, chloride or potassium are low |
| Organ failure | Ventilatory failure traps the CO₂; kidney failure retains the sodium and bicarbonate |
Chemistry
- Sodium bicarbonate (NaHCO₃, MW 84.0); the HCO₃⁻/CO₂ pair has a pKa of 6.1 yet buffers well at 7.4 because the lungs remove CO₂ (an open system)
- 8.4% is 84 mg/mL, 1 mEq/mL each of Na⁺ and HCO₃⁻, so 50 mL holds 50 mEq; 4.2% (0.5 mEq/mL) is the infant strength
- Hypertonic: 2,000 mOsm/L calculated (Civica label; Hospira lists 1,560); pH about 8 (7.0–8.5); no preservative
- Releases CO₂ when acidified or heated; precipitates calcium as carbonate; inactivates catecholamines (the label names norepinephrine and dobutamine)
Adverse effects and cautions
In the one-pagers
- Toxidromes and AntidotesCardiotoxic drugs: TCA, sodium channel blockers: Sodium bicarbonate 50–150 mEq IV, repeat to narrow QRS: QRS ≥100 ms: seizures; ≥160 ms: VT/VF
- CapnographyPatterns and causes: Sudden rise: ROSC, IV sodium bicarbonate, tourniquet release
- Mental Health: Meds and CommunicationAntidepressants in the ICU and serotonin toxicity: TCA overdose layers sodium-channel blockade on an anticholinergic toxidrome: coma, seizures, hypotension and a wide QRS with a tall terminal R wave in aVR. A QRS of 100 ms or more predicts seizures and 160 ms or more ventricular arrhythmias (Boehnert 1985). Give sodium bicarbonate 1–2 mEq/kg IV boluses until the QRS narrows, without pushing pH abo
- ACLS Algorithms in BriefDrugs in arrest: what the trials show: Sodium bicarbonate: No survival benefit in unselected arrest: Hyperkalemia, sodium channel blocker toxicity
- Rhythm GalleryVentricular rhythms and wide-complex tachycardia: A wide, slowish tachycardia in renal failure or overdose may be hyperkalemia or sodium-channel blockade (TCA: terminal R in aVR): calcium or sodium bicarbonate, not procainamide or amiodarone.
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Sources
- FDA label: Sodium Bicarbonate 8.4% (Civica, 2026)
- FDA label: Sodium Bicarbonate (Hospira, 2018)
- Jung 2025 (BICAR-ICU-2, JAMA)
- AHA 2023 poisoning focused update
For education and exam preparation only. Follow your institution’s protocols. Typical adult values for study. Follow the order, the label and your institution's protocols.