How the dose is calculated
Sodium bicarbonate is dosed in mEq/kg; since 8.4% solution contains 1 mEq/mL (≈ 84 mg/mL), the mg-based figures shown correspond directly to mEq (1 mEq ≈ 84 mg NaHCO3).
Typical dosing by indication
| Indication | Dose | Max single dose |
|---|---|---|
| Severe metabolic acidosis / hyperkalaemia | 1 mEq/kg IV | 50 mEq |
| TCA overdose | 1-2 mEq/kg IV bolus, titrated to effect | 100 mEq |
Repeat dosing should be guided by arterial blood gas (for acidosis) or ECG QRS width (for TCA overdose) rather than given empirically beyond the first dose.
Clinical use
- Used cautiously in severe metabolic acidosis, generally reserved for situations with haemodynamic compromise rather than given routinely for a low pH alone.
- A key antidote in tricyclic antidepressant overdose, where it narrows the QRS complex and reduces the risk of ventricular arrhythmia by increasing extracellular sodium and alkalinising the blood.
- Also used as an adjunct in hyperkalaemia management, particularly when acidosis is also present.
Frequently asked questions
Why is sodium bicarbonate used in TCA overdose?
It narrows a widened QRS complex and reduces the risk of life-threatening ventricular arrhythmias in tricyclic antidepressant toxicity, through a combination of sodium loading and alkalinisation — repeat dosing is titrated to QRS narrowing, not given empirically.
Is sodium bicarbonate routinely given for all metabolic acidosis?
No — its use is generally reserved for severe acidosis with haemodynamic compromise, since routine correction of milder acidosis hasn't shown clear benefit and can cause complications (fluid/sodium overload, worsened intracellular acidosis).
Can sodium bicarbonate be given with calcium?
Not in the same IV line — the two precipitate together and can occlude the line. Use separate access or flush thoroughly between the two.
References
- American Heart Association. Advanced Cardiovascular Life Support (ACLS) Guidelines.
- Body R, Bartram T. Tricyclic antidepressant toxicity. In: Emergency Toxicology.