Bicarbonate Deficit Calculator

Frequently asked questions

What is the bicarbonate deficit formula?

Defisit (mEq) = (HCO3⁻ target − HCO3⁻ terukur) × berat (kg) × faktor distribusi. Example: Contoh: 70 kg, HCO3⁻ 10 mEq/L, target 20 mEq/L, faktor distribusi 0,5 → defisit 350,0 mEq; setengah dulu = 175,0 mEq → 175,0 mL NaHCO3 8,4%. The mEq value equals mmol for sodium bicarbonate (monovalent).

Should the target HCO3⁻ be the normal range (22–24 mEq/L)?

Usually not on the first correction. The literature targets a safe pH, not full normalization: a common bedside target is about 20 mEq/L; Medscape's alternative method uses 15 mEq/L as the end-point goal (Defisit (mEq) = 0,6 × berat (kg) × (15 − terukur)); and the MSD Manual uses Target HCO3⁻ (Kassirer–Bleich) = 0,30 × PCO2 (mmHg) → pH 7,10, then (target − measured) × 0.4 × weight (70 kg, HCO3⁻ 8, PCO2 40 → target 12,0 mEq/L → kebutuhan 112,0 mEq (MSD Manual).). Correcting only to a safe range limits overshoot into metabolic alkalosis.

Why is the distribution factor 0.5 — and when is 0.4 or 0.6 used?

Bicarbonate distributes mainly in extracellular fluid, and 50% of body weight is the standard bedside volume of distribution (ScyMed MediCalculator). Published practice varies: the MSD Manual pairs 0.4 with its pH-7.10 target, Medscape's method 2 effectively uses 0.6 with a target of 15, and some protocols use up to 0.8 at pH below 7.1. This tool defaults to 0.5 with a 0.4–0.6 range so you can see how the estimate changes.

Why give only half the deficit first?

Because the estimate is approximate and overshoot is dangerous. Medscape's critical-care guidance repletes roughly half the deficit within the first 4 hours and titrates the rest against repeat arterial blood gases; other protocols give half the calculated correction, then repeat the ABG. This calculator always shows the half-dose estimate alongside the full deficit — but the decision to give anything is the physician's.

How many mEq per mL are in 8.4%, 7.5%, and 4.2% sodium bicarbonate?

8,4% = 1,000 mEq/mL · 7,5% = 0,892 mEq/mL · 4,2% = 0,500 mEq/mL (per AHFS drug labeling). So a 50 mL ampule of 8.4% contains 50 mEq, and Referensi drip umum: 150 mEq NaHCO3 dalam 1000 mL D5W (0,15 mEq/mL).

What are the risks of bicarbonate correction?

Published risks include hypernatremia, hypokalemia (potassium shifts intracellularly as pH rises), paradoxical intracellular/CSF acidosis, hyperosmolarity from concentrated solutions, volume overload, and decreased ionized calcium (Medscape, MSD Manual). Effective ventilation is required to blow off the CO2 generated. These are reasons correction is cautious, partial, and physician-directed — never a fixed-dose rule.

When is bicarbonate therapy indicated at all?

The indication itself is debated. Most experts cited by the MSD Manual recommend IV bicarbonate for severe metabolic acidosis (pH below 7.0), mainly over concern for cardiovascular instability; outside that, routine use is controversial and underlying-cause treatment comes first. This tool assumes a physician has already decided correction is indicated — it cannot make that decision.

How is this different from the bicarbonate input in the APACHE II score?

APACHE II uses a single serum bicarbonate value as one of twelve physiologic inputs to score ICU severity of illness. This tool does something different: it computes a bicarbonate DEFICIT (target minus measured, times weight, times a distribution factor) to estimate how much HCO3⁻ would be needed to reach a target. Related tools: our APACHE II calculator and anion gap calculator for the broader acid–base picture.

Is this calculator medical advice? Who should use it?

No. It is an educational arithmetic tool for health professionals and students learning acid–base calculations. It shows estimates, not orders: it never tells you to 'give X mEq'. Every dosing decision, infusion rate, and repeat-ABG plan belongs to the treating physician. If you are a patient, discuss any lab result with your clinician — do not act on a calculator output.