Bicarbonate deficit formula for metabolic acidosis:

[ \boxed{\text{HCO}_3^- \text{ required (mEq or mmol)} = (\text{Target HCO}_3^- - \text{Measured HCO}_3^-)\times 0.4\text{ to }0.5 \times \text{body weight (kg)}} ]

A commonly used bedside estimate uses 0.4:

[ (\text{Desired HCO}_3^- - \text{actual HCO}_3^-)\times 0.4 \times \text{weight in kg} ]

For severe acute acidemia, rather than targeting a normal bicarbonate of 24 mEq/L immediately, target a safer pH around 7.10, using:

[ \text{Target HCO}3^- \approx 0.30 \times P{CO_2} ]

Then:

[ \text{NaHCO}_3\text{ dose} = (\text{target HCO}_3^- - \text{measured HCO}_3^-)\times0.4\times\text{weight} ]

Example: 70 kg patient, HCO₃⁻ = 8 mEq/L, target = 12 mEq/L:

[ (12-8)\times0.4\times70 = 112\text{ mEq} ]

Usually give only about one-half initially, repeat blood gas/electrolytes, and reassess. Excess or inappropriate bicarbonate can cause hypernatremia, volume overload, hypokalemia, CO₂ generation, and paradoxical intracellular/CNS acidosis.

A surgical-text estimate uses:

[ \text{Bicarbonate deficit} = \frac{1}{3} \times \text{weight (kg)} \times \text{base deficit} ]