Bicarbonate therapy in DKA: A Practical Approach

Bicarbonate Use in Diabetic Ketoacidosis

Venous / Arterial pH	Bicarbonate dose	How to mix (dilution + electrolytes)	Infusion rate	When to reassess / repeat
< 6.9	100 mmol NaHCO3 (two 50-mL amps of 8.4 %)	Dilute in 400 mL 0.45 % NaCl + 20 mmol KCl → ~250 mOsm L-1	200 mL h-1 (2 h total)	Check VBG/ABG q 2 h; repeat same dose if pH < 7.0
6.9 – 7.0	50 mmol NaHCO3 (one 50-mL amp)	Dilute in 200 mL 0.45 % NaCl ± 10 mmol KCl	200 mL h-1 (1 h total)	Re-check pH at end of infusion; rarely needs second dose
> 7.0	No bicarbonate indicated	—	—	Insulin + fluids will close the gap

Practical bedside recipe (pH < 6.9 example)

1. Draw 2 amps (100 mL) of 8.4 % NaHCO₃.
2. Add to a 500-mL bag of 0.45 % saline after discarding 100 mL (final volume = 400 mL).
3. Add 20 mmol KCl (e.g., 10 mL of 2 mEq mL^-1) unless K⁺ > 5.5 mEq L^-1.
4. Label “Sodium bicarbonate 100 mmol + KCl 20 mmol in 400 mL”; infuse at 200 mL h^-1.
5. Repeat VBG and electrolytes in 2 h; if pH < 7.0, mix and run the same bag again.

Key reminders

• Use venous blood gas for trending; pH difference from ABG is < 0.03.
• Stop bicarbonate once pH ≥ 7.0 or HCO₃^- > 18 mEq L^-1; overshooting delays anion-gap closure.
• Bicarbonate adds the same millimoles of Na⁺; monitor sodium balance and osmolality.
• Insulin and volume resuscitation correct keto-acid production—the NaHCO₃ drip is only a bridge while pH is critically low.

Bottom line

When venous/arterial pH in DKA falls below 6.9, give 100 mmol (two amps) of 8.4 % sodium bicarbonate only after diluting to 400 mL with 0.45 % saline and adding potassium. Infuse over 2 hours, then reassess; repeat only if pH remains < 7.0. For pH > 7.0, bicarbonate therapy offers no benefit and may be harmful.