From the Research
D5 1/2 NS with 75 mEq/L of sodium bicarbonate is isotonic. To create this isotonic solution:
- Start with 1 liter of D5 1/2 NS (which contains 77 mEq/L of sodium)
- Add 75 mEq of sodium bicarbonate This combination results in an isotonic solution with approximately 300 mOsm/L, which is close to the osmolality of human plasma (285-295 mOsm/L). The reasoning behind this:
- D5 1/2 NS contributes 77 mEq/L of sodium and 77 mEq/L of chloride
- Adding 75 mEq/L of sodium bicarbonate provides additional sodium and bicarbonate ions
- The dextrose (50 g/L) contributes to osmolality but doesn't affect tonicity
- The final solution has a balanced electrolyte composition that mimics physiological fluids This solution is useful for fluid replacement and mild metabolic acidosis correction, as supported by a study on the stability of bicarbonate in normal saline 1. Always verify the final concentration and adjust as needed based on the patient's specific clinical condition and electrolyte needs.
Key points to consider:
- The concentration of sodium bicarbonate required to make D5 1/2 NS isotonic is 75 mEq/L
- The resulting solution has an osmolality of approximately 300 mOsm/L
- This solution is suitable for fluid replacement and mild metabolic acidosis correction, as shown in a study on the correction of hyponatremia by infusing D5W in patients receiving continuous renal replacement therapy 2
- The stability of bicarbonate in the solution is crucial, and a study has shown that bicarbonate concentration remains stable over a 48-hour period when diluted in normal saline 1
- Clinicians should be aware of the potential for sodium bicarbonate therapy to be successfully blinded, as shown in a study on the ability of clinicians to identify the contents of bags containing sodium bicarbonate or D5W 3
- A recent study has highlighted the efficacy of isotonic sodium bicarbonate-based continuous hemodiafiltration in correcting severe metabolic acidosis by eliminating chloride and supplementing bicarbonate 4