From the Guidelines
A 150ml solution of 3% hypertonic saline contains 77.25 mEq of sodium. To calculate this, I first determined that 3% saline means 3 grams of sodium chloride per 100ml, so 150ml contains 4.5 grams of NaCl (3g × 1.5) [ 1 ]. Since sodium has a molecular weight of 23 and chloride has a molecular weight of 35.5, the total molecular weight of NaCl is 58.5. Sodium accounts for 23/58.5 or about 39.3% of this weight. Therefore, 4.5g of NaCl contains 1.77g of sodium (4.5g × 0.393). Converting to milliequivalents, since sodium has a valence of 1, we use the formula mEq = weight in mg ÷ (atomic weight ÷ valence). This gives us 1,770mg ÷ (23 ÷ 1) = 77.25 mEq of sodium.
Calculation Breakdown
- 3% saline solution contains 513 mmol/L of sodium [ 1 ]
- For 150ml, the sodium content is 513 mmol/L * 0.150 L = 76.95 mmol
- Since 1 mmol of sodium is equal to 1 mEq, the sodium content in mEq is approximately 76.95 mEq, which is very close to our initial calculation of 77.25 mEq
- This calculation is important for monitoring sodium administration in clinical settings, especially when treating conditions like hyponatremia or increased intracranial pressure where precise sodium management is critical.
Clinical Implications
- Accurate calculation of sodium content is crucial in critical care settings to avoid sodium overload or deficiency
- The use of 3% hypertonic saline solution should be carefully monitored, especially in patients with severe hyponatremia or those at risk of osmotic demyelination syndrome [ 1 ]
- Clinicians should be aware of the potential risks and benefits of hypertonic saline solution and use it judiciously to optimize patient outcomes.
From the Research
Sodium Content in 3% Hypertonic Saline Solution
To determine the sodium content in milliequivalents (mEq) in 150 milliliters (mL) of 3% hypertonic saline solution, we need to understand the composition of the solution.
- 3% hypertonic saline solution contains 3 grams of sodium chloride (NaCl) per 100 mL of solution.
- The molecular weight of NaCl is approximately 58.44 g/mol.
- Sodium (Na) has a molecular weight of approximately 22.99 g/mol.
- Therefore, the amount of sodium in 3% hypertonic saline solution can be calculated as follows: 3 g NaCl / 100 mL * (22.99 g/mol / 58.44 g/mol) = 1.18 g Na / 100 mL.
- Since 1 gram of sodium is equivalent to 43.5 mEq (1 mmol = 1 mEq for monovalent ions like sodium), the sodium content in 100 mL of 3% hypertonic saline solution is: 1.18 g Na / 100 mL * 43.5 mEq/g = 51.33 mEq / 100 mL.
- For 150 mL of 3% hypertonic saline solution, the sodium content would be: 51.33 mEq / 100 mL * 150 mL = 76.995 mEq, which can be approximated to 77 mEq.
This calculation is based on the chemical properties of sodium chloride and its solution, and is supported by the medical use of hypertonic saline solutions as described in studies such as 2, 3, 4, 5, 6.