Question

Strength of Isotonic sodium bicarbonate is

• A. 1%
• B. 1.3%
• C. 2.5%
• D. 5%

Hint:

Isotonic crystalloid concentrations to remember: Sodium chloride = \(0.9\%\), Dextrose = \(5\%\), Sodium bicarbonate = \(1.3\%\).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Isotonic solutions exert the same osmotic pressure as plasma and extracellular fluid, preventing net movement of water across semipermeable cell membranes.
In veterinary clinical practice, fluid therapy utilizes various isotonic crystalloids to restore blood volume and correct acid-base imbalances.
Sodium bicarbonate is commonly administered intravenously to correct metabolic acidosis in conditions such as severe neonatal calf diarrhea.
Key Formula or Approach:
The osmolarity of bovine plasma is approximately \( 280\text{ to }310\text{ mOsm/L} \).
For a solution of sodium bicarbonate (\(\text{NaHCO}_3\), molecular weight \(\approx 84\text{ g/mol}\)) to be isotonic, its osmolarity must match plasma:
\[ \text{NaHCO}_3 \rightarrow \text{Na}^+ + \text{HCO}_3^- \quad (\text{yields 2 osmoles per mole}) \] An isotonic solution of sodium bicarbonate is calculated to be approximately \( 1.3\% \text{ to } 1.4\% \) in water (w/v), providing approximately \( 150\text{ mEq/L} \) of sodium and bicarbonate ions.

Step 2: Detailed Explanation:
Using hypertonic sodium bicarbonate solutions (such as \( 5\% \) or \( 8.4\% \)) can cause rapid intracellular dehydration and severe localized vascular irritation if not diluted.
Administering an isotonic \( 1.3\% \) sodium bicarbonate solution allows for safe, direct intravenous infusion.
This concentration maintains normal erythrocyte volume and avoids the risks of hemolysis or crenation associated with hypotonic or hypertonic fluids.

Step 3: Final Answer:
The strength of isotonic sodium bicarbonate is \( 1.3\% \).