1. What is the Henderson-Hasselbalch Equation?

The Henderson-Hasselbalch equation is a mathematical expression that relates pH, bicarbonate concentration, and the partial pressure of carbon dioxide (pCO₂) in blood. It's derived from the carbonic acid-bicarbonate buffer system equation and is widely used in acid-base physiology.

2. How Does the Calculator Work?

The calculator uses the Henderson-Hasselbalch equation:

Where:

• \( pCO_2 \) — Partial pressure of carbon dioxide (mmHg)
• \( [HCO_3^-] \) — Bicarbonate concentration (mmol/L)
• \( pH \) — pH value (dimensionless)
• 0.03 — Solubility coefficient of CO₂ in plasma
• 6.1 — pKa of carbonic acid

Explanation: The equation calculates the partial pressure of CO₂ based on the bicarbonate concentration and pH level, using the known constants for CO₂ solubility and carbonic acid dissociation.

3. Importance of pCO₂ Calculation

Details: Accurate pCO₂ calculation is essential for assessing acid-base balance, diagnosing respiratory and metabolic disorders, and monitoring patients with respiratory conditions or metabolic acidosis/alkalosis.

4. Using the Calculator

Tips: Enter bicarbonate concentration in mmol/L and pH value (typically between 6.8-7.8 for physiological ranges). All values must be valid (HCO₃⁻ > 0, pH between 0-14).

5. Frequently Asked Questions (FAQ)

Q1: What is the normal range for pCO₂?
A: Normal arterial pCO₂ ranges from 35-45 mmHg. Values outside this range may indicate respiratory acidosis (high pCO₂) or alkalosis (low pCO₂).

Q2: How does this relate to blood gas analysis?
A: This calculation provides an estimated pCO₂ that can be compared with measured values from arterial blood gas analysis to assess acid-base status.

Q3: When is this calculation most useful?
A: It's particularly useful in clinical settings where direct pCO₂ measurement is unavailable, or for educational purposes to understand acid-base relationships.

Q4: Are there limitations to this equation?
A: The equation assumes standard temperature and pressure conditions and may not account for all physiological variables affecting acid-base balance.

Q5: Can this be used for venous blood calculations?
A: While the equation can be applied, venous pCO₂ is typically 4-6 mmHg higher than arterial pCO₂, so results should be interpreted accordingly.