Arterial Blood Gas Interpretation

Study Notes

Acidic and Basic Definitions:
- Arrhenius: Acids increase hydronium ion concentration; bases increase hydroxide ion concentration.
- Bronsted-Lowry: Acids donate protons; bases accept protons.
- Lewis: Acids accept electron pairs; bases donate unshared electron pairs.
Buffers:
- Solutions that resist drastic pH changes when small amounts of acids or bases are added.
- Important buffers include aluminum hydroxide and magnesium hydroxide, often used as antacids.
Acid-Base Balance:
- The human body functions optimally at a specific pH range (7.35-7.45).
- Extreme pH levels can denature biomolecules, affecting cellular processes like division and metabolism.

Purpose: Diagnostic tool for:
- Assessing acid-base balance.
- Evaluating oxygenation status.
- Identifying respiratory and kidney function abnormalities.
Weak and Strong Acids/Bases:
- Weak acids/bases do not readily dissociate into ionic components; strong acids/bases do.
- Dissociation constant for weak acids is defined as K = [H+][A]/[HA].
- Henderson-Hasselbalch equation: pH = pK + log10[A]/[HA], relates pH, the dissociation constant, and concentrations.

pH:
- Measures blood acidity; normal range is 7.35-7.45.
pCO2:
- Partial pressure of carbon dioxide, indicative of respiratory function.
HCO3:
- Bicarbonate level in the blood, crucial for metabolic balance.

Respiratory Acidosis: Occurs when pCO2 exceeds normal levels due to decreased respiration.
Respiratory Alkalosis: Occurs when pCO2 falls below normal levels due to hyperventilation.
Metabolic Acidosis: Imbalance characterized by low pH and low HCO3 levels.
Metabolic Alkalosis: Condition recognized by high pH and elevated HCO3 levels.