Lecture Notes on Acid-Base Balance and Disorders

Lecture Overview

• Two lectures this week: one on acid-base disorders and one on two markers.

Acid-Base Disorders

• Focus on pathophysiology of acid-base balance.
• Main buffering system involves CO2 (acid) and bicarbonate (base).

Key Concepts

• Henderson-Hasselbalch Equation: Relates pH to bicarbonate and CO2 levels.
• Normal arterial pH range: $7.35$ to $7.45$, average $7.4$.
• Bicarbonate (HCO3) in millimoles per liter; CO2 and PO2 in mmHg.

CO2 and Bicarbonate Relationship

• Inverse relationship: Increased CO2 -> Decreased pH (acidosis).
• Proportional relationship: Increased bicarbonate -> Increased pH (alkalosis).
• Normal ratio: 20 bicarbonate to 1 carbonic acid.

Acid-Base Imbalances

• Acidosis: pH < $7.35$; Alkalosis: pH > $7.45$.
• Major types: Metabolic (bicarbonate issue) and Respiratory (CO2 issue).

Regulation Mechanisms

• Respiratory (fast response, minutes): CO2 elimination via ventilation.
• Renal (slower response, hours to days): Bicarbonate resorption and proton excretion.

Clinical Applications

• Analyze ABG results to identify imbalances and appropriate compensatory mechanisms.
• Common disorders include metabolic acidosis (e.g., DKA, renal failure) and respiratory alkalosis (e.g., anxiety).

Compensation Examples

• Respiratory compensation for metabolic acidosis via hyperventilation.
• Renal compensation for respiratory acidosis involves bicarbonate conservation.

Case Study Analysis

• Example case highlighting assessment of acid-base disorders and interventions (e.g., breathing into a bag for hyperventilation).