Acid-Base Imbalances: Overview and Memory Tricks

Introduction

• Topics Covered: Basic overview including pathophysiology, memory tricks, and practice questions on AVGs.

What are Acid-Base Imbalances?

• Definition: Balance of acid and base in the body measured by blood pH.
• Normal pH Range: 7.35 to 7.45.
  • Below 7.35: Acidosis.
  • Above 7.45: Alkalosis.

Key Players in Acid-Base Balance

• HCO3 (Bicarb): Alkalotic effect.
  • Memory Trick: Base equals bicarb.
• CO2 (Carbon Dioxide): Acidotic effect.
  • Memory Trick: Carbon dioxide is carbon diacid.
• Hydrogen Ions: Acidic effect.
  • Memory Trick: Hydrogen ions is high acid.

Organs Involved

• Lungs: Control CO2 levels.
  • Decreased breathing: More CO2 retained, more acidic.
  • Increased breathing: Less CO2, more alkalotic.
• Kidneys: Control HCO3 and hydrogen ions.
  • Excrete acid and retain base to balance acid-base.

Types of Imbalances

• Respiratory Acidosis: Caused by low respiratory rate.
  • Causes: Sleep apnea, head trauma, CNS depressants (opioids, benzodiazepines), impaired gas exchange.
• Respiratory Alkalosis: Caused by high respiratory rate.
  • Causes: Hyperventilation (e.g., panic attacks).
• Metabolic Acidosis: Loss of base or retention of acid.
  • Causes: Diarrhea, renal failure, diabetic ketoacidosis (DKA).
• Metabolic Alkalosis: Loss of acid.
  • Causes: Vomiting, NG tube suctioning.

Compensation

• Concept: Body's attempt to balance pH by adjusting rates of respiration or kidney function.
  • Example: Increased breathing to correct acidosis.

Practice Questions and Memory Tricks

• Metabolic Alkalosis: Vomiting, NG suctioning.
• Metabolic Acidosis: Diarrhea, renal failure ("if kidneys fail, acid prevails").
• Respiratory Acidosis: Slow breathing, snoring (e.g., sleep apnea, CNS depressants).
• Respiratory Alkalosis: Fast breathing, panic attack ("hulkalosis").

ABG Interpretation

• Three Steps:
  1. Identify pH level (acid or base).
  2. Match pH with CO2 or HCO3.
  3. Determine compensation (fully, partially, or uncompensated).
• Compensation Types:
  • Fully Compensated: pH in normal range.
  • Partially Compensated: pH not normal, but adjustments occur.
  • Uncompensated: pH not normal, no compensation.

Practice ABG Questions

• Key Steps: Identify pH, match with CO2 or HCO3, check compensation.
• Example: pH 7.25, CO2 55, HCO3 25 → Respiratory Acidosis, Uncompensated.

Conclusion

• Download study guides and take practice quizzes for further study.