ABG Interpretation and Compensation Mechanisms

Jul 12, 2024

ABG Interpretation and Compensation Mechanisms

Introduction

  • Presenter: Eddie Watson
  • Channel: ICU Advantage
  • Video Lesson: Part 4 in series on Arterial Blood Gases (ABG)
  • Topics: ABG interpretation, compensation mechanisms

Review from Previous Lesson

  • First four steps of ABG interpretation to determine:
    • Normal ABG vs. abnormal
    • Acidosis or alkalosis
    • Primary cause: respiratory or metabolic

Compensation Mechanisms

  • Body Compensation: Adjusts bicarb (slow) or CO2 (fast) to balance pH
    • Respiratory Disturbance: Adjusts bicarb
    • Metabolic Disturbance: Adjusts CO2
  • Key Terms:
    • CO2 (acidic) and pH move in opposite directions
    • Bicarb (alkaline) and pH move in the same direction
  • Important Notes:
    • Body compensates in the same direction as disturbance
    • Compensation never fully normalizes the pH to perfect 7.4
    • Body will not overcompensate

Types of Compensation

  • Uncompensated: Abnormal pH, one abnormal value, one normal value
  • Fully Compensated: Normal pH, two abnormal values (matching)
  • Partially Compensated: Abnormal pH, two abnormal values (matching), compensation not complete

Examples

  1. Example 1

    • Values:
      • pH: 7.27 (low, acidosis)
      • CO2: 53 (high, respiratory acidosis)
      • Bicarb: 23 (normal)
    • Compensation: Uncompensated respiratory acidosis

  2. Example 2

    • Values:
      • pH: 7.36 (normal but low end)
      • CO2: 49 (high)
      • Bicarb: 28 (high)
    • Compensation: Fully compensated respiratory acidosis

  3. Example 3

    • Values:
      • pH: 7.44 (normal but high end)
      • CO2: 49 (high)
      • Bicarb: 29 (high)
    • Compensation: Fully compensated metabolic alkalosis

  4. Example 4

    • Values:
      • pH: 7.32 (low, acidosis)
      • CO2: 34 (low)
      • Bicarb: 20 (low)
    • Compensation: Partially compensated metabolic acidosis

  5. Example 5

    • Values:
      • pH: 7.49 (high, alkalosis)
      • CO2: 29 (low, respiratory alkalosis)
      • Bicarb: 20 (low)
    • Compensation: Partially compensated respiratory alkalosis

Conclusion

  • Practice examples online to solidify understanding
  • Next lesson: Tic-Tac-Toe method for ABG interpretation
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