Interpreting Arterial Blood Gases (ABGs)

Introduction

• This lecture covers interpreting ABGs in six easy steps.
• Key focus: Learning lab values and knowing patient care based on these.

Homeostasis and Normal Values

• Homeostasis: A state of balance in the body, where enzymes and cells function optimally.
  • "There’s no place like homeostasis."
• Normal pH: 7.35 - 7.45
• Normal CO2 (Carbon Dioxide): 35 - 45 mmHg
• Normal Bicarbonate (HCO3): 22 - 26 mmol/L
• Important to remember normal values for pH, CO2, and bicarb before proceeding further.

pH and the "Couch of Homeostasis"

• Conceptualize pH with the "couch of homeostasis" where pH between 7.35 and 7.45 is comfortable.
• pH represents acidity or basicity of blood:
  • Less than 7.35: Acidic (Acidosis)
  • Greater than 7.45: Basic (Alkalosis)
• pH affects how well the body functions - balance is key.

Carbon Dioxide (CO2)

• Controlled by the lungs.
• Normal range: 35 - 45 mmHg.
• Changes in breathing affect CO2 levels:
  • Hyperventilation decreases CO2 (more basic).
  • Hypoventilation increases CO2 (more acidic).

Bicarbonate (HCO3)

• Controlled by the kidneys.
• Normal range: 22 - 26 mmol/L.
• More bicarb increases alkalinity (basicity).

Key Concepts

• Lungs adjust CO2 levels quickly.
• Kidneys adjust bicarb levels but take longer.
• Increase in CO2 leads to acidosis; increase in bicarb leads to alkalosis.

Quick Review

• Key Values for ABG Analysis:
  • pH
  • CO2
  • Bicarb
• Control Mechanisms:
  • Kidneys control bicarb.
  • Lungs control CO2.

Study Tips

• Actively pause and review during learning.
• Focus on understanding core concepts before moving forward.

Remember, consistent review and understanding of the body's mechanisms for maintaining balance are critical for interpreting arterial blood gases effectively.