Lecture on Tissue Oxygenation

Introduction

• Speaker: Tonya Peel
• Topic: Tissue Oxygenation
• Resources: Free instructional videos on YouTube and website

Blood Flow Through the Heart

• Systemic Circulation
  • Deoxygenated blood returns via inferior and superior vena cava
  • Enters right atrium
  • Passes through tricuspid valve
  • Enter right ventricle
  • Right ventricle pumps blood to lungs
• Pulmonary Circulation
  • CO2 dropped off, O2 picked up in lungs
  • Oxygenated blood returns to left atrium via pulmonary vein
  • Passes through mitral valve to left ventricle
  • Left ventricle pumps through aortic valve into systemic circulation

Tissue Oxygenation

• Starting Point: Alveoli
  • Diaphragm drops, air enters alveoli until pressure equilibrium
  • Alveolar Oxygen Tension: Pressure called PAO2
  • Oxygen driven into pulmonary capillary bed
  • Carried two ways: bound to hemoglobin and dissolved in plasma

Oxygen Content

• Combination of O2 bound to hemoglobin and dissolved in plasma
• Starts at the alveolar-capillary (AC) membrane
• Oxygenated blood sent to left side of heart
• CaO2: Oxygen content in arterial blood

Oxygen Delivery to Tissues

• Blood travels to body tissues
• Tissues extract necessary oxygen
• Deoxygenated blood returns to right heart side

Mixed Venous Oxygen

• Not fully devoid of oxygen: "Mixed Venous Oxygen" (CVO2)
• Measured in pulmonary artery with special catheter and blood gas machine

Formulas and Measurements

• Similarity to O2 content formula
  • Hemoglobin-bound (SVO2)
  • PV O2 times 0.003
• Simplified calculation
  • Example: O2 content starts at 20 volume percent, returns at 15
  • Tissue extraction: 20 - 15 = 5 volume percent

Conclusion

• Understanding tissue oxygenation through simple arithmetic and formulas
• Encourage use of components to assess tissue oxygenation