Oxygen Delivery

Oxygen Delivery (DO2) = Arterial O2 Content (CaO2) x Cardiac Output (CO)

DO2 = CO x (Hgb x SaO2 x 1.34 + PaO2 x 0.003)

Arterial Oxygen Content (CaO2)

CaO2 = (Hgb x SaO2 x 1.34) + (PaO2 x 0.003)
Hgb: Hemoglobin
Oxygen Carrying Capacity = 1.34
SaO2: Percent Arterial Oxygen Saturation of Hgb
- SpO2: Peripheral Oxygen Saturation is Detected on Pulse Oximeter and Used to Estimate SaO2
PaO2: Partial Pressure of Dissolved Oxygen in Blood (Oxygen Tension)

Level of Importance

Hemoglobin is Generally the Most Clinically Significant Determinant of Arterial Oxygen Content (CaO2)
SaO2 Has the Same Impact as Hemoglobin but Generally Has Less Variance
PaO2 is the Least Important Measure and Only Contributes 1-2%

Cardiac Output (CO)

CO = Heart Rate (HR) x Stroke Volume (SV)
Factors that Increase Stroke Volume:
- Increased Preload (End-Diastolic Volume)
- Increased Contractility
- Decreased Afterload

Compares Partial Pressure of Oxygen (PaO2) to Percent Oxygen Saturation of Hemoglobin (SaO2)

Shifts:
- Left Shift – Increased Affinity Supports O2 Binding
- Right Shift – Decreased Affinity Causes O2 Unloading
Factors that Cause a Leftward Shift:
- Decreased CO2
- Decreased Temperature
- Decreased H+ (Increased pH)
- Decreased 2,3-Diphosphoglycerate (DPG)
- Carbon Monoxide Exposure – Increases Affinity at Other Binding Sites
Factors that Cause a Rightward Shift:
- Increased CO2
- Increased Temperature
- Increased H+ (Decreased pH)
- Increased 2,3-DPG (2,3-Diphosphoglycerate)
  - Hypoxia Further Decreases Oxygen Affinity Due to 2,3-DPG Having Increased Affinity for Deoxygenated Hemoglobin
  - Fetal Hemoglobin Has a Low Affinity for 2,3-DPG Resulting in Overall Higher Affinity for Oxygen

Quartz 5