Answer:
The calculation of cardiac output (CO) using the Fick principle involves several parameters, including oxygen consumption, hemoglobin (Hb) concentration, and the difference in oxygen content between arterial (AO) and mixed venous (MV) blood. The formula for calculating CO using the Fick principle is:
CO = (O2 consumption) / [(Hb in g/dL) × (1.34) × (AO - MV)]
1. Oxygen content in AO:
AO content = (Hb × 1.34 × AO) + (0.003 × PO2)
Given:
- Hb = 10 g/dL
- 1.34 is the oxygen-carrying capacity of 1g of Hb
- AO = 95% (0.95) of saturation (assumed as SaO2)
Calculate AO content:
AO content = (10 g/dL × 1.34 × 0.95) + (0.003 × PO2)
AO content = 12.749 + 0.003 × PO2
2. Oxygen content in mixed venous blood (MV):
MV content = (Hb × 1.34 × MV) + (0.003 × PvO2)
Given:
- Hb = 10 g/dL
- 1.34 is the oxygen-carrying capacity of 1g of Hb
- MV = 95% (0.95) of saturation (assumed as SvO2)
- RA = 71% (0.71) of saturation (assumed as PvO2)
Calculate MV content:
MV content = (10 g/dL × 1.34 × 0.95) + (0.003 × 0.71 × PO2)
MV content = 12.749 + 0.002133 × PO2
3. Calculate the oxygen content difference:
ΔO2 content = AO content - MV content
ΔO2 content = (12.749 + 0.003 × PO2) - (12.749 + 0.002133 × PO2)
ΔO2 content = (0.003 - 0.002133) × PO2
ΔO2 content = 0.000867 × PO2
4. Calculate cardiac output (CO):
CO = (O2 consumption) / [(Hb in g/dL) × (1.34) × ΔO2 content]
Given:
- O2 consumption = 150 ml/min
- Hb = 10 g/dL
- ΔO2 content = 0.000867 × PO2
Calculate CO:
CO = (150 ml/min) / [(10 g/dL × 1.34) × (0.000867 × PO2)]
CO = (150 ml/min) / (13.4 × 0.000867 × PO2)
CO ≈ 8.62 / PO2
This calculation gives you the estimated cardiac output (CO) in ml/min based on the provided parameters. However, to obtain a numerical value, you would need to know the partial pressure of oxygen in arterial blood (PO2). Without that specific value, we cannot provide an exact CO estimation.