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Cardiac Output (Fick) in L/min = (135 ml O2/min/M2*BSA)/(13*Hgb*(SaO2-SvO2))
Cardiac Output (Fick) in L/min = (135 ml O2/min/M2*BSA)/(13*Hgb*(SaO2-SvO2))
- A commonly-used value for O2 consumption at rest is 125 or 135 ml O2 per minute per square meter of body surface area.
- The calculation of the arterial and venous oxygen concentration of the blood is a straightforward process. Almost all oxygen in the blood is bound to hemoglobin molecules in the red blood cells. Measuring the content of hemoglobin in the blood and the percentage of saturation of hemoglobin (the oxygen saturation of the blood) is a simple process and is readily available to physicians. Using the fact that each gram of hemoglobin can carry 1.36 ml of O2, the oxygen content of the blood (either arterial or venous) can be estimated by the following formula:
![\text{Oxygen Content of blood} = \left [\text{Hb} \right] \left ( \text{g/dl} \right ) \ \times\ 1.36 \left ( \text{ml}\ O_2 /\text{g of Hb} \right ) \times\ O_2^{\text{saturation fraction}} +\ 0.0032\ \times\ P_{O_2} (\text{torr})](https://lh3.googleusercontent.com/blogger_img_proxy/AEn0k_v2-Dl4Nff4tomWNXb6B9H4lFvLKLWnac86pYip3U1wnamYQcH2QAqQnuhtrWrYChU9YFyFMm5fSkhh-oViG6pG6QBvXVW9_xScCwil44NVbaNM7W2U6gfgNBkmxgI3Bt7VffMTx_77gpsGIsi7LwS4oGUScMSynj3Tmg=s0-d){kind=small}
Assuming a hemoglobin concentration of 15g/dl and an oxygen saturation of 99%, the oxygen concentration of arterial blood is approximately 200ml of O2 per litre.
The saturation of mixed venous blood is approximately 75% in health. Using this value in the above equation, the oxygen concentration of mixed venous blood is approximately 150ml of O2 per litre.
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