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oxygenation1
Question | Answer |
---|---|
Oxygen Delivery equals | Blood O2 content x Amount of blood going to the tissue |
DO2 equation | CaO2 x CO |
Normal DO2 | 600 - 1000 ml/min |
CaO2 (Blood O2 content) | (Hg x 1.34 x SaO2)+(PaO2 x 0.003) |
Factors affecting DO2 in order of importance | CO, Hb, Hb Sat, PaO2 |
Oxygen Index (OI) normal | DO2/BSA = 500-600 |
Two methods of VO2 Oxygen consumption assessment | 1) Indirect calorimetry 2) Fick Equation |
Fick Equation | V02 = (Ca02-CvO2) x CO |
Normal VO2 Oxygen consumption | 250 ml/min |
Normal V02/BSA | 3-4 ml/min/kg |
Fick Equation Limitation | requires PA catheter and artline affected by measurement error: thermodilution CO, hb measurement, Sat measurement |
O2ER is | Oxygen balance comparing O2 transport vs O2 consumption |
O2ER | V02/D02 |
O2ER | (Ca02-Cv02)/Ca02 |
O2ER 40% range | suggest disturbances in cellular oxygenation |
SvO2 / mixed venous saturation | estimate of adequancy of balance between O2 transport and O2 consumption |
PAO2 Alveolar equation | [(PB-PH20)x FiO2)] - (PaCO2/0.8) |
P(A-a)gradient | PAO2 - PaO2 |
Alveolar Ventilation (VA) | (Vt-VD) x RR OR VE - VD (deadspace vent.) |
VD.; deadspace ventilation | VD x RR |
Deadspace volume | Vt x (PaCO2 - PeCO2)/PaCO2 |