Oxygen-haemoglobin dissociation curve - factors shifting left/right
Core concept
- Sigmoid because binding is cooperative - each O2 bound raises the affinity of the remaining haems (T -> R state)
- Flat above PaO2 ~60 -> SaO2 well preserved despite a falling PaO2
- Steep below PaO2 ~60 -> large unloading for a small PO2 fall, and rapid desaturation clinically
- Right shift = dec affinity = more unloading to tissue
- CADET, face Right - CO2, Acid, 2,3-DPG, Exercise, Temperature
- Left shift = inc affinity = avid uptake in lung, poor release to tissue
3 more sections, plus exam facts
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