Step I goljan?

[majik1213]

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can someone please help me understand two things?

1. goljan said that CO poisoning decreases O2 saturation; however, I was taught that the pulse oximeter cannot discern between Hb saturated with O2 and Hb saturated with CO .. instead, it can say only whether Hb is saturated .. so should I assume that the decrease in O2 saturation is theoretically possible but not clinically measurable?

2. goljan said that in respiratory acidosis the oxygen saturation decreases because P_O2 decreases; however, I'm under the impression that the Bohr effect is responsible for diminished oxygen saturation.

3. just for poops and giggles, but, what would life be like if RBCs underwent aerobic cellular respiration?

 

[McGillGrad]

1. everything you said is right. There is no discrepancy.

2. don't understand your question.

3. you would be dead

 

[turkeyjerky]

can someone please help me understand two things?

1. goljan said that CO poisoning decreases O2 saturation; however, I was taught that the pulse oximeter cannot discern between Hb saturated with O2 and Hb saturated with CO .. instead, it can say only whether Hb is saturated .. so should I assume that the decrease in O2 saturation is theoretically possible but not clinically measurable?

2. goljan said that in respiratory acidosis the oxygen saturation decreases because P_O2 decreases; however, I'm under the impression that the Bohr effect is responsible for diminished oxygen saturation.

3. just for poops and giggles, but, what would life be like if RBCs underwent aerobic cellular respiration?

1) CO binds to the same sites on Hb as O2 does, thus if 50% of the binding sites are occupied by Hb, the max O2 saturation is 50, rather than 100%. CO also shift the Hb-O2 dissociation curve to the left, which reduces oxygen unloading in tissue--leading to hypoxic injury. The Hb looks like it's chuck full of oxygen, so the pulse oximeter reads the blood as being completely saturated.

2) The interruption in respiration causes a decrease in oxygen tension, leading to decreased oxygen saturation. I guess the bohr effect could play a role, but I'm betting that's a bigger factor in metabolic acidosis.

3) You'd poop and giggle yourself a lot.

 

[McGillGrad]

The definitive method to determine CO poisoning is via co-oximeter that measures the percent of hemoglobin that is bound to carbon monoxide instead of oxygen!

That is step II material.