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Carbon Monoxide Poisoning

Hi guys,

I did a quiz and the question asked why doesn't carbon monoxide poisioning increase ventilatory drive?

I'm confused because I thought that it would increase it, seeing as less oxygen would be bound to Hb as CO has a much higher affinity for Hb than oxygen, resulting in an increase in ventilation.

Please help!

Thanks :smile:

Reply 1

username2396569

Original post by tissues1234

So I had a brief look into this and couldn't find much, but I would assume it's because changes in ventilation are driven by CO2 levels rather than O2 levels. Chemoreceptors in blood vessels detect changes in pH and send signals to the medulla in the brainstem, which alters breathing rate and tidal volume. Changes in pH are due to changes in CO2 (as CO2 dissolves in blood plasma to form carbonic acid). The relative amount of O2 bound to Hb has no affect on the pH, and so has no affect on the "ventilatory drive". I hope that's right, and I hope it helped!