4 ms·

Losing O2 has an effect on cognition.

lambdaphagy 5y ago
It's 0.002%/yr. Mostly just impressed that we can measure this at all.
neolefty 5y ago
Gaining CO2 has more of an effect: https://www.news-medical.net/news/20200421/Atmospheric-CO2-levels-can-cause-cognitive-impairment.aspx https://www.news-medical.net/news/20200421/Atmospheric-CO2-l...
noduerme 5y ago
TIL that pulse oxymeters can read over 95% in the presence of carbon monoxide poisoning. https://pubmed.ncbi.nlm.nih.gov/8037391/ https://pubmed.ncbi.nlm.nih.gov/8037391/
- slavik81 5y ago
  However, the point of that study is that the oxygen levels are not 95%. The pulse oxymeter is wrong, and that study is about determining how wrong it is. The abstract basically says you can subtract the blood carbon monoxide level from the pulse oxymeter's reported blood oxygen level to find the actual blood oxygen level. (They were a bit more precise than that, but it was very nearly one-to-one.) A pulse oxymeter measures oxygen levels indirectly. It works by checking the colour of your blood. I suppose that the colour of carbon-monoxide poisoned blood must be similar to that of oxygenated blood. Perhaps because carbon monoxide attaches to blood cells in a similar way to pure oxygen.
  - noduerme 5y ago
    Right - I get it. It can read over 95% in the absence of oxygen if carboxyhemoglobin tricks it out. I thought this might explain why during the pandemic, I could get a pulse ox reading of 85%, then smoke a cigarette and make the little bastard stop beeping.
  - beowulfey 5y ago
    Yes this is correct. Heme binds to CO in the same way it binds to O2–the iron is oxidized and has the same color. This is also the source of carbon monoxide toxicity, as it binds to CO tighter than O2.
    - noduerme 5y ago
      Yup. Same reason cyanide is deadly. Ain't chemistry grand? Good for a smoker to know since we're carrying quite a bit more than your average jogger... https://en.wikipedia.org/wiki/Carboxyhemoglobin#Affinity_of_hemoglobin_for_carbon_monoxide https://en.wikipedia.org/wiki/Carboxyhemoglobin#Affinity_of_...
kadoban 5y ago
This amount? I really doubt it.
kolinko 5y ago
But in practical circumstances (indoor air) you will suffocate through co2 poisoning long before you would notice less o2.

It's 0.002%/yr. Mostly just impressed that we can measure this at all.

Gaining CO2 has more of an effect: https://www.news-medical.net/news/20200421/Atmospheric-CO2-levels-can-cause-cognitive-impairment.aspx https://www.news-medical.net/news/20200421/Atmospheric-CO2-l...

noduerme 5y ago

TIL that pulse oxymeters can read over 95% in the presence of carbon monoxide poisoning. https://pubmed.ncbi.nlm.nih.gov/8037391/ https://pubmed.ncbi.nlm.nih.gov/8037391/

slavik81 5y ago
However, the point of that study is that the oxygen levels are not 95%. The pulse oxymeter is wrong, and that study is about determining how wrong it is. The abstract basically says you can subtract the blood carbon monoxide level from the pulse oxymeter's reported blood oxygen level to find the actual blood oxygen level. (They were a bit more precise than that, but it was very nearly one-to-one.) A pulse oxymeter measures oxygen levels indirectly. It works by checking the colour of your blood. I suppose that the colour of carbon-monoxide poisoned blood must be similar to that of oxygenated blood. Perhaps because carbon monoxide attaches to blood cells in a similar way to pure oxygen.
- noduerme 5y ago
  Right - I get it. It can read over 95% in the absence of oxygen if carboxyhemoglobin tricks it out. I thought this might explain why during the pandemic, I could get a pulse ox reading of 85%, then smoke a cigarette and make the little bastard stop beeping.
- beowulfey 5y ago
  Yes this is correct. Heme binds to CO in the same way it binds to O2–the iron is oxidized and has the same color. This is also the source of carbon monoxide toxicity, as it binds to CO tighter than O2.
  - noduerme 5y ago
    Yup. Same reason cyanide is deadly. Ain't chemistry grand? Good for a smoker to know since we're carrying quite a bit more than your average jogger... https://en.wikipedia.org/wiki/Carboxyhemoglobin#Affinity_of_hemoglobin_for_carbon_monoxide https://en.wikipedia.org/wiki/Carboxyhemoglobin#Affinity_of_...

kadoban 5y ago

This amount? I really doubt it.

kolinko 5y ago

But in practical circumstances (indoor air) you will suffocate through co2 poisoning long before you would notice less o2.