Asklemmy

You should talk to your doctor about what you're doing and experiencing. Because it sure sounds like you're either doing a breathing technique wrong and suffocating yourself or you're doing it right and have an underlying condition that's making whatever you're doing dangerous.

TLDR talk to a medical professional not social media about it.

You're thinking of Nitrous Oxide (N~2~O). Nitrous Oxide is used during some surgeries (I took it when they pulled my wisdom teeth) and abused by people trying to get high. Nitric Oxide (NO) is apparently a vasodilator (it relaxes blood vessels allowing more blood to flow). It's produced naturally by the body, and you can buy supplements if you really want your pee to have more Nitric Oxide in it (taking most supplements just makes your body get rid of the extra by filtering it through the kidneys).

I don't know anything about the Buteyko method, but it sounds like a fad/scam medical practice with no proven benefits. But you do you, just don't do the tape thing, that sounds dangerous.

You should watch out because nitric oxide is highly explosive. About the same as nitroglycerin. No but seriously: While it is true that nitric oxide is released in the nasal cavity (always not just during buteyko), the amounts are waay to low to have any noticeable impact. If you are doing breathing exercises any visual effects you notive are probably coming from too much oxygen.

That's usually what happens when I'm missing air... Stop immediately, you may even pass out