[remcob]

> carbon dioxide

You probably mean nitrous oxide (N₂O). Both are sold in small aluminum canisters for culinary use. CO₂ is acidic and is quite unpleasant to inhale. N₂O is listed in the article (Table 1) as one of the inhalant anesthetics.

I had the experience of going through both IV general anesthesia (presumably propofonol) and syncope in the last two weeks and for me propofonol was much faster getting in and out of: like falling asleep and I woke pleasantly remembering a dream. Syncope for me was much harsher: tunnel vision as a passed out and I came by initially not remembering where or who I was, like my brain did a cold boot.

[throwanem]

You're right, it was nitrous oxide. I gather also the name originates from a trademark "Whip-its" under which these "charger" canisters are sold.

This was probably all explained to me at the time, but mainly what I remember of it is a large balloon followed by spending an indefinite but subjectively very long time in a clangingly silent gray hell.