thank you for your query.
first of all thanks a lot for the detailed summary.it is very helpful.yes gas leak is a very good possibility for your symptoms because you mentioned that your oxygen
level was very low when you reached ER.as the gas can mix with blood,form compounds and reduce the ability of hemoglobin
to absorb oxygen..
but to be on a safer side i would also advise you to get your blood pressure checked up to know there arent any residual effects.
wishing you good health