Naturally, to ensure all of his patients get the best treatment he can offer, Rubberheart takes it upon himself to give each new piece of equipment he receives a thorough testing after-hours, before they’re put to use. Seems that whoever sold him that most recent batch of nitrious oxide canisters neglected to add any sort of pressure regulators to them, and poor Rubberheart only figured this out after strapping that gas mask on nice and tight to ensure a firm seal…
 
Hopefully somepony comes along to help him out, or take him for themselves - there’s a lot of fun to be had with a thoroughly knocked-out rubber-clad balloon of a pony, after all~