It's any short acting bronchodilator, usually a variation of albuterol. If your doc hasn't heard of it, I think you want to find a doc who at least has some experience with asthma (recognizing the rescue inhaler would be a good indication of that) and you really should find a pulmonologist. Sounds like your guy may be fine for the common cold but not for COPD.
I think your doctor is an idiot
I think you need a smarter doctor.
I agree if the doctor does not know what a rescue inhaler is. Then time to look for someone else to treat you. I would start by getting a good pulmonary specialist.
I hope you're not talking about your lung doctor, if he/she does not know what a rescue inhaler is I think I would be looking for another doctor. What it is used for is if you're doing something and exert yourself to where you're having a hard time breathing and then you use your rescue inhaler with albuterol sulfate that helps relax your airway so you can breathe again.