Methacholine Challenge experience for asthma diagnosis

Have you had one? If so, did the medical professional conducting the challenge stay with you the whole time?

I had one years ago. The person administering the challenge put me in a glass chamber, explained the amount of methacholine would increase until it induced an asthma attack and that how much methacholine it took would determine whether I have asthma or not, then left the room for 10-15 minutes. Looking back now, it seems wild that one would leave when trying to give a person an asthma account. What if I had asthma and was stuck without help for 10+ minutes?

Curious what others have experienced, whether they were left to deal with a possible asthma attack alone or if they were monitored?