YES inflate the bag. Why-because that is the way it works and if it is not filled it does not work. Cover the hole in the mask and connect with high flow O2 on until the bag fills. No question is stupid-always ask. The bag allows the patient to breath pure O2. In between breaths the bag fills with pure O2 vs a mixture of O2 and room air on only high flow O2.
That bag is a reservoir that fills between breaths. The valves on the side of the mask help prevent room air from entering the mask, thus keeping the concentration of oxygen inside the mask as high as possible. The liter flow needs to be around 15 LPM to ensure that the reservoir bag stays inflated, but it's not enough to inflate the bag right away, so fill it before you put it on the patient. At that flow rate, you can get oxygen concentrations greater than 95% inside that mask. You won't get 100%, but 95% is darned close, and without a good mask seal or a closed system, it's nearly impossible to get a 100% concentration anyway.
It's good that you asked the question. Someone else probably had the same question and hasn't asked it yet. Because you asked, you and the other person both have the answer!
In my very humble opinion, the only dumb question is the one that isn't asked.
Glad to see another EMTLIFE'r on here Akulahawk. Others have already answered your question but I just want to echo what they said, definitely not a stupid question. I have seen numerous people in the hospital slap a Non-inflated NRB on their patient and then sit there and wonder why the Sats are still low. Much better to ask on here then to do it the wrong way in real life.
I just want to second that this is most definitely NOT a stupid question. There are many nurses who have no idea when and how to use the different types of tubing, masks etc. I have no idea why this is not standard education for all nurses on orientation or in nursing school. I know I didn't know how to use one properly until I was taught by a RT. Good for you and your future patients for being pro-active!
I'll echo the above statements....not a stupid question. I actually worked almost exclusively with vent kids. I never needed to use the non-rebreather mask (even though I was a "pulmonary" nurse) until I started working in a GI lab. How embarrassed I was to not have used it properly coming out of an ICU! But your right, prepping the bag was a small detail that was never really taught to me either. I thought it just did what it had to do on it's own after you hook it up to the O2 source.