Sounds like you did fine for your first code! It can often be helpful when you're learning to have a debriefing session with the staff involved afterwards, where you can all discuss who did what, and how to improve next time. I know my hospital did this while we were new in ICU.
Please don't take this as critical, as it is not intended that way, but to give you a couple of ideas for next time which helped me
- Our units required someone to check the crash cart every day and sign it off as stocked. Can you see if you can do this, or even informally as suggested above. Going through every single thing in the cart and checking it off gives you a good understanding of how the equipment is laid out and can make it that little bit easier next time.
- If I encountered the situation above, I may have stayed with the patient while the CNA went to get the nursing manager (if you don't have a code alarm at the bedside like we do). It's so understandable and natural to freak out and forget everything, but as the first nurse on the scene, you can get a lot done before the code team arrives; assess level of consciousness, check airway, apply high flow oxygen, get vitals and attach a monitor if they don't have one, get the patient positioned right in case they need CPR, move stuff from around the bedside and start writing down the time of events (you'll definitely forget later!).
I don't know your doc, but they feel just as bad as we do when a patient codes, so he may have just been trying to identify any signs he missed which could have prevented the code. Try not to take it too personally - the medical profession has a culture of examining treatment events and critiquing their role, so they can improve next time (morbidity and mortality meetings etc). I'm sure this guy needed to answer to his boss as to why he didn't see this coming, and was trying to gather information.
It's awful, but at least it's over! Well done, and keep your chin up