I don't mean to sound insensitive or disrespectful, but we are NURSES, not MDs. Our job is to advocate for our patients, give them the best care possible, and to notify the MDs if we see a change in condition or throw up a red flag for an alarming trend. If you are more experienced ,then you can add guiding the MD's decision with your input and insight to the list as well.
If you don't like what the resident says then page the fellow, if you don't like what the fellow says then page the attending, if you don't like what the attending says, page another attending. If you still do not like the answers you are getting then you are out of luck and all that you can do is chart that you notified everybody. If the patient ends up passing because of the actions of the MDs or the lack thereof, you did everything that you were supposed to and you shouldn't feel bad or guilty.
My philosophy is that I will follow any order, no matter how weird or even if it is a 4th quarter 3 seconds left on the clock long shot hail mary, as long as it IS NOT criminally negligent. It sucks to have so many losses in such short succession but you also have to remember that you have a lot of wins as well. But like you said, many of those things happened outside of your control and you are unfortunately left to clean and salvage the mess. This happens to all of us at one point or another when the losses start to bother you.
Through some pretty emotionally taxing work related events early on in my career, I made the decision to forge myself into the best nurse that I can be. I did this because I want to be the best, I want to give my patients the best possible care, and if there is a weak link in a team that is caring for a patient, it is NOT going to come from the nursing aspect of it. Through hard work and determination I have made sure that is the case for every single patient that I am tasked to manage. As long as you did everything in your power to advocate for the patient, you made all of the right moves, there were no better interventions, then you can still leave your shift with your head held high.
This is something that we all go through as Critical Care Nurses and you will get through it in one way or another. Whether you stay on The Units and make yourself into a Beast Mode member of it, continue to be an All-Star, or if you decide to do something else, you will make it out alive on the other side. But only you can decide what is right for you. Good luck and stay strong!