Hang in there. It's get's better with time (years ... not weeks
I did 12 years in a major CVICU (heart and lung transplants, LVADS, BiVads, total artificial hearts) and it just takes time to get the repetition. To see the same problems over and over so that you see them coming, or better yet, prevent them from even beginning to occur. No, you never really get it out of your head and what I found to help was to do something else immediately after work. Go for a walk, go to the store, anything to have that fresh in your mind instead of work. That pushes your work day one step out of your immediate consciousness and helps you relax.
Now I work in a smaller (14 beds compared with 30+) cardiac ICU and it's a day at the beach. Sure, there are super sick patients, but it's not every other one and there hasn't been one yet with a room full of machines and a patient bed sandwiched in between there somewhere.
Have fun and enjoy the ride!