The thing is, in a CVICU these are HUGE mistakes. A chest tube with suction disconnected will allow fluid to accumulate around the lungs or heart, because it's not being pulled out. Forgetting to mix antibiotics, just giving 50-100 ml of NS (while that vial of powder is hanging conspicuously below the bag?) and letting pathogenic microbes live? Infection in these people can be life threatening! You don't say what type of pt this was, but if you forget the medication for someone who is given an ATB prophylactically, you can forget it for someone who is post heart or lung transplant. Forgetting to attach heparin can mean reocclusion of blood vessels...........
I mean this is basic, basic stuff. We're not talking about being proficient at interpreting all of those hemodynamic numbers.
The one issue I have with your preceptor is, why isn't s/he catching these mistakes right away? With two of you assigned to the pt, the next shift really shouldn't be finding your mistakes.
But I wholeheartedly disagree that they should be reassuring (e.g. "assuring you that the pt is fine.") With mistakes as basic as med administration, it's time to get serious -- lives depend on it.
ALL THAT SAID:
Are you using a good brain sheet? I forgot things during clinicals my last semester; actually my instructor said she was close to failing me! My passing was contingent on solving my problem, and agreeing to a med-surg final practicum. (Because she felt I would gain the most competence there. I had requested either neuro or PACU, if I remember correctly) I ended up being placed on the med-tele floor and doing well.
From that discussion and still to this day, I write important tasks/times in red. Timed head CT, labs at 1800, meds q 1 hr -- written in red, and crossed off as completed. Unique/important things such as "No info," "Bloodless Surgery pt," "Keep SBP 180-220" are written in big block letters at the top, by their name/dx.
Have you met with your preceptor, manager, educator to come up with an improvement plan? That should happen.
Please know that I am not trying to make you feel bad. I have nothing to gain by hurt feelings, and your pts don't have anything to gain either. You might be a fine nurse...but possibly in over your head FOR NOW. CVICU is a Himalayan learning curve! It's incredibly complex, and much of the info is not taught in nursing school
. If it doesn't click soon, you may need to work somewhere less acute for a while to get the basics down pat, THEN come back in a better place to learn the critical care pieces.