As a manager, I have had to go through similar situations with nurses and it is so hard to watch them beat themselves up when this clearly a process problem and not all the blame belongs to you. Because of short staffing and sick calls etc, new nurses are allowing themselves to work in float pools when clearly, they are not ready. The lure of money and flexible hours is too great. ICU step down is the worst floor in the hospital (PCU here) because of the patient turn over rates, higher acuity and higher nurse to patient ratios. Float pool should not include units like this but have to because no one wants to work here for long. The fact that you feel a deep sense of responsibility and you are asking for help tells me that you are a good nurse who is growing into greatness. I'd love to have you on my team. Keep your head up, learn from this and use it to do something positive, like mentor other new nurses or get smart pumps at your facility. Good luck to you!