The definition of practicum will depend on the hospital. From what I was told by Hopkins, you must have done a related senior practicum in the desired type of unit. For instance, I did a clinical rotation in the ICU, but it DOESN'T count toward the hours required by the unit, it must be from my senior practicum / preceptorship.
Some hospitals do count your clinical hours as time in a related unit, it just depends on what they are looking for. Best bet is to give the recruiters a call, the ones at Hopkins are extremely helpful.