I worked in Health Care for 40 years and never heard it
called that. Always the Neo-Natal Unit or the Neo-Natal ICU. Besides working in Emergency Departments and as an EMT, I have worked Neuro-Surgery, Orthopedics, General Medicine and Surgery, Thoracic Surgery, and all of the ICU's (Neuro surgical, Thoracic, Cardiac, Respiratory) though I grant you it was in an adult hospital, the Children's Hospital was across the road. Both my wife and I were friends with a woman who worked Neo-Natal ICU. The only place I didn't work was Maternity. My last years were spent working on ventilators and respiratory equipment for the hospital, and the generic ICU at St. Joseph's Health Centre here in Toronto. Oh, and the Renal Dialysis unit, I worked there too.
Because I was articulate I got along with doctors, to the point that I was asked routinely to set up traction for Orthopedic Patients, and was moved to the Respiratory ICU where I took care of patients for 12 years before moving to the Tech job handling the equipment.
However it is clear that PICU is a term which is in use, I just never ran across it before. So thanks.