The first psychiatric intensive care unit (PICU) opened in the early 1970's in New York. This ward was designed to manage patient that did not respond to treatment in open psychiatric wards. There are about 15 PICUs in Sweden but the concept has not been specified by any public organs. In many county hospitals, both acute and intensive care units exists parallel.

Therefore, the aim of this study was to describe the core characteristics of PICU in Sweden and to describe the care activities provided for patients admitted to PICU.

Critical incident technique was used. In the study, eighteen caregivers at a PICU participated by completing a semi-structured questionnaire. Additional, in-depth interviews with three nurses and two assistant nurses also constitute the data.

Four categories were identified that characterise the core of PICU: the dramatic admission, protests and refusal of treatment, escalating behaviours and temporarily coercive measure. Care activities for PICU were also analysed and identified as controlling - establishing boundaries, protecting - warding off, supporting - giving intensive assistance and structuring the environment.

PICU were interpreted as a level of care as it is composed by limited structures and closeness in care.