In this article, the functioning of a Canadian psychiatric intensive care unit, (PICU), in a general hospital context is reviewed. Statistically significant changes in average length of stay were observed, and a possible deskilling of the staff in other wards is discussed. The factors influencing the functioning of length-of-stay of this PICU is analyzed. Alternative explanations are hypothesized in an attempt to shed light on the interaction between this unit and its environment (authors).