UVI stands for "unidad de vigilancia intensiva" which means intensive observation unit, UCI stands for "unidad de cuidados intensivos" which means intensive care unit. Patients in the UCI are those who need continuous care to stay alive (like being intubated for example). Patients in the UVI are those who do not need that continuous care but are at risk of needing immediate medical assistance.
Used in US as well
"He just got out of the UCI but they are keeping him in the UVI for now, just in case"
UVI is an acronym in Spanish of intensive care unit, while ICU intensive care unit of hospitals where special assistance is provided to the most serious or most sensitive health patients means. In some hospitals of Spain there are also the UCC that is critical care unit and the UMI unit of intensive medicine, where serving patients is critically ill or require some specialized care.