The therapy device stores the time profiles of the blood pressure and of other influencing variables during preceding therapy procedures. The time profile of the blood pressure and of other influencing variables during the actual therapy is also recorded. An analytical comparison is then made between the time profiles of the blood pressure and of other influencing variables during the actual measurement procedure and those during preceding therapy procedures. Depending on the comparison, a prospective blood pressure control is carried out in order to prevent drops in blood pressure in a subsequent time period.