Guidelines in analgesia: tolerance and dependence.

The desidered level of analgo-sedation for the critically ill patients has undergone an important change. In the past the goal was meanly sedation in order to completely detach the patient from his environment. Nowadays, the goal is to keep the patient confortable by bilance analgesia and sedation. Continous infusions are preferred on drug administration by intermittent bolus injection. Continous infusions allow for greater controller administration, minimize high blood concentration and avoids subtherapeutic level. However, it is very easy to start an infusion, but much more difficult to stop. Drugs can accumulate because of overdosing or elimination impairment. Consequences of the prolonged administration of sedative and analgesic agents to the intensive care unit (ICU) include tolerance, physical dependance and withdrawal due to abrupt discontinuation of drug therapy