The study will evaluate the pharmaco-economic consequences of the use of a remifentanil based regimen compared with a conventional sedative based regimen in terms of duration of mechanical ventilation, length of stay in ICU, difference in extubation time and use of concomitant sedative agents.

Inclusion Criteria:

• ICU patients with an expected duration of mechanical ventilation for 2 to 3 days and requiring analgesia and sedation.

Exclusion criteria:

• ICU patients resuscitated in the previous 24 hours, neurotrauma or expecting major surgery, not likely to survive of with limit care status.