• The percentage of time spent within the protocol specified sedation range during the study drug administration period.
  

• Number of subjects able to maintain a specified sedation range without study drug interruption; the amount of time required to regain the specified level of sedation; number of subjects displaying delirium characteristics.
  

Traditional agents such benzodiazepines and propofol have long been used to sedate critically ill patients. Unfortunately, these agents have serious disadvantages that may have a negative impact on patient outcomes. These disadvantages include respiratory depression, prolonged mechanical ventilation, paradoxical agitation, myocardial depression, hypotension, tachyphylaxis, physical dependence, and an unpredictable duration of action following long term infusions. Additionally, concomitant use of an opioid or other analgesic is often required for ICU patients to achieve adequate levels of pain relief, which may also prolong awakening and possibly increase respiratory depression.

Dexmedetomidine may offer a new treatment option that remedies many of the deficiencies of traditional sedatives. This agent would provide for accurate, titratable sedation and analgesia without the concurrent respiratory depression and accumulation common to other agents. It may permit greater patient interaction due to reduced impairment of cognition and may reduce risks associated with opioids due to its analgesia sparing property. Although such a drug may have important benefits for ICU patients requiring sedation for greater than 24 hours, dexmedetomidine is not currently approved for such long-term usage.