The purpose of this study was to evaluate effects, safety and cost of midazolam used alone or sequential use of midazolam and propofol/dexmedetomidine for long-term sedation in critically ill, mechanically ventilated patients.

It is well known that sedation is frequently required as a component of compassionate care in critically ill patients. Until now, there is no ideal sedation drug and every sedation drug has its advantage and disadvantage for long-term sedation in critically ill, mechanically ventilated patients. The sequential use of midazolam and propofol for long-term sedation was associated with a faster recovery, earlier extubation, shorter mechanical ventilation time and less cost of total ICU treatment compared with midazolam alone, The protocol was associated with less cost of pharmaceutical sedation compared with propofol alone. But, propofol and midazolam may cause respiratory depression and delirium. Both drugs should be stopped after the patient passed the screen of weaning from mechanical ventilation, then it would induce the stress response and agitation, it would cause prolonged sedation and delay extubation.

Dexmedetomidine is a centrally acting a2-receptor agonist, has less effect on arousability and respiratory depression. The purpose of this study was to evaluate effects, safety and cost of midazolam used alone or sequential use of midazolam and propofol/dexmedetomidine for long-term sedation in critically ill, mechanically ventilated patients.

Inclusion Criteria:

1. Intubated patients;
2. Age≥18 years old;
3. Anticipated Ventilation and sedation duration of at least 72 hours.

Exclusion Criteria:

1. Allergy to the study drug;
2. suspected pregnancy;
3. gross obesity;
4. Extremely unstable of circulatory system, such as systolic blood pressure less than 90 mm Hg despite plasma volume expansion and continuous infusions of vasopressors before the start of study drug infusion;
5. Uncontrolled abnormal hypertension, such as systolic blood pressure more than 180 mmHg or diastolic more than105 mmHg;
6. Heart rate less than 50 bpm;
7. Second or third degree heart block;
8. moribund state;
9. history of alcoholism or intake of anti-anxiety drugs or hypnotics;
10. chronic renal failure;
11. coma by cranial trauma or neurosurgery or unknown etiology or epileptic state;
12. History of neuromuscular disease;
13. unwillingness to provide informed consent by patients or their authorized surrogates following ICU admission.