Sedation of critically ill patients in the intensive care unit (ICU) often requires potentially invasive or uncomfortable procedures, such as mechanical ventilation. In the UK, the most commonly used sedatives are propofol, benzodiazepines (for example, midazolam and lorazepam) and α2-agonists (dexmedetomidine and clonidine). The main difference between α2-agonists and the other sedatives is that patients can readily be aroused, which is an important aspect of maintaining minimal levels of sedation.

This NIHR HTA-funded systematic review compared the clinical effectiveness of α2-agonists (dexmedetomidine and clonidine) with propofol or benzodiazepines (midazolam and lorazepam) in mechanically ventilated patients in the ICU. Major electronic databases were searched for RCTs comparing dexmedetomidine with clonidine, or dexmedetomidine or clonidine with propofol or benzodiazepines. Methods recommended by the Centre for Reviews and Dissemination and Cochrane Handbook for Systematic Reviews of Interventions were used. The findings from 18 RCTs involving 2489 adult patients showed that length of ICU stay and time to extubation were significantly shorter for patients receiving dexmedetomidine. Dexmedetomidine was associated with a higher risk of bradycardia than propofol or benzodiazepines but not of overall mortality. Evidence on clonidine was very limited. Further research was recommended to assess the use of clonidine in this clinical context and identify subgroups of patients more likely to benefit from dexmedetomidine.

Details of the study can be found here:


Miriam Brazzelli:




Cruickshank M, Henderson L, MacLennan G, Fraser C, Campbell M, Blackwood B, et al. Alpha-2 agonists for sedation of mechanically ventilated adults in intensive care units: a systematic review.  Health Technol Assess 2016;20(25).