Alpha2-adrenoceptor agonists: analgesia, sedation, anxiolysis, haemodynamics, respiratory function and weaning

Over-sedation and subsequent prolonged mechanical ventilation are frequently observed in ICUs and may lead to an increase in morbidity and mortality. No single agent currently used in ICUs incorporates all the properties of an ideal sedative. However, dexmedetomidine, a potent and selective α2-adrenoceptor agonist, possesses most of these: it is a sedative that preserves rousability, it induces analgesia, it has predictable haemodynamic effects and it does not cause respiratory depression. Pre-clinical and clinical studies performed on post-operative patients requiring mechanical ventilation for less than 24 hours support that this agent could be safely used as a primary sedative agent in ICUs. Whether dexmedetomidine offers a clinically relevant benefit in terms of outcome over any other agent used for ICU sedation remains to be assessed by large comparative, randomized, double-blind trials.