Pharmacology

Dexmedetomidine

Dexmedetomidine (Precedex) is a selective intravenous alpha-2 agonist approved for sedation in non-intubated patients in the perioperative setting as well as short term sedation for patients on mechanical ventilation in the ICU. By binding alpha 2 receptors, a negative feedback loop is potentiated decreasing the further release of neurotransmitters from the pre-synaptic neuron. This decreases the sympathetic outflow which can lead to bradycardia (rarely asystole) and hypotension. Despite the 1600 to 1 ratio for alpha 2 : alpha 1 receptor selectivity, sometimes hypertension can be noted (especially with boluses) through alpha 1 and alpha 2B subtype receptor activation.

As an intensivist, I often use dexmedetomidine to transition patients off of mechanical ventilation. I’ll continue a low-dose infusion during extubation to smooth out emergence because it doesn’t significantly depress the respiratory drive and provides some degree of analgesia and anxiolysis, The literature in critically ill patients is somewhat controversial regarding the anti-deliriogenic effects of dexmedetomidine, but I’ll definitely consider nocturnal infusions to simulate patterns found in non-REM sleep.

As an anesthesiologist, I use dexmedetomidine often for a variety of purposes – as an anesthetic adjunct, as an anxiolytic, and to transport patients who are still intubated to the ICU. In both the OR and ICU, I’ll use this medication to provide procedural sedation whether I’m performing an awake fiberoptic intubation, chest tube placement, line placement, etc. It’s also the cornerstone of many of my MAC sedation cases.

Drop me a comment below with questions! 🙂

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