Dexmedetomidine

Aka: Dexmedetomidine, Precedex, Dexdor, Dexdomitor

1. Indications
   1. Post-Intubation Sedation and Analgesia
      1. Short-term sedation (<24 hours) in ICU patients on Mechanical Ventilation
      2. Tachyphylaxis occurs with use >24 hours
   2. Noninvasive Positive Pressure Ventilation or NIPPV (e.g. BIPAP)
      1. Dexmedetomidine may help patients tolerate the NIPPV mask
   3. Other patients requiring sedation
      1. Alcohol Withdrawal
      2. Peri-procedure sedation
      3. Neurocritical care patients
      4. Tachycardic patients on Vasopressors
2. Contraindications
   1. Severe Bradycardia
3. Mechanism
   1. Selective central alpha-2-adrenergic agonist (similar to Clonidine) with sedative properties
      1. Lacks the peripheral effects on vascular resistance of Clonidine
      2. However, sedation effect is maintained
   2. Brainstem G-Protein activation inhibits Norepinephrine release
      1. Decreases sympathetic tone and peripheral vascular resistance
4. Advantages
   1. Keeps a patient sleepy but awakenable and will respond to questions
   2. Patients maintain their wairway and respiratory drive
   3. Generic (previously very expensive as a trade name drug)
   4. Opioid sparing (offers sedation and Analgesic properties)
5. Pharmacokinetics
   1. Onset: 10 minutes
   2. Duration: 1-2 hours
   3. Renal and hepatic metabolism
6. Dosing: General
   1. Load: 1 mcg/kg in adults (0.5 to 1 mcg/kg in children) over 10 minutes, then
      1. Precaution: Bolus may result in Hypotension
   2. Infusion: 0.2 to 0.7 mcg/kg/hour in adults (0.2 to 0.5 mcg in children)
      1. Titrate to desired level of sedation, modifying dose every 30 min to 0.2 to 1.5 mcg/kg/hour
      2. Decrease dosing in hepatic dysfunction and the elderly
   3. Reduce dose in over age 65 years or renal/hepatic Impairment
7. Dosing: Post-Intubation Sedation
   1. Another sedative (e.g. Propofol or Ketamine) should be used initially to maintain initial sedation
   2. Start Dexmedetomidine at 0.5 mcg/kg/h infusion
   3. Increase Dexmedetomidine by 0.1 mcg/kg/h as needed up to 1.5 mcg/kg/h
8. Dosing: Intranasal for Procedural Sedation
   1. Dose: 2-3 mcg/kg
   2. Onset in 13-25 minutes and duration for 85 minutes (longer in adults)
   3. Intranasal use rarely causes Bradycardia or Syncope
   4. Oriby (2019) Anesth Pain Med 9(1): e85227 +PMID:30881910 [PubMed]
9. Adverse Effects
   1. Severe Bradycardia
      1. If Heart Rate drops below minimum threshold, stop infusion for 30 min, and restart at 1/2 prior rate
   2. Hypotension
      1. Transient Hypertension may occur with rapid infusion or bolus
   3. Dry Mouth
   4. Potent Diuretic
10. References
    1. Swaminathan and Weingart in Herbert (2019) EM:Rap 19(6): 14
    2. Fisher and Fisher (2018) Crit Dec Emerg Med 32(1): 24
    3. Kay (2015) Crit Dec Emerg Med 29(8): 11-17