What is the recommended dose for dexmedetomidine (alpha-2 adrenergic agonist) infusion?

Dexmedetomidine Infusion Dosing

For ICU sedation in hemodynamically stable adults, start with a loading dose of 1 μg/kg over 10 minutes, followed by a maintenance infusion of 0.2-0.7 μg/kg/hour, which can be titrated up to 1.5 μg/kg/hour as tolerated. 1

Loading Dose Protocol

• Administer 1 μg/kg IV over 10 minutes in hemodynamically stable patients 1, 2
• Skip the loading dose entirely in hemodynamically unstable patients due to risk of biphasic cardiovascular response (transient hypertension followed by hypotension within 5-10 minutes) 1, 2
• Never administer faster than 5 minutes, even in urgent situations 1
• For elderly patients or those with severe cardiac disease, consider omitting the loading dose or extending administration to 15-20 minutes 1

Maintenance Infusion Dosing

• Start at 0.2-0.7 μg/kg/hour 1, 2, 3
• Titrate up to maximum 1.5 μg/kg/hour based on validated sedation scales to achieve target sedation level 1, 2
• Most patients achieve adequate sedation with 0.4-0.5 μg/kg/hour 4
• When starting without a loading dose, begin at 0.4 μg/kg/hour and adjust within the 0.2-0.7 μg/kg/hour range 5

Preparation and Administration

• Dilute to a final concentration of 4 mcg/mL in 0.9% normal saline for ease of dosing 1
• For a 100 mcg ampoule: add to 25 mL normal saline 1
• For a 200 mcg ampoule: add to 50 mL normal saline 1
• Example for 70 kg patient: Loading dose = 70 mcg (17.5 mL) over 10 minutes; maintenance at 0.5 μg/kg/hour = 35 mcg/hour (8.75 mL/hour) 1

Special Population Adjustments

• Severe hepatic dysfunction: Start at the lower end (0.2 μg/kg/hour) due to impaired clearance and prolonged elimination half-life 1, 2
• Older patients (≥65 years): ED90 for smooth emergence is 0.34 μg/kg/hour when started 30 minutes before surgery completion 6
• Pediatric patients: Loading dose 0.5-1 μg/kg IV; maintenance 0.2-0.7 μg/kg/hour 1

Context-Specific Dosing

Perioperative/VATS Surgery

• Single bolus of 1 μg/kg IV 20 minutes before end of surgery reduces postoperative pain and opioid requirements 7
• Alternative: Loading dose before induction followed by 0.5 μg/kg/hour infusion until 20 minutes before surgery end 7
• Postoperative low-dose infusion of 0.15 μg/kg/day reduces pain scores and opioid consumption 7

Neurosurgical ICU

• Standard ICU dosing applies (loading 1 μg/kg over 10 minutes, maintenance 0.2-0.7 μg/kg/hour) 8
• Particularly valuable for light sedation allowing frequent neurological assessments 8
• Provides significant opioid-sparing effects in traumatic brain injury patients 8

Palliative Care/Agitated Delirium

• Subcutaneous administration: 0.2-0.7 μg/kg/hour titrated to achieve Richmond Agitation-Sedation Scale (RASS) of -1 to +1 4
• Most patients require maximum dose of 0.4-0.5 μg/kg/hour 4

Critical Monitoring Requirements

• Continuous hemodynamic monitoring is mandatory throughout administration 1, 2
• Check blood pressure and heart rate every 2-3 minutes during loading dose 1
• Hypotension occurs in 10-20% of patients 1, 2, 3
• Bradycardia occurs in approximately 10% of patients, with rare reports of cardiac arrest 2
• Have atropine immediately available for bradycardia 1
• Monitor for respiratory compromise in non-intubated patients, as dexmedetomidine can cause loss of oropharyngeal muscle tone leading to airway obstruction 8

Pharmacokinetic Considerations

• Elimination half-life: 1.8-3.1 hours in normal liver function 1, 3.7 hours in critically ill patients 9
• Onset of sedation: within 15 minutes, peak effects at 30 minutes to 1 hour 8, 5
• Clearance: 39.7-53.1 L/hour in critically ill patients 9
• Linear pharmacokinetics demonstrated up to 2.5 μg/kg/hour 9
• After abrupt cessation, blood pressure and heart rate rise by only 7% and 11% respectively within 24 hours, indicating minimal rebound effect 5

Common Pitfalls to Avoid

• Do not use loading doses in any patient with hemodynamic instability, severe bradycardia, or advanced heart block 1, 2
• Do not administer loading dose faster than 5 minutes under any circumstances 1
• Do not assume respiratory depression is absent—while minimal compared to other sedatives, airway obstruction can occur in non-intubated patients 8
• Do not use standard doses in severe hepatic dysfunction without downward adjustment 1, 2