An alpha-2 adrenoceptor agonist (Alpha-adrenergic agonist). Acts in locus coeruleus and dorsal root ganglion. It has both sedative and analgesic properties and dramatically reduce the risk of respiratory depression and the number of narcotic analgesics required. Reduces shivering.

℞: usual loading dose is 1 mcg/kg IV over 10 minutes (loading dose not needed if patient already sedated with other agents), followed by continuous IV infusion of 0.2–1.0 mcg/kg/hr titrated to desired effect, not to exceed 24 hours (for short sedation or use as a “transition” drug). Side effects: clinically significant bradycardia and sinus arrest have occurred in young, healthy volunteers with increased vagal tone (anticholinergics such as atropine 0.2 mg IV or glycopyrrolate 0.2 mg IV may help). Use with caution in patients with advanced heart block, baseline bradycardia, using other drugs that lower heart rate, and hypovolemia. Supplied: 2 ml vials of 100 mcg/ml to be diluted in 48 ml NS for a final concentration of 4 mcg/ml for IV use.

Dexmedetomidine has 8 times more affinity than clonidine for α-2 receptors is bringing newer concepts in anesthesia and intensive care practice. It was approved by the Food and Drug Administration (FDA) in 1999 for use in humans for short term sedation in the intensive care unit. Initially used for sedation and analgesia in intensive care, its use has been extended to other various clinical situations as well as in regional anesthesia as a useful adjunct.

Metaanalysis shows evidence that Dexmedetomidine DEX as an anesthetic adjuvant during intracranial procedures leads to better perioperative hemodynamic control, less intraoperative opioid consumption, and fewer postoperative antiemetic requests 1).

There is high-quality evidence that Nonsteroidal anti-inflammatory drugs reduces pain up to 24 hours postoperatively. The evidence for reductions in pain with dexmedetomidine, pregabalin or gabapentin, scalp blocks, and scalp infiltration is less certain and of very low to moderate quality. There is low-quality evidence that scalp blocks and dexmedetomidine may reduce additional analgesics requirements. There is low-quality evidence that gabapentin or pregabalin may decrease nausea and vomiting, with the caveat that the total number of events for this comparison was low 2).

There are few side-effects of dexmedetomidine, which should always be kept in mind before choosing the patients for its use. The various side-effects associated with dexmedetomidine include, but are not limited to hypotension, bradycardia, worsening of heart block, dry mouth, and nausea 3) 4).

Twenty-five consecutive patients received surgical implantation of a spinal cord stimulation electrode under conscious sedation using dexmedetomidine and local anesthesia. Vanhauwaert et al. evaluated the effects of the administered drug, patient comfort, and the adequacy of the stimulation pattern.

Twenty-four patients completed the procedure with only dexmedetomidine and local anesthetic. An infusion was started on average 55 minutes (sd 29) prior to incision. The mean dose of lidocaine was 430 mg (sd 95). There were no significant hemodynamic changes. The median time to reach Modified Aldrete's score postoperative was 67 minutes (sd 38). In 46% of the patients, the position of the electrode was changed guided by the feedback of the patient. More than half of the patients remember most details of the procedure. Only four patients mentioned substantial discomfort and only three would definitely not want to undergo this procedure again.

Implantation of spinal cord stimulation electrodes through a surgical laminectomy using dexmedetomidine is a safe and feasible procedure with adequate comfort for patients and surgeons. This way of working increases the optimal position of the electrode resulting in the most convenient stimulation pattern and avoiding revisions 5).

Ten consecutive patients(5 boys and 5 girls)who underwent surgical revascularization were enrolled, and 16 hemispheres(8 boys and 8 girls)were sedated with DEX postoperatively between August 2011 and August 2016.

During extubation after revascularization, DEX was started at 0.4μg/kg/hr under spontaneous breathing and its dose was increased depending on the degree of consciousness, to maintain sedation of at least 3 on the Ramsay scale. DEX administration was terminated the next morning.

Sedation was maintained well in all patients without hypocapnia, and no ischemic complications were observed. One patient cried and needed additional intravenous DEX injections and was immediately re-sedated;no hypocapnia developed. Respiratory depression did not occur and changes in respiratory rate and decreases in SpO2 were not observed. No significant changes in systolic blood pressure and heart rate were observed.

Dexmedetomidine is safe and useful for postoperative sedation in children with moyamoya disease 6).

Peng K, Wu S, Liu H, Ji F. Dexmedetomidine as an anesthetic adjuvant for intracranial procedures: Meta-analysis of randomized controlled trials. J Clin Neurosci. 2014 Nov;21(11):1951-8. doi: 10.1016/j.jocn.2014.02.023. Epub 2014 Jun 25. PubMed PMID: 24974190.
Galvin IM, Levy R, Day AG, Gilron I. Pharmacological interventions for the prevention of acute postoperative pain in adults following brain surgery. Cochrane Database Syst Rev. 2019 Nov 21;2019(11). doi: 10.1002/14651858.CD011931.pub2. Review. PubMed PMID: 31747720.
Bajwa S, Kulshrestha A. Dexmedetomidine: an adjuvant making large inroads into clinical practice. Ann Med Health Sci Res. 2013 Oct;3(4):475-83. doi: 10.4103/2141-9248.122044. Review. PubMed PMID: 24379995; PubMed Central PMCID: PMC3868110.
Sakaguchi Y, Takahashi S. [Dexmedetomidine]. Masui. 2006 Jul;55(7):856-63.Review. Japanese. PubMed PMID: 16856546.
Vanhauwaert DJ, Couvreur T, Vandebroek A, De Coster O, Hanssens K. Conscious Sedation Using Dexmedetomidine During Surgical Paddle Lead Placement Improves Outcome in Spinal Cord Stimulation: A Case Series of 25 Consecutive Patients. Neuromodulation. 2020 Feb 19. doi: 10.1111/ner.13124. [Epub ahead of print] PubMed PMID: 32074387.
Honjo K, Osato T, Omori S, Muraki T, Ishikawa K, Okamura N, Nakamura H. [Preventing Crying after Revascularization Surgery in Pediatric Patients with Moyamoya Disease:Sedation with Dexmedetomidine]. No Shinkei Geka. 2019 May;47(5):525-530. Japanese. doi: 10.11477/mf.1436203976. PMID: 31105075.
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