Dexmedetomidine and ketamine: an effective alternative for procedural sedation?

OBJECTIVES Although generally effective for sedation during noninvasive procedures, dexmedetomidine as the sole agent has not been uniformly successful for invasive procedures. To overcome some of the pitfalls with dexmedetomidine as the sole agent, there are an increasing number of reports regarding its combination with ketamine. This article provides a descriptive account of the reports from the literature regarding the use of a combination of dexmedetomidine and ketamine for procedural sedation. DATA SOURCE A computerized bibliographic search of the literature regarding dexmedetomidine and ketamine for procedural sedation. MEASUREMENTS AND MAIN RESULTS The literature contains four reports with cohorts of more than ten patients with a total of 122 patients. Two of these studies were prospective randomized trials. Additionally, there are eight single case reports or small case series (six patients or less) with an additional 21 pediatric patients. When used together, dexmedetomidine may prevent the tachycardia, hypertension, salivation, and emergence phenomena from ketamine, whereas ketamine may prevent the bradycardia and hypotension, which has been reported with dexmedetomidine. An additional benefit is that the addition of ketamine to initiate the sedation process speeds the onset of sedation, thereby eliminating the slow onset time when dexmedetomidine is the sole agent. Although various regimens have been reported in the literature, the most effective regimen appears to be the use of a bolus dose of both agents, dexmedetomidine (1 µg/kg) and ketamine (1-2 mg/kg), to initiate sedation. This can then be followed by a dexmedetomidine infusion (1-2 µg/kg/hr) with supplemental bolus doses of ketamine (0.5-1 mg/kg) as needed. CONCLUSIONS The available literature except for one trial is favorable regarding the utility of a combination of ketamine and dexmedetomidine for procedural sedation. Future studies with direct comparisons to other regimens appear warranted for both invasive and noninvasive procedures.