MedWire News: Dexmedetomidine is an effective sedative for patients undergoing monitored anesthesia care (MAC) and causes less respiratory depression than current options, research suggests.

Midazolam, propofol, and fentanyl are commonly used during MAC, but all of these cause respiratory depression.

“The adverse respiratory profile of benzodiazepines, propofol, and opioids, along with the stress response to surgery, create the need for a sedative drug that can be used safely during MAC in both healthy and high-risk patients, with limited adverse effects,” say Keith Candiotti (University of Miami, Florida, USA) and team.

The researchers tested dexmedetomidine in 326 patients undergoing surgical or diagnostic procedures that required MAC. The patients were randomly assigned at a ratio of 2:2:1 to receive dexmedetomidine 0.5 or 1.0 µg/kg followed by maintenance infusion of 0.2 to 1.0 µg/kg/hour, or placebo followed by placebo infusion.

The dexmedetomidine dose was intended to maintain a sedation level of 4 or less on the Observer’s Assessment of Alertness/Sedation Scale (OAA/S).

Patients were given as-needed midazolam on exhibiting a OAA/S score greater than 4. This was required by 59.7% and 45.7% of the 0.5 and 1.0 µg/kg dexmedetomidine groups, respectively, compared with 96.8% of the placebo group. The required midazolam dose was also lower, at 1.4 and 0.9 versus 4.1 mg, respectively.

Patients given dexmedetomidine also required less fentanyl for pain relief, at 84.8 and 83.6 µg for the 0.5 and 1.0 µg/kg groups, compared with 144.4 µg for the placebo group.

The researchers defined clinically significant respiratory depression as a respiratory rate of less than 8 breaths/minute or an oxygen saturation of less than 90%. This occurred in 3.7% and 2.3% of the 0.5 and 1.0 µg/kg dexmedetomidine groups, respectively, compared with 12.7% of the placebo group.

The most frequent side effects were hypotension, which affected 11.9% of the 0.5 µg/kg dexmedetomidine group versus 3.2% of the placebo group, and bradycardia, which affected 4.7% of the 1.0 µg/kg dexmedetomidine group compared with none of the placebo-treated patients.

“The surgical procedures that were studied in this trial were notably diverse, and it is possible that dexmedetomidine may prove more suitable for some procedures than others,” say Candiotti et al in the journal Anesthesia and Analgesia.

“We believe that additional trials delineating the advantages and disadvantages of dexmedetomidine in specific procedures and populations are justified.”