Is dexmedetomidine the perfect adjuvant drug to propofol during endoscopy?

Use of dexmedetomidine has lessened the effective concentration (EC₅₀) of propofol administered via plasma target-controlled infusion (TCI) during gastrointestinal endoscopy, a study has found. A 0.5‒1 μg/kg dose of dexmedetomidine results in a lower heart rate (HR) without bradycardia.

In addition, “[t]he decrease in dosage of propofol with increasing doses of dexmedetomidine caused more stable mean arterial pressure (MAP),” the authors said.

In this randomized controlled trial, 90 adult patients were assigned to 0.5 μg/kg dexmedetomidine (DEX0.5), 1.0 μg/kg dexmedetomidine (DEX1.0), or control. Anaesthesia during endoscopy was given by plasma TCI of propofol with varying doses of dexmedetomidine. The first patient of each group had TCI concentration of 2.5 μg/mL, while the consecutive adjacent concentration gradient was 0.5 μg/mL.

The authors determined the median EC₅₀ of propofol by TCI using the modified Dixon’s up-and-down method. They also measured the cardiovascular variables.

The EC₅₀ of propofol by TCI was 3.77 (95 percent confidence interval [CI], 3.48‒4.09) in the control group, 2.51 (95 percent CI, 2.27‒2.78) in the DEX0.5 group, and 2.10 (95 percent CI, 1.90‒2.33) in the DEX1.0 group.

Percent change of HR from baseline had an average of 2.8, ‒7.4, and ‒10.5 (p<0.001) in the control, DEX0.5, and DEX1.0 groups, respectively, while the corresponding average percent change of MAP from baseline was ‒10.6, ‒9.5, and ‒4.0.

“Dexmedetomidine is an ideal adjuvant drug to propofol during gastrointestinal endoscopy,” said the authors, noting that the agent provides both analgesia and sedation without respiratory depression.