Postoperative pain control after the use of dexmedetomidine and propofol to sedate patients undergoing ankle surgery under spinal anesthesia: a randomized controlled trial

Abstract

Background: Dexmedetomidine is widely used for conscious sedation in patients undergoing lower-extremity surgery under regional anesthesia. We evaluated the postoperative analgesic effects of intravenous dexmedetomidine given during ankle surgery under spinal anesthesia. Methods: Forty-three participants underwent repair of lateral angle ligaments under spinal anesthesia. For sedation during surgery, participants were allocated to a dexmedetomidine group (n=22) that received a loading dose of 1 mcg.kg^-1 over 10 min, followed by a maintenance dose of 0.2-0.7 μg.kg^-1.h^-1; and a propofol group (n=21) that received an effective site concentration of 0.5-2.0 μg.mL^-1 via target-controlled infusion. The primary outcome was the postoperative, cumulative, intravenous (IV) morphine equivalent dose delivered via IV patient-controlled anesthesia (PCA) and rescue analgesic consumption in the first 24 h after surgery. We recorded sensory and motor block durations. Results: The postoperative IV morphine equivalent dose was 14.5 mg (0.75-31.75 mg) in the dexmedetomidine group compared to 48.0 mg (31.5-92.5 mg) in the propofol group (median difference, 33.2 mg; 95% confidence interval, 21.0-54.8 mg; P<0.001). The time to the first complaint of surgical site pain was significantly prolonged in the dexmedetomidine group (P<0.001), but the duration of motor block was comparable between the two groups (P=0.55). Conclusion: IV dexmedetomidine given as a sedative during ankle surgery under spinal anesthesia reduced postoperative opioid consumption in the first 24 h. Thus, intraoperative dexmedetomidine is a versatile sedative adjunct. Level of evidence: Level I, prospective randomized trial.

Keywords: ankle surgery; dexmedetomidine; postoperative analgesia; spinal anesthesia.

Figure 1

The CONSORT diagram.

Figure 2

Postoperative, cumulative, IV, morphine-equivalent opioid consumption at 8, 16, and 24 h. Boxes represent the medians with the 25th/75th percentiles. Whiskers represent the minimum/maximum values, excluding outliers. Points represent the outliers. *P<0.05 between the dexmedetomidine and propofol groups.

Figure 3

Postoperative pain severity NRS scores while resting at 8, 16, and 24 h. Boxes represent the medians with the 25th/75th percentiles. Whiskers represent the minimum/maximum values, excluding outliers. Points represent the outliers. *P<0.05 between the dexmedetomidine and propofol groups. Abbreviation: NRS, numeric rating scale.

Figure 4

Kaplan–Meier survival plots showing the durations of postoperative analgesia in the two study groups. P<0.001 (log-rank test).