The effects of perineural dexmedetomidine on the pharmacodynamic profile of femoral nerve block: a dose‐finding randomised, controlled, double‐blind study

Abstract

This randomised, controlled, double-blind study investigated the effects of different doses of perineural dexmedetomidine on the pharmacodynamic profile of femoral nerve block in patients undergoing arthroscopic knee surgery. Ultrasound-guided femoral nerve block was performed before general anaesthesia using 25 ml of bupivacaine 0.5% combined with normal saline in the control group, and 25 μg, 50 μg or 75 μg of dexmedetomidine in three treatment groups (n = 15 for each group). All patients received a standard general anaesthetic and multimodal postoperative analgesic regimen. The use of the 50 μg and 75 μg dose levels of dexmedetomidine was associated with reduction of the onset time, extension of the duration of block, prolonged time to the first postoperative request for rescue analgesia, and reduced postoperative morphine requirements. The times to first request for postoperative analgesia were mean (SD) 10.8 (1.6) h in the control group and 11.0 (7.1), 21.8 (3.0) and 28.6 (10.0) in the 25 μg, 50 μg and 75 μg treatment groups, respectively. These times were significantly longer in the 50 μg and 75 μg treatment groups compared with the 25 μg (p < 0.0001) and control group (p < 0.0001). The total 24-h postoperative morphine consumption was 7.6 (5.1) mg in the control group, and 6.5 (3.5), 3.9 (3.4), 1.8 (2.6) in the 25 μg, 50 μg and 75 μg treatment groups, respectively. Postoperative morphine consumption was significantly higher in the control group compared with the 50 μg (p = 0.045) and the 75 μg (p = 0.001) treatment groups. The best analgesic profile was achieved at the 75 μg dose, but this was associated with increased risk of hypotension.

Effect of dexmedetomidine as an adjuvant to bupivacaine in femoral nerve block for perioperative analgesia in patients undergoing total knee replacement arthroplasty: A dose–response study

“…There are mixed reports on the incidence of systemic adverse effects with perineural dexmedetomidine. [121316] A few of the above-mentioned studies have observed significant bradycardia and hypotension after dexmedetomidine use,[111421] which we did not notice in our study. Considering the low incidence of systemic adverse effects associated with perineural dexmedetomidine, our study was not powered to find any significant difference in the incidence of adverse effects between the groups.…”

“…In a similar dose comparison study,[11] authors performed femoral nerve block for knee arthroscopies using 25, 50, and 75 μg of dexmedetomidine with bupivacaine. They found a significant prolongation in duration of analgesia, especially at 50 and 75 μg doses.…”

Dexmedetomidine as an adjunct to local anesthetics in nerve block relieved pain more effectively after TKA: A meta-analysis of randomized controlled trials

“…Median quality evidence showed the similar incidence of postoperative nausea and vomiting, and other related complications between the two groups. Nausea and vomiting, hypotension, bradycardia, neuropathy, infection, excessive sedation are the possible complications related to dexmedetomidine or nerve block (23)(24)(25), while they were not increased in our meta-analysis, which was consistent with another meta-analysis explored in knee arthroscopy (26). On the contrary, Qi Yang et al (16) in their metaanalysis found that dexmedetomidine treatment could decrease the incidence of postoperative nausea and vomiting, and increase the risk of bradycardia in TKA.…”

Imaging of the Vasa Nervorum Using Contrast‐Enhanced Ultrasound

“…Median nerve has been identified on high‐resolution ultrasound with enlargement prior to entry into the carpal tunnel and flattening within the tunnel in patients with carpal tunnel syndrome. Femoral nerve has been visualized using ultrasound for performing nerve blocks for knee joint surgical procedures . Because of the proximity of the nerve to the artery, the nerve is likely to receive multiple pedicles from the artery along its length.…”

“…We had previously described the use of contrast‐enhanced ultrasound to study perfusion of skeletal muscles in a dynamic manner through various phases . Although ultrasound imaging of the nerves is commonly used, contrast‐enhanced ultrasound has not been used to study vasa nervorum and nerve tissue perfusion. We describe our initial experience of using contrast‐enhanced ultrasound to study the vasa nervorum of median, femoral, or sciatic nerves in 4 patients.…”