Intravenous versus perineural dexmedetomidine as adjuvant in adductor canal block for total knee arthroplasty.

Background: The shivering effect after spinal anesthesia in total knee arthroplasty (TKA) is challenging for anesthesiologists. This study aimed to compare two administration routes of dexmedetomidine as a post-neuraxial shivering prevention measure and an adjunctive analgesic and sedative agent.

Methods: Fifty-six patients were randomly allocated into two equal groups. The intravenous dexmedetomidine (IV dex) group received an IV infusion of 0.5 µg/kg dexmedetomidine diluted in 20 ml saline and an adductor canal block (ACB) consisting of 20 ml of 0.25% levobupivacaine and 1 ml saline. The adductor canal block dexmedetomidine (ACB dex) group received a 20 ml IV infusion of saline and an ACB consisting of 20 ml 0.25% levobupivacaine and 1 ml of 0.5 µg/kg dexmedetomidine.

Results: The incidence of shivering 1 h post spinal anesthesia was equal in both groups (50%); however, the shivering grade was significantly lower in the IV dex group 1 h postoperatively. The onset of sensory block was significantly later in the IV dex group (22.14 ± 2.52 min) than in the ACB dex group (12 ± 3.31 min). Postoperative analgesic duration (h) was significantly longer in the ACB dex group (12.28 ± 4.47) compared to the IV dex group (9.28 ± 1.90). The sedation scores were also significantly higher in the IV dex group in the preoperative, intraoperative, and immediate postoperative periods.

Conclusions: While perineural ACB dexmedetomidine had similar intraoperative anti-shivering with less sedative effects as IV dexmedetomidine, it was associated with both less shivering control and superior analgesia post-TKA under spinal anesthesia.