Dexmedetomidine Added to Bupivacaine versus Bupivacaine in Transincisional Ultrasound-Guided Quadratus Lumborum Block in Open Renal Surgeries: A Randomized Trial

Abstract

Background: General anesthesia (GA) is the preferred anesthetic modality for open renal surgeries to ensure a patent airway while the patient is in the lateral decubitus position. However, these surgeries are usually accompanied by severe postoperative pain with increased requirements for multimodal pain management strategies. Regional blocks provide better postoperative pain control with less systemic opioid consumption. Objectives: The aim of this study was to describe the ultrasound (US)-guided transincisional quadratus lumborum block (TiQLB) as a new approach, and to compare the addition of dexmedetomidine to bupivacaine versus bupivacaine alone for TiQLB in combination with GA regarding postoperative analgesia and adverse effects in open renal surgery. Study Design: A prospective, randomized, double-blind, controlled trial. Setting: Ain Shams University Hospitals. Methods: Eighty patients who were scheduled for an elective open renal surgery, aged 20 to 65 years, of either gender, and American Society of Anesthesiologists physical status I to II were enrolled in the study. They were randomly allocated into 2 equal groups: group dexmedetomidine-bupivacaine (DB) (n = 40) in which patients received combined GA plus TiQLB with 30 mL bupivacaine 0.25% plus 1 μg/kg dexmedetomidine, and group bupivacaine (B) (n = 40) in which patients received combined GA plus TiQLB with 30 mL bupivacaine 0.25% only. The primary outcome was the total morphine consumption among both groups, whereas the secondary outcomes were the Visual Analog Scale (VAS) scores and the time to first analgesic requirement during the first 24 hours. Postoperative side effects, such as sedation, nausea, vomiting, shivering, pruritus, bradycardia, hypotension, and respiratory depression, were also recorded. Results: Patients in the DB group experienced lower total morphine consumption and lower VAS scores when compared with patients in the B group (P < 0.001). Time to first analgesic requirement was prolonged in patients in the DB group (18.6 ± 2.4 hours) in comparison to patients in the B group (7.3 ± 1.1 hours). Ten minutes after the block there was a significant reduction in mean blood pressure and heart rate in the DB group than in the B group. Regarding postoperative adverse effects, sedation scores were higher in the DB group than in the B group, postoperative nausea, vomiting, and shivering were significantly higher in the B group than in the DB group. Bradycardia was significantly more frequent among the DB group. Although nonsignificant, pruritus was more frequent in the B group than in the DB group. No cases of respiratory depression were reported in both groups. Limitations: The used technique US-guided TiQLB could be performed in open renal surgeries only. Conclusions: The new approach US-guided TiQLB was effective and easy to be performed. Adding dexmedetomidine to bupivacaine in TiQLB was associated with potent and prolonged postoperative analgesia with fewer postoperative adverse effects. Key words: Quadratus lumborum block, dexmedetomidine, open renal surgery, postoperative pain, bupivacaine