The impact of dexmedetomidine added to ropivicaine for transversus abdominis plane block on stress response in laparoscopic surgery: a randomized controlled trial

Abstract Background: Intravenous dexmedetomidine is known to attenuate stress response in patients undergoing laparoscopic surgery. We investigated whether the addition of the highly selective alpha-2 adrenergic agonist dexmedetomidine into ropivacaine for ultrasound-guided transversus abdominis plane block could inhibit stress response during laparoscopic surgery, and determined the optimal dose of dexmedetomidine in it. Methods: One hundred and twenty-five patients undergoing laparoscopic gynecological surgery were included in this prospective and randomized double-blind study. Patients received general anesthesia with or without a total of 60 ml of 0.2% ropivacaine in combination with low (0.25 µg/kg), medium (0.50 µg/kg) or high dose (1.0 µg/kg) of dexmedetomidine for the four-quadrant transversus abdominis plane block ( n = 25). The primary outcomes were stress marker levels during the operation. Results: One hundred and twenty patients completed the study protocol. Dexmedetomidine added to ropivacaine for transversus abdominis plane block significantly reduced serum levels of cortisol, norepinephrine, epinephrine, interleukin-6, blood glucose, mean arterial pressure and heart rate in a dose-dependent manner ( P < 0.05 ), accompanied with decreased anesthetic and opioid consumption during the operation ( P < 0.05 ), but the high dose of dexmedetomidine induced higher incidences of bradycardia than low or medium dose of dexmedetomidine ( P < 0.05 ). Conclusion: The addition of dexmedetomidine at the dose of 0.5 µg/kg into ropivacaine for ultrasound-guided transversus abdominis plane block is the optimal dose to inhibit stress response with limited impact on blood pressure and heart rate in patients undergoing laparoscopy gynecological surgery. Trial registration : This study was registered at www.chictr.org.cn on November 6th, 2016 (ChiCTR-IOR-16009753). Keywords: Dexmedetomidine, Nerve block, Abdominal muscles, Stress response, Laparoscopy