To evaluate the effects of dexmedetomidine as a local anesthetic adjunct or intravenous infusion of dexmedetomidine on postoperative analgesia after retroperitoneal laparoscopic surgery under quadratus lumborum block (QLB).

A total of 88 patients who were scheduled for retroperitoneal laparoscopic surgery were selected. According to the random number table method, they were divided into three groups: a ropivacaine group (group R, n=30), a dexmedetomidine as an adjuvant to ropivacaine group (group RD, n=29) and an intravenous infusion of dexmedetomidine combined with ropivacaine group (group RDiv, n=29). All patients underwent QLB 30 min before anesthesia induction. Patients in group R and group RDiv were injected with 30 ml of 0.375% ropivacaine, while those in group RD were injected with 1 μg/kg dexmedetomidine combined with 30 ml of 0.375% ropivacaine. Then, 15 min before the surgery, group RDiv was injected with 50 ml of 1 μg/kg dexmedetomidine, while group R and group RD were given 50 ml normal saline. The same other anesthetics were given in the three groups and all the patients were subject to patient-controlled intravenous analgesia (PCIA) after surgery. Then, the effective duration of analgesia, Visual Analogue Scale (VAS) scores at rest and during movement at postoperative 2, 6, 12, 24 h and 48 h were recorded. The intraoperative consumption of propofol and remifentanil were recorded. The consumption of sufentanil and effective pressing times of PCIA within 48 h after surgery were recorded. The number of patients with remedial analgesia, 15-item Quality of Recovery (QoR-15) scores 48 h after surgery, the time to first exhaust and the time to first postoperative off-bed activity, the length of postoperative hospitalization stay, postoperative adverse reactions (bradycardia, hypotension, nausea and vomiting), Ramsay sedation scores and lower extremity muscle strength 2 h after surgery were recorded.

The effective duration of analgesia in group RD was significantly longer than those in group R and group RDiv (P<0.05). There was no statistical difference in the effective duration of analgesia between group R and group RDiv (P>0.05). Group RD showed decreases in VAS score at rest at postoperative 6, 12 h and 24 h and decreases in VAS during movement at postoperative 2, 6 h and 12 h, compared with group R (P<0.05). Group RDiv presented decreases in VAS score at rest at postoperative 2 h and 6 h and decreases in VAS during movement at postoperative 2 h, compared with group R (P<0.05). There was no statistical difference in VAS scores at rest and during movement at postoperative 2, 6, 12, 24 h and 48 h between group RD and group RDiv (P>0.05). The effective pressing times of PCIA and the consumption of sufentanil within 48 h after surgery in group RD were lower than those in group R and group RDiv (P<0.05). At postoperative 48 h, the QoR-15 scores in group RD were higher than those in group R (P<0.05). There was no statistical difference in the intraoperative consumption of propofol and remifentanil, the number of patients with remedial analgesia after surgery, the time to first exhaust and the time to first postoperative off-bed activity, the length of postoperative hospitalization stay, postoperative adverse reactions, postoperative Ramsay sedation scores and postoperative lower extremity muscle strength among the three groups (P>0.05).

Dexmedetomidine can act as an adjuvant to ropivacaine and significantly prolong the effective duration of analgesia after retroperitoneal laparoscopic surgery under QLB, and its effect is superior to intravenous infusion of dexmedetomidine.

Quadratus lumborum block; Dexmedetomidine; Ropivacaine; Postoperative analgesia