Efficacy of ultrasound-guided adductor canal block for postoperative analgesia in pediatric patients undergoing knee operation

Abstract

Objective To investigate the efficacy of adductor canal block (ACB)under the guidance of ultrasound for postoperative analgesia in the pediatric patients undergoing knee operation. Methods Sixty pediatric patients, aged 3-12 yr, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ, weighing 12-35 kg, scheduled for elective unilateral knee operation, were selected and randomly divided into 2 equal groups using a random number table: ultrasound-guided ACB group (group ACB)and ultrasound-guided femoral nerve block (FNB) group (group FNB). After induction of general anesthesia, ACB or FNB was performed under the guidance of ultrasound, and 0.3% ropivacaine 1 ml/kg was injected.Anesthesia was maintained with intravenous infusion of remifentanil combined with propofol, and bispectral index value was maintained at 40-60.Immediately after injection of local anesthetics (T0), and at 4, 8, 12 and 24 h after injection (T1-4), analgesic efficacy was assessed using the FLACC pain scale, and quadriceps strength was assessed by manual muscle testing.Satisfactory analgesia was defined as FLACC score ≤3, and obvious quadriceps weakness was defined as manual muscle testing grade 0-2.The complications associated with nerve block (such as local anesthetic toxicity, bleeding at the puncture site, hematoma), and occurrence of postoperative nausea and vomiting and delayed emergence were recorded. Results There was no significant difference between two groups in the rate of satisfactory analgesia at T1-T4 (P>0.05). Compared with group FNB, the incidence of obvious quadriceps weakness was significantly lower at T1-T3 (P 0.05). There was no significant difference in the incidence of nausea or retching between two groups (P>0.05). Complications associated with nerve block, vomiting and delayed emergence were not observed in the two groups. Conclusion Ultrasound-guided ACB can be safely and effectively used for postoperative analgesia in the pediatric patients undergoing knee operation, and it has less influence on the quadriceps strength than FNB. Key words: Ultrasonography; Nerve block; Child; Knee joint; Analgesia