Dexamethasone as an Adjuvant to Femoral Nerve Block in Children and Adolescents Undergoing Knee Arthroscopy: A Prospective, Randomized, Double-Blind, Placebo-Controlled Trial.

Abstract

Perineural dexamethasone has been demonstrated to extend postsurgical analgesia after peripheral nerve blockade in adults. The mechanism of action of dexamethasone as a regional anesthetic adjuvant is unclear as intravenous dexamethasone has been shown to have similar analgesic efficacy as perineural dexamethasone. The efficacy of perineural dexamethasone has not been previously explored in the pediatric population. After obtaining informed consent, children (aged 10-18 years) presenting for arthroscopic knee surgery with a femoral nerve block were randomized to 1 of 3 groups: ropivacaine 0.5% and intramuscular saline (group R), ropivacaine 0.5% plus perineural dexamethasone 0.1 mg/kg (maximum 4 mg) and intramuscular saline (group D), and ropivacaine 0.5% and intramuscular dexamethasone 0.1 mg/kg (maximum 4 mg) (group M). The primary outcome was the number of doses of analgesic agents in the first 48 hours after hospital discharge. The number of doses was compared across study groups using Wilcoxon rank sum tests. Seventy-seven patients were enrolled in the study, of whom 4 were withdrawn because of additional surgical repair being performed, emergence delirium requiring unblinding, or loss to follow-up. The remaining 36 boys and 37 girls (aged 15 ± 2 years) included 23 patients randomized to group D, 23 patients randomized to group M, and 27 patients randomized to group R. The median number of pain medication doses within 48 hours of discharge was 2, 3, and 2 in groups D, M, and R, respectively. There were no significant differences in this outcome between groups D and M (difference in medians, 1; 95% confidence interval [CI] of difference in medians, -1 to 2; P = 0.475), groups D and R (difference in medians, 0; 95% CI of difference, -2 to 1; P = 0.821), or groups M and R (difference in medians, -1; 95% CI of difference, -2 to 1; P = 0.594). Other secondary outcomes, including time to first analgesic consumption after discharge, visual analog scale pain score, and subjective intensity of motor block, did not evince statistically significant differences among the study groups. In the pediatric population, perineural or intramuscular dexamethasone did not improve analgesia after femoral nerve blockade for knee arthroscopy. Whether the observed lack of benefit reflects a true adult-pediatric difference or a limitation of the study could not be determined. Future pediatric studies are needed to evaluate dexamethasone for other block types and other types of surgery. This study was registered at ClinicalTrials.gov, identifier NCT01971645.