The effect of perineural dexamethasone on rebound pain after ropivacaine single-injection nerve block: a randomized controlled trial

BACKGROUND: Rebound pain after a single-shot nerve block challenges the real benefit of this technique. We aimed to investigate whether perineural dexamethasone addition decreased the incidence of rebound pain after a single-shot nerve block. METHODS: We randomly allocated 132 patients scheduled for open reduction internal fixation of an upper extremity closed fracture under single-shot peripheral nerve block and sedation into two groups. Patients in the dexamethasone group received nerve block with 0.375% ropivacaine and 8 mg dexamethasone, while those in the control group received ropivacaine only. Sixty-three patients in the dexamethasone group and 60 patients in the control group were analyzed for the incidence of rebound pain 48 h after block administration, which was the primary outcome. The secondary outcomes included the highest self-reported numeric rating scale (NRS) pain score, and NRS at 8, 12, 24, and 48 h after the block, sufentanil consumption, sleep quality on the night of surgery, patient satisfaction with the pain therapy, blood glucose at 6 h after the block, pain and paresthesia at 30 days after surgery. RESULTS: The incidence of rebound pain was significantly lower in the dexamethasone group (7 [11.1%] of 63 patients) than in the control group (28 [48.8%] of 60 patients [RR = 0.238, 95% CI (0.113–0.504), p = 0.001]. Dexamethasone decreased opioid consumption in 24 h after surgery (p < 0.001) and improved the sleep quality score on the night of surgery (p = 0.01) and satisfaction with pain therapy (p = 0.001). Multivariate logistic regression analysis showed that only group allocation was associated with the occurrence of rebound pain [OR = 0.062, 95% CI (0.015–0.256)]. Patients in the dexamethasone group reported later onset pain (19.7 ± 6.6 h vs 14.7 ± 4.8 h since block administration, mean ± SD, p < 0.001) and lower peak NRS scores [5 (3, 6) vs 8 (5, 9), median (IQR), p < 0.001] than those in the control group. CONCLUSIONS: The perineural administration of 8 mg dexamethasone reduces rebound pain after a single-shot nerve block in patients receiving ORIF for an upper limb fracture. TRIAL REGISTRATION: This study was retrospectively registered in the Chinese Clinical Trial Registry (ChiCTR-IPR-17011365) on May 11th, 2017. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12871-021-01267-z.