Adding perineural dexamethasone as an adjunct to traditional brachial plexus block radically extends the duration of the block and improves postoperative pain outcomes, a meta-analysis has found. Additionally, no reports of persistent nerve injury were attributed to perineural dexamethasone administration in the nine trials comprising the analysis.
“Our group has done quite a bit of research with respect to quality of recovery,” said Meghan E. Rodes, MD, assistant professor of anesthesiology at Northwestern University, Chicago. “But one area where we don’t have any data is the effect of adding dexamethasone to brachial plexus block. Obviously, there are data out there suggesting this may be helpful in prolonging block. We still don’t know whether it actually makes patients feel like they have a better experience.
“There are also questions as to whether the addition of dexamethasone has a negative impact as far as nerve injury and other complications like infection and glucose hemostasis,” she said.
To help answer these questions, Dr. Rodes and her colleagues performed a systematic search to identify randomized controlled trials evaluating the effects of perineural dexamethasone as a block adjunct on postoperative pain outcomes in patients receiving regional anesthesia. The meta-analysis was performed using a random-effects model; publication bias was evaluated by examining the presence of asymmetric funnel plots using Egger’s regression.
As Dr. Rodes told Anesthesiology News at the 2014 annual meeting of the American Society of Anesthesiologists (abstract A1304), the search yielded nine trials comprising 760 patients. It was found that the weighted mean difference of the combined effects favored perineural dexamethasone over controls for both the duration of analgesia (473 minutes; 99% confidence interval [CI], 264-682 minutes) and motor block (500 minutes; 99% CI, 154-846 minutes). Patients receiving perineural dexamethasone also had reduced postoperative opioid consumption (–8.5-mg morphine equivalents; 99% CI, –12.3 to –4.6 mg).
Interestingly, the meta-analysis revealed that perineural administration might not be the only way to use dexamethasone for improved postoperative analgesia. “Desmet and colleagues [Br J Anaesth 2013;111:445-452] examined both perineural and IV dexamethasone administration and found no significant difference in efficacy between those two treatment groups,” Dr. Rodes said. “Those results made me think that in a nondiabetic patient, I’d strongly consider going the IV route.”
Although Dr. Rodes acknowledged the efficacy of perineural administration of dexamethasone, she recognized that more research is necessary before any definitive conclusions can be made. “The question is whether we have captured enough patients to determine dexamethasone’s true effect,” she said. “In the end, there’s definitely more room for study. For even though no significant neurologic symptoms were attributed to the use of perineural dexamethasone, you have to use caution anytime you use a medication that’s off-label and has potential toxicity,” she said.
Jeff Gadsden, MD, applauded the authors for systematically investigating what has become a common question at meetings and workshops, with little apparent consensus among anesthesiologists. “Although these results have shown that dexamethasone extends both motor and sensory blocks, they lead to the question of where these relatively modest gains will fit with respect to clinical decision making,” said the associate professor of anesthesiology at Duke University Medical Center in Durham, N.C. “For example, if a duration of analgesia well beyond the typical 16 to 24 hours is desired, is eight hours of additional blockade acceptable? If not, a catheter technique may be more appropriate. Newer, long-acting local anesthetics are also likely to impact the way we think about these choices.”
All told, Dr. Gadsden agreed that more research is required, particularly when it comes to potential neurotoxic sequelae for an off-label adjuvant. “Although there are small animal models showing that dexamethasone may not cause damage when combined with local anesthetics, it is very difficult to draw conclusions about toxicity given the relatively small numbers we have to date,” he said.