Background: The transversus abdominis plane (TAP) block serves as a straightforward regional technique employed to alleviate postoperative pain in patients undergoing abdominal surgeries. Over the years, various additives have been utilized to prolong the analgesic effects of peripheral nerve blocks. Several studies have investigated the effectiveness of adding dexamethasone to local anesthetics such as bupivacaine, with promising results. However, there is still a lack of studies directly comparing the efficacy of dexamethasone when combined with ropivacaine. Objectives: To investigate whether combining dexamethasone 8 mg with ropivacaine 0.2% in a TAP block would result in a prolonged analgesic effect compared to using ropivacaine 0.2% alone following inguinal hernia repair. Study Design: A prospective study conducted in a teaching hospital, utilizing a randomized, double-blinded and placebo-controlled design. Methods: The study enrolled a total of 62 patients undergoing either inguinal hernia repair. Among them, 31 patients were administered a TAP block with ropivacaine combined with saline, while the remaining 31 received ropivacaine with    dexamethasone immediately after the surgery. Both the proceduralist (resident) and the patient were kept unaware of the solution used. Pain levels were assessed using visual analog pain scores (ranging from 0 to 10) before and immediately after the block. Our main focus was the visual analog pain score at the 12-hour mark, with pain scores at 24 and 48 hours serving as secondary endpoints. Results: In the saline group, the average pre-block pain score was 7.8 ± 1.8 while in the dexamethasone group, it was 7.9 ± 2.3. Both groups experienced an improvement in pain scores compared to baseline at 12 hours post-block administration. Although    the dexamethasone group exhibited a greater reduction in pain score (-3.2) compared to the saline group (-2.2), this discrepancy between the two groups did not reach statistical significance (p = 0.08). Furthermore, there were no significant variances in the change from baseline observed at 24 and 48 hours between the two groups (p values = 0.74 and 0.44, respectively)  Limitations: We opted not to evaluate the cumulative dose of analgesics administered during surgery under the assumption that the impact of intraoperative analgesia would diminish by the time we assessed the 12-hour pain score. We also did not standardize for the proficiency of the block provider, considering that certain providers might have been junior residents lacking extensive experience in this domain. Furthermore, we couldn’t incorporate postoperative opioid consumption due to concerns regarding potential disparities in patient reporting and data reliability.  

Conclusion: In summary, our study did not demonstrate a statistically significant extension of analgesia for TAP blocks with ropivacaine when dexamethasone was included. However, there was a notable one-point reduction in pain scores at 12 hours following the addition of dexamethasone to the block solution. Despite the absence of statistical significance, this reduction in pain scores at the 12-hour mark could still contribute to enhanced patient satisfaction, especially considering the favorable side effect profile of dexamethasone. Given that ropivacaine has a lower pH compared to other local anesthetic agents, further well-designed studies are warranted to explore its combination with more alkaline drugs such as corticosteroids.