The Impact of Intraperitoneal Dexmedetomidine with Bupivacaine on Patients’ Postoperative Pain in Endometriosis Laparoscopic Surgery; A Randomized, Clinical Trial

The results of the present study on the assessment of postoperative VAS scores showed significantly less pain in group 3 (DEX + bupivacaine) than group 2 (bupivacaine) and group 1 (normal saline) in the recovery room, and 2, 6, 12, 24, and 48 hours after the surgery (P < 0.001) and fewer rescue analgesic requirement in group 3. While the longest time to the first rescue analgesic requirement was in group 2. As pain relief after gynecologic laparoscopic interventions has remained a critical issue, researchers broadly investigated to determine the highest safety and tolerance to analgesic techniques among patients who planned for surgery ( 20). Our study demonstrated that intraperitoneally distillated DEX with bupivacaine significantly attenuated postoperative pain and declined postoperative rescue analgesic consumption compared with intraperitoneally administered bupivacaine alone or normal saline. Meta-analysis studies on minor gynecologic procedures (such as tubal ligation) confirmed the efficacy of intraperitoneal bupivacaine on postoperative pain ( 21). However, research on patients undergoing minimally invasive gynecologic surgery has provided diverse results on the efficacy of intraperitoneal administration of bupivacaine on postoperative pain control. In this regard, Rivard et al. has found it efficient ( 19), while other researchers did not find any improvement in the pain control, narcotic use, length of hospital stay, or the level of patients’ satisfaction following the use of bupivacaine ( 22, 23), which is consistent with our study findings. It may also reflect this fact that intraperitoneal normal saline and intraperitoneal bupivacaine alone have similar effectiveness, as reported by Esmat and colleagues ( 6). As hypothesized, the local anesthetic agent administration causes visceral afferent signaling, and modification of visceral nociception that will block sodium channels ( 24). Thus recent studies have evaluated the efficacy of the combination of intraperitoneal bupivacaine with another local anesthetic agent. Ahmed et al. showed that intraperitoneal instillation of meperidine or DEX in combination with bupivacaine 0.25% significantly decreased the postoperative analgesic requirements and the incidence of shoulder pain compared with bupivacaine 0.25% alone in patients undergoing laparoscopic gynecological surgeries ( 25). Memis et al. also demonstrated that administrating a combination of clonidine and bupivacaine via intra-peritoneal root could provide more effective analgesia compared to bupivacaine alone during the early postoperative period ( 26). Narasimham and Rao also found that the intraperitoneal administration of bupivacaine alone or combined with DEX or tramadol could relieve procedure-related following after laparoscopic cholecystectomy ( 27). The prolonged sedation of DEX is attributed to its longer half-life than clonidine ( 28). The results of the above-mentioned studies are consistent with the results of the present study, confirming the efficacy of the combination of DEX with another analgesic; however, the surgical type and the adjuvant analgesic differ among studies. Similar to the results of the present study, other researchers have also revealed that intraperitoneal administration of DEX with bupivacaine, in laparoscopic gynecologic surgeries, was associated with a reduction in VAS and postoperative analgesic requirements in the hours of surgery ( 29- 31). In addition to these results, the present study showed maximum painlessness at 48th hour postoperatively in DEX plus bupivacaine group. Additionally, there was no statistically significant difference in the place of maximum pain in 24 hours and administration of local anesthetic had no efficiency on trocar site pain. As far as the authors are concerned, the combination of DEX with bupivacaine has not been studied on the laparoscopic procedure for the treatment of endometriosis and the origin of postoperative pain depends on the surgical technique. Therefore, further studies on the pain origin of this specific type of surgery may elucidate the mode of analgesia in the present study. The strengthening point of the present study was comprised of a combination of gynecologic procedures such as retroperitoneal dissection, endometrioma, endometriotic nodule resection, and hysterectomy; all patients were postoperatively planned for similar pain regimen, suggesting the differences in pain controlling due to administrating intra-peritoneal local anesthetics. Also, the extended follow-up period of 48 hours (compared to 24 hours in previous studies) is the other strength of our study. The limitation of our study included small sample size and all surgeries were not performed by a single surgeon; however, the surgical techniques and equipment were unified. As there are few studies on using a combination of DEX and bupivacaine, further studies considering different dosages and roots of local anesthetics are required to compare this approach of analgesia with other regional techniques with the goal of achieving more benefit with regard to postoperative pain relief along with minimized adverse effects following laparoscopic surgeries.