Effect of Tramadol as an adjuvant to local anesthetics for brachial plexus block: A systematic review and meta-analysis

During the surgery, brachial plexus block (BPB) method was used as anesthesia and analgesia. Also, local anesthetics (LA) have been used as an adjuvant to extend the pain relief. However, the effect of LA on BPB are controversial. Therefore, this meta-analysis describes the use of tramadol 100 mg as an adjuvant to LA to prolong the duration of sensory block, motor block, and analgesia.

A 4-phenyl-piperidine analogue of codeine, Tramadol presents known for its central opioidergic, serotonergic analgesic,  peripheral local anaesthetic, and noradrenergic attributes. Several studies have described contradictory verdicts about the peripheral analgesic influence of Tramadol as an adjuvant to LA during brachial plexus block (BPB). This meta-analysis intended to assess the impacts of Tramadol as an adjunct to LA in BPB during the shoulder or upper extremity surgery.

EMBASE, KoreaMed databases, PubMed, Google Scholar, and Cochrane were searched to find the suitable randomised controlled trials (RCTs) that involved comparison of BPB with LA and Tramadol and BPB with LA alone. The impacts of Tramadol as an adjuvant on the duration of the motor block, sensory block, and analgesia were considered as the primary endpoints. The implications of Tramadol as an adjuvant on time to onset of motor block and sensory block and adverse events were regarded as the secondary endpoints. Review Manager 5.3 software was used to conduct the meta-analysis.

A total of 16 RCTs comprising 751 patients were selected. As compared to the BPB without Tramadol, BPB with Tramadol prolonged the duration of the motor block, sensory block, and analgesia. The time to onset of motor block and sensory block also reduced using the Tramadol. The duration of the motor block, sensory block and analgesia were increased for BPB with Tramadol 100 mg but not with Tramadol 50 mg. As per the GRADE system, the duration of analgesia exhibited a high quality of evidence. The studies showed similar adverse effects. 

In upper extremity surgery conducted below BPB, an introduction of 100 mg Tramadol as an adjuvant to LA seems to increase the duration of the motor block, sensory block, and analgesia, and decrease the time to onset of motor and sensory blocks without affecting adverse effects.