Fentanyl versus Magnesium Sulfate with 0.5% Ropivacaine in Adductor Canal Block for Knee Surgeries

Abstract

Background: Adductor canal block (ACB) is an emerging technique for postoperative analgesia following knee surgery. ACB technique is relatively easy and is performed under ultrasound guidance. Aims: This study aimed to compare the efficacy of fentanyl and magnesium sulfate as adjuvants with 0.5% ropivacaine in ACB for patients undergoing knee surgeries. Adverse events if any were also noted. Materials and Methods: The study was conducted on 100 patients aged 40–80 years posted for knee surgeries. They were divided into two groups of 50 each: Group ropivacaine with fentanyl (RF) and Group ropivacaine with magnesium (RM). Group RF received 30 mL of 0.5% ropivacaine with 50 μg of fentanyl. Group RM received 30 mL of 0.5% ropivacaine with 125 mg of magnesium sulfate. Both the groups were compared on the basis of time for the first rescue analgesia given after the block. The results were analyzed using the SPSS software. Results: The mean time of the first rescue analgesia was 8.40 ± 0.85 h in Group RF and 10.63 ± 1.10 h in Group RM, which was higher and statistically significant (P = 0.002). Rescue analgesia was given more frequently in Group RF (5.77±3.84) compared to group RM (3.20±1.27) and this was statistically significant (P = 0.000). There were no significant adverse events noted in both the groups. Conclusion: Both the adjuvants, when added to ropivacaine, prolong the duration of blockade and reduce the requirement of rescue analgesia without causing significant adverse effects, but magnesium sulfate has an extra edge over fentanyl in terms of longer duration of postoperative analgesia.