Comparison between adenosine and magnesium sulfate as an adjuvant for ultrasound-guided rectus sheath block. A prospective randomized controlled study

Background Rectus sheath block (RSB) is an effective nerve block. This study aimed to compare adenosine and magnesium sulfate as an adjuvant for ultrasound-guided RSB (UG-RSB).Methods This prospective controlled randomized trial was performed on 96 adult patients (ASA I and II) undergoing umbilical or epigastric hernia repair. The patients were assigned randomly to three equal groups and got bilateral UG-RSB. Adenosine group: using 20 ml bupivacaine hydrochloride 0.25% + 12 mg of adenosine (4 ml) +1 ml saline 0.9%. Magnesium group: using 20 ml bupivacaine hydrochloride 0.25% + 500 mg of magnesium sulfate (5 ml). Control group: using 20 ml bupivacaine hydrochloride 0.25% + 5 ml of saline 0.9%. Registration No.: 6/2018ANET17Results A significant postoperative reduction of VAS up to 18 h was detected in the magnesium sulfate group and up to 12 h was detected in the adenosine group. A statistically significant prolongation of time to the first analgesia in magnesium and adenosine groups than control groups (483.44 & PLUSMN; 48.03 & 415.28 & PLUSMN; 29.81 than 325.31 & PLUSMN; 50.29, respectively), as well as the mean postoperative morphine consumption was 5.94 & PLUSMN; 1.61, 8.03 & PLUSMN; 1.0 and 16.69 & PLUSMN; 2.49 among magnesium, adenosine, and control groups, respectively. The postoperative complications were statistically significantly higher in the control group.Conclusion This study validates the effectiveness of adenosine versus magnesium sulfate as good adjuvants for improving the quality and duration of UG-RSB and reduction of postoperative narcotic requirements. However, the duration was relatively longer with magnesium sulfate.