Transversus Abdominis Plane Block: Comparison of Efficacy of Varying Doses of Clonidine Combined with Levobupivacaine – A Double-Blind Randomized Trail

BACKGROUND: Transversus abdominis plane block (TAP) has an evolving role in postoperative analgesia following laparoscopic-assisted vaginal hysterectomy (LAVH). AIMS: This study was carried out to evaluate 75 μg and 150 μg of clonidine added to 0.25% levobupivacaine, with regard to the duration of analgesia. Our study also sought to assess the hemodynamic effects, sedation, and adverse effects. SETTINGS AND DESIGN: This was a prospective, randomized, double-blinded, comparative study. METHODS: A total number of 80 patients undergoing elective LAVH surgery under general anesthesia were randomly assigned to one of the two equal groups to receive either of the following: Group LC75 – 29 ml of 0.25% levobupivacaine plus 75 μg of clonidine diluted in 1 ml of normal saline (total 30 ml) and Group LC150 – 29 ml of 0.25% levobupivacaine plus 150 μg of clonidine diluted in 1 ml of normal saline (total 30 ml). Duration of analgesia was the primary outcome. Hemodynamic variables, sedation score, and adverse effects were secondary outcomes. STATISTICAL ANALYSIS: The data were analyzed with Student's t-test and Chi-square test. RESULTS: The duration of analgesia was significantly prolonged in Group LC150 (609.18 ± 6.59 vs. 410.52 ± 7.18 min; P = 0.001). The visual analog scale score in patients who received clonidine 150 μg Group LC150 as an adjunct was significantly lower than who received 75 μg Group LC75. Significantly higher sedation score was observed in Group LC150. The incidence of bradycardia was also significant between two groups. Significantly fewer patients in Group LC150 required rescue analgesia. CONCLUSION: The 150 μg dose of clonidine in TAP block prolongs the duration of analgesia but with higher incidence of sedation.