Comparison of Analgesic Effect of Clonidine as an Adjuvant with Different Concentration of Ropivacaine (0.35% and 0.2%) in Thoracic Paravertebral Block among Modified Radical Mastectomy Patients: A Randomised Double Blinded Clinical Study

Abstract

Introduction: Thoracic Paravertebral Block (TPVB) appears promising for reduction of postoperative pain in Modified Radical Mastectomy (MRM). Various combinations of local anaesthetics and adjuvants have been tried in TPVB but search for an ideal combination is still on. Aim: To evaluate analgesic efficacy of clonidine (1 µg/kg) as adjuvant with different concentrations of ropivacaine (0.35%, 0.2%) for TPVB in MRM surgery. Materials and Methods: This randomised double blind comparative clinical study was carried out in a tertiary care centre in Southern Rajasthan from January 2019 to March 2020, clinical study, 120 American Society of Anaesthesiologists (ASA) grade I, II patients aged 18-60 years female patients undergoing MRM surgery were randomised into three groupsRP, RC and LDRC to receive 0.35% Ropivacaine 19 mL, 0.35% Ropivacaine 19 ml+Clonidine (1 µg/kg) and 0.2% Ropivacaine 19 ml+Clonidine(1 µg/kg) diluted upto total 20 ml with normal saline, respectively. TPVB was performed at T4 level as single injection followed by administration of general endotracheal anaesthesia. The primary outcome measured was duration of analgesia. Secondary outcomes measured included consumption of rescue analgesic, Visual analog scale and perioperative haemodynamic parameters. Quantitative and qualitative data were analysed using Analysis of Variance (ANOVA) and Chi-square test respectively. p<0.05 was considered statistically significant. Results: Mean duration of analgesia was prolonged in clonidine groups RC and LDRC (811.5±110.99 and 753±119.76 min, respectively) as compared to group RP (400.125±108.13 min), although no statistically significant difference was noted between group RC and LDRC. Similar observations were noted when total dose of rescue analgesic in group RC (82.50±7.21 mg) and LDRC (99.38±35.57 mg) was compared to group RP (142.50±53.169 mg) as well as when total number of rescue analgesic doses in group RC (1.10±0.496) and group LDRC (1.32±0.474) were compared to group RP (1.92±0.694). Visual Analogue Scale (VAS) was noted at rest, cough, movement at 0, 4, 8, 12, 24 hours and showed a statistically significant difference between ropivacaine group RP and ropivacaine clonidine groups. Conclusion: Addition of clonidine to ropivacaine in TPVB during breast cancer surgery results in lower pain scores, prolong duration of analgesia and reduce postoperative requirement of rescue analgesics. Both lower (0.2%) and higher (0.35%) concentrations of ropivacaine provide equally effective postoperative analgesia.