A COMPARATIVE STUDY OF THE INCIDENCE OF INTRAOPERATIVE HYPOTENSION FOLLOWING SPINAL ANAESTHESIA WITH DEXMEDETOMIDINE VERSUS DEXAMETHASONE AS ADJUVANTS TO

Background: Spinal anaesthesia is commonly used for lower-limb orthopaedic surgery, but sympathetic blockade may cause intraoperative hypotension. Intrathecal adjuvants may influence haemodynamic stability. 
Aim: To compare the incidence of intraoperative hypotension following spinal anaesthesia using bupivacaine with either dexmedetomidine or dexamethasone in patients undergoing tibiofibular fracture fixation. 
Methods: This prospective, randomized, double-blind study was conducted at the University College Hospital, Ibadan, over 6months. Sixty-eight adults (ASA I–II), aged 18–65 years, were randomized into two equal groups. Both groups received 15 mg of 0.5% hyperbaric bupivacaine, combined with either dexmedetomidine 5 µg (BDM) or dexamethasone 4 mg (BDA). Haemodynamic parameters were monitored intraoperatively. Hypotension was defined as systolic blood pressure below 100 mmHg or a reduction greater than 20% from baseline. Data were analysed using SPSS version 23, with statistical significance set at p<0.05. 
Results: Hypotension occurred in 10 (29.4%) patients in the BDM group compared with 1 (2.9%) in the BDA group (p=0.003). Bradycardia occurred in 4 (11.8%) versus 2 (5.9%) patients (p=0.393), while tachycardia occurred in 3 (8.8%) versus 1 (2.9%) (p=0.303), respectively. These latter differences were not statistically significant. 
Conclusion: Intrathecal dexmedetomidine was associated with a significantly higher incidence of intraoperative hypotension than dexamethasone. Dexamethasone may provide a more favourable haemodynamic profile, although larger studies are required to confirm this finding.