Cesarean Sections Under Spinal Anaesthesia: Comparison of Varying Doses of Dexmedetomidine Combined with 0.75% Hyperbaric Ropivacaine: A Double-Blind Randomized Trial.

Objective: The primary aim of this study was to evaluate the effects of 5 μg, 7.5 μg, and 10 μg doses of dexmedetomidine added to hyperbaric 0.75% ropivacaine on the duration of analgesia during cesarean section. Furthermore, the onset of sensory and motor block, hemodynamics, sedation, and adverse effects were investigated.

Methods: A total of 120 full-term parturients scheduled for cesarean section under spinal anaesthesia were randomized into three groups. Group RD5 received intrathecal hyperbaric 0.75% ropivacaine 15 mg (2 mL) plus dexmedetomidine 5 μg (0.5 mL), group RD7.5 received intrathecal hyperbaric 0.75% ropivacaine 15 mg (2 mL) plus dexmedetomidine 7.5 μg (0.5 mL), and group RD10 received intrathecal hyperbaric 0.75% ropivacaine 15 mg (2 mL) plus dexmedetomidine 10 μg (0.5 mL). Sensorimotor blockade characteristics, analgesia duration, hemodynamic variables, and adverse events were documented. Student's t-test and the chi-square test were used for data analysis.

Results: In groups RD5, RD7.5, and RD10, the onset of sensory block was 2.96±1.32 min, 2.26±1.50 min, and 1.96±0.93 min, respectively, while the onset of motor block was 9.63±0.11 min, 8.63±0.58 min, and 6.40±0.14 min, respectively. The duration of analgesia was significantly prolonged in group RD10 compared with groups RD7.5 and RD5 (483.43±76.21 vs. 398.74±73.59 vs. 362.58±79.87 min, respectively, P=0.001). Group RD10 also exhibited significantly higher incidences of sedation, bradycardia, and vomiting.

Conclusion: We conclude that increasing dexmedetomidine doses decreases the onset of sensory and motor blockade while prolonging analgesia duration in a dose-dependent manner.