Effect of adding clonidine to intrathecal bupivacaine on the quality of subarachnoid block: A prospective randomized double-blind study

CONTEXT: The purpose of adding an adjuvant to local anesthetic in a central neuraxial blockade is to augment the desirable pharmacological actions of the agent and/or to minimize its undesirable pharmacological effects. Clonidine is an alfa-2 receptor agonist which has gained popularity in recent times as an adjuvant in spinal anesthesia. AIMS: To evaluate the influence of clonidine on the hemodynamic stability and the duration of anesthesia when added to intrathecal hyperbaric bupivacaine. SETTINGS AND DESIGN: Prospective randomized double blind study. SUBJECTS AND METHODS: Fifty patients scheduled for spinal anesthesia were randomized into two Groups A and B with 25 in each. Group A patients received 3 ml 0.5% heavy bupivacaine + 30 μg (0.2 ml) clonidine and Group B patients received 3 ml 0.5% heavy bupivacaine + 0.2 ml normal saline in the subarachnoid space. The blood pressure and heart rate were closely monitored. The time for attaining peak sensory block, time for two segment regression, decrease in the heart rate, total requirement of mephentermine to counter the hypotension, and the number of patients requiring mephentermine in each group was tabulated and analyzed. STATISTICAL ANALYSIS USED: Descriptive and inferential statistical methods were used to analyse the data. The power of the study was calculated using online power calculator for two independent sample study. RESULTS: The time for attaining peak sensory block was similar in both the groups. The time for two segment regression in Group A was 62.6 min and in Group B was 38.08 min. Twelve percent of patients in Group A and 52% of patients in Group B required mephentermine with the mean consumption being 0.72 mg in Group A and 5.65 mg in Group B. CONCLUSIONS: Addition of low-dose clonidine to intrathecal bupivacaine not only prolonged the duration of spinal anesthesia but also provided a stable intraoperative hemodynamic profile.