Clonidine premedication in spinal anaesthesia: Effect on hemodynamic status and vasopressor response to ephedrine

Introduction: Premedication has an important role to play in modern day anaesthesia care. In recent years, clonidine is making a comeback as a premedicant. Our study deals with haemodynamic changes to ephedrine after oral clonidine premedication for spinal anaesthesia with or without concurrent administration of drugs.The purpose of the study is to know the effect of oral clonidine premedication on haemodynamic status including vasopressor response of ephedrine during spinal anaesthesia.   Materials: This is a prospective randomized double blinded controlled study. Sixty adult patients belonging to ASA I scheduled for elective surgery under spinal anaesthesia were selected. The patients were randomly assigned to 2 groups.Oral  clonidine 4 microgram/kg was administered to group A(Clonidine group, n equal to 30) and  90 and   one tablet of vitamin (placebo) orally 90 minutes was administered to group B (Control group, n equal to 30)90 minutes  prior to anaesthesia. On the morning of surgery, blood pressure was measured before premedication and 90 minutes later. Sedation and anxiolysis were  scored during clonidine premedication and 90th minute afterwards. When SBP decreased to 80% of the pre-spinal value, bolus IV injection of ephedrine 0.1 mg/kg was administered. After ephedrine injections, blood pressure and heart rate were recorded at 1 minute interval for 10 minutes.   Results: Group A patients were found to have low SBP, DBP, MBP and HR when compared to group B. Intravenous ephedrine augmented blood pressure more than the control group. Statistically significant difference was found for SBP after 5 minutes, for MBP after 4 minutes of ephedrine administration and no significant difference was found for DBP.   Conclusion: We conclude from our study that clonidine administered orally in a dose of 4 microgram/kg as a premedicant increases the pressor responses to IV injection ephedrine 0.2 mg/kg in patients with subarachnoid block.