Intravenous Labetalol vs Intravenous Clonidine for Attenuation of Haemodynamic Responses during Laryngoscopy and Intubation in Controlled Hypertensive Patients Undergoing General AnaesthesiaA Randomised Clinical Trial

Abstract

Introduction: Laryngoscopy and endotracheal intubation during general anaesthesia are associated with haemodynamic surges which can be detrimental, particularly if there is preexisting hypertension or cardiovascular disease. Intravenous (i.v.) labetalol, a β-adrenergic blocker with additional α1- adrenoceptor blocking activity, and clonidine, a centrally acting α2 agonist, are known to attenuate this haemodynamic response. Aim: To compare the effects of i.v. labetalol and clonidine in attenuating haemodynamic changes during laryngoscopy and intubation in controlled hypertensive patients. Materials and Methods: This single centre, parallel-group, double-blind, randomised clinical trial was conducted in the Surgery Operation Theater (OT) of Midnapore Medical College, District Paschim Medinipur, West Bengal, India, from February 2018 to August 2019. The study included 90 adult patients of either sex, who were randomly allocated to receive either clonidine 1 mcg/kg or labetalol 0.15 mg/kg by intravenous route. After recording baseline parameters, patients were preoxygenated with 100% oxygen for 3 min and the study drug was given 5 min prior to induction. Heart Rate (HR), Systolic Blood Pressure (SBP) and Diastolic Blood Pressure (DBP) and the rate pressure product were recorded prior to induction, at the time of intubation and 1, 3, 5, and 10 min after intubation. General anaesthesia maintenance was done in a similar manner in both groups. Two-sample t-test was used to assess significance of difference in means between independent samples. Fisher’s exact test was employed for comparing categorical data. Analysis was two-tailed and p-value<0.05 was considered statistically significant. Results: Both the groups were evenly matched at baseline with respect to age and sex as well as standard anthropometric parameters (p-value>0.05). Both drugs were able to attenuate the expected rise in HR following intubation but labetalol was more effective than clonidine throughout the postintubation period. SBP and DBP were comparable between the two groups at baseline but underwent greater attenuation in the labetalol group at intubation and subsequent measurements. The differences were around 10 bpm for HR, 20-30 mmHg for SBP and 10 mmHg for DBP, in favour of labetalol. Adverse events like bradycardia, hypotension, sedation or undesirable ECG changes were not encountered. Conclusion: Intravenous labetalol is more effective than i.v. clonidine in controlling haemodynamic changes during laryngoscopy and intubation in controlled hypertensive patients undergoing general anaesthesia without any complications