Comparative Efficacy of Oral Clonidine versus Intravenous Esmolol for Attenuating the Pressor Response to Laryngoscopy and Tracheal Intubation: A Randomised Controlled Trial

Abstract

Background: Direct laryngoscopy and endotracheal intubation elicit a brisk sympathetic surge that may precipitate myocardial ischaemia or cerebrovascular events in high-risk patients. Although several pharmacologic strategies exist, the relative effectiveness of an α₂-agonist versus an ultra-short-acting β-blocker in routine elective surgery remains uncertain.

Objective: To compare the haemodynamic-stabilising efficacy and safety of oral clonidine (2 µg kg⁻¹) and intravenous esmolol (0.5 mg kg⁻¹) administered before anaesthetic induction.

Methods: In this single-centre, parallel-group trial, 116 ASA I–II adults (18–60 y) scheduled for elective surgery under general anaesthesia were randomised to receive clonidine 90 min pre-induction (Group C, n = 58) or esmolol 90 s pre-intubation (Group E, n = 58). Standardised anaesthesia (fentanyl–propofol–atracurium, sevoflurane MAC 1•0) was used. Heart rate (HR), systolic (SBP), diastolic (DBP) and mean arterial pressure (MAP) were recorded at baseline, post-induction, immediately after intubation, and 1, 3, 5, 7 and 10 min thereafter. Primary end-points were peak HR and SBP within 3 min of intubation.

Results: Baseline variables were comparable. Peak HR (mean ± SD) rose to 92 ± 6 bpm in Group E but fell to 66 ± 5 bpm in Group C (p < 0.001). Corresponding SBP values were 143 ± 8 vs 116 ± 8 mmHg (p < 0.001). MAP, DBP and rate-pressure product followed similar patterns. Haemodynamics in Group C returned to baseline by 10 min; Group E remained significantly elevated. No clinically important bradycardia, bronchospasm or hypotension occurred.

Conclusions: A single pre-operative oral dose of clonidine 2 µg kg⁻¹ provides superior attenuation of intubation-induced tachycardia and hypertension compared with esmolol 0.5 mg kg⁻¹. Clonidine is a simple, inexpensive, and well-tolerated option for routine adult elective surgery.