Clonidine versus diazepam as preanesthetic agents and their effects on cardiovascular and sympathoadrenal responses to laryngoscopy and intubation

Laryngoscopy and tracheal intubation frequently induce a cardiovascular stress response, characterized by hypertension, tachycardia and increased serum concentrations of catecholamines. Three qroups each contained 10 patients undergoing elective surgery under general anaesthesia were studied. Preanesthetic medications were nothing, oral diazepam 10 mg and oral clonidine 10 mg in each group. Heart rate, systolic arterial pressure, diastolic arterial pressure, HR, SAP, DAP and MAP were recorded. Estimation of plasma concentrations of catecholamines were performed. There were lack of significant changes in HR and MAP in the clonidine group in comparison to control group but diazepam group showed a significant reduction in HR. Plasma norepinephrine showed a significant decrease in both groups. It also showed a significant correlation between plasma norepinephrine concentration and MAP only in the clonidine group. Although clonidine has some side effects as sedation and dry mouth. It is preferable than diazepam as a premedicant agent as it causes analgesia, anxiolysis and sedation

Attenuation of some haemodynamic responses to laryngoscopy and endotracheal intubation by clonidine hydrochloride

The present work is a study of the effect of intravenous clonidine hydrochloride on laryngoscopy and intubation in an attempt to prevent the well predictable tachycardia and hypertension associated with it. The present study was carried out on 40 adult patients. They were classified into two equal groups: Group A [control] atropine hydrochloride 1 mg was given i.v. as the only premedication and group B [clonidine], where clonidine hydrochloride 300 mug was given i.v. The results showed that laryngoscopy and intubation were associated with a mean rise of HR of 24.2 +/- 15.929 bpm in the control group versus 2.75 +/- 0.096 bpm in clonidine premedicated group, accompanied by a mean rise in the mean ABP of 30.8 +/- 10.486 mmHg in the control group versus 8.6 +/- 7.148 mmHg in clonidine group. Clonidine premedicated group presented no dysrhythmic changes, while 40% of patients of atropine group developed different types of arrhythmias during and after laryngoscopy. These effects are, most probably, due to the alpha 2-adrenoceptor agonistic effects of clonidine on central and peripheral adrenergic receptors