Effects of Urapidil on the intubation response during general anesthesia and its complications: After induction of general anesthesia, laryngoscopy (curved or straight) is used to reveal the glottis and perform endotracheal intubation. During this process, due to stimulation of the epiglottis and base of the tongue by the sympathetic nervous system, blood pressure often increases sharply (SBP may rise by 6kPa). A transient reaction may occur with increased heart rate or bradycardia, which generally poses no harm in younger patients due to its short duration. However, for elderly patients or those with hypertension, it can be very dangerous, and efforts should be made to prevent or avoid such occurrences.
Urapidil is a highly selective alpha receptor blocker, with its main active component being a phenyl piperazine-substituted urea derivative. It has dual mechanisms of action affecting both the central and peripheral systems. Its central effect primarily activates 5-HT1A receptors, causing a reduction in sympathetic feedback from the cardiovascular control center in the medulla oblongata, leading to an antihypertensive effect. Its peripheral vasodilatory effects mainly result from blocking synaptic receptors, causing vasodilation and significantly reducing peripheral resistance, while also moderately blocking the vasoconstrictor effects of catecholamines. Urapidil lowers blood pressure without causing reflex tachycardia, does not increase myocardial oxygen demand, and improves conditions for hypertensive patients or those with accompanying myocardial ischemia, thereby enhancing surgical safety.
For hypertensive patients, intravenous urapidil administered before induction of general anesthesia helps prevent elevated blood pressure and increased heart rate caused by subglottic irritation during laryngoscopy and intubation. Clinical observation of 32 cases showed that injecting 25mg of urapidil over 2 minutes, followed by endotracheal intubation after induction, resulted in significant reductions in blood pressure at 5 minutes and 30 minutes post-injection compared to pre-injection levels (P < 0.05). Therefore, intravenous urapidil administration before induction of general anesthesia in hypertensive patients can be considered a safe and effective method for preventing vascular side effects associated with the intubation period.