EFFECTIVENESS OF TOPICAL AND INTRAVENOUS APPLICATION OF LIDOCAINE FOR BLUNTING INCREASES IN HEART RATE AND BLOOD PRESSURE DURING LARYNGOSCOPY AND INTUBATION
Increased heart rates and arterial blood pressure are commonly found following laryngoscopy and endotracheal intubation and these effects can result in increased danger for coronary-artery disease patients (Bidwal, Bidwal, Rogers, & Stanely, 1979; Hamill, Bedford, Weaver, & Colohan, 1981). Lidocaine administered to suppress these effects has been shown to be beneficial and has been used as a supplement to general anesthesia for years. Early studies demonstrated its positive effect of suppressing the cough reflex (Steinhaus & Gaskin, 1963), while Demczuk (1984) demonstrated that it also can depress the sinus node and result in sinus bradycardia. Research regarding mechanisms of action remain unclear. Takki, Tammisto, Nikki, and Jaattela (1972) found no changes in catecholamine levels during laryngoscopy, and yet Derbyshire, Chmielewski, Feli, Vater, Achola, and Smith (1983) found mean arterial pressure increases were related to increased plasma catecholamine concentrations in response to tracheal intubation.
Laryngoscopy and intubation can lead to tachacardia and hypertension. Laryngoscopy and intubation interrupt an individual's reflex action. Protective airway reflexes are in place and when violated they lead to tachycardia and hypertension. These responses can be blunted with the use of intravenous and topical administration of lidocaine (1.5 mg/kg 1-2 minutes before laryngoscopy has been recommended) (Morgan & Mikhail, 1992). These reactions may not present problems for the healthy individual, however, for those with accompanying cardiovascular problems, these consequences may be life-threatening. Lidocaine and other local anesthetics are used to attenuate the side effects of laryngoscopy and intubation. (Lidocaine is theorized to act as a vasodilator with dire...