Laryngoscopy and intubation can lead to tachacardia and hypertension, which 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 these conditions. Lidocaine acts as a vasodilator with direct results of smooth muscle relaxation (Forbes & Dally, 1970; Nagelhout & Zaglaniczny, 2001).
Lidocaine can be sprayed topically or it can be administered intravenously. Both administrations result in a blocking of sodium channels, a decrease in depolarization, a decrease in sympathetic nervous system stimulation, and a decrease in catecholamine release. This leads to a blunting of the side effects of endotracheal intubation (tachacardia and hypertension) (Morgan & Mikhail, 1996).
While research presents findings regarding the negative effects of laryngoscopy and endotracheal intubation, as well as positive effects of lidocaine use, it remains unclear as to which method of administration is more effective. Some have shown that both intravenous and topical use of lidocaine had positive effects, others have shown intravenous administration to be superior to topical administration, and still others have shown no protection from either type of administration (Laurito, Baughman, Becker, Polek, Riegler, & VadeBoncouer, 1988; Stoelting, 1977; Youngberg, Graybar, & Hutchings, 1983). Previous research also demonstrates differences in findings resulting from timing of administration, which may have effected results in all studies. For example, Wilson, Meiklejohn, & Smith, 1991) found that intravenous administration of lignocaine 4 minutes prior to laryngoscopy was effective but 2 minutes prior had no effect. A study is needed to resolve this controversy and determine the most effective route of lidocaine administration.
The purpose of this study is to determine if there is a di...