Comparison of intravenous and topical lidocaine in attenuating the cardiovascular responses to endotracheal intubation

We administered lidocaine intravenously or topically to the larynx to compare the cardiovascular response to intubation between the two techniques and to determine if these responses were related to blood levels of lidocaine. Sixteen patients were randomly selected into group A (100 mg intravenous lidocaine) or group B (160 mg topical lidocaine). Neither method was completely effective in abolishing hypertension and tachycardia on intubation. The increase in pulse rate (PR) was more significant than the rise in mean arterial pressure (MAP) and was of longer duration. Significant increases in MAP were evident for less than two minutes in group A and less than three minutes in group B. Significant increases in PR were observed for approximately four minutes in group A and six minutes in group B. The average lidocaine blood level in group A was approximately 20 times that in group B at the time of intubation. The more prolonged and more significant increase in PR observed in group B indicates that intravenous administration of lidocaine may be superior to topical administration.