Effects of epinephrine and norepinephrine contained in 2% lidocaine on hemodynamics of the carotid and cerebral circulation in older and younger adults.

The effects of vasoconstrictor-containing local anesthetics on the carotid and cerebral circulation were investigated using an ultrasonic quantitative blood flow measurement system. Nineteen healthy adult volunteers were divided into two groups according to age. The local anesthetics used were 2% lidocaine containing 1:80,000 epinephrine and 2% lidocaine containing 1:25,000 norepinephrine. One (1.8 mL) or two (3.6 mL) cartridges of each anesthetic were injected into unilateral or bilateral maxillary gingivae. Epinephrine-containing lidocaine had little effect on carotid and cerebral hemodynamics. Norepinephrine-containing lidocaine increased arterial blood pressure, decreased heart rate, and decreased carotid arterial blood flow and velocity, which caused increased cerebrovascular resistance and decreased cerebrovascular capacitance. The results suggest that norepinephrine may induce vasoconstriction of the cerebral blood vessels in both young and old adults in a dose-dependent manner. These changes appear to be greater in older people.