Comparison of the pharmacological effects of epinephrine administered by the intravenous and endotracheal routes.

Epinephrine in various dosages was administered to anesthetized dogs by intravenous and endotracheal routes. Both methods produced measurable effects on heart rate, blood pressure, and respiration. Tachycardia occurred more rapidly after endotracheal administration than after intravenous administration. Respiration appeared to be supported more advantageously with the larger endotracheal dosages. The maximum blood pressure rise was delayed only 60 seconds by the endotracheal route. With an endotracheally administered dose of ten times the intravenous dose, equal responses in blood pressure were obtained. However, when equal doses are compared, there is only a two to three fold increase with the intravenous route. The endotracheal route may be less toxic at higher doses, affording greater safety when large amounts of epinephrine are used. It is concluded that endotracheally administered epinephrine produces significant pharmacologic effects in anesthetized dogs.