Plasma catecholamine levels following tracheal and intravenous epinephrine administration in swine

We compared plasma epinephrine levels after three different tracheal epinephrine application techniques and intravenous injection in male and female anesthetized and paralyzed domestic pigs. Epinephrine was administered intravenously (10 microg/kg) (group i.v.) or tracheally (100 microg/kg) either by direct injection into the upper end of the tracheal tube (group Tube), via a suction tube placed into the bronchial system (group Catheter) or using an EDGAR tube (group EDGAR), each group: n = 8. Arterial plasma samples were drawn before and 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7 and 10 min after epinephrine administration. Plasma concentrations of epinephrine were measured with high pressure liquid chromatography using electrochemical detection. Analysis was performed by regression analysis for correlated data. Total plasma epinephrine concentrations showed a significant increase within 0.5 min in all groups. However, peak plasma epinephrine levels in group i.v. were significantly higher than in tracheal groups, while no differences between tracheal groups over the time were found. We conclude that in swine with spontaneous circulation tracheal instillation techniques using special devices such as suction tubes or EDGAR tubes result in onset and peak plasma epinephrine levels equivalent to those after direct injection into the upper end of the tracheal tube.