• Mikhail Y Maslov, Abraham E Wei, Matthew J Pezone, Elazer R Edelman, and Mark A Lovich.
• Tufts University School of Medicine, Department of Anesthesiology and Pain Medicine, Elizabeth's Medical Center, Boston, Massachusetts, 02135, USA. Electronic address: mikhail.maslov@steward.org.
• Heart Lung Circ. 2015 Sep 1; 24 (9): 912-8.

BackgroundWhile epinephrine infusion is widely used in critical care for inotropic support, there is no direct method to detect the onset and measure the magnitude of this response. We hypothesised that surrogate measurements, such as heart rate and vascular tone, may indicate if the plasma and tissue concentrations of epinephrine and cAMP are in a range sufficient to increase myocardial contractility.MethodsCardiovascular responses to epinephrine infusion (0.05-0.5 mcgkg(-1)min(-1)) were measured in rats using arterial and left ventricular catheters. Epinephrine and cAMP levels were measured using ELISA techniques.ResultsThe lowest dose of epinephrine infusion (0.05 mcgkg(-1)min(-1)) did not raise plasma epinephrine levels and did not lead to cardiovascular response. Incremental increase in epinephrine infusion (0.1 mcgkg(-1)min(-1)) elevated plasma but not myocardial epinephrine levels, providing vascular, but not cardiac effects. Further increase in the infusion rate (0.2 mcgkg(-1)min(-1)) raised myocardial tissue epinephrine levels sufficient to increase heart rate but not contractility. Inotropic and lusitropic effects were significant at the infusion rate of 0.3 mcgkg(-1)min(-1). Correlation of plasma epinephrine to haemodynamic parameters suggest that as plasma concentration increases, systemic vascular resistance falls (EC50=47 pg/ml), then HR increases (ED50=168 pg/ml), followed by a rise in contractility and lusitropy (ED50=346 pg/ml and ED50=324 pg/ml accordingly).ConclusionsThe dose response of epinephrine is distinct for vascular tone, HR and contractility. The need for higher doses to see cardiac effects is likely due to the threshold for drug accumulation in tissue. Successful inotropic support with epinephrine cannot be achieved unless the infusion is sufficient to raise the heart rate.Copyright © 2015 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

30 keywords...

hide…