%0 Journal Article
%T The physiologic responses to epinephrine during cooling and after rewarming in vivo
%A Torkjel Tveita
%A Gary C Sieck
%J Critical Care
%D 2011
%I BioMed Central
%R 10.1186/cc10465
%X Sprague-Dawley rats were instrumented to measure mean arterial pressure (MAP), and left ventricular (LV) pressure-volume changes were recorded by using a Millar pressure-volume conductance catheter. Core temperature was reduced from 37¡ãC to 28¡ãC and returned to 37¡ãC by using both internal and external heat exchangers. Two groups of rats were infused with either saline (n = 7), or Epi 0.125 ¦Ìg/min continuously (n = 7). At 33¡ãC, 30¡ãC, and 28¡ãC, the Epi infusion was temporarily increased from 0.125 to 1.25 ¦Ìg/min.Before cooling, Epi infusion in both groups resulted in a significant, dose-dependent increase in heart rate (HR), stroke volume (SV), cardiac output (CO), LV dP/dtmax (maximum derivative of systolic pressure over time), but only Epi infusion at 1.25 ¦Ìg/min caused elevation of MAP. During cooling to 30¡ãC, Epi infusion at 0.125 ¦Ìg/min caused a significant elevation of central hemodynamic variables, whereas MAP remained unchanged. In contrast, Epi infusions at 1.25 ¦Ìg/min caused a significant elevation of MAP during cooling to 28¡ãC but no increases in central hemodynamics. After rewarming, all hemodynamic variables returned to baseline in both groups, but only the saline-treated animals displayed the prehypothermic hemodynamic dose responses to Epi infusions.This study shows that hypothermia causes a change in the physiological hemodynamic response to Epi, which is not reversed by rewarming.Guidelines for using inotropic drugs to support cardiovascular function at low core temperatures are not well characterized. Such guidelines are essential for treating patients in acute heart failure, as will be the case during induced therapeutic hypothermia, as well as during rewarming from accidental hypothermia. Detailed knowledge of temperature-dependent changes in pharmacodynamics and pharmacokinetics of such cardioactive drugs is essential for establishing treatment guidelines.Over the last decade, induced hypothermia is being increasingly used to reduce cerebral damag
%U http://ccforum.com/content/15/5/R225