title: Early norepinephrine infusion delays cardiac arrest after hemorrhagic shock in rats.
abstract: BACKGROUND
  Severe hemorrhagic shock often results in cardiac arrest due to vital organ hypoperfusion, especially of the heart. Although fluid resuscitation is the mainstay of management in hemorrhagic shock, treatment of cardiac arrest in association with severe hemorrhagic shock is unclear.
  
  
  OBJECTIVE
  This study was designed to determine the effect of early infusion of norepinephrine on hemodynamics and survival in hemorrhagic shock.
  
  
  METHODS
  Twelve Sprague-Dawley rats were bled to about 35% of estimated blood volume for 30 min and randomized to one of two groups: the study group received norepinephrine (10 microg/kg/min) in 5% dextrose solution (n = 6); the control group received the same volume of 5% dextrose (n = 6) concurrently with Lactated Ringer's solution. After 30 min of resuscitation, half of the shed blood was transfused in both groups. Time to cardiac arrest and mean arterial pressure (MAP) were compared between the two groups.
  
  
  RESULTS
  MAP during the resuscitation period was higher in the norepinephrine group than in the control group. Five of 6 rats in the norepinephrine group but none of the control group survived until the transfusion period (83.3% vs. 0.0%, respectively; p = 0.003). Median time to cardiac arrest was significantly longer in the norepinephrine group (67.0 min, interquartile range [IQR] 60.0-77.0) than in controls (41.0 min, IQR 40.0-47.0; p = 0.002).
  
  
  CONCLUSIONS
  Early use of norepinephrine in a rat model of hemorrhagic shock increased mean arterial pressure during the resuscitation period and delayed the onset of cardiac arrest.
authors.affiliation: Department of Emergency Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Jae Hyuk
authors.initials: JH
authors.lastname: Lee
authors.forename: Kyuseok
authors.initials: K
authors.lastname: Kim
authors.forename: You Hwan
authors.initials: YH
authors.lastname: Jo
authors.forename: Kyung Su
authors.initials: KS
authors.lastname: Kim
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Lee
authors.forename: Woon Yong
authors.initials: WY
authors.lastname: Kwon
authors.forename: Joong Eui
authors.initials: JE
authors.lastname: Rhee
authors.forename: Gil Joon
authors.initials: GJ
authors.lastname: Suh
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Singer
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D005440:Fluid Therapy; D006323:Heart Arrest / Q000209:etiology / Q000517:prevention & control*; D007262:Infusions, Intravenous; D053208:Kaplan-Meier Estimate; D008297:Male; D009638:Norepinephrine / Q000008:administration & dosage*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012771:Shock, Hemorrhagic / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology
chemical_list: D000316:Adrenergic alpha-Agonists; D009638:Norepinephrine