title: Determination of the optimal mean arterial pressure for postbleeding resuscitation after hemorrhagic shock in rats.
abstract: BACKGROUND
  The authors previously found that 50-60 mmHg mean arterial blood pressure (MAP) was an optimal target resuscitation pressure for hemorrhagic shock before bleeding was controlled in rats. However, the optimal target resuscitation pressure for hemorrhagic shock after bleeding has been controlled has not been determined.
  
  
  METHODS
  A model of uncontrolled hemorrhagic shock was initiated in anesthetized Wistar rats. After 1-h hypotensive resuscitation and bleeding was stopped, rats received fluid resuscitation to different target MAPs (50, 70, or 90 mmHg) with lactated Ringer's solution (LR), 6% hydroxyethyl starch (HES), LR+HES (2:1) or LR+whole blood (2:1) for 2 h. Animal survival, hemodynamic parameters, and vital organ functions were observed.
  
  
  RESULTS
  After bleeding had been controlled, mildly hypotensive resuscitation at a target MAP of 70 mmHg increased the survival time and survival rate compared with a target MAP of 50 mmHg and 90 mmHg (P < 0.05 or 0.01). Hemodynamic parameters, cardiac output, oxygen delivery, and vital organ function (including mitochondrial function) in 70 mmHg target MAP groups were better than in other two-target pressure groups (P < 0.05 or 0.01). Among the fluids tested, LR+whole blood (2:1) or LR+HES130 (2:1) had better effects than LR or HES alone at each level of target blood pressure.
  
  
  CONCLUSIONS
  Mildly hypotensive resuscitation is also needed for hemorrhagic shock after bleeding has been controlled, irrespective of whether crystalloids or colloids are used. The optimal target pressure was 70 mmHg in our rat model. A resuscitation pressure that is too low or too high cannot produce a good resuscitative effect.
authors.affiliation: State Key Laboratory of Trauma, Burns and Combined Injury, Second Department of Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Li
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhu
authors.forename: Yuqiang
authors.initials: Y
authors.lastname: Fang
authors.forename: Liangming
authors.initials: L
authors.lastname: Liu
mesh_terms: D000818:Animals; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000502:physiology*; D001834:Body Water / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D005260:Female; D005440:Fluid Therapy / Q000379:methods; D006439:Hemodynamics / Q000502:physiology; D006895:Hydroxyethyl Starch Derivatives / Q000627:therapeutic use; D007552:Isotonic Solutions; D007668:Kidney / Q000378:metabolism; D008102:Liver Circulation / Q000502:physiology; D008297:Male; D008930:Mitochondria, Liver / Q000378:metabolism; D010100:Oxygen / Q000008:administration & dosage; D010101:Oxygen Consumption / Q000502:physiology; D010952:Plasma Substitutes / Q000627:therapeutic use; D051381:Rats; D017208:Rats, Wistar; D012039:Regional Blood Flow; D012079:Renal Circulation / Q000502:physiology; D012151:Resuscitation / Q000379:methods*; D000077331:Ringer's Solution; D012771:Shock, Hemorrhagic / Q000503:physiopathology* / Q000628:therapy*; D013534:Survival
chemical_list: D006895:Hydroxyethyl Starch Derivatives; D007552:Isotonic Solutions; D010952:Plasma Substitutes; D000077331:Ringer's Solution; D010100:Oxygen