title: Direct vascular control results in less physiologic derangement than proximal aortic clamping in a porcine model of noncompressible extrathoracic torso hemorrhage.
abstract: BACKGROUND
  The optimal method of vascular control and resuscitation in patients with life-threatening, extrathoracic torso hemorrhage remains debated. Guidelines recommend emergency department thoracotomy (EDT) with aortic clamping, although transabdominal aortic clamping followed by vascular control and direct vascular control (DVC) without aortic clamping are alternatives. The objective of this study is to compare the effectiveness of three approaches to extrathoracic torso hemorrhage in a large animal model.
  
  
  METHODS
  Adolescent swine (Sus Scrofa) (mean weight = 80.9 kg) were randomized into three groups all of which had class IV shock established by hemorrhage from an iliac artery injury. Group 1: EDT with thoracic aortic clamping (N = 6); group 2: transabdominal supraceliac aortic clamping (SCC; N = 6); and group 3: DVC of bleeding site without aortic clamping (N = 6). After hemorrhage, EDT or SCC was performed in groups 1 and 2, respectively, with subsequent exploration of the bleeding site and placement of a temporary vascular shunt (TVS). Group 3 (DVC) underwent direct exploration of the injury and placement of a TVS. All groups were resuscitated to predefined physiologic endpoints over 6 hours with repeated measures of central and cerebral perfusion and end-organ function at standardized time points. Postmortem tissue analysis was performed to quantify injury to critical tissue beds.
  
  
  RESULTS
  There was no difference in mortality among the groups and no TVS failures. Central aortic pressure, carotid flow, and partial pressure brain tissue oximetry, all demonstrated increases in EDT and SCC after application of the aortic clamp relative to DVC (p < 0.05). During resuscitation, serum lactate levels were higher in EDT compared with SCC and DVC (6.85 vs. 3.08 and 2.15, respectively; p < 0.05) and serum pH in EDT reflected greater acidosis than SCC and DVC (7.24 vs. 7.36 and 7.39, respectively; p < 0.05). EDT and SCC required more intravenous fluid than DVC (2,166 mL and 2,166 mL vs. 667 mL, respectively; p < 0.05) and more vasopressors were used in EDT and SCC compared with DVC (52.1 μg and 43.5 μg vs. 12.4 μg, respectively; p < 0.05). Brain and myocardial tissue stains demonstrated the same degree of acute ischemic changes in all groups.
  
  
  CONCLUSIONS
  Although aortic clamping increases central and cerebral perfusion, DVC results in less physiologic derangement. The optimal method of aortic control would incorporate the benefits of maintained central pressure with less associated morbidity. Clinical studies evaluating DVC are warranted.
authors.affiliation: United States Army Institute of Surgical Research, Fort Sam, Houston, Texas 78236, USA.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: White
authors.forename: Jeremy W
authors.initials: JW
authors.lastname: Cannon
authors.forename: Adam
authors.initials: A
authors.lastname: Stannard
authors.forename: Gabriel E
authors.initials: GE
authors.lastname: Burkhardt
authors.forename: Jerry R
authors.initials: JR
authors.lastname: Spencer
authors.forename: Ken
authors.initials: K
authors.lastname: Williams
authors.forename: John S
authors.initials: JS
authors.lastname: Oh
authors.forename: Todd E
authors.initials: TE
authors.lastname: Rasmussen
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000293:injuries*; D004195:Disease Models, Animal; D007083:Iliac Artery / Q000293:injuries*; D007773:Lactates / Q000097:blood; D008991:Monitoring, Physiologic; D010100:Oxygen / Q000097:blood; D011446:Prospective Studies; D011897:Random Allocation; D012151:Resuscitation; D012771:Shock, Hemorrhagic / Q000503:physiopathology* / Q000628:therapy*; D013525:Surgical Instruments; D013552:Swine; D014947:Wounds and Injuries / Q000503:physiopathology* / Q000628:therapy*
chemical_list: D007773:Lactates; D010100:Oxygen