title: Extending the golden hour: Partial resuscitative endovascular balloon occlusion of the aorta in a highly lethal swine liver injury model.
abstract: BACKGROUND
  Combat-injured patients may require rapid and sustained support during transport; however, the prolonged aortic occlusion produced by conventional resuscitative endovascular balloon occlusion of the aorta (REBOA) may lead to substantial morbidity. Partial REBOA (P-REBOA) may permit longer periods of occlusion by allowing some degree of distal perfusion. However, the ability of this procedure to limit exsanguination is unclear. We evaluated the impact of P-REBOA on immediate survival and ongoing hemorrhage in a highly lethal swine liver injury model.
  
  
  METHODS
  Fifteen Yorkshire-cross swine were anesthetized, instrumented, splenectomized, and subjected to rapid 10% total blood loss followed by 30% liver amputation. Coagulopathy was created through colloid hemodilution. Randomized swine received no intervention (control), P-REBOA, or complete REBOA (C-REBOA). Central mean arterial pressure (cMAP), carotid blood flow, and blood loss were recorded. Balloons remained inflated in the P-REBOA and C-REBOA groups for 90 minutes followed by graded deflation. The study ended at 180 minutes from onset of hemorrhage or death of the animal. Survival analysis was performed, and data were analyzed using repeated-measures analysis of variance with post hoc pairwise comparisons.
  
  
  RESULTS
  Mean survival times in the control, P-REBOA, and C-REBOA groups were, 25 ± 21, 86 ± 40, and 163 ± 20 minutes, respectively (p < 0.001). Blood loss was greater in the P-REBOA group than the C-REBOA or control groups, but this difference was not significant (4,722 ± 224, 3,834 ± 319, 3,818 ± 37 mL, respectively, p = 0.10). P-REBOA resulted in maintenance of near-baseline carotid blood flow and cMAP, while C-REBOA generated extreme cMAP and prolonged supraphysiologic carotid blood flow. Both experimental groups experienced profound decreases in cMAP following balloon deflation.
  
  
  CONCLUSIONS
  In the setting of severe ongoing hemorrhage, P-REBOA increased survival time beyond the golden hour while maintaining cMAP and carotid flow at physiologic levels.
authors.affiliation: From the Department of Surgery (R.M.R., T.K.W., J.M.G., L.P.N.), UC Davis Medical Center, Sacramento; Clinical Investigation Facility (R.M.R., T.K.W., J.K.G., C.M.L., L.P.N.), and Departments of Vascular and Endovascular Surgery (T.K.W., C.M.L.), Pathology (N.F.C.), and General Surgery (L.P.N.), David Grant USAF Medical Center, Travis Air Force Base, Fairfield, California; Department of Surgery (J.W.C.), Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania; and Academic Department of Military Surgery and Trauma (C.M.L.), Royal Centre for Defense Medicine, Birmingham, United Kingdom.
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Russo
authors.forename: Timothy K
authors.initials: TK
authors.lastname: Williams
authors.forename: John Kevin
authors.initials: JK
authors.lastname: Grayson
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Lamb
authors.forename: Jeremy W
authors.initials: JW
authors.lastname: Cannon
authors.forename: Nathan F
authors.initials: NF
authors.lastname: Clement
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Galante
authors.forename: Lucas P
authors.initials: LP
authors.lastname: Neff
mesh_terms: D000007:Abdominal Injuries / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D000818:Animals; D001013:Aorta, Thoracic / Q000601:surgery*; D021721:Balloon Occlusion / Q000379:methods*; D004195:Disease Models, Animal; D057510:Endovascular Procedures / Q000379:methods*; D058734:Exsanguination / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D006439:Hemodynamics / Q000502:physiology; D008099:Liver / Q000098:blood supply / Q000293:injuries*; D012151:Resuscitation / Q000379:methods*; D013552:Swine