title: Noninvasive muscle oxygenation to guide fluid resuscitation after traumatic shock.
abstract: BACKGROUND
  Three different protocols tested the hypothesis that hind limb muscle tissue O(2) saturation (StO(2)), measured noninvasively with near-infrared spectroscopy (NIRS), is as reliable as invasive systemic oxygenation indices to guide fluid resuscitation.
  
  
  METHODS
  In series 1, swine (n=30) were hemorrhaged, then received either no fluid, a fixed volume of colloid (15 mL/kg), or shed blood plus lactated Ringer's (LR) titrated to MAP >60 mm Hg. In series 2, swine (n=16) received a penetrating femur injury, a 47% to 55% hemorrhage to determine a median lethal dose (LD(50)) then shed blood plus LR titrated to MAP >60 mm Hg. In series 3, swine (n=5) received the femur injury plus LD(50) hemorrhage, and were resuscitated with LR titrated to StO(2) >50%.
  
  
  RESULTS
  In series 1, StO(2) tracked mixed venous O(2) saturation (SvO(2)), but discriminated between 3 survivor groups better than SvO(2), arterial lactate, or arterial base excess. In series 2, StO(2) tracked SvO(2) but discriminated between 2 survivor groups better than SvO(2), arterial lactate, or arterial base excess. In series 3, animals survived to extubation when resuscitated to an StO(2) target.
  
  
  CONCLUSIONS
  Noninvasive muscle StO(2) determined by NIRS was more reliable than invasive oxygenation variables as an index of shock. Because muscle StO(2) can be easily monitored in emergency situations, it may represent an improved method to gauge the severity of shock or the adequacy of fluid resuscitation after trauma.
authors.affiliation: Daughtry Family Department of Surgery, University of Miami School of Medicine, FL 33136, USA.
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Crookes
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Cohn
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Burton
authors.forename: Jacob
authors.initials: J
authors.lastname: Nelson
authors.forename: Kenneth G
authors.initials: KG
authors.lastname: Proctor
mesh_terms: D000818:Animals; D001158:Arteries / Q000378:metabolism; D005260:Female; D005269:Femur / Q000293:injuries; D005440:Fluid Therapy / Q000592:standards; D006614:Hindlimb; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000097:blood; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D012151:Resuscitation / Q000592:standards; D012774:Shock, Traumatic / Q000175:diagnosis / Q000628:therapy*; D019265:Spectroscopy, Near-Infrared; D015996:Survival Rate; D013552:Swine
chemical_list: D019344:Lactic Acid; D010100:Oxygen