title: Investigation of muscle pH as an indicator of liver pH and injury from hemorrhagic shock.
abstract: BACKGROUND
  During hemorrhagic shock blood flow to vital organs is maintained by the diversion of blood from both the splanchnic organs and skeletal muscle. In this swine study, we tested the hypotheses that (1). liver and muscle pH are correlated during both shock and resuscitation and (2). muscle pH during shock is an indicator of potential liver injury after resuscitation.
  
  
  METHODS
  Hemorrhagic shock was induced over 15 min to lower systolic blood pressure to 40 mm Hg and was maintained for 60 (n = 5) or 90 (n = 5) min. Resuscitation was achieved with shed blood and warm saline to maintain mean pressure >60 mm Hg for 120 min. Liver and muscle pH were measured with microelectrodes throughout the entire shock and resuscitation periods, along with hepatic venous oxygen saturation. Arterial lactate and aspartate aminotransferase were measured at baseline, end of shock, and resuscitation. Correlation between muscle and liver pH was determined. The ability of muscle pH to predict liver injury (40% increase in arterial aspartate aminotransferase) was compared with other predictors: liver pH, arterial lactate, and tonometric-arterial PCO(2) gap.
  
  
  RESULTS
  pH values and rates of change were similar in both muscle and liver tissue. Liver pH was well correlated with muscle pH during both shock and resuscitation, R(2) = 0.84. Muscle pH predicts potential liver injury with the same sensitivity as blood lactate in this swine shock model.
  
  
  CONCLUSIONS
  Minimally invasive measurement of muscle pH warrants further study as a method to assess splanchnic hypoperfusion and resultant injury.
authors.affiliation: Department of Surgery, University of Massachusetts Medical School, Worcester, MA, USA. babs.soller@umassmed.edu
authors.forename: Babs R
authors.initials: BR
authors.lastname: Soller
authors.forename: Tania
authors.initials: T
authors.lastname: Khan
authors.forename: Janice
authors.initials: J
authors.lastname: Favreau
authors.forename: Charles
authors.initials: C
authors.lastname: Hsi
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Puyana
authors.forename: Stephen O
authors.initials: SO
authors.lastname: Heard
mesh_terms: D000818:Animals; D001219:Aspartate Aminotransferases / Q000378:metabolism; D015415:Biomarkers; D001794:Blood Pressure; D004195:Disease Models, Animal; D006503:Hepatic Veins / Q000503:physiopathology; D006863:Hydrogen-Ion Concentration; D008099:Liver / Q000503:physiopathology*; D008839:Microelectrodes; D018482:Muscle, Skeletal / Q000503:physiopathology*; D010100:Oxygen / Q000097:blood; D012151:Resuscitation; D012771:Shock, Hemorrhagic / Q000503:physiopathology*; D013552:Swine
chemical_list: D015415:Biomarkers; D001219:Aspartate Aminotransferases; D010100:Oxygen