title: Relationship between systemic oxygen supply dependency and gastric intramucosal PCO2 during progressive hemorrhage.
abstract: BACKGROUND
  As systemic oxygen delivery (DO2) is reduced, oxygen consumption (VO2) is maintained until a critical level is reached (DO2crit) below which VO2 becomes supply-dependent and anaerobic metabolism ensues. We examined the relationship between gastric intramucosal PCO2 (PiCO2) and the onset of systemic supply dependency. We also compared PiCO2 to mixed venous and portal venous blood PCO2 (PmvCO2 and PpvCO2) to assess their utility as premonitory indicators of supply dependency.
  
  
  METHODS
  Six dogs were subjected to stepwise hemorrhage to effect a progressive decrease in DO2. Inflection points for changes in VO2, PiCO2, PmvCO2, and PpvCO2 versus DO2 were determined.
  
  
  RESULTS
  Mean DO2crit was 6.0 +/- 0.7 mL x kg(-1) x min(-1), whereas the DO2 at which inflection points occurred for PiCO2 and PpvCO2 were 13.2 +/- 1.4 and 11.2 +/- 1.5 mL x kg(-1) x min(-1), respectively (p < 0.05 for both).
  
  
  CONCLUSIONS
  Continuous monitoring of PiCO2 using capnometric recirculating gas tonometry can serve as an early indicator of systemic hypoperfusion before the onset of systemic supply dependency.
authors.affiliation: Section of Critical Care Medicine, Wayne State University School of Medicine, Detroit, Michigan, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Guzman
authors.forename: F J
authors.initials: FJ
authors.lastname: Lacoma
authors.forename: J A
authors.initials: JA
authors.lastname: Kruse
mesh_terms: D015308:Anaerobic Threshold; D000818:Animals; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000032:analysis* / Q000378:metabolism; D004195:Disease Models, Animal; D004285:Dogs; D005753:Gastric Mucosa / Q000737:chemistry / Q000378:metabolism*; D006439:Hemodynamics; D006470:Hemorrhage / Q000378:metabolism* / Q000503:physiopathology; D006863:Hydrogen-Ion Concentration; D008991:Monitoring, Physiologic; D010100:Oxygen / Q000032:analysis / Q000378:metabolism; D010101:Oxygen Consumption; D013152:Splanchnic Circulation
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen