title: End-tidal partial pressure of carbon dioxide as a noninvasive indicator of systemic oxygen supply dependency during hemorrhagic shock and resuscitation.
abstract: When oxygen delivery (DO2) critically decreases, oxygen consumption (VO2) becomes supply dependent. We examined whether end-tidal PCO2 (PetCO2) would identify supply dependency during shock. Five dogs (Group I) underwent progressive hemorrhage to decrease DO2 until they could no longer maintain a stable blood pressure. Five additional animals (Group II) were bled until VO2 decreased to 70% of baseline, followed by resuscitation. The PetCO2 versus time inflection point was compared with the DO2 at onset of supply dependency (DO2crit). DO2crit for Groups I and II were 6.9 +/- .4 and 8.1 +/- 1.3, respectively (p = NS), and not statistically different from the DO2 values at which PetCO2 decreased (6.6 +/- .7 and 6.3 +/- .7 mL/kg per min, respectively). AT constant minute volume, PetCO2 effectively indicated the onset of supply dependency and rapidly increased during resuscitation, paralleling the changes in VO2 in this model of hemorrhagic shock.
authors.affiliation: Section of Critical Care Medicine, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Guzman
authors.forename: F J
authors.initials: FJ
authors.lastname: Lacoma
authors.forename: A
authors.initials: A
authors.lastname: Najar
authors.forename: J A
authors.initials: JA
authors.lastname: Kruse
mesh_terms: D000818:Animals; D001803:Blood Transfusion; D002245:Carbon Dioxide / Q000097:blood*; D004285:Dogs; D006439:Hemodynamics; D019344:Lactic Acid / Q000097:blood; D010100:Oxygen / Q000008:administration & dosage; D010101:Oxygen Consumption / Q000502:physiology*; D010313:Partial Pressure; D012044:Regression Analysis; D012119:Respiration / Q000502:physiology; D012151:Resuscitation; D012771:Shock, Hemorrhagic / Q000097:blood* / Q000503:physiopathology*; D013990:Tidal Volume
chemical_list: D002245:Carbon Dioxide; D019344:Lactic Acid; D010100:Oxygen