title: Comparison of pH and carbon dioxide tension values of central venous and intraosseous blood during changes in cardiac output.
abstract: OBJECTIVE
  To compare the pH and PCO2 values determined from of simultaneously corrected samples of central venous and intraosseous blood during sequential changes in cardiac output.
  
  
  METHODS
  Prospective, descriptive study.
  
  
  METHODS
  An animal laboratory in a university medical center.
  
  
  METHODS
  Fourteen mixed breed 4-wk-old piglets.
  
  
  METHODS
  Animals were anesthetized with ketamine hydrochloride and neuromuscular blockade was induced by the administration of pancuronium bromide. After endotracheal intubation and the institution of mechanical ventilation, a 4-Fr pulmonary artery catheter and a carotid artery cannula were inserted via a cutdown into the right neck of each piglet. A 16-gauge intraosseous needle was inserted into the anteromedial surface of the right tibia.
  
  
  RESULTS
  Central venous and intraosseous blood gas samples were obtained simultaneously with thermodilution cardiac output measurements. Cardiac output measurements were as follows: during steady state (0.80 +/- 0.14 L/min), after volume loading of 15 mL/kg (1.00 +/- 0.25 L/min), after three successive bleeds of 15 mL/kg each at 30-min intervals (0.70 +/- 0.28, 0.54 +/- 0.22, and 0.43 +/- 0.16 L/min, respectively) and at exsanguination (unrecordable). Paired t-tests demonstrated no significant differences in pH and PCO2 values between intraosseous and central venous samples under all study conditions. Limits of agreement for difference in PCO2 between sites, within the range of cardiac outputs studied, were -12.86 to 11.38 torr (-1.71 to 1.46 kPa) and for pH were -0.09 to 0.15.
  
  
  CONCLUSIONS
  Intraosseous blood samples can be obtained without difficulty even during extreme hypovolemia. The pH and PCO2 values of intraosseous and central venous blood samples were similar under all study conditions. Intraosseous blood may be a useful alternative to central venous blood to assess tissue acid-base status during hemorrhagic shock and other low-flow states.
authors.affiliation: Department of Pediatrics, University of Florida, Jacksonville.
authors.forename: N
authors.initials: N
authors.lastname: Kissoon
authors.forename: R
authors.initials: R
authors.lastname: Peterson
authors.forename: S
authors.initials: S
authors.lastname: Murphy
authors.forename: M
authors.initials: M
authors.lastname: Gayle
authors.forename: E
authors.initials: E
authors.lastname: Ceithaml
authors.forename: A
authors.initials: A
authors.lastname: Harwood-Nuss
mesh_terms: D000818:Animals; D001810:Blood Volume / Q000502:physiology; D001842:Bone and Bones / Q000098:blood supply; D002245:Carbon Dioxide / Q000097:blood*; D002302:Cardiac Output / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D010313:Partial Pressure; D011446:Prospective Studies; D012771:Shock, Hemorrhagic / Q000097:blood / Q000453:epidemiology / Q000503:physiopathology; D013552:Swine; D013997:Time Factors; D014680:Veins
chemical_list: D002245:Carbon Dioxide