title: Intraosseous blood gases during hypothermia: correlation with arterial, mixed venous, and sagittal sinus blood.
abstract: OBJECTIVE
  Especially in pediatric patients with severe hypothermia, intraosseous access may be more readily available than intravascular access during an early phase of treatment and therefore, may be helpful to optimize management. The purpose of this study was to determine whether intraosseous blood gases are comparable with arterial, mixed venous, and sagittal sinus blood gases during different degrees of hypothermia.
  
  
  METHODS
  Prospective, descriptive laboratory investigation using a porcine model.
  
  
  METHODS
  University hospital laboratory.
  
  
  METHODS
  Twelve anesthetized, 12- to 16-wk-old domestic pigs weighing 30-35 kg.
  
  
  METHODS
  Volume-controlled ventilated animals were instrumented with arterial, pulmonary artery, sagittal sinus, and 16-gauge intraosseous catheters. Blood samples were obtained from each site every 15 mins during surface cooling with crushed ice until mean +/- SEM core temperature decreased from 38.5+/-0.1 degrees C [101.3+/-0.2 degrees F] to 27+/-0.5 degrees C [80.5+/-0.9 degrees F] over 2 hrs.
  
  
  RESULTS
  Intraindividual correlation of Pco2 and pH values were determined as the difference (delta) between intraosseous and reference blood samples. With hypothermia, absolute values of Pco2 decreased and pH increased in samples from all sites. At 27 degrees C, intraosseous--arterial delta P(CO2) and delta pH (mean +/- 95% confidence intervals) were 2.6+/-10.6 torr [0.35+/-1.4 kPa] and -0.11+/-0.07 units; intraosseous - mixed venous were 0.4+/-12.2 torr [0.05+/-1.6 kPa] and -0.06+/-0.08 units; and intraosseous - sagittal sinus were -7.3+/-16 torr [-0.97+/-2.1 kPa] and 0.001+/-0.14 units, respectively. Intraosseous Pco2 was not comparable to end-tidal values (deltaP(CO2) 17.4+/-14.6 torr [2.3+/-1.9 kPa]), and intraosseous lactate did not correlate with arterial, mixed venous, or sagittal sinus values.
  
  
  CONCLUSIONS
  During hypothermia, intraosseous P(CO2) values were predictable for mixed venous Pco2 and arterial P(CO2). Intraosseous pH values also correlated with mixed venous and sagittal sinus blood samples. Accordingly, interpretation of blood gas values obtained from bone marrow aspirates may be helpful to adjust ventilation and optimize fluid and drug therapy during the early treatment of patients with severe hypothermia.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Leopold-Franzens-University of Innsbruck, Austria.
authors.forename: W G
authors.initials: WG
authors.lastname: Voelckel
authors.forename: K H
authors.initials: KH
authors.lastname: Lindner
authors.forename: V
authors.initials: V
authors.lastname: Wenzel
authors.forename: A C
authors.initials: AC
authors.lastname: Krismer
authors.forename: W
authors.initials: W
authors.lastname: Hund
authors.forename: G
authors.initials: G
authors.lastname: Müller
authors.forename: S
authors.initials: S
authors.lastname: Oroszy
authors.forename: E
authors.initials: E
authors.lastname: Kornberger
authors.forename: K G
authors.initials: KG
authors.lastname: Lurie
authors.forename: P
authors.initials: P
authors.lastname: Mair
mesh_terms: D000818:Animals; D001784:Blood Gas Analysis / Q000379:methods*; D001842:Bone and Bones / Q000737:chemistry*; D007035:Hypothermia / Q000097:blood*; D011446:Prospective Studies; D013552:Swine