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. Design: Prospective, descriptive laboratory investigation using a porcine model. Setting: University hospital laboratory. Subjects: Twelve anesthetized, 12- to 16-wk-old domestic pigs weighing 30-35 kg. Interventions: Volume-controlled ventilated animals were instru-mented 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°C [101.3 ± 0.2°F] to 27 ± 0.5°C [80.5 ± 0.9°F] over 2 hrs. Measurements and Main Results: Intraindividual correlation of Pco2 and pH values were determined as the difference (δ) between intraosseous and reference blood samples. With hypothermia, absolute values of Pco2 decreased and pH increased in samples from all sites. At 27°C, intraosseous - arterial δ Pco2 and δ 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 (δPco2 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 Pco2 values were predictable for mixed venous Pco2 and arterial Pco2. 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.
- Acid-base equilibrium
- Blood gas analysis
- Carbon dioxide partial pressure
- Cerebral sinus sagittalis cathete-rization
- Intraosseous access