Intraosseous pressure tracings mimic arterial pressure tracings in timing and contour [poster]
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Study Objectives: Rapid access to the vascular system for fluid resuscitation and medication administration via an intraosseous (IO) line has become a common practice in emergency medicine. However, if vascular dynamics can be determined from the intramedullary space, additional monitoring information may be available. To investigate this possibility, we measured intraosseous (IO) pressures in a porcine model. Methods: Preparation involved surgical dissections for placement of a femoral arterial line and central venous pressure (CVP) catheter via jugular vein access. IO access was obtained by standard technique (EZIO ®, Vidacare Corporation, San Antonio, TX) in the femur, humerus and tibia. Vascular pressure transducers were simultaneously calibrated and signals were transmitted to a data acquisition system (Dataq Instruments,Inc., Akron, OH). All pressures were centrally displayed for review, normalized to their maximum height, overlaid in Excel and analyzed using correlation coefficients for comparison to arterial and central venous pressures. Results: For the 6 animals studied, mean arterial pressure was 78.5 6.5 mmHg and mean CVP was 6.6 2.0 mmHg. IO pressures did not differ significantly between sites (humerus = 17.9 3.5; femur = 17.1 3.3; tibia = 14.8 5.5 mmHg) and were 25% of arterial pressure. Correlation analysis (R2) between arterial pressure and humerus, femoral, and tibial pressures were .59, .74 and .82, respectively. A corresponding comparison found R2 to be .07, .005 and .005 between central venous pressure and IO pressures. The timing and contour of IO pressures mimicked arterial pressure tracings (Figure 1). A sampling of IO blood gases revealed oxygenation levels of venous blood (PIOO2 between 40-45 mmHg). IO pressure excursions were moderately dampened if the IO catheter was embedded in the bone cortex. Conclusions: This is the first investigation to report consistent data capture of intraosseous pressure tracings for potential use in monitoring hemodynamics. Each IO site evaluated displayed pressure excursions that mimicked arterial pressure tracings at 25% of the arterial pressure magnitude. Intraosseous blood gases reflect venous blood oxygenation levels.