Abstract 47: Comparison between Intraosseous and Central Venous Drug Delivery in Normovolemic and Hypovolemic Swine
In traumatic injuries vascular access must be secured promptly. Peripheral intravenous access is the most common form of emergency vascular access. However, a number of studies suggest that establishing IV access can take minutes to occur. The intraosseous (IO) route delivers drugs to the non-collapsible vessels of the bone and can be established in <60 seconds. We compared tracer delivery to the systemic circulation via the tibial IO route versus the central venous route in normovolemic and hypovolemic swine.
METHODS: Isoflurane anesthetized swine N=6 were instrumented and allowed to stabilize. IO de were placed in the proximal tibia using the EZ-IO® (Vidacare Corporation) device. Central venous (CV) tracer delivery was via the right atrial port on a pulmonary catheter. Animals were hemorrhaged to 45 mmHg and held for 5 min. Cardiac output decreased to 45– 60% of baseline. Simultaneous injections of different dye tracers (indocyanine green and Evan’s blue) were delivered via the IO and the CV routes. The time course (in seconds) for arterial blood sampling included pre-injection T-8, T-6, T-4, T-2, and at T0 dye boluses were delivered. Samples were taken at 2 second intervals until 50 seconds post-injection. Samples were analyzed by spectrophotometer and dye concentrations were determined. Normovolemic N=6 evaluations of drug delivery utilized the same drug delivery protocol.
RESULTS: Peak appearance times of tracer detection were 7.2 ±.1.3 s and 10.8 ± 1.8s for CV and T delivery respectively in normovolemia. The total dose of tibial delivery was 83% that of CV delivery in normovolemia as measured by area under the curve (AUC). Peak appearance time of tracers for the hemorrhaged group was 7.3 ± .6 s and 11.7 ± 1.2 s for CV and tibia groups, respectively. The IO tibial delivery was 70% that of CV delivery in the hemorrhage group.
CONCLUSIONS: Normovolemic drug delivery was marginally faster and more effective than drug delivery during hemorrhage for both CV and IO routes. These small differences are not likely to be clinically relevant. Tibial IO delivery is an effective alternative to central venous delivery in emergent care situations. Tibial IO delivery should be considered when time is a critical factor involved in drug delivery and venous access is not available.