Journal of Bioengineering & Biomedical Science

Elevated Pressure Aqueous Hemostasis: Experimental and Mathematical Modeling

Abstract

Matt T Oberdier and James F Antaki

Elevated Pressure Aqueous Hemostasis is defined as the use of hydrostatic pressure via an isotonic liquid medium in a closed surgical field to control bleeding. It is an effective yet under-characterized means of achieving hemostasis; however, compromised perfusion is a potential complication. Therefore, the objective of this study was to determine the optimal range of extravascular pressure that both limits hemorrhage and allows antegrade flow. A steady-state experimental flow system was employed to simulate series arterial and venous hemodynamics, venous collapse, and arterial hemorrhage. A corresponding lumped-parameter mathematical model, calibrated to experimental data, was then used to extrapolate to conditions of hypotension, normotension, hypertension, limited venous collapse, venous hemorrhage, and simultaneous arterial and venous hemorrhages. Experiments with an elastomeric phantom vessel showed that hemorrhage from a stab incision was diminished with increasing extravascular pressure but was accompanied by decreased antegrade flow due to venous collapse. Above arterial pressure, flow ceased. Hence, a preferred pressure domain for aqueous hemostasis was defined to be greater than venous pressure to reduce bleeding and at least ten mmHg below arterial pressure to allow antegrade flow. Results from the lumped-parameter model suggest that i) a tethered vein may permit more antegrade flow for a given extravascular pressure; and ii) an elevated extravascular pressure in the presence of a venous rent may cause intravasation. A set of indices of perfusion and hemorrhage were introduced to generalize these results and suggest guidelines for clinical practice.