Hemodynamics and tissue oxygenation after hemodilution with ultrahigh molecular weight polymerized albumin

Compared to blood transfusion, plasma expanders (PEs) are more cost effective, have a longer shelf-life, and elicit a milder immune response. High molecular weight (MW) dextrans preserve microvascular function during extreme hemodilution. Dextrans, however, evokes negative hemostatic effects, including red blood cell (RBC) aggregation and reduce platelet adhesion, that limit their clinical use. Therefore, polymerization of human serum albumin (HSA) presents a simple strategy to increase HSA's molecular size.

This study was designed to test the hypothesis that polymerized HSA (PolyHSA) biophysical properties improves systemic and microvascular hemodynamics when used as a PE under anemic conditions. The study was implemented using the hamster window chamber model. Animals were first hemodiluted to 18% hematocrit (Hct) using 6% dextran 70 kDa and then to 11% Hct using either 10% PolyHSA, 10% unpolymerized HSA, or 6% dextran 70 kDa. Systemic and microvascular hemodynamics, including cardiac output (CO), mean arterial blood pressure (MAP), functional capillary density (FCD), microvascular perfusion, and oxygen tension were measured.

Posthemodilution, PolyHSA improved MAP, CO, and oxygen delivery compared to HSA and dextran. Additionally, PolyHSA improved microvascular function in terms of blood flow and FCD. Although oxygen carrying capacity is limited at 11% Hct, tissue pO2 and oxygen delivery were higher for PolyHSA compared to HSA and dextran.

PolyHSA during extreme anemia supported systemic and microvascular hemodynamics by increasing plasma viscosity without increasing vascular resistance. These findings can aid to design of studies to understand the role of the PE biophysical properties in clinical scenarios.