Optimizing Packed Red Blood Cell Transfusions: Viscosity, Volume, and Time

A straightforward formula, V = \left(\frac{H{\kern.5pt}_{\rm i}\cdot b}{2}-1\right) \cdot V_{\rm i}, which minimizes the product of transfusion time and volume has been derived. Vi represents the initial volume of the packed red blood cells (PRBCs) whereas Hi represents their initial hematocrit. The coefficient b is based upon an approximate exponential representation of viscosity as a function of added volume V and Hi. This formula allows for the minimization of both the volume of diluent, added to a known volume of PRBCs, as well as a minimization of the transfusion time.