Basic Design Criteria for Rotary Blood Pumps

Summary

Currently developed blood pumps can be classified into two main categories: displacement pumps and hydrodynamically operating rotary pumps [1]. The latter are characterized by their inherently high energy density [2] and simplicity, culminating in compact dimensions and the lack of valves and compliant diaphragms.

Without specifically addressing one of the most difficult aspects of rotary blood pump design, namely the centering and/or sealing of the pump rotor, it is important to classify possible pump designs, whether radial, diagonal, or axial, and to contrast impeller design with hydraulic flow capabilities and blood trauma.

Generally speaking, rotary blood pumps are best suited for high flows up to 201/min at differential pressures <500 mmHg. The radial design is most capable of producing high pressures and low flows, whereas axial pumps generate high flows at low pressure differences. Diagonal pumps, often referred to as mixed flow systems, tend to be capable of high generated pressures and high flows. This simple classification of possible pump designs within the limits below discussed is normalized with respect to pump size, taking into consideration that a Ø60.0 mm centrifugal pump can naturally pump more fluid at significantly higher pressures than a Ø6.0 mm axial pump. In addition, all pump designs are characterized with respect to achievable efficiencies and anticipated blood trauma.