Analysis of optimal design configurations for a multiple disk centrifugal blood pump

A multiple disk centrifugal pump was analyzed as a blood pump for use in ca rdiac assistance or as a bridge to transplant device. The original configur ation consisted of 6 parallel disks with 0.016 inch spacing between disks. This pump suffered from a degradation of now with increasing afterload. A s tudy was conducted to analyze flow performance as a function of afterload, preload, and motor speed. Configurations were examined including 4, 5, and 6 disks each with spacings of 0.15, 0.20, and 0.25 inches. Flow rates were examined for variations in afterload from 60-130 mm Hg, in preload from 0-2 0 mm Hg and for motor speeds of 1,250, 1,500, and 1,750 rpm. Analyses of af terload effects were intended to determine those configurations that produc ed less flow degradation with increasing afterload. Analyses of motor speed effects were intended to determine any configurations that produced greate r flow increases with increasing motor speed. A hemolysis study was also pe rformed. Both plasma free hemoglobin and the index of hemolysis were compar ed to data reported for other centrifugal blood flow devices. Results indic ated that a 5 disk configuration with a 0.15 inch spacing produced optimal flow results with minimal degradation at higher afterloads. No optimal conf iguration based upon motor speed was indicated. Preload effects on pump per formance were minimal. Hemolysis results indicated minimal blood damage wit h levels below those of many other centrifugal blood pump designs.