Method for reducing pumping damage to blood

• US 5,678,306 A
• Filed: 05/26/1995
• Issued: 10/21/1997
• Est. Priority Date: 11/10/1993
• Status: Expired due to Term

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Svejkovsky, Paul A., Akkerman, James W., Damm, George Arthur Van, Benkowski, Robert J., Aber, Gregory S., Bacak, James W., Bozeman, Richard J. Jr.
• Primary Examiner(s): Thorpe, Timothy
• Assistant Examiner(s): Korytnyk, Peter G.
• Application Number:
  US08/451,709
• Time in Patent Office: 879 Days
• Field of Search: 417/45, 417/44.11, 417/244, 417/366, 417/423.5, 417/423.12, 417/423.1, 415/900, 623/3, 600/16-18, 29/888.025, 29/888.021, 29/888.02
• US Class Current: 29/888.025
• CPC Class Codes: A61M 2205/3334 Measuring or controlling the flow rate
• CPC Class Codes: A61M 60/113 in other functional devices, e.g. dialysers or heart-lung machines
• CPC Class Codes: A61M 60/148 in line with a blood vessel using resection or like techniques, e.g. permanent endovascular heart assist devices
• CPC Class Codes: A61M 60/178 drawing blood from a ventricle and returning the blood to the arterial system via a cannula external to the ventricle, e.g. left or right ventricular assist devices
• CPC Class Codes: A61M 60/237 the blood flow through the rotating member having mainly axial components, e.g. axial flow pumps
• CPC Class Codes: A61M 60/422 the force acting on the blood contacting member being electromagnetic, e.g. using canned motor pumps
• CPC Class Codes: A61M 60/538 Regulation using real-time blood pump operational parameter data, e.g. motor current
• CPC Class Codes: A61M 60/546 of blood flow, e.g. by adapting rotor speed
• CPC Class Codes: A61M 60/562 for making blood flow pulsatile in blood pumps that do not intrinsically create pulsatile flow
• CPC Class Codes: A61M 60/812 Vanes or blades, e.g. static flow guides
• CPC Class Codes: A61M 60/816 Sensors arranged on or in the housing, e.g. ultrasound flow sensors
• CPC Class Codes: A61M 60/822 specially adapted for being actively controlled
• CPC Class Codes: A61M 60/824 Hydrodynamic or fluid film bearings
• CPC Class Codes: A61M 60/825 Contact bearings, e.g. ball-and-cup or pivot bearings
• CPC Class Codes: A61M 60/827 Sealings between moving parts
• CPC Class Codes: B33Y 80/00 Products made by additive manufacturing
• CPC Class Codes: F04B 17/03 driven by electric motors
• CPC Class Codes: F04B 49/06 Control using electricity regulating by means of floats actuating electric switches F04B49/04
• CPC Class Codes: F16C 17/08 for supporting the end face of a shaft or other member, e.g. footstep bearings
• CPC Class Codes: F16C 2316/18 Pumps for pumping blood
• CPC Class Codes: Y10S 415/90 : Rotary blood pump
• CPC Class Codes: Y10T 29/49236 : Fluid pump or compressor making
• CPC Class Codes: Y10T 29/49238 : Repairing, converting, servicing or salvaging
• CPC Class Codes: Y10T 29/49245 : Vane type or other rotary, e.g., fan

Abstract

Methods are provided for minimizing damage to blood in a blood pump wherein the blood pump comprises a plurality of pump components that may affect blood damage such as clearance between pump blades and housing, number of impeller blades, rounded or flat blade edges, variations in entrance angles of blades, impeller length, and the like. The process comprises selecting a plurality of pump components believed to affect blood damage such as those listed hereinbefore. Construction variations for each of the plurality of pump components are then selected. The pump components and variations are preferably listed in a matrix for easy visual comparison of test results. Blood is circulated through a pump configuration to test each variation of each pump component. After each test, total blood damage is determined for the blood pump. Preferably each pump component variation is tested at least three times to provide statistical results and check consistency of results. The least hemolytic variation for each pump component is preferably selected as an optimized component. If no statistical difference as to blood damage is produced for a variation of a pump component, then the variation that provides preferred hydrodynamic performance is selected. To compare the variation of pump components such as impeller and stator blade geometries, the preferred embodiment of the invention uses a stereolithography technique for realizing complex shapes within a short time period.

Claims

1. A method for optimizing each of a plurality of blood pump configuration parameters, comprising the following steps:

selecting a plurality of blood pump configuration parameters for determining a corresponding effect of each parameter on the damage level to blood;

determining at least one variation of each of said blood pump configuration parameters to be optimized;

selecting a first blood pump configuration parameter to be optimized;

circulating blood through a blood pump;

determining blood damage to said blood;

changing said first blood pump configuration parameter to said at least one variation of said blood pump configuration parameters while retaining all remaining blood pump configuration parameters treehanged;

circulating blood through said blood pump after said change to said first blood pump configuration parameter;

determining blood damage to said blood after said change;

selecting an optimal variation of said first blood pump configuration parameter which reduces said blood damage level to a minimum;

wherein said step of determining blood damage further comprises;

determining an index of hemolysis such that ##EQU2## where;

IH equals amount of hemoglobin liberated in grams per 100 liters of blood pumped against 100 mm Hg;

Ht is the hematocrit in decimal percent;

V is the blood volume in liters;

Δ

Hb is the amount of hemoglobin liberated in a fixed time period in grams/liter,

Flow is the flow rate in liters per minute; and

Time is the total time in minutes at that flow rate.