# US 9,039,595 B2 · Control systems for rotary blood pumps > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,039,595 B2 - Document ID: US9039595B2 - Status: Granted - Kind: B2 - Application number: 14/162,599 - Filed: 2014-01-23 - Published: 2014-05-22 - Granted: 2015-05-26 - Earliest claimed: 2005-11-04 - Assignees: Thoratec Corporation - Applicants: Thoratec Corporation - Inventors: Peter Joseph Ayre; Lee Thomas Glanzmann; Nicholas Oliver Von Huben - Web page: https://patentgrep.com/patent/US9039595B2 ## CPC - A61B 5/4836: {Diagnosis combined with treatment in closed-loop systems or methods (A61B5/0036 takes precedence)} - A61B 5/0215: by means inserted into the body - A61B 5/14535: {for measuring haematocrit} - A61B 5/686: {Permanently implanted devices, e.g. pacemakers, other stimulators, biochips (A61B5/6861 takes precedence)} - A61M 60/104: Extracorporeal pumps, i.e. the blood being pumped outside the patient's body - 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 - A61M 60/216: including a rotating member acting on the blood, e.g. impeller - A61M 60/422: the force acting on the blood contacting member being electromagnetic, e.g. using canned motor pumps - A61M 60/531: using blood pressure data, e.g. from blood pressure sensors - A61M 60/538: Regulation using real-time blood pump operational parameter data, e.g. motor current - A61M 60/569: synchronous with the native heart beat - A61M 60/585: User interfaces - A61M 60/148: in line with a blood vessel using resection or like techniques, e.g. permanent endovascular heart assist devices - A61M 2205/3334: Measuring or controlling the flow rate - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)} ## Abstract The present invention generally relates to a control system for a rotary blood pump adapted to move blood in a patient. The control system comprises a means for measuring and varying the speed of the pump and a means for measuring the pulsatility index of a patient, and the control system is adapted to maintain the pulsatility index at or near a predetermined value by varying the speed of the pump. The pulsatility index is derived from the amplitude of the actual pump speed over a predetermined time period. Optionally, also, the control system can calculate the second derivative of instantaneous speed of the rotary blood pump and use the calculation of the second derivative of instantaneous speed to detect a suction event, and help prevent it. ## Claims ### Claim 1 A method, implemented on a controller, for controlling a blood pump, comprising: calculating a pulsatility index (PI) based on a speed of the pump; deriving pulmonary capillary wedge pressure (PCWP) based on the calculated PI; estimating a flow rate through the pump based on the derived PCWP; calculating a preferred flow rate based on a theoretical Starling-like response and the derived PCWP; comparing the estimated flow rate to the preferred flow rate; and adjusting the pump speed based on the comparison. ### Claim 2 (depends on 1) The method of claim 1, wherein the deriving of the PCWP comprises using expert data acquired during treatment of a heart failure patient. ### Claim 3 (depends on 1) The method of claim 1, wherein the deriving of the PCWP comprises using a look-up-table (LUT). ### Claim 4 (depends on 1) The method of claim 1, further comprising modifying the flow rate estimating using expert data. ### Claim 5 (depends on 4) The method of claim 4, wherein the expert data is a member selected from the group consisting of measured haemocrit (Hct), measured PCWP, and a combination of the same. ### Claim 6 (depends on 5) The method of claim 5, wherein the Hct is derived from pathology testing. ### Claim 7 (depends on 4) The method of claim 4, wherein the modifying the flow rate estimating further comprises: estimating another flow rate based on Hct, power, and pump speed; comparing the another flow rate to the estimated flow rate based on the derived PCWP; and adjusting the estimating the flow rate based on a difference between the estimated flow rate based on the derived PCWP and the another flow rate. ### Claim 8 (depends on 7) The method of claim 7, wherein the calculating a PI; the deriving PCWP; the estimating a flow rate; the adjusting the estimating flow rate; the calculating a preferred flow rate; the comparing the estimated flow rate and the preferred flow rate; and the adjusting pump speed are repeated for each of a plurality of cycles. ### Claim 9 (depends on 1) The method of claim 1, wherein the adjusting pump speed comprises setting a pump speed such that the PI is within the range of about 20 to about 45 units. ### Claim 10 A control system for a blood pump having an impeller, comprising: a commutation module for sending a drive signal to rotate the impeller; a sensor configured to receive an input indicative of or measure a speed of the pump; and a controller device for generating a control signal to adjust the speed of the impeller, the controller device configured to: calculate a pulsatility index (PI) based on a speed of the pump; derive pulmonary capillary wedge pressure (PCWP) based on the calculated PI; estimate a flow rate based on the derived PCWP; calculate a preferred flow rate based on a theoretical Starling-like response and the derived PCWP; compare the estimated flow rate to the preferred flow rate; and wherein the control signal is based on the comparison of the estimated flow rate to the preferred flow rate. ### Claim 11 (depends on 10) The control system of claim 10, wherein the sensor is included with the commutation module and the sensor measures the speed of the pump by back EMF detection. ### Claim 12 (depends on 10) The control system of claim 10, wherein the controller device includes a first module configured to receive the calculated PI and derive the PCWP; a second module configured to receive the derived PCWP and calculate the preferred flow rate; and a third module configured to receive the preferred flow rate and the estimated flow rate and perform the comparison between the estimated flow rate and preferred flow rate. ### Claim 13 (depends on 12) The control system of claim 12, further including a fourth module configured to estimate another flow rate based on haemocrit (Hct), pump power and pump speed, and wherein the estimated flow rate received by the third module is the estimated flow rate based on the derived PCWP and modified by the another flow rate. ### Claim 14 (depends on 10) The control system of claim 10, wherein the controller device is further configured to estimate another flow rate based on expert data selected from the group consisting of measured haemocrit (Hct), measured PCWP, and a combination of the same. ### Claim 15 (depends on 10) The control system of claim 10, further including expert data selected from the group consisting of measured haemocrit (Hct), measured PCWP, and a combination of the same. ### Claim 16 (depends on 15) The control system of claim 15, wherein the expert data includes a plurality of measured PCWP values for corresponding PI values. ### Claim 17 (depends on 15) The control system of claim 15, wherein the expert data includes Hct derived from pathology testing.