# US 2025/0143586 A1 · System and method for evaluating cardiac pumping function > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0143586 A1 - Document ID: US20250143586A1 - Status: Published application - Kind: A1 - Application number: 19/017,712 - Filed: 2025-01-12 - Published: 2025-05-08 - Earliest claimed: 2022-01-20 - Inventors: Guy P. Curtis - Web page: https://patentgrep.com/patent/US20250143586A1 ## CPC - A61B 5/02028: {Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction} - A61B 5/7239: {using differentiation including higher order derivatives} - A61B 5/0205: Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition - A61B 5/02116: {of pulse wave amplitude (A61B5/02225 takes precedence)} - A61B 5/0261: {using optical means, e.g. infrared light} - A61B 5/7246: {using correlation, e.g. template matching or determination of similarity} - A61B 5/742: {using visual displays (displays for heart-related electrical signals, e.g. ECG, A61B5/339)} - G06F 9/44: Arrangements for executing specific programs - H04L 67/12: specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks - A61B 5/024: Measuring pulse rate or heart rate - A61B 5/14551: {for measuring blood gases} - G06F 2218/00: Aspects of pattern recognition specially adapted for signal processing - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A system for evaluating a cardiac pumping function includes an oximeter which is attached to a patient for the purpose of recording a pulse oximeter waveform. A computer is connected to the oximeter to receive metric information from the waveform. With this information, the computer determines the value and location of a second derivative acceleration, d2A/dt2 in the waveform, which indicates the rate of rise/fall of the waveform. A comparator in the computer then compares this with the value and location of maximum second derivative acceleration, d2A/dt2, in earlier waveforms. With this comparison, the computer identifies a trend which can be clinically used to evaluate the efficacy of a cardiac pumping function. ## Claims ### Claim 1 A method for evaluating a cardiac pumping function which comprises the steps of: attaching an oximeter to a patient to monitor a pulse oximeter waveform of the patient; providing metric information received from the pulse oximeter waveform as input to a computer for calculating the rate of rise of the pulse oximeter waveform per unit time; expressing the rate of rise of the pulse oximeter waveform mathematically as a second derivative; and comparing a maximum value of the second derivative to a previously calculated value of the second derivative to determine the state of the cardiac pumping function. ### Claim 2 (depends on 1) The method of claim 1 wherein each pulse oximeter waveform has a time interval that begins at a time to and ends at a time te, with a plurality of time segments Δt therebetween, wherein each time segment Δt of the pulse oximeter waveform has a respective amplitude A, and wherein the mathematical expression for the second derivative is d2A/dt2 and has a respective value for each time segment Δt. ### Claim 3 (depends on 2) The method of claim 2 further comprising the step of calculating the second derivative of A over the entire time interval from to to te at each time segment Δt. ### Claim 4 (depends on 3) The method of claim 3 further comprising the step of identifying a time segment Δt having a maximum value of the second derivative of A in the pulse oximeter waveform. ### Claim 5 (depends on 4) The method of claim 4 further comprising the step of comparing the location for the maximum value of the second derivative with the value of the second derivative at the same location in the immediately preceding waveform to determine a trend in the value of the second derivative. ### Claim 6 (depends on 5) The method of claim 5 wherein a rise in the second derivative is indicative of an improving cardiac pumping function and a drop in the second derivative is indicative of a worsening cardiac pumping function. ### Claim 7 (depends on 6) The method of claim 6 wherein the maximum value of the second derivative occurs during a plurality of time segments Δt immediately following to. ### Claim 8 A non-transitory, computer-readable medium having executable instructions stored thereon that direct a computer system to perform a process for evaluating a cardiac pumping function, the medium comprising instructions for: receiving metric information from a pulse oximeter waveform as input to a computer for calculating the rate of rise of the pulse oximeter waveform per unit time; expressing the rate of rise of the pulse oximeter waveform mathematically as a second derivative; and comparing a maximum value of the second derivative to a previously calculated value of the second derivative to determine the state of the cardiac pumping function. ### Claim 9 (depends on 8) The medium of claim 8 wherein the pulse oximeter waveform has a time interval that begins at a time to and ends at a time te, with a plurality of time segments Δt therebetween, wherein each time segment Δt of the pulse oximeter waveform has a respective amplitude A, and wherein the mathematical expression for the second derivative is d2A/dt2 and has a respective value for each time segment Δt. ### Claim 10 (depends on 9) The medium of claim 9 further comprising instructions for: calculating the second derivative of A over the entire time interval from to to te at each time segment Δt; and identifying a time segment Δt having a maximum value of the second derivative of A in the pulse oximeter waveform. ### Claim 11 (depends on 10) The medium of claim 10 further comprising an instruction for comparing the location for the maximum value of the second derivative with the value of the second derivative at the same location in the immediately preceding waveform to determine a trend in the value of the second derivative. ### Claim 12 (depends on 11) The medium of claim 11 further comprising an instruction for displaying a rising trend in the second derivative as indicative of an improving cardiac pumping function and a dropping trend in the second derivative as indicative of a worsening cardiac pumping function. ### Claim 13 (depends on 12) The medium of claim 12 wherein the maximum value of the second derivative occurs during a plurality of time segments Δt immediately following to. ### Claim 14 A method for measuring changes of an amplitude “A” in a blood flow waveform of a patient to determine a blood flow value which comprises the steps of. Dividing the time interval of the blood flow waveform into a pluraliy of consecutive time segments Δt, wherein each time segment Δt of the waveform has a respective blood flow amplitude A and a respective location in the blood flow waveform; Determine a change in blood amplitude Δt between adjacent time segment Δt of the blood flow waveform; and Comparing the change of Δt between a downstream time segment Δt and its adjacent upstream time segment Δt at a redetermined location in the blood flow waveform to establish the blood flow value. ### Claim 15 (depends on 14) The method of claim 14 further comprising the step of using a pulse oximeter to present the blood flow waveform. ### Claim 16 (depends on 15) The method of claim 15 wherein the steps are performed using a computer. ### Claim 17 (depends on 16) The method of claim 16 wherein the change of Δt between adjacent time segments Δt is evidenced by a rise/fall rate of A at respective predetermined locations in the time segments, wherein the rise/fall rate is mathematically expressed as d2A/dt2. ### Claim 18 (depends on 17) The method of claim 17 wherein the predetermined location on the waveform for determining blood flow value is where the magnitude of the second derivative d2A/dt2 has a maximum value. ### Claim 19 (depends on 18) The method of claim 18 wherein changes in the second derivative d2A/dt2 between successive time segments Δt provide an indication of trends in the patient's overall heart function. ### Claim 20 (depends on 19) The method of claim 19 wherein changes in the second derivative d2A/dt2 between successive time segments Δt require immediate corrective action.