PERFUSION TREND INDICATOR

• US 20140163344A1
• Filed: 02/14/2014
• Published: 06/12/2014
• Est. Priority Date: 01/20/2007
• Status: Active Grant

• Current Assignee: Masimo Corporation
• Original Assignee: Masimo Corporation
• Inventors: Al-Ali, Ammar
• Granted Patent: US 11,234,655 B2
• Time in Patent Office: Days
• US Class Current: 600/324
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/026 Measuring blood flow A61B3/1233, A61B3/1241 take precedence
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7275 Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: A61B 5/743 Displaying an image simultaneously with additional graphical information, e.g. symbols, charts, function plots
• CPC Class Codes: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B
• CPC Class Codes: A61M 2230/205 partial oxygen pressure (P-O2)
• CPC Class Codes: G16H 20/00 ICT specially adapted for therapies or health-improving plans, e.g. for handling prescriptions, for steering therapy or for monitoring patient compliance

Abstract

A perfusion trend indicator inputs a plethysmograph waveform having pulses corresponding to pulsatile blood flow within a tissue site. Perfusion values are derived corresponding to the pulses. Time windows are defined corresponding to the perfusion values. Representative perfusion values are defined corresponding to the time windows. A perfusion trend is calculated according to differences between representative perfusion values of adjacent ones of the time windows.

Claims

1. A perfusion trend method comprising:

inputting a plethysmograph waveform having a plurality of pulses corresponding to pulsatile blood flow within a tissue site;

deriving a plurality of perfusion values corresponding to the pulses;

defining a plurality of time windows corresponding to the perfusion values;

determining a plurality of representative perfusion values corresponding to the time windows; and

calculating a perfusion trend according to differences between representative perfusion values of adjacent ones of the time windows.

2. The perfusion trend method according to claim 1 wherein determining representative perfusion values comprises:

trimming the perfusion values within each of the time windows; and

calculating a mean perfusion value for each of the time windows according to the trimmed perfusion values.

3. The perfusion trend method according to claim 2 wherein trimming comprises:

sorting the perfusion values within each of the time windows from the largest of the perfusion values to the smallest of the perfusion values; and

deleting at least one of the largest perfusion values and at least one of the smallest perfusion values from each of the time windows.

4. The perfusion trend method according to claim 3 wherein deriving perfusion values comprises:

identifying peaks and valleys for the pulses;

calculating AC values for the pulses from the peaks and the valleys;

calculating DC values for the pulses; and

normalizing the AC values with the DC values.

5. The perfusion trend method according to claim 4 wherein inputting comprises using an IR channel for the plethysmograph waveform, the perfusion trend method further comprising identifying physiologically acceptable pulses of the plethysmograph waveform using a red channel.

6. A perfusion trend indicator comprising:

an optical sensor that transmits multiple wavelengths of optical radiation into a tissue site, detects the optical radiation after attenuation by pulsatile blood flowing within the tissue site, and generates a sensor signal responsive to the detected optical radiation;

a patient monitor that demodulates the sensor signal so as to generate a plurality of plethysmograph channels;

a digital signal processor (DSP) within the patient monitor that inputs at least one of the plethysmograph channels and outputs a perfusion parameter accordingly;

a perfusion process that executes on the DSP so as to derive a perfusion trend from at least one of the plethysmograph channels; and

a patient monitor output that is responsive to the perfusion trend.

7. The perfusion trend indicator according to claim 6 wherein the perfusion process comprises:

a plethysmograph input corresponding to the at least one plethysmograph channel having pleth features; and

a measure pleth process that extracts a plurality of perfusion values from the plethysmograph according to the pleth features.

8. The perfusion trend indicator according to claim 7 wherein the perfusion process further comprises:

a perfusion trend calculation that generates a plurality of trend values from the perfusion values.

9. The perfusion trend indicator according to claim 8 wherein the perfusion process further comprises a trim process that deletes outlying ones of the perfusion values within a time window according to predetermined criterion.

10. The perfusion trend indicator according to claim 9 wherein the patient monitor output generates a perfusion trend graph of the trend values versus time.

11. The perfusion trend indicator according to claim 10 wherein the perfusion trend graph pops-up in a patient monitor display when the trend values after a predetermined time Δ

T are less than a predetermined change in perfusion index Δ

PI.

12. The perfusion trend indicator according to claim 11 wherein the trend values are each responsive to a median of a plurality of perfusion index values.

13. A perfusion trend indicator having a sensor that transmits multiple wavelengths of optical radiation into a tissue site and that detects the optical radiation after attenuation by pulsatile blood flow within a tissue site so as to provide a plethysmograph input to a digital signal processor (DSP), the input selected from a plurality of channels corresponding to the multiple wavelengths, the DSP executes instructions for deriving perfusion index values from the plethysmograph, comprising:

a plethysmograph input;

a measuring means for generating perfusion index (PI) values from the plethysmograph input according to predefined plethysmograph features; and

a calculation means for deriving PI trend values from the PI values.

14. The perfusion trend indicator according to claim 13 further comprising a window means for identifying groups of PI values.

15. The perfusion trend indicator according to claim 14 further comprising a trimming means for deleting outlying values from each of the identified PI value groups.

16. The perfusion trend indicator according to claim 15 further comprising a median means for deriving PI trend values from the trimmed PI values.

17. The perfusion trend indicator according to claim 16 further comprising summing means for determining a PI trend from the PI trend values.

18. The perfusion trend indicator according to claim 17 further comprising a pop-up means for displaying the PI trend when the PI trend is less than a predetermined perfusion index Δ

PI after a predetermined time Δ

T.