Hypovolemia diagnosis technique

• US 10,092,193 B2
• Filed: 10/08/2014
• Issued: 10/09/2018
• Est. Priority Date: 02/24/2012
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Mestek, Michael, Lisogurski, Daniel
• Primary Examiner(s): Roy, Baisakhi
• Application Number:
  US14/509,302
• Publication Number:
  US 20150025336A1
• Time in Patent Office: 1,462 Days
• CPC Class Codes: A61B 5/02042 Determining blood loss or bleeding, e.g. during a surgical procedure
• 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 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/02427 Details of sensor
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• 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 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/4848 Monitoring or testing the effects of treatment, e.g. of medication
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7246 using correlation, e.g. template matching or determination of similarity
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• 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 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B

Abstract

Embodiments of the present disclosure relate to a system and method for determining a risk, onset, or presence of hypovolemia based on one or more features of a plethysmographic waveform during a patient breathing cycle. For example, a hypovolemic patient may exhibit characteristic changes in pulse amplitude or stroke volume during inhalation and exhalation relative to a healthy patient. Further, a trend or pattern of such features may be used to assess the patient'"'"'s fluid condition.

Claims

1. A method, comprising:

using a processor for;

receiving a plethysmographic waveform signal from a sensor applied to a patient;

determining one or more features of the plethysmographic waveform over time;

correlating in time the one or more features of the plethysmographic waveform to an exhalation portion and an inhalation portion of a respiratory cycle of the patient; and

determining an indication of the patient'"'"'s blood volume based on a change in the one or more features of the plethysmographic waveform correlated in time with the respiratory cycle during the exhalation portion or the inhalation portion of the respiratory cycle, wherein the one or more features comprise a pulse amplitude, wherein the change comprises an increase in pulse amplitude relative to a baseline pulse amplitude value during the exhalation portion of the respiratory cycle that is greater than a range or threshold and a decrease in pulse amplitude relative to the baseline pulse amplitude value during the inhalation portion of the respiratory cycle that is greater than a second range or threshold, and wherein the indication comprises a risk of hypovolemia.

2. The method of claim 1, comprising analyzing the one or more features of the plethysmographic waveform over time after fluid therapy has been administered to the patient;

and

determining if the patient'"'"'s blood volume has changed after administration of fluid therapy.

3. The method of claim 1, wherein determining the one or more features of the plethysmographic waveform over time comprises extracting the one or more features from a wavelet transform of the plethysmographic waveform signal.

4. The method of claim 3, comprising eliminating arrhythmic beats from the plethysmographic waveform signal before determining the one or more features of the plethysmographic waveform over time.

5. The method of claim 3, wherein the one or more features of the plethysmographic waveform over time comprise a number of arrhythmic beats.

6. The method of claim 1, comprising determining a trend of the one or more features of the plethysmographic waveform during the inhalation portion or the exhalation portion of the respiratory cycle and determining the risk of hypovolemia based on the trend.

7. The method of claim 6, wherein determining the trend comprises determining the decrease in pulse amplitude during the inhalation portion of the respiratory cycle.

8. The method of claim 6, wherein determining the trend comprises determining the increase in pulse amplitude during the exhalation portion of the respiratory cycle.

9. The method of claim 1, wherein a trend of the increase in pulse amplitude during the exhalation portion of the respiratory cycle and a trend of the decrease in pulse amplitude during the inhalation portion of the respiratory cycle are indicative of hypovolemia.

10. The method of claim 1, comprising displaying an indicator related to the risk of hypovolemia on a display.

11. The method of claim 1, wherein determining the one or more features of the plethysmographic waveform over time comprises determining the one or more features of the plethysmographic waveform over time in a time window.

12. The method of claim 11, wherein the time window advances with respect to time.

13. A method, comprising:

using a processor for;

receiving a plethysmographic waveform signal from a sensor applied to a patient;

determining one or more features of the plethysmographic waveform over time;

correlating in time the one or more features of the plethysmographic waveform to an exhalation portion of a respiratory cycle of the patient;

extracting one or more portions of the plethysmographic waveform correlated in time with the exhalation portion of the respiratory cycle;

determining a baseline value for the one or more features of the plethysmographic waveform over a period of time;

determining a trend of the one or more features of the plethysmographic waveform during the exhalation portion of the respiratory cycle, wherein the trend is indicative of a trending change in the one or more features of the plethysmographic waveform relative to the baseline value, wherein the one or more features comprise a pulse amplitude, and wherein the trending change comprises an increase in pulse amplitude relative to the baseline value during the exhalation portion of the respiratory cycle that is greater than a range or threshold; and

determining a risk of hypovolemia based on a comparison of the trend to the baseline value.

14. The method of claim 13, comprising triggering an alarm if the risk of hypovolemia is determined.

15. The method of claim 13, wherein determining the trend comprises determining an increased risk based on the trend of the increase in the pulse amplitude during the exhalation portion of the respiratory cycle.