Pulse Oximetry For Determining Heart Rate Variability As A Measure Of Susceptibility To Stress
Embodiments of the present disclosure relate to systems and methods for determining a physiologic parameter of a patient. Specifically, embodiments provided herein include methods and systems for determining or predicting the presence and/or severity of stress in a patient based on heart rate variability. The information relating to stress may be used as part of a broader physiological assessment.
1 . A method of determining relative stress level in a subject comprising:
using a monitor to:
receive a signal from a pulse oximetry sensor, wherein the signal is representative of a heart rate of a patient;
determine a heart rate variability of the subject based at least in part on the signal; and
determine or predicting a stress response of the subject based in part on the heart rate variability, wherein a higher determined or predicted stress response is associated with increased heart rate variability relative to a baseline heart rate variability.
2 . The method of claim 1 , wherein the signal is from a time period.
3 . The method of claim 2 , wherein the time period is associated with a stress event.
4 . The method of claim 2 , wherein the time period is associated with a physical activity, a psychological test, or a physical stimulus.
5 . The method of claim 2 , comprising using the monitor to sample the signal at a higher rate during a period when heart rate variability is being determined and sample the signal at a lower rate when heart rate variability is not being determined.
6 . The method of claim 5 , wherein using the monitor to determine the heart rate variability comprises assessing pulse intervals from the signal and rejecting invalid pulse intervals.
7 . The method of claim 1 , comprising using the monitor to provide an indication of stress based on the heart rate variability.
8 . The method of claim 1 , wherein using the monitor to determine the heart rate variability comprises applying a smoothing filter to the signal.
9 . The method of claim 1 , comprising using the monitor to receive a second signal from the pulse oximetry sensor, wherein the second signal is used to determine a blood oxygen saturation and a heart rate of the subject.
10 . A monitor, comprising:
an input circuit configured to receive a pulse oximetry signal;
a memory storing an algorithm configured to calculate a heart rate variability based at least in part on the pulse oximetry signal;
a processor configured to execute the algorithm;
and
a display configured to provide an indication of stress based on the heart rate variability, wherein the indication of stress is associated with increased heart rate variability relative to a threshold.
11 . The monitor of claim 10 , wherein the algorithm comprises determining a pulse interval.
12 . The monitor of claim 10 , wherein the algorithm comprises a beat-to-beat heart rate variability determination.
13 . The monitor of claim 10 , wherein the algorithm comprises a time domain heart rate variability determination.
14 . The monitor of claim 10 , wherein the algorithm comprises a frequency domain heart rate variability determination.
15 . The monitor of claim 10 , wherein the algorithm comprises a geometric heart rate variability determination.
16 . The monitor of claim 10 , wherein the algorithm uses a signal quality input to determine a sampling rate for the pulse oximetry signal.
17 . The monitor of claim 10 , wherein the indication of stress comprises a numerical index or a graphical icon.
18 . A system for determining patient stress, comprising:
a sensor configured to acquire pulse oximetry data and generate a signal relating to the pulse oximetry data; and
a monitor configured to:
sample the signal at a rate of 2000 Hz or higher;
determine a heart rate variability based at least in part on the signal; and
provide an indication of stress based on the heart rate variability.
19 . The system of claim 18 , wherein the indication of stress is associated with an increased heart rate variability as compared to a threshold or baseline value.
20 . The system of claim 19 , wherein heart rate variability below the threshold or baseline value is associated with a lack of stress.