Hypovolemia diagnosis technique
First Claim
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1. A method, comprising:
- using a processor;
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 at least one of an exhalation portion or an inhalation portion of a respiratory cycle of the patient; and
determining a measure 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 at least one of the exhalation portion or the inhalation portion of the respiratory cycle, wherein the one or more features comprise a pulse amplitude and wherein an increase in pulse amplitude during the exhalation portion of the respiratory cycle that is greater than a range or threshold is indicative of a change in the patient'"'"'s blood volume.
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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.
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Citations
19 Claims
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1. A method, comprising:
using a processor; 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 at least one of an exhalation portion or an inhalation portion of a respiratory cycle of the patient; and determining a measure 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 at least one of the exhalation portion or the inhalation portion of the respiratory cycle, wherein the one or more features comprise a pulse amplitude and wherein an increase in pulse amplitude during the exhalation portion of the respiratory cycle that is greater than a range or threshold is indicative of a change in the patient'"'"'s blood volume. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method, comprising:
using a processor; receiving a plethysmographic waveform signal from a sensor applied to a patient; transforming the plethysmographic waveform signal using a wavelet transform to generate a scalogram from the plethysmographic waveform; estimating a stroke volume over time for the patient based on the scalogram; correlating the stroke volume in time to an exhalation portion of a respiratory cycle of the patient; and determining if the patient is at risk of developing hypovolemia based on an increase in the stroke volume during the exhalation portion of the respiratory cycle relative to a range or threshold. - View Dependent Claims (13, 14)
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15. A monitor, comprising:
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an input circuit configured to receive a plethysmographic waveform signal; a memory storing an algorithm configured to; determine a pattern of one or more features of the plethysmographic waveform over time; correlate in time the pattern of the one or more features of the plethysmographic waveform to a portion of a breathing cycle of the patient; and calculate a presence or risk of hypovolemia based on the pattern of the one or more features of the plethysmographic waveform correlated in time with the breathing cycle during only the portion of the breathing cycle of the patient, wherein the one or more features comprise a pulse amplitude and wherein a pattern of an increase in pulse amplitude during an exhalation portion of the breathing cycle that is greater than a range or threshold is indicative of the presence or risk of hypovolemia; and an output circuit configured to provide an indication of the presence or risk of hypovolemia. - View Dependent Claims (16, 17, 18)
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19. A monitor, comprising:
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an input circuit configured to receive a plethysmographic waveform signal from a patient; a memory storing an algorithm configured to; transform the plethysmographic waveform signal using a wavelet transform to generate a scalogram from the plethysmographic waveform; estimate a stroke volume over time for the patient based on the scalogram; correlate the stroke volume in time to an exhalation portion of a respiratory cycle of the patient; and determine if the patient is at risk of developing hypovolemia based on an increase in the stroke volume during the exhalation portion of the respiratory cycle relative to a range or threshold; and an output circuit configured to provide an indication if the patient is at risk of developing hypovolemia.
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Specification