System and method for venous pulsation detection using near infrared wavelengths

1. A method for detecting venous pulsation, comprising:

acquiring a first signal corresponding to absorption at a first near-infrared wavelength from a sensor;

acquiring a second signal corresponding to absorption at a second near-infrared wavelength from the sensor;

deriving an offset metric from the first and second signals with a processor, wherein the offset metric comprises a difference between current and historical values of a ratio-of-ratios of the absorption at the first near-infrared wavelength to the absorption at the second near-infrared wavelength; and

detecting the presence of venous pulsation based on comparing the offset metric with a threshold value and determining whether the offset metric exceeds the threshold value using the processor.

2. The method of claim 1 , comprising providing, with a monitor, a notification of the presence of venous pulsation when detected.

3. The method of claim 1 , comprising acquiring a third signal corresponding to absorption at a third wavelength from the sensor and calculating a physiological parameter with the processor based on the second and third signals.

4. The method of claim 3 , comprising correcting, with the processor, the calculation of the physiological parameter by subtracting an AC offset of the third signal from an AC measurement of the second signal utilized in the calculation of the physiological parameter.

5. The method of claim 3 , wherein the second near-infrared wavelength comprises a wavelength of about 900 nm and wherein the third wavelength comprises a wavelength of about 660 nm.

6. The method of claim 1 , wherein the first near-infrared wavelength comprises a wavelength in a range of 1,050 to 1,350 nm where hemoglobin has a lower absorption than at the second near-infrared wavelength, which comprises a wavelength of approximately 900 nm.

7. The method of claim 6 , wherein the wavelength of approximately 900 nm is 918 nm.

8. The method of claim 1 , wherein the first near-infrared wavelength comprises a wavelength from 1,050 to 1,350 nm.

9. The method of claim 1 , wherein the first near-infrared wavelength comprises a wavelength from 1,050 to 1,160 nm.

10. The method of claim 1 , wherein the threshold value comprises at least one of a fixed value or a value based on a plurality of historic ratios-of-ratios.

11. A device for detecting venous pulsation, comprising: a monitor configured to:

acquire a first signal corresponding to absorption at a first near-infrared wavelength and a second signal corresponding to absorption at a second near-infrared wavelength;

derive an offset metric from the first and second signals, wherein the offset metric comprises a difference between current and historical values of a ratio-of-ratios of the absorption at the first near-infrared wavelength to the absorption at the second near-infrared wavelength; and

detect the presence of venous pulsation based on comparing the offset metric with a threshold value and determining whether the offset metric exceeds the threshold value.

12. The device of claim 11 , wherein the monitor is configured to provide a notification of the presence of venous pulsation when detected.

13. The device of claim 11 , wherein the monitor is configured to acquire a third signal corresponding to absorption at a third wavelength and to calculate a physiological parameter based on the second and third signals.

14. The device of claim 13 , wherein the monitor is configured to correct the calculation of the physiological parameter by subtracting an AC offset of the third signal from an AC measurement of the second signal utilized in the calculation of the physiological parameter.

15. A system for detecting venous pulsation, comprising: a sensor configured to:

emit light at three or more wavelengths into a patient's tissue; and detect absorption of the light; and

a monitor configured to:

acquire a first signal from the sensor corresponding to absorption at a first near-infrared wavelength and a second signal from the sensor corresponding to absorption at a second near-infrared wavelength;

derive an offset metric from the first and second signals, wherein the offset metric comprises a difference between current and historical values of a ratio-of-ratios of the absorption at the first near-infrared wavelength to the absorption at the second near-infrared wavelength; and

detect the presence of venous pulsation based on comparing the offset metric with a threshold value and determining whether the offset metric exceeds the threshold value.

16. The system of claim 15 , wherein the first near-infrared wavelength comprises a wavelength in a range of 1,050 to 1,350 nm where hemoglobin has a lower absorption than at the second near-infrared wavelength, which comprises a wavelength of approximately 900 nm.

17. The system of claim 16 , wherein the wavelength of approximately 900 nm is 918 nm.

18. The device of claim 15 , wherein the three or more wavelengths comprise about 660 nm, about 900 nm, and about 1,126 nm.

19. The device of claim 15 , wherein the monitor is configured to provide a notification of the presence of venous pulsation when detected.

20. The device of claim 15 , wherein the monitor is configured to acquire a third signal corresponding to absorption at a red wavelength from the sensor and to calculate a physiological parameter based on the second and third signals.

21. The device of claim 20 , wherein the monitor is configured to correct the calculation of the physiological parameter by subtracting an AC offset of the third signal from an AC measurement of the second signal utilized in the calculation of the physiological parameter.