Stereo pulse oximeter

• US 20040059209A1
• Filed: 09/22/2003
• Published: 03/25/2004
• Est. Priority Date: 06/03/1998
• Status: Active Grant

• Current Assignee: Ammar Al-Ali, David Tobler, Massi E. Kiani, Mohamed K. Diab, Robert James Kopotic
• Original Assignee: Ammar Al-Ali, David Tobler, Massi E. Kiani, Mohamed K. Diab, Robert James Kopotic
• Inventors: Kopotic, Robert James, Tobler, David, Al-Ali, Ammar, Diab, Mohamed K., Kiani, Massi E.
• Granted Patent: US 6,898,452 B2
• Time in Patent Office: Days
• US Class Current: 600/323
• 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 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 takes precedence
• CPC Class Codes: A61B 5/6814 Head
• CPC Class Codes: A61B 5/6815 Ear
• CPC Class Codes: A61B 5/6819 Nose
• CPC Class Codes: A61B 5/6825 Hand
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6829 Foot or ankle
• CPC Class Codes: A61B 5/6838 Clamps or clips
• 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
• CPC Class Codes: A61M 16/00 Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes stimulating the respiratory movement by mechanical, pneumatic or electrical means, iron lungs combined with gas breathing means A61H31/00
• CPC Class Codes: A61M 16/021 operated by electrical means A61M16/202 – A61M16/205 take precedence
• CPC Class Codes: A61M 2230/205 partial oxygen pressure (P-O2)

Abstract

An improved pulse oximeter provides for simultaneous, noninvasive oxygen status and photoplethysmograph measurements at both single and multiple sites. In particular, this multiple-site, multiple-parameter pulse oximeter, or “stereo pulse oximeter” simultaneously measures both arterial and venous oxygen saturation at any specific site and generates a corresponding plethysmograph waveform. A corresponding computation of arterial minus venous oxygen saturation is particularly advantageous for oxygen therapy management. An active pulse-inducing mechanism having a scattering-limited drive generates a consistent pulsatile venous signal utilized for the venous blood measurements. The stereo pulse oximeter also measures arterial oxygen saturation and plethysmograph shape parameters across multiple sites. A corresponding calculation of delta arterial saturation and comparison of plethysmograph shape parameters between multiple sites is particularly advantageous for the detection and management of persistent pulmonary hypertension in neonates (PPHN), a patent ductus arteriosis (PDA), and aortic coarctation.

Claims

1. A physiological monitor comprising:

a sensor interface in communication with a peripheral tissue site and having an interface output responsive to light transmitted through said site; and

a signal processor in communication with said sensor interface output that provides a plurality of parameters corresponding to oxygen status or plethysmograph features of said site.

2. The physiological monitor of claim 1 wherein said parameters comprise a first value and a second value related to said site.

3. The physiological monitor of claim 2 wherein said first value is an arterial oxygen saturation and said second value is a venous oxygen saturation.

4. The physiological monitor of claim 3 wherein said parameters further comprise the difference between said arterial oxygen saturation and said venous oxygen saturation.

5. The physiological monitor of claim 3 wherein said second value is derived from an active pulse generated at said site.

6. The physiological monitor of claim 5 wherein:

said signal processor output further comprises a scattering indicator corresponding to said site; and

said sensor interface further comprises a pulser drive controlling the amplitude of said active pulse, said drive responsive to said indicator.

7. The physiological monitor of claim 2 wherein at least one of said values is an indication of perfusion.

8. A physiological monitor comprising:

a plurality of sensor interfaces each in communications with one of a plurality of peripheral tissue sites, each of said interfaces having one of a plurality of outputs responsive to light transmitted through a corresponding one of said sites; and

a signal processor in communication with said sensor interface outputs, said processor having an output comprising a plurality of parameters corresponding to oxygen status or plethysmograph features of said sites.

9. The physiological monitor of claim 8 wherein said parameters comprise a first value relating to a first of said peripheral tissue sites and a second value relating to a second of said peripheral tissue sites.

10. The physiological monitor of claim 9 wherein said first value and said second value are arterial oxygen saturations.

11. The physiological monitor of claim 9 wherein said first value and said second value are plethysmograph waveform phases.

12. The physiological monitor of claim 8 further comprising a sensor attachable to each of said sites, said sensor comprising:

a plurality of emitters and a plurality of detectors, at least one of said emitters and at least one of said detectors being associated with each of said sites;

a connector in communications with said sensor interfaces; and

a plurality of signal paths attached between said emitters and said detectors at a first end and said connector at a second end.

13. A physiological monitoring method comprising the steps of:

deriving a reference parameter and a test parameter from oxygen status measured from at least one of a plurality of peripheral tissue sites; and

comparing said reference parameter to said test parameter so as to determine a patient condition.

14. The physiological monitoring method according to claim 13 wherein said reference parameter is a first oxygen saturation value and said test parameter is a second oxygen saturation value and said comparing step computes a delta oxygen saturation value equal to the arithmetic difference between said first oxygen saturation value and said second oxygen saturation value.

15. The physiological monitoring method of claim 14 wherein said reference parameter is an arterial oxygen saturation measured at a particular one of said sites, said test parameter is a venous oxygen saturation measured at said particular one site and said comparing step determines the presence of a patient abnormality based on a negative delta oxygen saturation value.

16. The physiological monitoring method according to claim 14 wherein said reference parameter is an arterial oxygen saturation value at a particular one of said sites, said test parameter is a venous oxygen saturation value at said particular site, said method further comprising the steps of:

monitoring changes in said delta oxygen saturation as a function of inspired oxygen; and

adjusting inspired oxygen so that said delta oxygen saturation value remains constant with changes in inspired oxygen.

17. The physiological monitoring method according to claim 14 wherein said reference parameter is a first arterial oxygen saturation value at a first of said sites, said test parameter is a second arterial oxygen saturation value at a second of said sites, said method further comprising the step of detecting a patent ductus arteriosus when said delta saturation value is substantially zero.

18. The physiological monitoring method according to claim 14 wherein said reference parameter is a first arterial oxygen saturation value at a first of said sites, said test parameter is a second arterial oxygen saturation value at a second of said sites, said method further comprising the step of detecting pulmonary hypertension when said delta saturation value is substantially non-zero.

19. The physiological monitoring method according to claim 14, wherein said reference parameter is a first arterial oxygen saturation value at a first of said sites, said test parameter is a second arterial oxygen saturation value at a second of said sites, said method further comprising the step of detecting an aortic coarctation when said delta saturation is substantially non-zero.

20. The physiological monitoring method according to claim 13, wherein said reference parameter is a plethysmograph feature measured at a first of said sites, said test parameter is a plethysmograph feature measured at a second of said sites.

21. The physiological monitoring method according to claim 20, wherein said comparing step determines the phase difference between plethysmographs at said first site and said second site.

22. The physiological monitoring method according to claim 21, further comprising the step of detecting a patent ductus arteriosus when said phase difference is substantially non-zero.

23. The physiological monitoring method according to claim 21, further comprising the step of detecting an aortic coarctation when said phase difference is substantially non-zero.

24. The physiological monitoring method according to claim 20, wherein said comparing step determines a relative amount of damping between plethysmographs at said first site and said second site.

25. The physiological monitoring method according to claim 24, further comprising the step of detecting a patent ductus arteriosus when said damping is substantially non-zero.

26. The physiological monitoring method according to claim 24, further comprising the step of detecting an aortic coarctation when said damping is substantially non-zero.

27. The physiological monitoring method according to claim 24, further comprising the step of detecting pulmonary hypertension when said damping is substantially non-zero.