Stereo pulse oximeter

• US 6,714,804 B2
• Filed: 12/21/2001
• Issued: 03/30/2004
• Est. Priority Date: 06/03/1998
• Status: Expired due to Term

• Current Assignee: Masimo Corporation
• Original Assignee: Masimo Corporation
• Inventors: Kopotic, Robert James, Tobler, David, Al-Ali, Ammar, Diab, Mohamed K., Kiani, Massi E.
• Primary Examiner(s): WINAKUR, ERIC FRANK
• Application Number:
  US10/026,013
• Publication Number:
  US 20020082488A1
• Time in Patent Office: 830 Days
• Field of Search: 600/322, 600/323, 600/331, 600/334, 600/335, 600/336, 600/340, 600/310
• 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 at least one sensor adapted to be positioned at at least one peripheral tissue site and having an interface output responsive to light attenuated by said at least one 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 at least one site, wherein said parameters comprise a first value and a second value related to said at least one site, wherein said first value is an arterial oxygen saturation and said second value is a venous oxygen saturation, wherein said second value is derived from an active pulse generated at said at least one site, wherein said signal processor output further comprises a scattering indicator corresponding to said at least one site, and said sensor interface further comprises a pulse drive controlling the amplitude of said active pulse, said drive responsive to said indicator.

2. 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, 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, and 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.

3. 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;

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

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.

4. 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;

comparing said reference parameter to said test parameter so as to determine a patient condition, 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, 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; and

detecting a patent ductus arteriosus when said delta saturation value is substantially zero.

5. 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;

comparing said reference parameter to said test parameter so as to determine a patient condition, 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, 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; and

detecting pulmonary hypertension when said delta saturation value is substantially non-zero.

6. 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;

comparing said reference parameter to said test parameter so as to determine a patient condition, 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, 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; and

detecting an aortic coarctation when said delta saturation is substantially non-zero.

7. 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, 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, and wherein said comparing step determines the phase difference between plethysmographs at said first site and said second site.

8. The physiological monitoring method of claim 7, further comprising the step of detecting a patent ductus arteriosus when said phase difference is substantially non-zero.

9. The physiological monitoring method of claim 7, further comprising the step of detecting an aortic coarctation when said phase difference is substantially non-zero.

10. 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;

comparing said reference parameter to said test parameter so as to determine a patient condition, 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, wherein said comparing step determines a relative amount of damping between plethysmographs at said first site and said second site; and

detecting a patent ductus arteriosus when said damping is substantially non-zero.

11. 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;

comparing said reference parameter to said test parameter so as to determine a patient condition, 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, wherein said comparing step determines a relative amount of damping between plethysmographs at said first site and said second site; and

detecting an aortic coarctation when said damping is substantially non-zero.

12. 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;

comparing said reference parameter to said test parameter so as to determine a patient condition, 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, wherein said comparing step determines a relative amount of damping between plethysmographs at said first site and said second site; and

detecting pulmonary hypertension when said damping is substantially non-zero.