Optical cerebral oximeter
DCFirst Claim
1. A spectrophotometric cerebral instrument suitable for conducting in vivo clinical examinations, comprising in combination:
- means for applying selected spectra in the near infrared range to the head of a patient at a first location so that they transmiss at least selected portions of the brain after entry through the scalp and skull, said spectra including at least one reference wavelength and at least one investigative wavelength;
means for receiving light energy resulting from said applied spectra at second and third selected locations on the outside of said skull after said applied spectra have passed through said selected brain portions, said second and third locations being spaced from said first location by different distances;
means for producing corresponding and representative signals from the light energy received at said second and third locations;
and means for processing said signals by contrasting certain of said signals representative of light energy corresponding to said reference wavelength and received at said second location with signals representative of light energy corresponding to said investigative wavelength received at said second location to obtain a first resultant signal, contrasting certain of said signals representative of light energy corresponding to said reference wavelength received at said third location with signals representative of light energy corresponding to said investigative wavelength received at said third location to obtain a second resultant signal, and then contrasting said first and second resultant signals, to produce an output which is directly indicative of a predetermined regional cerebral pathology condition in said portion of said brain.
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Abstract
A spectrophotometric instrument for conducting in vivo patient examinations has a sensor which is applied to the patient target area, e.g. the forehead, which includes a source for emitting electromagnetic energy e.g. selected wavelengths in the near infrared range, such that the energy passes through the underlying tissue and is emitted at other locations spaced from the point of entry. The sensor also includes detectors for receiving the resulting light energy at two or more such other locations and sending corresponding signals to a processor for analysis, by which characteristics of the tissue transmissed by the examination wavelengths may be determined. Processing of such signals includes the contrasting of detected intensity levels corresponding to a reference wavelength received at one detection location with intensity signals representative of an investigative wavelength also received at such location to determine a first resultant signal, repeating the process for the same wavelengths at another detection location, to thus determine another resultant signal, and the contrasting of such two resultant signals. In a particular application, the instrument is used to determine regional cerebral blood oxygenation by processing the detection signals to obtain a first resultant having a value proportional to the ratio of deoxygenated hemoglobin with respect to oxygenated hemoglobin and then using the value of such resultant to compute a further resultant having a value proportional to the ratio of oxygenated hemoglobin with respect to the sum of oxygenated hemoglobin and deoxygenated hemoglobin.
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Citations
19 Claims
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1. A spectrophotometric cerebral instrument suitable for conducting in vivo clinical examinations, comprising in combination:
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means for applying selected spectra in the near infrared range to the head of a patient at a first location so that they transmiss at least selected portions of the brain after entry through the scalp and skull, said spectra including at least one reference wavelength and at least one investigative wavelength; means for receiving light energy resulting from said applied spectra at second and third selected locations on the outside of said skull after said applied spectra have passed through said selected brain portions, said second and third locations being spaced from said first location by different distances; means for producing corresponding and representative signals from the light energy received at said second and third locations; and means for processing said signals by contrasting certain of said signals representative of light energy corresponding to said reference wavelength and received at said second location with signals representative of light energy corresponding to said investigative wavelength received at said second location to obtain a first resultant signal, contrasting certain of said signals representative of light energy corresponding to said reference wavelength received at said third location with signals representative of light energy corresponding to said investigative wavelength received at said third location to obtain a second resultant signal, and then contrasting said first and second resultant signals, to produce an output which is directly indicative of a predetermined regional cerebral pathology condition in said portion of said brain. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of determining cerebral blood oxygenation by in vivo optical spectrophotometry comprising the steps of:
- applying selected light spectra in the near infrared range to the head of a patient at a first location so as to transmiss portions of the brain through the scalp and skull;
receiving light energy resulting from and corresponding to said applied spectra at second and third selected locations on the outside of said skull, each spaced from one another and from said first location;
producing corresponding signals representative of the light received at both said second and third locations; and
processing said signals to produce therefrom a readout which is indicative of cerebral blood oxygen saturation in at least portions of said brain transmissed by said light spectra;
said processing including the steps of contrasting certain of said signals representative of light energy corresponding to a selected wavelength received at said second location with signals representative of light energy corresponding to another selected wavelength received at said third location to obtain a first resultant signal having a value which is proportional to the ratio of deoxygenated hemoglobin with respect to oxygenated hemoglobin in at least said portions of said brain, and then using the value of said resultant signal to compute a further resultant signal having a value which is proportional to the ratio of oxygenated hemoglobin with respect to the sum of oxygenated hemoglobin and deoxygenated hemoglobin, said further resultant signal being indicative of cerebral blood oxygen saturation in said at least portions of said brain transmissed by said light spectra. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
- applying selected light spectra in the near infrared range to the head of a patient at a first location so as to transmiss portions of the brain through the scalp and skull;
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19. A method of determining cerebral blood oxygenation by in vivo optical spectrotometry comprising the steps of:
- applying selected light spectra in the near infrared range to the head of a patient so as to transmiss portions of the brain through the scalp and skull and to transmiss the overall vasculature present within said brain portions, including each of the various types of blood supply present within at least said brain portions, whether arterial, venous or capillary in nature;
receiving light energy resulting from and corresponding to said applied spectra at selected locations on the outside of said skull, and producing corresponding and representative signals therefrom; and
processing said signals in a manner to produce a readout which is indicative of the oxygen content of a composite of the total blood supply in said overall vasculature by calculating an average representative of the oxygen content present in all of said types of blood supply present within said brain portions and calculating a weighted average based upon said representative average and upon an assumed relative blood volume present for each of said different types of blood supply present within said brain portions.
- applying selected light spectra in the near infrared range to the head of a patient so as to transmiss portions of the brain through the scalp and skull and to transmiss the overall vasculature present within said brain portions, including each of the various types of blood supply present within at least said brain portions, whether arterial, venous or capillary in nature;
Specification