Autoregulation system and method using tissue oximetry and blood pressure
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Publication Number
US-12121352-B2
Publication Date
2024-10-22
Expiration Date
Abstract
A method and apparatus for monitoring a subject's autoregulation function state is provided. The method includes: a) continuously sensing a tissue region of the subject with a tissue oximeter, the sensing producing first signals, and determining frequency domain tissue oxygen parameter values; b) continuously measuring a blood pressure level of the subject using a blood pressure sensing device, the measuring producing second signals, and determining frequency domain blood pressure values; c) determining a coherence value indicative of the subject's autoregulation state in each of a plurality of different frequency bands; and d) determining a peak coherence value indicative of the subject's autoregulation state based on the determined coherence value from each of the plurality of different frequency bands.
Core Innovation
The disclosed method determines a subject’s autoregulation function state from tissue oxygenation and blood pressure signals measured during the same period. It determines frequency-domain tissue oxygen parameter values and frequency-domain blood pressure values, calculates coherence as a function of frequency in multiple frequency bands, and identifies a peak coherence value indicative of the autoregulation state.
The disclosed apparatus incorporates a NIRS tissue oximeter, a blood pressure sensing device, and a controller or data processing unit to determine and output the peak coherence value. The disclosure also describes evaluating multiple NIRS indices, filtering coherence by phase relationship, and fitting autoregulation data with sigmoidal curves against mean blood pressure to estimate lower and upper autoregulation limits.
Claims Coverage
The claims contain three inventive features across independent claims covering a method, an apparatus, and a data processing unit for determining a subject’s autoregulation function state.
Determining autoregulation state using frequency-domain coherence
The method senses a tissue region with a tissue oximeter and measures blood pressure during the same period, determines frequency-domain tissue oxygen parameter values and frequency-domain blood pressure values, calculates coherence across multiple frequency bands, and determines a peak coherence value indicative of the subject’s autoregulation state.
Nirs and blood pressure sensing apparatus
The apparatus includes a NIRS tissue oximeter, a blood pressure sensing device, and a controller configured to determine frequency-domain values from tissue oxygen and blood pressure signals, calculate coherence across multiple frequency bands, and determine a peak coherence value indicative of the subject’s autoregulation state.
Data processing unit for outputting peak coherence
The data processing unit includes a signal input port for receiving tissue oxygenation and blood pressure signals measured during the same period, a signal coherence component that determines coherence across multiple frequency bands and a peak coherence value, and a signal output port configured to output the peak coherence value.
The three independent claims cover measuring tissue oxygenation and blood pressure, determining frequency-domain coherence across multiple frequency bands, and identifying a peak coherence value as an indicator of autoregulation state through a method, an apparatus, and a data processing unit.
Stated Advantages
Using multiple frequency bands and sampling windows is intended to improve sensitivity and response to both rapid and gradual physiological changes.
Documented Applications
Determining and monitoring a subject’s autoregulation function state using tissue oxygenation and blood pressure signals.
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