Method and apparatus for monitoring the autonomic nervous system
First Claim
1. An apparatus for monitoring human autonomic nervous system activity using pulsatile blood volume waveform signals, said apparatus comprising:
- a photoplethysmographic probe having a light emitting element and an opposing light detecting element, and having an output signal indicating changes in blood volume on at least one alpha andrenergic receptor site of a human body;
a processor element, responsive to said output signal indicating changes in blood volume, for reducing said waveform signals to a slope value;
said processor element containing an algorithm for normalization of the slope value;
said processor element containing an artifact rejection algorithm for eliminating from further processing slope values less that one; and
amplifier and filter circuitry for rendering output signals representative of said slope values.
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Abstract
An apparatus and method for detection and monitoring of autonomic nervous system (ANS) activity in humans, primarily in the field of sleep research. The present invention discloses a portable, simple, and cost-effective electronic device containing hardware and software that permits real-time monitoring of a pulsatile blood volume waveform obtained through use of a photoplethysmographic (optical volume detecting) probe, thereby allowing signal conditioning, waveform slope analysis, display, recording, and output of pulse transitional slope data representative of activity in the ANS.
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Citations
17 Claims
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1. An apparatus for monitoring human autonomic nervous system activity using pulsatile blood volume waveform signals, said apparatus comprising:
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a photoplethysmographic probe having a light emitting element and an opposing light detecting element, and having an output signal indicating changes in blood volume on at least one alpha andrenergic receptor site of a human body;
a processor element, responsive to said output signal indicating changes in blood volume, for reducing said waveform signals to a slope value;
said processor element containing an algorithm for normalization of the slope value;
said processor element containing an artifact rejection algorithm for eliminating from further processing slope values less that one; and
amplifier and filter circuitry for rendering output signals representative of said slope values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus for monitoring human autonomic nervous system activity using pulsatile blood volume waveform signals, said apparatus comprising:
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a photoplethysmographic probe having a light emitting element and an opposing light detecting element, and haying an output signal indicating changes in blood volume on at least one alpha andrenergic receptor site of a human body;
a power supply having a battery with capacity for at least 12 hours;
analog circuitry for power supply voltage regulation and conditioning;
an interface for an OEM supplied finger pulse oximetry probe;
a low frequency front-end filter for conditioning a probe input signal;
an input signal pre-amplifier stage;
a high frequency filter for conditioning probe input signal;
a gain-controlled signal amplifier stage;
a bar graph display for visual indication of a pulse signal;
a polygraph output port for pulse signal data;
a digital processing unit, such as a microprocessor or microcontroller, to provide slope detection and peak to peak height determination of each systolic finger pulse, mathematical normalization of input signal slope, digital to analog (D/A) conversion of the slope value for a polysomnographic display, and digital control of finger probe gain, and having a status indicator LED;
a plurality of user controls comprising on/off, start/stop and transmit functions;
a display for visual indication of slope ratio information;
a data storage unit, such as such as an on-board multi-media card, to permit at least 5 hours of data storage; and
a plurality of output ports for providing analog and digital output of the pulsatile waveform and a DC level representative of the normalized slope, and slope ratio data.
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11. A method for identification of human autonomic nervous system activity, the method comprising the steps of:
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disposing a photoplethysmographic probe proximate to a single alpha andrenergic receptor site of a human body part;
obtaining an electrical signal from said probe representative of pulsatile blood volume within said body part;
deriving a pulsatile blood volume waveform as a function of amplitude and time;
defining a time interval for calculation of a slope of the pulsatile blood volume waveform;
applying an algorithm that continuously provides real-time calculation of the slope along said waveform within said time interval;
dividing peak amplitude values by a time constant and eliminating slope values less than 1, whereby artifact elimination is achieved;
normalizing slope values; and
providing information representative of slope values, whereby autonomic nervous system activity is monitored. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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Specification