Abstract: Apparatus, systems and methods are provided for using the PG waveform to determine peripheral venous and arterial saturations. Generally, saturations are determined by isolating an indicator of venous or arterial blood volume in each of a plurality of PG waveforms and using the isolated indicators to determine saturation in the corresponding region of the vasculature. Indicators may include respiratory induced variations of AC and/or DC components of the PG waveforms, peaks of the PG waveforms, troughs of the PG waveforms, venous pulsations of the PG waveforms, etc. Indicators may further be isolated in either the time or frequency domain. The isolated indicators may advantageously be normalized, e.g., based on a baseline of the PG waveform or a derivative thereof.

Abstract: Systems and methods are provided for monitoring changes in blood volume using waveforms in the peripheral vasculature. In particular, the systems and methods relate to detecting ventilation-induced variation (VIV) of waveforms in the peripheral vasculature. Advantageously, the systems and methods may relate to analyzing VIV in peripheral venous pressure (PVP). Thus, the VIV of PVP may be measured, wherein decreased VIV is indicative of decreased blood volume In exemplary embodiments, such as involving spontaneous breathing, it may be necessary to account for changes in respiratory signal strength. Thus systems and methods are also provided for assessing coherence between ventilation and VIV for a flow or pressure waveform. Specifically, coherence is evaluated by comparing the waveform to a detected respiratory signal. Finally, systems and method are provided for distinguishing the impact of respiration on the PG signal during hypervolemia as compared to hypovolemia.

Abstract: Apparatus, systems and methods are provided for analyzing relative compliance in the peripheral vasculature that generally involve generating a plethysmograph (PG) signal, generating one or more pressure waveforms and comparing the pressure waveform(s) relative to the PG signal to determine compliance indexes associated particular regions of the vasculature. A relative compliance ratio may also be determined by comparing arterial and venous relative compliance indexes. Apparatus, systems and methods are also provided for analyzing a PG waveform that generally involve generating a plethysmograph (PG) signal and comparing amplitude modulation of the PG signal relative to baseline modulation of the PG signal to estimate a relationship between left ventricular end diastolic pressure and stroke volume. The estimated relationship may account for a phase offset for the time between when changes in venous return affect left ventricular end diastolic pressure and stroke volume.

Abstract: Apparatus, systems and methods are provided for analyzing relative compliance in the peripheral vasculature. Such apparatus, systems and methods generally involve generating a plethysmograph (PG) signal, generating one or more pressure waveforms and comparing the pressure waveform(s) relative to the PG signal to determine compliance indexes associated particular regions of the vasculature. A relative compliance ratio may also be determined by comparing arterial and venous relative compliance indexes. Apparatus, systems and methods are also provided for analyzing a PG waveform. Such apparatus, systems and methods generally involve generating a plethysmograph (PG) signal and comparing amplitude modulation of the PG signal relative to baseline modulation of the PG signal to estimate a relationship between left ventricular end diastolic pressure and stroke volume.

Abstract: A method and system for assessing blood volume within a subject includes generating a cardiovascular waveform representing physiological characteristics of a subject and determining blood volume of the subject by analyzing the cardiovascular waveform. The step of analyzing includes generating a first trace of the per heart-beat maximums of the cardiovascular waveform, which is representative of the systolic pressure upon the cardiovascular signal, generating a second trace of the per heart-beat minimums of the cardiovascular waveform, which is representative of the diastolic pressure upon the cardiovascular signal, and comparing the respective first trace and the second trace to generate an estimate of relative blood volume within the subject. In accordance with an alternate method of analyzing harmonic analysis is applied to the cardiovascular waveform, extracting a frequency signal created by ventilation and applying the extracted frequency signal in determining blood volume of the subject.

Abstract: Disclosed are apparatus, systems and methods utilizing attributes of the cardiac signal to calibrate/normalize components of the plethysmographic (PG) waveform indicating changes in venous and arterial blood volume. In the time-domain, amplitudes of respiratory-induced variations of the DC and AC components of the PG waveform may be calibrated/normalized based on an average amplitude of the PG waveform, e.g., over a respiratory cycle. Similarly, in the frequency domain, respiratory signal strength and side-band signal strength may be advantageously calibrated/normalized based on the strength of the cardiac signal or a harmonic thereof.

Abstract: A method and system for assessing blood volume within a subject includes generating a cardiovascular waveform representing physiological characteristics of a subject and determining blood volume of the subject by analyzing the cardiovascular waveform. The step of analyzing includes generating a first trace of the per heart-beat maximums of the cardiovascular waveform, which is representative of the systolic pressure upon the cardiovascular signal, generating a second trace of the per heart-beat minimums of the cardiovascular waveform, which is representative of the diastolic pressure upon the cardiovascular signal, and comparing the respective first trace and the second trace to generate an estimate of relative blood volume within the subject. In accordance with an alternate method of analyzing harmonic analysis is applied to the cardiovascular waveform, extracting a frequency signal created by ventilation and applying the extracted frequency signal in determining blood volume of the subject.

Abstract: Apparatus, systems and methods are provided for using the PG waveform to determine peripheral venous and arterial saturations. Generally, saturations are determined by isolating an indicator of venous or arterial blood volume in each of a plurality of PG waveforms and using the isolated indicators to determine saturation in the corresponding region of the vasculature. Indicators may include respiratory induced variations of AC and/or DC components of the PG waveforms, peaks of the PG waveforms, troughs of the PG waveforms, venous pulsations of the PG waveforms, etc. Indicators may further be isolated in either the time or frequency domain. The isolated indicators may advantageously be normalized, e.g., based on a baseline of the PG waveform or a derivative thereof.

Abstract: Systems and methods are provided for monitoring changes in blood volume using waveforms in the peripheral vasculature. In particular, the systems and methods relate to detecting ventilation-induced variation (VIV) of waveforms in the peripheral vasculature. Advantageously, the systems and methods may relate to analyzing VIV in peripheral venous pressure (PVP). Thus, the VIV of PVP may be measured, wherein decreased VIV is indicative of decreased blood volume In exemplary embodiments, such as involving spontaneous breathing, it may be necessary to account for changes in respiratory signal strength. Thus systems and methods are also provided for assessing coherence between ventilation and VIV for a flow or pressure waveform. Specifically, coherence is evaluated by comparing the waveform to a detected respiratory signal. Finally, systems and method are provided for distinguishing the impact of respiration on the PG signal during hypervolemia as compared to hypovolemia.

Abstract: A method and system for assessing blood volume within a subject includes generating a cardiovascular waveform representing physiological characteristics of a subject and determining blood volume of the subject by analyzing the cardiovascular waveform. The step of analyzing includes generating a first trace of the per heart-beat maximums of the cardiovascular waveform, which is representative of the systolic pressure upon the cardiovascular signal, generating a second trace of the per heart-beat minimums of the cardiovascular waveform, which is representative of the diastolic pressure upon the cardiovascular signal, and comparing the respective first trace and the second trace to generate an estimate of relative blood volume within the subject. In accordance with an alternate method of analyzing harmonic analysis is applied to the cardiovascular waveform, extracting a frequency signal created by ventilation and applying the extracted frequency signal in determining blood volume of the subject.