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H. Harry Asada - One of the best experts on this subject based on the ideXlab platform.

  • Motion based adaptive calibration of pulse transit time measurements to arterial Blood Pressure for an autonomous, wearable Blood Pressure Monitor
    Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and, 2008
    Co-Authors: Devin B. McCombie, Andrew T. Reisner, H. Harry Asada
    Abstract:

    This paper presents a novel adaptive algorithm for calibrating non-invasive pulse transit time (PTT) measurements to arterial Blood Pressure (BP). This new algorithm allows complete calibration of PTT to BP without the use of an oscillometric Blood Pressure cuff or external Pressure sensor. Further, the algorithm can be used to continually update the identified parameters in the calibration equation while the patient is wearing the device. The technique utilizes natural patient motion to generate a known change in the transmural Pressure (input) acting on the arteries Monitored by our device to produce a measurable change in pulse transit time (output). The natural motion includes varying the height of the sensor relative to the heart to alter hydrostatic Pressure at the measurement site and adjusting proximal joint posture to vary the external arterial Pressure at the measurement site. This new algorithm is applied to a unique wearable sensor architecture that combines two in-line PPG sensors, one located at the ulnar artery of the wrist and one located at the digital artery of the little finger along with a multi-axis accelerometer for height measurement. Initial human subject tests results using the new algorithm and device will be presented.

  • Adaptive hydrostatic Blood Pressure calibration: Development of a wearable, autonomous pulse wave velocity Blood Pressure Monitor
    Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings, 2007
    Co-Authors: Devin B. McCombie, Phillip A. Shaltis, Andrew T. Reisner, H. Harry Asada
    Abstract:

    A technique for calibrating non-invasive peripheral arterial sensor signals to peripheral arterial Blood Pressure (BP) is proposed. The adaptive system identification method utilizes a measurable intra-arterial hydrostatic Pressure change in the sensor outfitted appendage to identify the transduction dynamics relating the peripheral arterial Blood Pressure and the measured arterial sensor signal. The proposed algorithm allows identification of the calibration dynamics despite unknown physiologic fluctuations in arterial Pressure during the calibration period under certain prescribed conditions. By employing unique wearable sensor architecture to estimate pulse wave velocity (PWV), this technique is used to calibrate peripheral pulse transit time measurements to arterial Blood Pressure. This sensor architecture is comprised of two inline photoplethysmograph sensors one in the form of a wristwatch measuring the pulse waveform in the ulnar artery and one in the form of a ring measuring the pulse waveform from the digital artery along the base of the little finger. Experimental results using the proposed algorithm to calibrate PTT to BP on human subjects will be presented.

  • Wearable, cuff-less PPG-based Blood Pressure Monitor with novel height sensor
    Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings, 2006
    Co-Authors: Phillip A. Shaltis, Andrew T. Reisner, H. Harry Asada
    Abstract:

    A truly wearable non-invasive Blood Pressure (NIBP) sensor--light-weight, compact, unobstrusive, and essentially unnoticeable to the patient--could revolutionize healthcare delivered beyond the traditional walls of medical facilities, offering new ways to care for patients in their everyday surroundings. This paper presents results from our work towards the development of a self-contained, wearable Blood Pressure sensor. A PPG-based approach to Blood Pressure Monitoring is presented. The design enables significant miniaturization of traditional oscillometric devices without the need for occlusive circumferential Pressures. It will be shown how natural raising and lowering of the arm replaces the need for bulky actuators. Additionally, a dual-accelerometer height sensor that is tetherless is proposed and supported by experimental results.

Hao Min Cheng - One of the best experts on this subject based on the ideXlab platform.

  • comparison of two generalized transfer functions for measuring central systolic Blood Pressure by an oscillometric Blood Pressure Monitor
    Journal of Human Hypertension, 2013
    Co-Authors: Yuanta Shih, Hao Min Cheng, Shihhsien Sung, C H Chen
    Abstract:

    Comparison of two generalized transfer functions for measuring central systolic Blood Pressure by an oscillometric Blood Pressure Monitor

  • measurement accuracy of a stand alone oscillometric central Blood Pressure Monitor a validation report for microlife watchbp office central
    American Journal of Hypertension, 2013
    Co-Authors: Hao Min Cheng, Yuanta Shih, Shihhsien Sung, Shaoyuan Chuang, Chenhuan Chen
    Abstract:

    Background The superiority of prognostic value of Blood Pressure (BP) measured at central aorta (CBP) over conventional brachial BP measured by cuff-based BP Monitors has reignited the development of new noninvasive techniques for estimating CBP. The present study validated the accuracy of CBP measured by a newly developed stand-alone CBP Monitor. Methods The CBP Monitor provided readings of brachial systolic BP (SBP), brachial diastolic BP (DBP), central SBP, and central pulse Pressure (PP). Brachial PP and central DBP were calculated from the relevant readings. The accuracy of the brachial and central SBP, PP, and DBP was validated against the simultaneously recorded invasively measured central aortic SBP, PP, and DBP, according to the invasive standard requirements for the noninvasive brachial BP Monitors from the Association for the Advancement of Medical Instrumentation (AAMI) in 85 subjects (255 measurements; age range, 30-93 years). Results The mean differences of cuff BP with reference to the invasively measured central SBP, PP, and DBP were -2.6 ± 9.0, -8.6 ± 11.2, and 6.1 ± 7.0 mm Hg, respectively, with the former two being obviously underestimated at high CBP and overestimated at low CBP. In contrast, the corresponding differences for the central SBP, PP, and DBP measured by the CBP Monitor were -0.6 ± 5.5, -0.4 ± 7.0, and -0.2 ± 6.5 mm Hg, respectively, without obvious systematic bias. The distribution of measurement errors for central SBP, PP, and DBP surpassed the AAMI criteria. Conclusion Central SBP, PP, and DBP can be measured accurately by a stand-alone automatic BP Monitor.

  • measurement of central systolic Blood Pressure by pulse volume plethysmography with a noninvasive Blood Pressure Monitor
    American Journal of Hypertension, 2012
    Co-Authors: Hao Min Cheng, Kangling Wang, Yinghwa Chen, Yuanta Shih, Shihhsien Sung, Shaoyuan Chuang
    Abstract:

    Background Central systolic Blood Pressure (SBP) can be estimated by an oscillometric method developed from a pulse volume plethysmography (PVP) device. The present study applied this novel method to a noninvasive Blood Pressure Monitor (NBPM). Methods We enrolled 50 patients (37 men, age range 30–84 years) referred for cardiac catheterization. Invasive right brachial and central aortic Pressures (using a dual-sensor Pressure catheter), and noninvasive left brachial SBP and diastolic Blood Pressure (DBP), and PVP waveform (using a customized NBPM) were simultaneously recorded. Central SBP was estimated by analysis of the PVP waveform calibrated to the noninvasive SBP and DBP, using both the original (CSBP-O) and the newly generated (CSBP-N) regression equations. The reproducibility of the invasive central SBP by CSBP-O and CSBP-N was examined using the concordance correlation coefficient. results Overall, the invasive central aortic SBP ranged 86–176 with a mean of 124 ± 21 mm Hg. The mean differences between the estimated and the invasive central SBP were −1.3 ± 6.7 mm Hg for CSBP-O and 0.0 ± 6.2 mm Hg for CSBP-N, respectively. The concordance correlation coefficients for CSBP-O and CSBP-N were 0.94 (95% confidence interval (CI): 0.93–0.94) and 0.95 (95% CI: 0.95–0.96), and both were significantly better than that for the noninvasive brachial SBP (0.87, 0.84–0.91) indicated by non-overlapping CIs. conclusions The PVP method for noninvasive estimation of central SBP can be applied to a commonly used NBPM. Whether the NBPM-derived central SBP is superior to the noninvasive brachial SBP in the prediction of cardiovascular risks remains to be investigated.

  • estimation of central systolic Blood Pressure using an oscillometric Blood Pressure Monitor
    Hypertension Research, 2010
    Co-Authors: Hao Min Cheng, Kangling Wang, Yinghwa Chen, Shingjong Lin, Lungching Chen
    Abstract:

    Current noninvasive techniques for assessing central aortic Pressure require the recording of an arterial Pressure wave using a high-fidelity applanation tonometer. We therefore developed and validated a novel method to estimate the central aortic systolic Pressure using an oscillometric Blood Pressure Monitor alone. Invasive high-fidelity right brachial and central aortic Pressure waves, and left-brachial pulse volume plethysmography from an oscillometric Blood Pressure Monitor, were obtained at baseline and 3 min after administration of sublingual nitroglycerin in 100 patients during cardiac catheterization. In the initial 50 patients (Generation Group), Central systolic Blood Pressure was predicted by a multi-variate prediction model generated from the comprehensive analysis of the invasive brachial Pressure wave, including brachial late-systolic shoulder Pressure value and parameters related to wave reflection and arterial compliance. Another prediction model was similarly constructed from the noninvasively calibrated pulse volume plethysmography. Both models were validated in the subsequent 50 patients (Validation Group) with results: r=0.98 (P<0.001) and mean difference=0.5+/-4.5 (95% confidence interval -8.3 to 9.3) mm Hg for the invasive model, and r=0.93 (P<0.001) and mean difference=-0.1+/-7.6 (95% confidence interval -15.0 to 14.8) mm Hg for the noninvasive model. Thus, our results indicate that central aortic systolic Blood Pressure could be estimated by analysis of the noninvasive brachial Pressure wave alone from an oscillometric Blood Pressure Monitor.

Yinghwa Chen - One of the best experts on this subject based on the ideXlab platform.

  • measurement of central systolic Blood Pressure by pulse volume plethysmography with a noninvasive Blood Pressure Monitor
    American Journal of Hypertension, 2012
    Co-Authors: Hao Min Cheng, Kangling Wang, Yinghwa Chen, Yuanta Shih, Shihhsien Sung, Shaoyuan Chuang
    Abstract:

    Background Central systolic Blood Pressure (SBP) can be estimated by an oscillometric method developed from a pulse volume plethysmography (PVP) device. The present study applied this novel method to a noninvasive Blood Pressure Monitor (NBPM). Methods We enrolled 50 patients (37 men, age range 30–84 years) referred for cardiac catheterization. Invasive right brachial and central aortic Pressures (using a dual-sensor Pressure catheter), and noninvasive left brachial SBP and diastolic Blood Pressure (DBP), and PVP waveform (using a customized NBPM) were simultaneously recorded. Central SBP was estimated by analysis of the PVP waveform calibrated to the noninvasive SBP and DBP, using both the original (CSBP-O) and the newly generated (CSBP-N) regression equations. The reproducibility of the invasive central SBP by CSBP-O and CSBP-N was examined using the concordance correlation coefficient. results Overall, the invasive central aortic SBP ranged 86–176 with a mean of 124 ± 21 mm Hg. The mean differences between the estimated and the invasive central SBP were −1.3 ± 6.7 mm Hg for CSBP-O and 0.0 ± 6.2 mm Hg for CSBP-N, respectively. The concordance correlation coefficients for CSBP-O and CSBP-N were 0.94 (95% confidence interval (CI): 0.93–0.94) and 0.95 (95% CI: 0.95–0.96), and both were significantly better than that for the noninvasive brachial SBP (0.87, 0.84–0.91) indicated by non-overlapping CIs. conclusions The PVP method for noninvasive estimation of central SBP can be applied to a commonly used NBPM. Whether the NBPM-derived central SBP is superior to the noninvasive brachial SBP in the prediction of cardiovascular risks remains to be investigated.

  • estimation of central systolic Blood Pressure using an oscillometric Blood Pressure Monitor
    Hypertension Research, 2010
    Co-Authors: Hao Min Cheng, Kangling Wang, Yinghwa Chen, Shingjong Lin, Lungching Chen
    Abstract:

    Current noninvasive techniques for assessing central aortic Pressure require the recording of an arterial Pressure wave using a high-fidelity applanation tonometer. We therefore developed and validated a novel method to estimate the central aortic systolic Pressure using an oscillometric Blood Pressure Monitor alone. Invasive high-fidelity right brachial and central aortic Pressure waves, and left-brachial pulse volume plethysmography from an oscillometric Blood Pressure Monitor, were obtained at baseline and 3 min after administration of sublingual nitroglycerin in 100 patients during cardiac catheterization. In the initial 50 patients (Generation Group), Central systolic Blood Pressure was predicted by a multi-variate prediction model generated from the comprehensive analysis of the invasive brachial Pressure wave, including brachial late-systolic shoulder Pressure value and parameters related to wave reflection and arterial compliance. Another prediction model was similarly constructed from the noninvasively calibrated pulse volume plethysmography. Both models were validated in the subsequent 50 patients (Validation Group) with results: r=0.98 (P<0.001) and mean difference=0.5+/-4.5 (95% confidence interval -8.3 to 9.3) mm Hg for the invasive model, and r=0.93 (P<0.001) and mean difference=-0.1+/-7.6 (95% confidence interval -15.0 to 14.8) mm Hg for the noninvasive model. Thus, our results indicate that central aortic systolic Blood Pressure could be estimated by analysis of the noninvasive brachial Pressure wave alone from an oscillometric Blood Pressure Monitor.

Shihhsien Sung - One of the best experts on this subject based on the ideXlab platform.

  • comparison of two generalized transfer functions for measuring central systolic Blood Pressure by an oscillometric Blood Pressure Monitor
    Journal of Human Hypertension, 2013
    Co-Authors: Yuanta Shih, Hao Min Cheng, Shihhsien Sung, C H Chen
    Abstract:

    Comparison of two generalized transfer functions for measuring central systolic Blood Pressure by an oscillometric Blood Pressure Monitor

  • measurement accuracy of a stand alone oscillometric central Blood Pressure Monitor a validation report for microlife watchbp office central
    American Journal of Hypertension, 2013
    Co-Authors: Hao Min Cheng, Yuanta Shih, Shihhsien Sung, Shaoyuan Chuang, Chenhuan Chen
    Abstract:

    Background The superiority of prognostic value of Blood Pressure (BP) measured at central aorta (CBP) over conventional brachial BP measured by cuff-based BP Monitors has reignited the development of new noninvasive techniques for estimating CBP. The present study validated the accuracy of CBP measured by a newly developed stand-alone CBP Monitor. Methods The CBP Monitor provided readings of brachial systolic BP (SBP), brachial diastolic BP (DBP), central SBP, and central pulse Pressure (PP). Brachial PP and central DBP were calculated from the relevant readings. The accuracy of the brachial and central SBP, PP, and DBP was validated against the simultaneously recorded invasively measured central aortic SBP, PP, and DBP, according to the invasive standard requirements for the noninvasive brachial BP Monitors from the Association for the Advancement of Medical Instrumentation (AAMI) in 85 subjects (255 measurements; age range, 30-93 years). Results The mean differences of cuff BP with reference to the invasively measured central SBP, PP, and DBP were -2.6 ± 9.0, -8.6 ± 11.2, and 6.1 ± 7.0 mm Hg, respectively, with the former two being obviously underestimated at high CBP and overestimated at low CBP. In contrast, the corresponding differences for the central SBP, PP, and DBP measured by the CBP Monitor were -0.6 ± 5.5, -0.4 ± 7.0, and -0.2 ± 6.5 mm Hg, respectively, without obvious systematic bias. The distribution of measurement errors for central SBP, PP, and DBP surpassed the AAMI criteria. Conclusion Central SBP, PP, and DBP can be measured accurately by a stand-alone automatic BP Monitor.

  • measurement of central systolic Blood Pressure by pulse volume plethysmography with a noninvasive Blood Pressure Monitor
    American Journal of Hypertension, 2012
    Co-Authors: Hao Min Cheng, Kangling Wang, Yinghwa Chen, Yuanta Shih, Shihhsien Sung, Shaoyuan Chuang
    Abstract:

    Background Central systolic Blood Pressure (SBP) can be estimated by an oscillometric method developed from a pulse volume plethysmography (PVP) device. The present study applied this novel method to a noninvasive Blood Pressure Monitor (NBPM). Methods We enrolled 50 patients (37 men, age range 30–84 years) referred for cardiac catheterization. Invasive right brachial and central aortic Pressures (using a dual-sensor Pressure catheter), and noninvasive left brachial SBP and diastolic Blood Pressure (DBP), and PVP waveform (using a customized NBPM) were simultaneously recorded. Central SBP was estimated by analysis of the PVP waveform calibrated to the noninvasive SBP and DBP, using both the original (CSBP-O) and the newly generated (CSBP-N) regression equations. The reproducibility of the invasive central SBP by CSBP-O and CSBP-N was examined using the concordance correlation coefficient. results Overall, the invasive central aortic SBP ranged 86–176 with a mean of 124 ± 21 mm Hg. The mean differences between the estimated and the invasive central SBP were −1.3 ± 6.7 mm Hg for CSBP-O and 0.0 ± 6.2 mm Hg for CSBP-N, respectively. The concordance correlation coefficients for CSBP-O and CSBP-N were 0.94 (95% confidence interval (CI): 0.93–0.94) and 0.95 (95% CI: 0.95–0.96), and both were significantly better than that for the noninvasive brachial SBP (0.87, 0.84–0.91) indicated by non-overlapping CIs. conclusions The PVP method for noninvasive estimation of central SBP can be applied to a commonly used NBPM. Whether the NBPM-derived central SBP is superior to the noninvasive brachial SBP in the prediction of cardiovascular risks remains to be investigated.

Phillip A. Shaltis - One of the best experts on this subject based on the ideXlab platform.

  • Adaptive hydrostatic Blood Pressure calibration: Development of a wearable, autonomous pulse wave velocity Blood Pressure Monitor
    Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings, 2007
    Co-Authors: Devin B. McCombie, Phillip A. Shaltis, Andrew T. Reisner, H. Harry Asada
    Abstract:

    A technique for calibrating non-invasive peripheral arterial sensor signals to peripheral arterial Blood Pressure (BP) is proposed. The adaptive system identification method utilizes a measurable intra-arterial hydrostatic Pressure change in the sensor outfitted appendage to identify the transduction dynamics relating the peripheral arterial Blood Pressure and the measured arterial sensor signal. The proposed algorithm allows identification of the calibration dynamics despite unknown physiologic fluctuations in arterial Pressure during the calibration period under certain prescribed conditions. By employing unique wearable sensor architecture to estimate pulse wave velocity (PWV), this technique is used to calibrate peripheral pulse transit time measurements to arterial Blood Pressure. This sensor architecture is comprised of two inline photoplethysmograph sensors one in the form of a wristwatch measuring the pulse waveform in the ulnar artery and one in the form of a ring measuring the pulse waveform from the digital artery along the base of the little finger. Experimental results using the proposed algorithm to calibrate PTT to BP on human subjects will be presented.

  • Wearable, cuff-less PPG-based Blood Pressure Monitor with novel height sensor
    Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings, 2006
    Co-Authors: Phillip A. Shaltis, Andrew T. Reisner, H. Harry Asada
    Abstract:

    A truly wearable non-invasive Blood Pressure (NIBP) sensor--light-weight, compact, unobstrusive, and essentially unnoticeable to the patient--could revolutionize healthcare delivered beyond the traditional walls of medical facilities, offering new ways to care for patients in their everyday surroundings. This paper presents results from our work towards the development of a self-contained, wearable Blood Pressure sensor. A PPG-based approach to Blood Pressure Monitoring is presented. The design enables significant miniaturization of traditional oscillometric devices without the need for occlusive circumferential Pressures. It will be shown how natural raising and lowering of the arm replaces the need for bulky actuators. Additionally, a dual-accelerometer height sensor that is tetherless is proposed and supported by experimental results.