scholarly journals Can Photoplethysmography Replace Arterial Blood Pressure in the Assessment of Blood Pressure?

2018 ◽  
Vol 7 (10) ◽  
pp. 316 ◽  
Author(s):  
Gloria Martínez ◽  
Newton Howard ◽  
Derek Abbott ◽  
Kenneth Lim ◽  
Rabab Ward ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Transfer Function ◽  
Arterial Blood Pressure ◽  
Partial Coherence ◽  
Signal Acquisition ◽  
Directed Transfer Function ◽  
Statistical Measures ◽  
Arterial Blood ◽  
Frequency Domains

Arterial Blood Pressure (ABP) and photoplethysmography (PPG) are both useful techniques to monitor cardiovascular status. Though ABP monitoring is more widely employed, this procedure of signal acquisition whether done invasively or non-invasively may cause inconvenience and discomfort to the patients. PPG, however, is simple, noninvasive, and can be used for continuous measurement. This paper focuses on analyzing the similarities in time and frequency domains between ABP and PPG signals for normotensive, prehypertensive and hypertensive subjects and the feasibility of the classification of subjects considering the results of the analysis performed. From a database with 120 records of ABP and PPG, each 120 s in length, the records where separated into epochs taking into account 10 heartbeats, and the following statistical measures were performed: Correlation (r), Coherence (COH), Partial Coherence (pCOH), Partial Directed Coherence (PDC), Directed Transfer Function (DTF), Full Frequency Directed Transfer Function (ffDTF) and Direct Directed Transfer Function (dDTF). The correlation coefficient was r > 0.9 on average for all groups, indicating a strong morphology similarity. For COH and pCOH, coherence (linear correlation in frequency domain) was found with significance (p < 0.01) in differentiating between normotensive and hypertensive subjects using PPG signals. For the dataset at hand, only two synchrony measures are able to convincingly distinguish hypertensive subjects from normotensive control subjects, i.e., ffDTF and dDTF. From PDC, DTF, ffDTF, and dDTF, a consistent, a strong significant causality from ABP→PPG was found. When all synchrony measures were combined, an 87.5 % accuracy was achieved to detect hypertension using a Neural Network classifier, suggesting that PPG holds most informative features that exist in ABP.

Energy Harvesting From Arterial Blood Pressure for Embedded Brain Sensing

2016 ◽  
Author(s):  
Aditya Nanda ◽  
M. Amin Karami
Keyword(s):  
Blood Pressure ◽  
Transfer Function ◽  
Arterial Blood Pressure ◽  
Radial Pressure ◽  
Radial Breathing Mode ◽  
Curved Beam ◽  
Induced Voltage ◽  
Governing Equations ◽  
Arterial Blood ◽  
Straight Beam

This paper investigates energy harvesting from arterial blood pressure via the piezoelectric effect for the purpose of powering embedded micro-sensors in the brain. Blood flow is highly dynamic and arterial blood pressure varies, in the average human blood vessel, from 120 mm of Hg to 80 mm of Hg and we look at transduction of this pressure variation to electric energy via the piezoelectric effect. We propose two different geometries for this purpose. Initially, we look at the energy harvested by a cylinder, coated with PVDF (Polyvinylidene fluoride) patches, placed inside an artery acted upon by blood pressure. The arrangement is similar to that of a stent which is a cylinder placed in veins and arteries to prevent obstruction in blood flow. The governing equations of the harvester are obtained using Hamilton’s principle. Pressure acting in arteries is radially directed and this is used to simplify the governing equations. Specifically, radial pressure directed on the inner wall of the cylinder is assumed to excite only the radial breathing mode of vibration. Using this, the transfer function relating pressure to the induced voltage across the surface of the harvester is derived and the power harvested by the cylindrical harvester is obtained for different shunt resistances. However, the natural frequency of the radial breathing mode (RBM) is found to be very high and the harvested power at the frequencies of interest (3 Hz – 20 Hz) is very low. To decrease the natural frequency, we propose a novel streaked cylinder design that involves cutting the cylinder along the length, transforming it to a curved beam with an opening angle of 360 deg.. The governing equations corresponding to a circular curved beam, with PVDF patches on top and bottom surfaces, are derived using Hamilton’s principle and modal analysis is used to obtain the transfer function relating radial pressure to induced voltage. We validate the derived transfer function by evaluating the harvested power for a beam with very large radius of curvature; in which case, the curved beam becomes a straight beam and the harvested power is compared with the same for a straight beam (which exists in the literature). Further, we conduct design analyses and obtain the power as the geometric parameters of the harvester are varied for the purpose of optimizing the dimensions of harvester for maximal power generation. The power harvested by the harvester, at lower frequencies is deemed to be satisfactory.

Cerebral autoregulation in migraine with aura: A case control study

Cephalalgia ◽  
2018 ◽  
Vol 39 (5) ◽  
pp. 635-640 ◽  
Author(s):  
Cédric Gollion ◽  
Nathalie Nasr ◽  
Nelly Fabre ◽  
Michèle Barège ◽  
Marc Kermorgant ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Transfer Function ◽  
Arterial Blood Pressure ◽  
Migraine With Aura ◽  
Cerebral Autoregulation ◽  
Arterial Blood ◽  
Transfer Function Analysis ◽  
History Of

Background Migraine with aura is independently associated with increased risk of ischemic stroke, especially in younger subjects. This association might be related to an impairment of cerebral autoregulation, which normally maintains cerebral blood flow independent of arterial blood pressure variations. Methods Patients aged 30–55, fulfilling ICHD-3 beta criteria for migraine with aura, were prospectively enrolled and compared with gender- and age-matched healthy controls without a history of migraine. Patients and controls with a history of stroke or any disease potentially impairing cerebral autoregulation were excluded. We assessed cerebral autoregulation with two different methods: Transfer function analysis, and the correlation coefficient index Mx. The transfer function phase and gain reflect responses of cerebral blood flow velocities to relatively fast fluctuations of arterial blood pressure, whereas Mx also reflects responses to slower arterial blood pressure fluctuations. Results A total of 22 migraine with aura patients (median age [IQR]: 39.5 [12.5] years) and 22 controls (39 [9.75] years) were included. Transfer function parameters and Mx were not different between patients and controls. However, Mx was inversely correlated with age in patients (ρ = −0.567, p = 0.006) and not in controls (ρ = −0.084, p = 0.509). Mx was also inversely correlated with migraine with aura duration (ρ = −0.617, p = 0.002), suggesting improvement of cerebral autoregulation efficiency with disease duration. Conclusions Cerebral autoregulation did not differ between patients and controls aged 30–55. However, cerebral autoregulation efficiency was strongly correlated with migraine with aura duration. Further studies in younger patients are needed to determine whether cerebral autoregulation is impaired early in the course of disease. Trial Registration NCT02708797.

Resonant and notch behavior in intracranial pressure dynamics

2009 ◽  
Vol 3 (5) ◽  
pp. 354-364 ◽  
Author(s):  
Mark E. Wagshul ◽  
Erin J. Kelly ◽  
Hui Jing Yu ◽  
Barbara Garlick ◽  
Tom Zimmerman ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Intracranial Pressure ◽  
Transfer Function ◽  
Arterial Blood Pressure ◽  
Pulse Pressure ◽  
Function Analysis ◽  
Isotonic Saline ◽  
Pressure Amplitude ◽  
Arterial Blood ◽  
Transfer Function Analysis

Object The intracranial pulse pressure is often increased when neuropathology is present, particularly in cases of increased intracranial pressure (ICP) such as occurs in hydrocephalus. This pulse pressure is assumed to originate from arterial blood pressure oscillations entering the cranium; the fact that there is a coupling between the arterial blood pressure and the ICP is undisputed. In this study, the nature of this coupling and how it changes under conditions of increased ICP are investigated. Methods In 12 normal dogs, intracarotid and parenchymal pulse pressure were measured and their coupling was characterized using amplitude and phase transfer function analysis. Mean intracranial ICP was manipulated via infusions of isotonic saline into the spinal subarachnoid space, and changes in transfer function were monitored. Results Under normal conditions, the ICP wave led the arterial wave, and there was a minimum in the pulse pressure amplitude near the frequency of the heart rate. Under conditions of decreased intracranial compliance, the ICP wave began to lag behind the arterial wave and increased significantly in amplitude. Most interestingly, in many animals the pulse pressure exhibited a minimum in amplitude at a mean pressure that coincided with the transition from a leading to lagging ICP wave. Conclusions This transfer function behavior is characteristic of a resonant notch system. This may represent a component of the intracranial Windkessel mechanism, which protects the microvasculature from arterial pulsatility. The impairment of this resonant notch system may play a role in the altered pulse pressure in conditions such as hydrocephalus and traumatic brain swelling. New models of intracranial dynamics are needed for understanding the frequency-sensitive behavior elucidated in these studies and could open a path for development of new therapies that are geared toward addressing the pulsation dysfunction in pathological conditions, such as hydrocephalus and traumatic brain injury, affecting ICP and flow dynamics.

CLASSIFICATION OF CARDIAC ARRHYTHMIAS USING ARTERIAL BLOOD PRESSURE BASED ON DISCRETE WAVELET TRANSFORM

2017 ◽  
Vol 29 (05) ◽  
pp. 1750034 ◽  
Author(s):  
Roghayyeh Arvanaghi ◽  
Sabalan Daneshvar ◽  
Hadi Seyedarabi ◽  
Atefeh Goshvarpour
Keyword(s):  
Blood Pressure ◽  
Wavelet Transform ◽  
Discrete Wavelet Transform ◽  
Arterial Blood Pressure ◽  
Cardiac Arrhythmias ◽  
Support Vector ◽  
Discrete Wavelet ◽  
Ecg Signal ◽  
Arterial Blood

Early and correct diagnosis of cardiac arrhythmias is an important step in the treatment of patients. In the recent decades, a wide area of bio-signal processing is allocated to cardiac arrhythmia classification. Unlike other studies, which have employed Electrocardiogram (ECG) signal as a main signal to classify the arrhythmia and sometimes they have used other vital signals as an auxiliary signal to fill missing data and robust detections. In this study, the Arterial Blood Pressure (ABP) is used to classify six types of heart arrhythmias. In other words, in this study for first time, the arrhythmias are classified according ABP signal information. Discrete Wavelet Transform (DWT) is used to de-noise and decompose ABP signal. On feature extraction stage, three types of features including frequency, power, and entropy are extracted. In classification stage, Least Square Support Vector Machine (LS-SVM) is employed as a classifier. The accuracy, sensitivity, and specificity rates of 95.75%, 96.77%, and 96.32% are achieved, respectively. Currently, the classification of cardiac arrhythmias is based on the ABP signal which has some advantages. The recording of ABP signal is done by means of one electrode and therefore it has resulted in lower costs compared with the ECG signal. Finally, it has been shown that ABP has very important and valuable information about the heart performance and can be used in arrhythmia classification.

Influence of noninvasive peripheral arterial blood pressure measurements on assessment of dynamic cerebral autoregulation

2007 ◽  
Vol 103 (1) ◽  
pp. 369-375 ◽  
Author(s):  
Emily L. Sammons ◽  
Nilesh J. Samani ◽  
Stephen M. Smith ◽  
Wendy E. Rathbone ◽  
Steve Bentley ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Transfer Function ◽  
Arterial Blood Pressure ◽  
Cerebral Autoregulation ◽  
Aortic Pressure ◽  
Step Response ◽  
Pressure Measurements ◽  
Arterial Blood ◽  
Surface Ecg ◽  
Dynamic Cerebral Autoregulation

Assessment of dynamic cerebral autoregulation (CA) requires continuous recording of arterial blood pressure (ABP). In humans, noninvasive ABP recordings with the Finapres device have often been used for this purpose. We compared estimates of dynamic CA derived from Finapres with those from invasive recordings in the aorta. Measurements of finger noninvasive ABP (Finapres), intra-aortic ABP (Millar catheter), surface ECG, transcutaneous CO2, and bilateral cerebral blood flow velocity (CBFV) in the middle cerebral arteries were simultaneously and continuously recorded in 27 patients scheduled for percutaneous coronary interventions. Phase, gain, coherence, and CBFV step response from both the Finapres and intra-arterial catheter were estimated by transfer function analysis. A dynamic autoregulation index (ARI) was also calculated. For both hemispheres, the ARI index and the CBFV step response recovery at 4 s were significantly greater for the Finapres-derived estimates than for the values obtained from aortic pressure. The transfer function gain for frequencies <0.1 Hz was significantly smaller for the Finapres estimates. The phase frequency response was significantly greater for the Finapres estimates at frequencies >0.1 Hz, but not at lower frequencies. The Finapres gives higher values for the efficiency of dynamic CA compared with values derived from aortic pressure measurements, as indicated by biases in the ARI index, CBFV step response, gain, and phase. Despite the significance of these biases, their relatively small amplitude indicates a good level of agreement between indexes of CA derived from the Finapres compared with corresponding estimates obtained from invasive measurements of aortic ABP.

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