Abstract：
:In a previous paper we demonstrated that the linear portion of the pressure-velocity loop (PU-loop) corresponding to early systole could be used to calculate the local wave speed. In this paper we extend this work to show that determination of the time at which the PU-loop first deviates from linearity provides a convenient way to determine the arrival time of reflected waves (Tr). We also present a new technique using the PU-loop that allows for the determination of wave speed and Tr simultaneously. We measured pressure and flow in elastic tubes of different diameters, where a strong reflection site existed at known distances away form the measurement site. We also measured pressure and flow in the ascending aorta of 11 anaesthetised dogs where a strong reflection site was produced through total arterial occlusion at four different sites. Wave speed was determined from the initial slope of the PU-loop and Tr was determined using a new algorithm that detects the sampling point at which the initial linear part of the PU-loop deviates from linearity. The results of the new technique for detecting Tr were comparable to those determined using the foot-to-foot and wave intensity analysis methods. In elastic tubes Tr detected using the new algorithm was almost identical to that detected using wave intensity analysis and foot-to-foot methods with a maximum difference of 2%. Tr detected using the PU-loop in vivo highly correlated with that detected using wave intensity analysis (r (2) = 0.83, P < 0.001). We conclude that the new technique described in this paper offers a convenient and objective method for detecting Tr, and allows for the dynamic determination of wave speed and Tr, simultaneously.
journal_name
Med Biol Eng Computjournal_title
Medical & biological engineering & computingauthors
Khir AW,Swalen MJ,Feng J,Parker KHdoi
10.1007/s11517-007-0241-7subject
Has Abstractpub_date
2007-12-01 00:00:00pages
1201-10issue
12eissn
0140-0118issn
1741-0444journal_volume
45pub_type
杂志文章abstract：:To elucidate the mechanisms of localisation of intimal hyperplasia in anastomosed arteries, the effects of flow disturbances on the transport of low-density lipoproteins (LDLs) from the flowing blood to the wall of end-to-end anastomosed arteries, with and without a moderate stenosis, were studied theoretically by mea...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02345458
更新日期：2002-09-01 00:00:00
abstract：:This study examined the electroencephalogram functional connectivity (coherence) and effective connectivity (flow of information) of selected brain regions during three different attentive states: awake, meditation and drowsiness. For the estimation of functional connectivity (coherence), Welch and minimum variance di...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-015-1272-0
更新日期：2015-07-01 00:00:00
abstract：:We introduce a novel method for an automatic classification of subjects to those with or without neuromuscular disorders. This method is based on multiscale entropy of recorded surface electromyograms (sEMGs) and support vector classification. The method was evaluated on a single-channel experimental sEMGs recorded fr...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-010-0629-7
更新日期：2010-08-01 00:00:00
abstract：:This work addresses the problem of estimating the conduction velocity (CV) of single motor unit (MU) action potentials from surface EMG signals detected with linear electrode arrays during voluntary muscle contractions. In ideal conditions, that is without shape or scale changes of the propagating signals and with add...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02344807
更新日期：2001-03-01 00:00:00
abstract：:When the rib cage and abdomen are compressed during cardiopulmonary resuscitation (CPR), the effect on intrathoracic pressure, and therefore on haemodynamics, cannot be quantitatively predicted without a physiologically based mathematical model of chest wall dynamics. Using such a model, we compared model simulations ...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02441676
更新日期：1990-01-01 00:00:00
abstract：:We present an analytical solution for the electrical potential and activating function (AF) established by cylindrical needle electrodes in anisotropic tissue. We compare this activating function to (1) AF computed assuming line-source electrodes and (2) AF computed using a finite element program. The results show tha...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-009-0508-2
更新日期：2009-09-01 00:00:00
abstract：:The flow mechanisms that play a role on aerosol deposition were identified and presented in a companion paper (Timothy et al. in Med Biol Eng Comput. doi: 10.1007/s11517-015-1407-3 , 2015). In the current paper, the effects of invasive conventional mechanical ventilation waveforms and endotracheal tube (ETT) on the ae...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-015-1408-2
更新日期：2016-07-01 00:00:00
abstract：:In the PREVENIR-5 study, artificial neural networks (NN) were applied to a large sample of patients with recent first acute coronary syndrome (ACS) to identify determinants of persistence of evidence-based cardiovascular medications (EBCM: antithrombotic + beta-blocker + statin + angiotensin converting enzyme inhibito...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-011-0785-4
更新日期：2011-08-01 00:00:00
abstract：:A method for extrapolating the extracellular water (ECW) resistance from wrist-ankle resistance at 50 kHz (R (50)) is proposed in this paper, in order to enable 50 kHz impedancemeters to use the BIS-Hanai equation for determination of ECW. Values of R (50) and the ECW resistance extrapolated at zero frequency R (e) we...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-008-0394-z
更新日期：2009-01-01 00:00:00
abstract：:Bone mass and microarchitecture are the main determinants of bone strength. Three-dimensional micro-computed tomography has the potential to examine complete bones of small laboratory animals with very high resolution in a non-invasive way. In the presented work, the proximal part of the tibiae of hindlimb unloaded an...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02347054
更新日期：2000-05-01 00:00:00
abstract：:A method for the identification of the breast boundary in mammograms is presented. The method can be used in the preprocessing stage of a system for computer-aided diagnosis (CAD) of breast cancer and also in the reduction of image file size in picture archiving and communication system applications. The method starte...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02344632
更新日期：2004-03-01 00:00:00
abstract：:Obstructive sleep apnea syndrome (OSAS) is a major public health problem. The golden reference for diagnosing OSAS is the sleep-laboratory based polysomnography (PSG). However, screening of population for OSAS may be practical and cost efficient only through ambulatory home recordings. In this work we aimed to design,...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-008-0418-8
更新日期：2009-01-01 00:00:00
abstract：:The interactions between respiration, heart rate and blood pressure variability (HRV, BPV), are considered to be of paramount importance for the study of the functional organisation of the autonomic nervous system (ANS). The aim of the reported study is to detect and classify the intermittent phase locking (PL) phenom...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02345011
更新日期：2000-07-01 00:00:00
abstract：:Peripheral arterial occlusive disease is a serious cardiovascular disorder. The arterial occlusion leads to turbulent flow and arterial sound generation on the inner vessel wall. Stenosis-induced vibro-acoustic waves propagate through the surrounding soft tissues and reach the skin surface. In this study, the feasibil...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-019-01995-y
更新日期：2019-08-01 00:00:00
abstract：:The study and applications of in vivo skin optics have been openly documented as early as the year 1954, or possibly earlier. To date, challenges in analyzing the complexities of this field remain, with wide scopes requiring more scrutiny. Recent advances in spectroscopic research and multivariate analytics allow a cl...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章,评审
doi：10.1007/s11517-019-02077-9
更新日期：2020-06-01 00:00:00
abstract：:Nitric oxide (NO) released by endothelial cells in response to hemodynamic shear stress is a key controller molecule of the vascular functions and antiatherogenic mechanisms. Endothelial dysfunction is associated with increased cardiovascular events. Therefore, several indirect techniques have been employed to evaluat...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-008-0333-z
更新日期：2008-05-01 00:00:00
abstract：:The purpose of this study is to verify the applicability of a sixth-order model to the mechanomyogram (MMG) system of the parallel-fibered muscle, which was identified from the MMG of the pennation muscle. The median nerve was stimulated, and an MMG and torque of the abductor pollicis brevis muscle were measured. The ...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-013-1107-9
更新日期：2013-12-01 00:00:00
abstract：:Self-generated mobility is a major contributor to the physical, emotional, cognitive, and social development of infants and toddlers. When young children have disorders that hinder self locomotion, their development is at risk for delay. Independent mobility via traditional power mobility devices may prevent this dela...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-011-0820-5
更新日期：2011-10-01 00:00:00
abstract：:A generic framework for the automated classification of human movements using an accelerometry monitoring system is introduced. The framework was structured around a binary decision tree in which movements were divided into classes and subclasses at different hierarchical levels. General distinctions between movements...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02347551
更新日期：2004-09-01 00:00:00
abstract：:The understanding of cardiac arrhythmia under genetic mutations has grown in interest among researchers. Previous studies focused on the effect of the D172N mutation on electrophysiological behavior. In this study, we analyzed not only the electrophysiological activity but also the mechanical responses during normal s...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-020-02124-w
更新日期：2020-05-01 00:00:00
abstract：:Transurethral resection of the prostate is the most common method of relieving urinary outflow obstruction secondary to prostatic enlargement. However, this procedure can be responsible for various complications, including irrigant-fluid absorption and blood loss, both of which are strongly dependent on operation dura...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02510962
更新日期：1997-11-01 00:00:00
abstract：:Sealing resistance is highly significant with respect to the electrical neuron-electrode contact because it decreases the stimulation threshold of neurons cultured on a planar micro-electrode array. A method is proposed for measurement of the sealing resistance using impedance spectroscopy. The effect of the sealing r...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02524436
更新日期：1998-09-01 00:00:00
abstract：:Biological variation in branching patterns is likely to affect perfusion of tissue. To assess the fundamental consequences of branching characteristics, 50 stochastic asymmetrical coronary trees and one non-stochastic symmetrical branching tree were generated. In the stochastic trees, area growth, A, at branching poin...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-006-0139-9
更新日期：2007-01-01 00:00:00
abstract：:Tissue surface temperature distribution on the treatment site can serve as an indicator for the effectiveness of a photothermal therapy. In this study, both infrared thermography and theoretical simulation were used to determine the surface temperature distribution during laser irradiation of both gel phantom and anim...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-007-0251-5
更新日期：2008-02-01 00:00:00
abstract：:In a computer-aided diagnosis (CAD) system, especially for chest radiograph or chest X-ray (CXR) screening, CXR image view information is required. Automatically separating CXR image view, frontal and lateral can ease subsequent CXR screening process, since the techniques may not equally work for both views. We presen...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-018-1786-3
更新日期：2018-08-01 00:00:00
abstract：:Magnetoenterography (MENG) is a new, non-invasive technique that measures gastrointestinal magnetic signals near the body surface. This study was undertaken to evaluate the temporal and spatial characteristics of the magnetic signals generated by gastric and duodenal slow wave activity. The gastrointestinal magnetic f...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02513347
更新日期：1999-09-01 00:00:00
abstract：:High-frequency nanosecond-pulsed electric fields were recently introduced for tumor or abnormal tissue ablation to solve some problems of conventional electroporation. However, it is necessary to study the thermal effects of high-field-intensity nanosecond pulses inside tissues. The multi-parametric analysis performed...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-016-1589-3
更新日期：2017-07-01 00:00:00
abstract：:The regulation of cerebral blood flow (CBF) following changes in arterial blood pressure (ABP) and end-tidal pCO2 (EtCO2) are of clinical interest in assessing cerebrovascular reserve capacity. Linear finite-impulse-response modelling is applied to ABP, EtCO2 and CBF velocity (CBFV, from transcranial Doppler measureme...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/BF02345749
更新日期：2000-09-01 00:00:00
abstract：:Primary stability of refixated fractures in case of shoulder hemiarthroplasty is a prerequisite to restore physiological glenohumeral joint function. Clinical observations often show a secondary dislocation and subsequent resorption of the bony anchor points like the greater and lesser tuberosity at the rotator cuff t...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-009-0483-7
更新日期：2009-05-01 00:00:00
abstract：:The reconstruction of bioluminescence tomography (BLT) is severely ill-posed due to the insufficient measurements and diffuses nature of the light propagation. Predefined permissible source region (PSR) combined with regularization terms is one common strategy to reduce such ill-posedness. However, the region of PSR i...
journal_title：Medical & biological engineering & computing
pub_type： 杂志文章
doi：10.1007/s11517-018-1842-z
更新日期：2018-11-01 00:00:00
