Abstract:
:Cerebral autoregulation has been studied by linear filter systems, with arterial blood pressure (ABP) as the input and cerebral blood flow velocity (CBFV-from transcranial Doppler Ultrasound) as the output. The current work extends this by using adaptive filters to investigate the dynamics of time-varying cerebral autoregulation during step-wise changes in arterial PaCO(2). Cerebral autoregulation was transiently impaired in 11 normal adult volunteers, by switching inspiratory air to a CO(2)/air mixture (5% CO(2), 30% O(2) and 65% N(2)) for approximately 2 min and then back to the ambient air, causing step-wise changes in end-tidal CO(2) (EtCO(2)). Simultaneously, ABP and CBFV were recorded continuously. Simulated data corresponding to the same protocol were also generated using an established physiological model, in order to refine the signal analysis methods. Autoregulation was quantified by the time-varying phase lead, estimated from the adaptive filter model. The adaptive filter was able to follow rapid changes in autoregulation, as was confirmed in the simulated data. In the recorded signals, there was a slow decrease in autoregulatory function following the step-wise increase in PaCO(2) (but this did not reach a steady state within approximately 2 min of recording), with a more rapid change in autoregulation on return to normocapnia. Adaptive filter modelling was thus able to demonstrate time-varying autoregulation. It was further noted that impairment and recovery of autoregulation during transient increases in EtCO(2) occur in an asymmetric manner, which should be taken into account when designing experimental protocols for the study of autoregulation.
journal_name
Physiol Measjournal_title
Physiological measurementauthors
Liu J,Simpson MD,Yan J,Allen Rdoi
10.1088/0967-3334/31/10/001subject
Has Abstractpub_date
2010-10-01 00:00:00pages
1291-307issue
10eissn
0967-3334issn
1361-6579pii
S0967-3334(10)47553-Xjournal_volume
31pub_type
杂志文章abstract:OBJECTIVE:Metal exposures have been linked with many adverse health outcomes affecting nearly every system in the body. Exposure to metals has been tracked primarily using blood. Blood metal concentrations have drawbacks as biomarkers stemming from the metals' short biologic half-lives, shipping and storage requirement...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/1361-6579/aad947
更新日期:2018-08-31 00:00:00
abstract::Polysomnography (PSG) has been extensively studied for sleep staging, where sleep stages are usually classified as wake, rapid-eye-movement (REM) sleep, or non-REM (NREM) sleep (including light and deep sleep). Respiratory information has been proven to correlate with autonomic nervous activity that is related to slee...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/35/12/2529
更新日期:2014-12-01 00:00:00
abstract::We present the results of using electrical impedance tomographic spectroscopy (EITS) to follow the changes in lung water induced by oleic acid. Measurements were made on three goats before and after the injection of oleic acid. In addition to the EITs measurements, lung water was also measured using a double-indicator...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/17/4a/016
更新日期:1996-11-01 00:00:00
abstract::This paper investigates the main characteristics of the magneto-hemodynamic (MHD) response for application as a biomarker of vascular blood flow. The induced surface potential changes of a volunteer exposed to a 3 T static B0 field of a magnetic resonance imaging (MRI) magnet were measured over time at multiple locati...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/33/2/117
更新日期:2012-02-01 00:00:00
abstract::Unstable gait is a risk factor for falls. Wearable accelerometers enable remote monitoring of daily walking. Here, new methods for measuring stride-to-stride oscillations are validated against optical motion capture, normative data determined, and dependency on walking speed investigated. Walks by 13 young people (mea...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/36/5/857
更新日期:2015-05-01 00:00:00
abstract::In this study, we developed a novel technique for estimating non-constrained and cuffless blood pressure (BP) that was based on electrocardiogram (ECG) and ballistocardiogram (BCG). The BCG was non-invasively measured using a common electronic weighing scale when a subject was standing on it. The ECG was measured usin...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/30/7/011
更新日期:2009-07-01 00:00:00
abstract:OBJECTIVE:As the global burden of cardiovascular disease increases, proactive cardiovascular healthcare by means of accurate, precise, continuous, and non-invasive monitoring is becoming crucial. However, no current device is able to provide cardiac hemodynamic monitoring with the aforementioned criterion. Electrical i...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/1361-6579/abb141
更新日期:2020-10-06 00:00:00
abstract::Hand bone equivalent phantoms (250 ml) carrying selenium in various amounts were irradiated and counted for in vivo neutron activation analysis (IVNAA) by employing a 4π NaI(TI) based detection system. During the analysis of counting data, a feature at a higher energy than the gamma ray peak from (77m)Se (0.162 MeV) w...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/36/12/N127
更新日期:2015-12-01 00:00:00
abstract:OBJECTIVE:Characteristic impedance (Zc) is an important component in the theory of hemodynamics. It is a commonly used metric of proximal arterial stiffness and pulse wave velocity. Calculated using simultaneously measured dynamic pressure and flow data, estimates of characteristic impedance can be obtained using metho...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/1361-6579/aa9d60
更新日期:2018-01-31 00:00:00
abstract::Although cardiac arrhythmias have been studied extensively, little is known about arrhythmic phenomena in the gastrointestinal (GI) system. In this study, we demonstrate for the first time that the onset of GI arrhythmias is associated with statistically significant fluctuations in the information dimension of the ass...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/29/5/N01
更新日期:2008-05-01 00:00:00
abstract::Focused impedance measurements (FIM) are used in several fields, and address the problem of measuring the volume impedance of an object within a volume conductor. Several electrode configurations are possible, and these have different properties. Sensitivity fields of four configurations have been investigated. We pre...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/35/6/1067
更新日期:2014-06-01 00:00:00
abstract::A study of the concentrations of the common breath metabolites ammonia, acetone, isoprene, ethanol and acetaldehyde in the breath of five subjects over a period of 30 days has been carried out. Breath samples were taken and analysed in the early morning on arrival at the laboratory. The real time analyses of three con...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/24/1/308
更新日期:2003-02-01 00:00:00
abstract::A major problem confronting application of impedance techniques to studies of disease is the extraction of intrinsic properties of the tissue from the measured impedances, which unavoidably involve geometric factors as well. Amongst the foremost are the sizes and locations of the measuring electrode arrays, and this p...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/34/11/1513
更新日期:2013-11-01 00:00:00
abstract::Objective assessment of stroke-patients' ability to control arm movements is vital for evidence-based therapy and progress monitoring. This study compares three different indices to quantify the quality of wrist movement during a task involving tracking a target on a screen. Each method is assessed in terms of agreeme...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/28/8/011
更新日期:2007-08-01 00:00:00
abstract::In this paper a description is given of the development, characterisation and first results of a thermal imaging device aimed at significantly reducing the incidence of diabetic foot ulceration (DFU). These devices will be used in three clinical centres and in two preliminary clinical trials. The first will be on heal...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/1361-6579/aa56b1
更新日期:2017-03-01 00:00:00
abstract::Controversial data exist on acute and chronic effects of competitive sports on central hemodynamics and arterial stiffness. We investigated chronic as well as acute training effects in professional rowers. The trial was planned as a non-randomized, controlled pilot-study comparing athletes and controls. 13 German nati...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/37/4/544
更新日期:2016-04-01 00:00:00
abstract::Electrical impedance tomography is an imaging method, with which volumetric images of conductivity are produced by injecting electrical current and measuring boundary voltages. It has the potential to become a portable non-invasive medical imaging technique. Until now, implementations have neglected anisotropy even th...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/28/7/S10
更新日期:2007-07-01 00:00:00
abstract::The measurement of the complex respiratory impedance at a high temporal resolution is described. The measurement of impedance is correlated with the breathing cycle using electrical transthoracic impedance. This allows the determination of the complex impedance at any fixed point in the respiratory cycle, which result...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/14/3/019
更新日期:1993-08-01 00:00:00
abstract::Infant multiple breath washout (MBW) testing serves as a primary outcome in clinical studies. However, it is still unknown whether current software algorithms allow between-centre comparisons. In this study of healthy infants, we quantified MBW measurement errors and tried to improve data quality by simply changing so...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/37/3/L1
更新日期:2016-03-01 00:00:00
abstract::The goal of the present study was to develop and evaluate a new method for the prediction of unexplained syncope occurrences. Diagnosis of syncope is currently based on the reproduction of symptoms in combination with hypotension and bradycardia induced by a 45 min 60-70 degrees head-upright tilt test (HUTT). The main...
journal_title:Physiological measurement
pub_type: 临床试验,杂志文章
doi:10.1088/0967-3334/28/2/007
更新日期:2007-02-01 00:00:00
abstract::Remote sensing of the reflectance photoplethysmogram using a video camera typically positioned 1 m away from the patient's face is a promising method for monitoring the vital signs of patients without attaching any electrodes or sensors to them. Most of the papers in the literature on non-contact vital sign monitoring...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/35/5/807
更新日期:2014-05-01 00:00:00
abstract::The most common method of clinical measurement of arterial blood pressure is by means of the cuff sphygmomanometer. This instrument has provided fundamental quantitative information on arterial pressure in individual subjects and in populations and facilitated estimation of cardiovascular risk related to levels of blo...
journal_title:Physiological measurement
pub_type: 历史文章,杂志文章,评审
doi:10.1088/0967-3334/31/1/R01
更新日期:2010-01-01 00:00:00
abstract::A coordinated study of the dispersal of water between the various body compartments (stomach and gut, blood stream and tissue) and the similar dispersal kinetics of ethanol and its metabolism has been carried out involving two healthy volunteers using flowing afterglow mass spectrometry, FA-MS, and selected ion flow t...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/26/4/011
更新日期:2005-08-01 00:00:00
abstract:OBJECTIVE:To investigate the effect of maternal hyperoxygenation on fetal heart rate (FHR) when applied for suspected fetal distress during the second stage of term labor. APPROACH:A single-center randomized controlled trial was conducted in a tertiary care hospital in The Netherlands. Participants were included durin...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/1361-6579/abc0b6
更新日期:2020-12-11 00:00:00
abstract::In this phenomenological study we focus on dynamic measurements of volatile organic compounds (VOCs) in exhaled breath under exercise conditions. An experimental setup efficiently combining breath-by-breath analyses using proton transfer reaction mass spectrometry (PTR-MS) with data reflecting the behaviour of major h...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/31/9/008
更新日期:2010-09-01 00:00:00
abstract::The effects of mechanical stimulation on hemodynamics, such as due to mechanotransduction in vascular endothelial cells, have been widely discussed recently. We previously proposed a resonance model in which the arterial system is treated as a pressure-transmitting system, and suggested that the application of externa...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/27/2/004
更新日期:2006-02-01 00:00:00
abstract::Automatic sleep stage classification with cardiorespiratory signals has attracted increasing attention. In contrast to the traditional manual scoring based on polysomnography, these signals can be measured using advanced unobtrusive techniques that are currently available, promising the application for personal and co...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/36/10/2027
更新日期:2015-10-01 00:00:00
abstract::Imaging photoplethysmography is a relatively new technique for extracting biometric information from video images of faces. This is useful in non-invasive monitoring of patients including neonates or the aged, with respect to sudden infant death syndrome, sleep apnoea, pulmonary disease, physical or mental stress and ...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/36/1/67
更新日期:2015-01-01 00:00:00
abstract::The aim of this study was to investigate masticatory muscle activity during deliberately performed functional and non-functional oral tasks. Electromyographic (EMG) surface activity was recorded unilaterally from the masseter, anterior temporalis and suprahyoid muscles in 11 subjects (5 men, 6 women; age = 34.6 +/- 10...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/29/12/004
更新日期:2008-12-01 00:00:00
abstract::A majority of geriatric patients experience difficulty in performing sit-to-stand (SiSt) transitions. A detailed assessment of SiSt ability is a prerequisite for successful rehabilitation. Body fixed sensors (BFSs) are increasingly used to assess functional performances. As to date there is no system which analyzes cl...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/33/11/1931
更新日期:2012-11-01 00:00:00