Abstract:
:A gamma fit facilitates smoothing and extrapolation of distorted tracer-dilution curves in blood flow studies. Theoretically based empirical estimators were developed as simple alternatives to direct regression approaches from simulated gamma distributions with a wide range of shape asymmetry. Key curve features of peak height p, full width w at half peak height, rising and falling limb inflection tangents and asymmetry of the peak time with respect to the p/2 height occurrences were related to the parameters of the distribution by multiple linear regression after suitable transformations. The product pw was simply related to the total area A under the curve, pw/A being 0.93 +/- 0.01 in 70 cardiac output determinations from ten surgical patients. Shape and scale parameters were closely related to the standard deviation, inflection point properties and w for the curves. Mensuration devices suitable for cardiac output computers were developed that calculated total areas from incomplete portions under gamma curves and by-passed the need for parameter estimation. There was limited point in estimating the distribution parameters just to derive particle transit times, because of the ad hoc nature of the fitting form, which did not allow for the back-dispersion by Brownian motion of tracer molecules diluting in blood flow. Nonetheless, the accuracy of area prediction using a gamma fit was adequate for most clinical purposes and comparable to that via the random walk function, giving good insight to established results and computing procedures.
journal_name
Physiol Measjournal_title
Physiological measurementauthors
Lopatatzidis A,Millard RKdoi
10.1088/0967-3334/22/4/401subject
Has Abstractpub_date
2001-11-01 00:00:00pages
N29-33issue
4eissn
0967-3334issn
1361-6579journal_volume
22pub_type
杂志文章abstract::Despite significant advances in adult clinical electrocardiography (ECG) signal processing techniques and the power of digital processors, the analysis of non-invasive foetal ECG (NI-FECG) is still in its infancy. The Physionet/Computing in Cardiology Challenge 2013 addresses some of these limitations by making a set ...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/35/8/1569
更新日期:2014-08-01 00:00:00
abstract::Impedance cardiography (ICG) has been proposed to estimate the stroke volume (SV) and cardiac output (CO) in various medical indications. The aim of this study was to explore the reliability of ICG during pregnancy with respect to SV and CO measurements. Blood pressure, heart rate and thoracic impedance were monitored...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/33/6/1015
更新日期:2012-06-01 00:00:00
abstract::Cycling on an ergometer is one effective means of measuring cardiovascular function while applying stress on the heart. Bathing in a hot water bath applies a low stress to the heart. The electrocardiograms of a healthy adult male (aged 35 at the start of study) were recorded while taking a hot water bath with no elect...
journal_title:Physiological measurement
pub_type: 临床试验,杂志文章
doi:10.1088/0967-3334/20/4/304
更新日期:1999-11-01 00:00:00
abstract::Electrical impedance tomography (EIT) is a recent imaging technique based on electrical impedance, offering the possibility of measuring pulmonary perfusion. In the present study the influence of several pulmonary haemodynamical parameters on the EIT signal were investigated. First, the influence on the systolic wave ...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/19/2/013
更新日期:1998-05-01 00:00:00
abstract::Changes of the heart autonomic balance between morning (8-9 h) and afternoon (14-15 h) measurements were studied in 22 healthy subjects. The selection of these two daytime periods was substantiated by the established higher risk of cardiovascular incidents in the morning and the relative balance of the vegetative nerv...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/24/3/309
更新日期:2003-08-01 00:00:00
abstract::The relation between the right-side (RS) electrical impedance phase angle (PA) and segmental PA in five configurations at 50 kHz was analyzed in 23 peritoneal dialysis male patients before complete drainage of the abdominal cavity. The impedance vector (Z/H) components were standardized by the height H of the subjects...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/29/9/N01
更新日期:2008-09-01 00:00:00
abstract::If electrical impedance tomography is to be used as a clinical tool, the image reconstruction algorithms must yield accurate images of impedance changes. One of the keys to producing an accurate reconstructed image is the inclusion of prior information regarding the physical geometry of the object. To achieve this, ma...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/22/1/308
更新日期:2001-02-01 00:00:00
abstract::Acupuncture (ACU) is known to be effective in ischemia treatment, and glutamate (GLU) excitotoxicity is an important factor in neuronal cell death. We observed the effect of ACU on cerebral blood flow (%CBF) and DeltaGLU (the changes in GLU release) in the ischemic stroke rat model of diabetic mellitus (DM). A global ...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/31/5/003
更新日期:2010-05-01 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::The purpose of this study was to investigate the linearity and reliability of the mechanomyographic (MMG) amplitude versus submaximal isometric force relationship for the vastus lateralis. Twenty healthy subjects (mean +/- SD age = 24.0 +/- 4.3 years) volunteered to perform submaximal isometric muscle actions of the d...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/30/10/002
更新日期:2009-10-01 00:00:00
abstract:OBJECTIVE:The aim of this study was to monitor the physiological changes and cytotoxic effects of exogenous contrast agents during photoacoustic imaging (PAI) and photothermal therapy (PTT). In this paper, a low-power telemetric device for mouse vital signs monitoring was designed and demonstrated. APPROACH:The power ...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/1361-6579/aba6a1
更新日期:2021-01-01 00:00:00
abstract:OBJECTIVE:An artefact-free electrocardiogram (ECG) is essential during cardiac arrest to decide therapy such as defibrillation. Mechanical cardiopulmonary resuscitation (CPR) devices cause movement artefacts that alter the ECG. This study analyzes the effectiveness of mechanical CPR artefact suppression filters to rest...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/1361-6579/ab9e53
更新日期:2020-11-06 00:00:00
abstract::The pre-ejection period (PEP) has recently been described as a potential parameter for monitoring cardiac preload. This study further investigated the influence of changes in intravascular volume status and the application of positive end-expiratory pressure (PEEP) on the pre-ejection period. In ten pigs, ECG, arteria...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/26/6/012
更新日期:2005-12-01 00:00:00
abstract::An external electroenterogram (EEnG) is the recording of the small bowel myoelectrical signal using contact electrodes placed on the abdominal surface. It is a weak signal affected by possible movements and by the interferences of respiration and, principally, of the cardiac signal. In this paper an adaptive filtering...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/27/6/005
更新日期:2006-06-01 00:00:00
abstract:OBJECTIVE:Storage of physiological waveform data for retrospective analysis presents significant challenges. Resultant data can be very large, and therefore becomes expensive to store and complicated to manage. Traditional database approaches are not appropriate for large scale storage of physiological waveforms. Our g...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/1361-6579/ab7cb5
更新日期:2020-04-20 00:00:00
abstract::Energy scavenging has increasingly become an interesting option for powering electronic devices because of the almost infinite lifetime and the non-dependence on fuels for energy generation. Moreover, the rise of wireless technologies promises new applications in medical monitoring systems, but these still face limita...
journal_title:Physiological measurement
pub_type: 杂志文章,评审
doi:10.1088/0967-3334/30/9/R01
更新日期:2009-09-01 00:00:00
abstract::Electrocardiograms (ECGs) recorded from patients in intensive care were investigated to quantify any relationship between ECG signal quality and false monitoring alarms. False alarms are a considerable problem for nursing and medical staff as they distract from clinical care, and are also a problem for patients as the...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/37/8/1383
更新日期:2016-08-01 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::Previous studies have used isokinetic dynamometry to assess joint torques and angles during passive extension of the knee, often without reporting upon methodological errors and reliability outcomes. In addition, the reliability of the techniques used to measure passive knee extension torque-angle and the extent to wh...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/34/11/1483
更新日期:2013-11-01 00:00:00
abstract::Fetal hiccups emerge as early as nine weeks post-conception, being the predominant diaphragmatic movement before 26 weeks of gestation. They are considered as a programmed isometric inspiratory muscle exercise of the fetus in preparation for the post-natal respiratory function, or a manifestation of a reflex circuitry...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/28/6/005
更新日期:2007-06-01 00:00:00
abstract::Fetal heart rate monitoring is used for pregnancy surveillance in obstetric units all over the world but in spite of recent advances in analysis methods, there are still inherent technical limitations that bound its contribution to the improvement of perinatal indicators. In this work, a previously published wavelet t...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/35/8/1723
更新日期:2014-08-01 00:00:00
abstract::The non-invasive measurement of free field snoring sounds to estimate the site of snoring is an important development in the diagnosis, treatment and management of sleep-related breathing disorders. We investigated characteristics of the probability density function by testing the sensitivity of the statistical moment...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/28/10/008
更新日期:2007-10-01 00:00:00
abstract:OBJECTIVE:Predictive analytics monitoring that informs clinicians of the risk for failed extubation would help minimize both the duration of mechanical ventilation and the risk of emergency re-intubation in ICU patients. We hypothesized that dynamic monitoring of cardiorespiratory data, vital signs, and lab test result...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/1361-6579/aace95
更新日期:2018-07-16 00:00:00
abstract::Vital signs monitoring is ubiquitous in clinical environments and emerging in home-based healthcare applications. Still, since current monitoring methods require uncomfortable sensors, respiration rate remains the least measured vital sign. In this paper, we propose a video-based respiration monitoring method that aut...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/37/1/100
更新日期:2016-01-01 00:00:00
abstract:OBJECTIVE:Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal disease characterized by excessive deposition of collagen and associated stiffening of lung tissue. While it is known that inflammation and dysfunction of fibroblasts are involved in disease development, it remains poorly understood how cells and ...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/1361-6579/aaca86
更新日期:2018-06-28 00:00:00
abstract:OBJECTIVE:In this study, electroencephalography activity recorded during monotonous driving was investigated to examine the predictive capability of monopolar EEG analysis for fatigue/sleepiness in a cohort of train drivers. APPROACH:Sixty-three train drivers participated in the study, where 32- lead monopolar EEG dat...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/1361-6579/aae42e
更新日期:2018-10-30 00:00:00
abstract::Urinary catheters (drainage tubes) are in widespread use. The most common type of long-term catheter is the Foley, which is made from natural or synthetic rubber. Foley catheters are passed into the bladder via the urethra or the suprapubic puncture channel (through the abdominal wall). A simulator for the abdominal w...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/22/3/308
更新日期:2001-08-01 00:00:00
abstract::There has been a surge of interest in using electrical impedance tomography (EIT) for monitoring regional lung ventilation, however, EIT is an ill-conditioned problem, and errors/noise in the boundary voltages can have an undesirable effect on the quality of the final image. Most EIT systems in clinical usage use seri...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/0967-3334/34/6/659
更新日期:2013-06-01 00:00:00
abstract:OBJECTIVE:Bioimpedance has been used to investigate changes in electrical parameters during ischemia in various tissues. The small intestine is a multi-layered structure, with several distinct tissue types, and ischemia related changes occur at different times in the different intestinal layers. When investigating how ...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/1361-6579/aa67b7
更新日期:2017-05-01 00:00:00
abstract:OBJECTIVE:Atrial fibrillation (AF) causes marked risk for patients, while silent fibrillation may remain unnoticed if not suspected and screened. Development of comfortable yet accurate beat-to-beat heart rate (HR) monitoring with good AF detection sensitivity would facilitate screening and improve treatment. The purpo...
journal_title:Physiological measurement
pub_type: 杂志文章
doi:10.1088/1361-6579/aac9a9
更新日期:2018-06-27 00:00:00