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Journal of Clinical Hypertension... Dec 2018Reservoir pressure parameters [eg, reservoir pressure (RP) and excess pressure (XSP)] are biomarkers derived from blood pressure (BP) waveforms that have been shown to... (Comparative Study)
Comparative Study
Reservoir pressure parameters [eg, reservoir pressure (RP) and excess pressure (XSP)] are biomarkers derived from blood pressure (BP) waveforms that have been shown to predict cardiovascular events independent of conventional cardiovascular risk markers. However, whether RP and XSP can be derived non-invasively from operator-independent cuff device measured brachial or central BP waveforms has never been examined. This study sought to achieve this by comparison of cuff reservoir pressure parameters with intra-aortic reservoir pressure parameters. 162 participants (aged 61 ± 10 years, 72% male) undergoing coronary angiography had the simultaneous measurement of cuff BP waveforms (via SphygmoCor XCEL, AtCor Medical) and intra-aortic BP waveforms (via fluid-filled catheter). RP and XSP derived from cuff acquired brachial and central BP waveforms were compared with intra-aortic measures. Concordance between brachial-cuff and intra-aortic measurement was moderate-to-good for RP peak (36 ± 11 vs 48 ± 14 mm Hg, P < 0.001; ICC 0.77, 95% CI: 0.71-0.82), and poor-to-moderate for XSP peak (28 ± 10 vs 24 ± 9 mm Hg, P < 0.001; ICC 0.49, 95% CI: 0.35-0.60). Concordance between central-cuff and intra-aortic measurement was moderate-to-good for RP peak (35 ± 9 vs 46 ± 14 mm Hg, P < 0.001; ICC 0.77, 95% CI: 0.70-0.82), but poor for XSP peak (12 ± 3 vs 24 ± 9 mm Hg, P < 0.001; ICC 0.12, 95% CI: -0.13 to 0.31). In conclusion, both brachial-cuff and central-cuff methods can reasonably estimate intra-aortic RP, whereas XSP can only be acceptably derived from brachial-cuff BP waveforms. This should enable widespread application to determine the clinical significance, but there is significant room for refinement of the method.
Topics: Aged; Arterial Pressure; Australia; Blood Pressure; Blood Pressure Determination; Brachial Artery; Cardiovascular Diseases; Catheters; Coronary Angiography; Female; Hemodynamics; Humans; Male; Middle Aged; Oscillometry
PubMed: 30450732
DOI: 10.1111/jch.13411 -
PloS One 2018We present a robust method for testing and calibrating the performance of oscillometric non-invasive blood pressure (NIBP) monitors, using an industry standard NIBP... (Comparative Study)
Comparative Study
We present a robust method for testing and calibrating the performance of oscillometric non-invasive blood pressure (NIBP) monitors, using an industry standard NIBP simulator to determine the characteristic ratios used, and to explore differences between different devices. Assuming that classical auscultatory sphygmomanometry provides the best approximation to intra-arterial pressure, the results obtained from oscillometric measurements for a range of characteristic ratios are compared against a modified auscultatory method to determine an optimum characteristic ratio, Rs for systolic blood pressure (SBP), which was found to be 0.565. We demonstrate that whilst three Chinese manufactured NIBP monitors we tested used the conventional maximum amplitude algorithm (MAA) with characteristic ratios Rs = 0.4624±0.0303 (Mean±SD) and Rd = 0.6275±0.0222, another three devices manufactured in Germany and Japan either do not implement this standard protocol or used different characteristic ratios. Using a reference database of 304 records from 102 patients, containing both the Korotkoff sounds and the oscillometric waveforms, we showed that none of the devices tested used the optimal value of 0.565 for the characteristic ratio Rs, and as a result, three of the devices tested would underestimate systolic pressure by an average of 4.8mmHg, and three would overestimate the systolic pressure by an average of 6.2 mmHg.
Topics: Adult; Aged; Aged, 80 and over; Algorithms; Blood Pressure; Blood Pressure Determination; Blood Pressure Monitors; Calibration; Databases, Factual; Female; Humans; Male; Middle Aged; Oscillometry; Young Adult
PubMed: 30080862
DOI: 10.1371/journal.pone.0201123 -
Experimental Physiology May 2019What is the central question of this study? There is growing interest in the effects of sedentarism on central and peripheral cardiovascular health. To permit further... (Observational Study)
Observational Study
NEW FINDINGS
What is the central question of this study? There is growing interest in the effects of sedentarism on central and peripheral cardiovascular health. To permit further investigation, including larger epidemiological studies, there is a need to identify arterial health assessment tools that are valid (accurate) and reliable (precise), yet practical. What is the main finding and its importance? Lower-limb vascular health (femoral-ankle pulse-wave velocity) can be determined in a supine position with accuracy and precision using an oscillometrically based device. This technology might help to improve our understanding of the pathological mechanisms linking cardiovascular disease to sedentarism, including the interaction between peripheral and central vasculature.
ABSTRACT
There is a growing interest in the deleterious effects of sedentary behaviour on lower-limb arterial health. To permit further investigation, including larger epidemiological studies, there is a need to identify lower-limb arterial health assessment tools that are valid and reliable, yet simple to administer. In this study, we sought to determine the validity and between-day reliability of femoral-ankle pulse-wave velocity (faPWV) measures obtained using an oscillometrically based device (SphygmocCor XCEL) in supine and seated positions. Doppler ultrasound was used as the criterion. A total of 47 healthy adults were recruited for validity (n = 32) and reliability (n = 15) analyses. Validity was determined by measuring faPWV in seated and supine positions using the XCEL and Doppler ultrasound devices, in a randomized order. Between-day reliability was determined by measuring seated and supine faPWV using the XCEL on three different mornings, separated by a maximum of 7 days. The validity criterion [absolute standard error of estimate (aSEE) < 1.0 m s ] was met in the supine [aSEE = 0.8 m s , 95% confidence interval (CI) 0.4-1.0], but not in the seated (aSEE = 1.2 m s , 95% CI 1.1-1.2) position. Intraclass correlation coefficient (ICC) estimates revealed that the XCEL demonstrated good reliability in the supine position (ICC = 0.83, 95% CI 0.65-0.93), but poor reliability in the seated position (ICC = 0.29, 95% CI 0.23-0.63). The oscillometric XCEL device can be used to determine lower-limb pulse-wave velocity with acceptable validity and reliability in the conventionally recommended supine position, but not in the seated position.
Topics: Adolescent; Adult; Cardiac Output; Data Interpretation, Statistical; Female; Healthy Volunteers; Humans; Lower Extremity; Male; Oscillometry; Pulse Wave Analysis; Reproducibility of Results; Sitting Position; Stroke Volume; Supine Position; Ultrasonography, Doppler; Vascular Resistance; Vascular Stiffness; Young Adult
PubMed: 30770607
DOI: 10.1113/EP087444 -
Journal of the American Association For... Jul 2010This study compared torcetrapib-induced blood pressure (BP) changes simultaneously obtained by high-definition oscillometry (HDO) and telemetry. Male beagles (n = 6)... (Comparative Study)
Comparative Study
This study compared torcetrapib-induced blood pressure (BP) changes simultaneously obtained by high-definition oscillometry (HDO) and telemetry. Male beagles (n = 6) received single oral doses of vehicle or torcetrapib at 10 or 30 mg/kg; BP were acquired simultaneously by HDO and telemetry from 2 h before dosage until 7 h afterward. Systolic, diastolic, and mean arterial pressures (MAP) and heart rate were compared by using Altman-Bland agreement analysis. Dogs were allocated into subgroups according to temperament and baseline MAP (less than 110 mm Hg and 110 mm Hg or greater). Both methods demonstrated high precision. HDO recordings exhibited higher variability for all parameters (inclusive MAP SDs were 7.0 +/- 2.7 mm Hg for HDO compared with 3.4 +/- 1.9 mm Hg for telemetry), accompanied by a positive bias for all pressures (systolic, 10.4 mm Hg; diastolic, 5.7 mm Hg; MAP, 1.9 mm Hg). Both methods detected similar maximal increases in MAP with 30 mg/kg torcetrapib (HDO, 15.8 +/- 10.4 mm Hg; telemetry, 15.8 +/- 5.3 mm Hg). No significant effects were noted for heart rate. Torcetrapib elicited a dose-dependent increase in BP in dogs with baseline MAP of less than 110 mm Hg, whereas increases were maximal with 10 mg/kg in the other group, and dose-dependence was no longer observed. BP changes were influenced by animal temperament, demonstrating that HDO results must be interpreted with caution. HDO may provide a useful and accurate method for noninvasive BP measurements in canine studies.
Topics: Animals; Behavior, Animal; Blood Pressure; Blood Pressure Determination; Dogs; Heart Rate; Oscillometry; Quinolines; Reproducibility of Results; Telemetry
PubMed: 20819394
DOI: No ID Found -
Journal of Clinical Hypertension... Jul 2018Measurement of blood pressure (BP) using the auscultatory method must follow specific rules and conditions to be reliable. Nonetheless, these requirements are often not...
Measurement of blood pressure (BP) using the auscultatory method must follow specific rules and conditions to be reliable. Nonetheless, these requirements are often not followed in clinical practice, resulting in inaccurate BP readings. Simply replacing manual sphygmomanometers with an oscillometric device may still produce readings that are associated with a white coat effect. These limitations can be overcome by using an oscillometric sphygmomanometer that automatically records multiple readings with the patient resting quietly and alone, called automated office (AO)BP. AOBP produces office readings with a reduced white coat effect, which are also similar to the awake ambulatory BP. There is also evidence that AOBP is a better predictor of target organ damage than attended office BP. Furthermore, clinical outcome data support AOBP as having both a similar diagnostic threshold as awake ambulatory BP and a lower treatment target. Using AOBP in clinical practice simplifies recording office BP by not requiring an additional period of rest before activation of the device and by not having staff present during the actual measurements. Recent studies have reported that automatic BP measurements taken by staff in research studies with close adherence to guidelines using AOBP devices may produce similar readings to AOBP. Further research is needed to determine the best method for recording BP at systolic targets < 130 mm Hg and the relationship of office BP to ambulatory BP and home BP.
Topics: Aged; Aged, 80 and over; Auscultation; Automation; Blood Pressure; Blood Pressure Determination; Blood Pressure Monitoring, Ambulatory; Guideline Adherence; Humans; Hypertension; Office Visits; Oscillometry; Rest; Sphygmomanometers; Systole; White Coat Hypertension
PubMed: 30003698
DOI: 10.1111/jch.13276 -
The Netherlands Journal of Medicine Oct 2003Given the variability of blood pressure, it is often difficult to make a diagnosis of hypertension or to evaluate the effect of treatment on the basis of single blood...
Given the variability of blood pressure, it is often difficult to make a diagnosis of hypertension or to evaluate the effect of treatment on the basis of single blood pressure readings in the office. To obtain multiple measurements one can either turn to ambulatory blood pressure monitoring or have the patient take his or her own pressure. Both approaches require the availability of reliable, validated devices. Currently, only some instruments which measure blood pressure oscillometrically at the upper arm can be recommended for self-measurements. Studies are in progress to assess the prognostic significance of self-measured blood pressure data.
Topics: Automation; Blood Pressure Determination; Equipment Failure Analysis; Humans; Hypertension; Oscillometry; Self Care; Sphygmomanometers
PubMed: 14708906
DOI: No ID Found -
Analytical Chemistry Nov 2019Measuring ligand-protein interactions is critical for unveiling molecular-scale biological processes in living systems and for screening drugs. Various detection...
Measuring ligand-protein interactions is critical for unveiling molecular-scale biological processes in living systems and for screening drugs. Various detection technologies have been developed, but quantifying the binding kinetics of small molecules to the proteins remains challenging because the sensitivities of the mainstream technologies decrease with the size of the ligand. Here, we report a method to measure and quantify the binding kinetics of both large and small molecules with self-assembled nano-oscillators, each consisting of a nanoparticle tethered to a surface via long polymer molecules. By applying an oscillating electric field normal to the surface, the nanoparticle oscillates, and the oscillation amplitude is proportional to the number of charges on the nano-oscillator. Upon the binding of ligands onto the nano-oscillator, the oscillation amplitude will change. Using a plasmonic imaging approach, the oscillation amplitude is measured with subnanometer precision, allowing us to accurately quantify the binding kinetics of ligands, including small molecules, to their protein receptors. This work demonstrates the capability of nano-oscillators as an useful tool for measuring the binding kinetics of both large and small molecules.
Topics: Binding Sites; DNA; Kinetics; Ligands; Nanoparticles; Nanotechnology; Oscillometry; Particle Size; Proteins; Surface Properties
PubMed: 31593433
DOI: 10.1021/acs.analchem.9b04195 -
Optics Express Jan 2014Recently, the first microfluidic optomechanical device was demonstrated, capable of operating with non-solid states of matter (viscous fluids, bioanalytes). These...
Recently, the first microfluidic optomechanical device was demonstrated, capable of operating with non-solid states of matter (viscous fluids, bioanalytes). These devices exhibit optomechanical oscillation in both the 10-20 MHz and 10-12 GHz regimes, driven by radiation pressure (RP) and stimulated Brillouin scattering (SBS) respectively. In this work, we experimentally investigate aerostatic tuning of these hollow-shell oscillators, enabled by geometry, stress, and temperature effects. We also demonstrate for the first time the simultaneous actuation of RP-induced breathing mechanical modes and SBS-induced whispering gallery acoustic modes, through a single pump laser. Our result is a step towards completely self-referenced optomechanical sensor technologies.
Topics: Equipment Design; Equipment Failure Analysis; Micro-Electrical-Mechanical Systems; Optical Devices; Oscillometry; Pressure; Refractometry
PubMed: 24515132
DOI: 10.1364/OE.22.001267 -
Medical Physics Jun 2016Low temporal latency between a gating ON/OFF signal and the LINAC beam ON/OFF during respiratory gating is critical for patient safety. Here the authors describe a novel...
PURPOSE
Low temporal latency between a gating ON/OFF signal and the LINAC beam ON/OFF during respiratory gating is critical for patient safety. Here the authors describe a novel method to precisely measure gating lag times at high temporal resolutions.
METHODS
A respiratory gating simulator with an oscillating platform was modified to include a linear potentiometer for position measurement. A photon diode was placed at linear accelerator isocenter for beam output measurement. The output signals of the potentiometer and diode were recorded simultaneously at 2500 Hz with an analog to digital converter for four different commercial respiratory gating systems. The ON and OFF of the beam signal were located and compared to the expected gating window for both phase and position based gating and the temporal lag times extracted.
RESULTS
For phase based gating, a real-time position management (RPM) infrared marker tracking system with a single camera and a RPM system with a stereoscopic camera were measured to have mean gate ON/OFF lag times of 98/90 and 86/44 ms, respectively. For position based gating, an AlignRT 3D surface system and a Calypso magnetic fiducial tracking system were measured to have mean gate ON/OFF lag times of 356/529 and 209/60 ms, respectively.
CONCLUSIONS
Temporal resolution of the method was high enough to allow characterization of individual gate cycles and was primary limited by the sampling speed of the data recording device. Significant variation of mean gate ON/OFF lag time was found between different gating systems. For certain gating devices, individual gating cycle lag times can vary significantly.
Topics: Animals; Computer Simulation; Equipment Design; Fiducial Markers; Imaging, Three-Dimensional; Motion; Optical Imaging; Oscillometry; Particle Accelerators; Periodicity; Phantoms, Imaging; Photons; Respiration; Time Factors
PubMed: 27277028
DOI: 10.1118/1.4948500 -
Anesthesiology Nov 2020In most patients having noncardiac surgery, blood pressure is measured with the oscillometric upper arm cuff method. Although the method is noninvasive and practical, it...
BACKGROUND
In most patients having noncardiac surgery, blood pressure is measured with the oscillometric upper arm cuff method. Although the method is noninvasive and practical, it is known to overestimate intraarterial pressure in hypotension and to underestimate it in hypertension. A high-fidelity upper arm cuff incorporating a hydraulic sensor pad was recently developed. The aim of the present study was to investigate whether noninvasive blood pressure measurements with the new high-fidelity cuff correspond to invasive measurements with a femoral artery catheter, especially at low blood pressure.
METHODS
Simultaneous measurements of blood pressure recorded from a femoral arterial catheter and from the high-fidelity upper arm cuff were compared in 110 patients having major abdominal surgery or neurosurgery.
RESULTS
550 pairs of blood pressure measurements (5 pairs per patient) were considered for analysis. For mean arterial pressure measurements, the average bias was 0 mmHg, and the precision was 3 mmHg. The Pearson correlation coefficient was 0.96 (P < 0.0001; 95% CI, 0.96 to 0.97), and the percentage error was 9%. Error grid analysis showed that the proportions of mean arterial pressure measurements done with the high-fidelity cuff method were 98.4% in zone A (no risk), 1.6% in zone B (low risk) and 0% in zones C, D, and E (moderate, significant, and dangerous risk, respectively). The high-fidelity cuff method detected mean arterial pressure values less than 65 mmHg with a sensitivity of 84% (95% CI, 74 to 92%) and a specificity of 97% (95% CI, 95% to 98%). To detect changes in mean arterial pressure of more than 5 mmHg, the concordance rate between the two methods was 99.7%. Comparable accuracy and precision were observed for systolic and diastolic blood pressure measurements.
CONCLUSIONS
The new high-fidelity upper arm cuff method met the current international standards in terms of accuracy and precision. It was also very accurate to track changes in blood pressure and reliably detect severe hypotension during noncardiac surgery.
Topics: Adult; Aged; Aged, 80 and over; Arterial Pressure; Blood Pressure Determination; Female; Humans; Male; Middle Aged; Monitoring, Intraoperative; Oscillometry; Prospective Studies; Young Adult
PubMed: 33048167
DOI: 10.1097/ALN.0000000000003472