New Method For Noninvasive Measurement Research Articles

Airspace Dimension Assessment with Nanoparticles (AiDA) in Comparison to Established Pulmonary Function Tests.

BackgroundAirspace Dimensions Assessment with nanoparticles (AiDA) is a new method for non-invasive measurement of pulmonary distal airspaces. The aim of this study was to compare AiDA measurements with other pulmonary function variables to better understand the potential of AiDA in a clinical context.MethodsAiDA measurements and pulmonary function tests were performed in 695 subjects as part of the Swedish CArdioPulmonary bioImage Study. The measurement protocol included spirometry, measurement of diffusing capacity of carbon monoxide, oscillometry and pulmonary computed tomography. AiDA indices were compared to all other pulmonary examination measurements using multivariate statistical analysis.ResultsOur results show that AiDA measurements were significantly correlated with other pulmonary function examination indices, although covariance was low. We found that AiDA variables explained variance in the data that other lung function variables only influenced to a minor extent.ConclusionWe conclude that the AiDA method provides information about the lung that is inaccessible with more conventional lung function techniques.

Abstract 13654: Can a Novel Earbud Technology Detect Severe Aortic Stenosis? Modernizing the Wiggers Diagram Through Infrasonic Hemodynography Synchronized With Echocardiography and Cardiac Catheterization

Introduction: Severe aortic stenosis (AS) produces a typical systolic ejection sound detected by clinical auscultation with a characteristic feature on Doppler echocardiography (ECHO) & hemodynamics at cardiac catheterization (CC). We propose a new assessment of AS through ‘infrasonic hemodynography’ (IH) - cardiovascular monitoring by infrasound (<20 Hz) measured by a novel digital device. To assess AS, we aim to compare IH to standard ECHO & CC measurements. Methods: We report an N-of-1 analysis from an ongoing prospective clinical trial to validate IH on cardiac function. A study subject with severe AS wore the IH ear-bud (MindMics, Figure A) & underwent simultaneous measurements with IH-ECHO & IH-CC-ECG, with IH waveforms (in-ear acoustic pressure in Pascals) synchronized (via cross-correlation), stacked (11 heart beats), & averaged over the QRS complex of the ECG. The QRS complex was then used as a reference to generate a quantitative Wiggers diagram, aligning IH & CC waveforms with the aortic valve on ECHO. Time of aortic valve opening (AVO) & closure (AVC) were determined from the ECHO image. The systole & diastole were assessed by creating Wiggers diagrams from the LV outflow & mitral valve inflow ECHO images. Results: The peak systolic pressure in CC occurred close to the AVC derived from ECHO (Figure B), as is typical of the delayed peak pressure in severe AS. This was captured in the IH waveform & visualized by overlaid LV & AO pressures simultaneously collected during CC (Figure C). Additionally, the blood pressure increase seen on CC in response to AVC (the dicrotic notch) was also delayed & aligned with the drop in flow & the start of the E wave on ECHO, consistent with severe AS, & detected on IH. Conclusions: We describe in-ear IH as a new method for non-invasive measurement of severe AS. Infrasound assessment of cardiac function represents a potentially important development to modernize the Wiggers Diagram & to detect valvular disease that is independent of ECHO & CC.

P134 A New Method for Non-invasive Measurement of Arterial Wave Intensity, Speed and Reflection

P134 A New Method for Non-invasive Measurement of Arterial Wave Intensity, Speed and Reflection

A new method for noninvasive measurement of pulmonary gas exchange using expired gas

Measurement of the gas exchange efficiency of the lung is often required in the practice of pulmonary medicine and in other settings. The traditional standard is the values of the PO2, PCO2, and pH of arterial blood. However arterial puncture requires technical expertise, is invasive, uncomfortable for the patient, and expensive. Here we describe how the composition of expired gas can be used in conjunction with pulse oximetry to obtain useful measures of gas exchange efficiency. The new procedure is noninvasive, well tolerated by the patient, and takes only a few minutes. It could be particularly useful when repeated measurements of pulmonary gas exchange are required. One product of the procedure is the difference between the PO2 of end-tidal alveolar gas and the calculated PO2 of arterial blood. This measurement is related to the classical alveolar-arterial PO2 difference based on ideal alveolar gas. However that traditional index is heavily influenced by lung units with low ventilation-perfusion ratios, whereas the new index has a broader physiological basis because it includes contributions from the whole lung.

In situ measurement of liquid-liquid equilibria by medium field nuclear magnetic resonance

A new method for non-invasive measurement of liquid-liquid equilibria (LLE) using a compact medium field nuclear magnetic resonance (NMR) spectrometer is presented. Mixing of all components, phase separation, and analysis of the composition of the coexisting phases is performed in situ in an NMR glass tube. Thus, the experimental effort is reduced and errors caused by sampling are eliminated. Furthermore, calibration of the analysis method is not necessary as quantitative information is obtained directly from the NMR spectra. The proposed method for studying LLE in situ can be swiftly conducted in standard chemical laboratories as medium field NMR spectrometer do not require dedicated laboratory infrastructure but enable convenient handling and fast analysis of the samples. In the present work, four non-reactive ternary solvent systems with closed miscibility gap (toluene + acetone + water, diethyl ether + acetone + water, diethyl ether + methanol + water, and acetonitrile + ethanol + cyclohexane) and one reactive ternary system (water + acetic acid + acetic anhydride) were investigated at a temperature of 22.0 °C using 1H medium field NMR spectroscopic measurements. For comparison, the composition of the coexisting phases is also examined for one non-reactive system (acetonitrile + ethanol + cyclohexane) using 13C medium field NMR spectroscopy as well as spatially resolved spectroscopy in a conventional high field NMR spectrometer. The comparison of the results of the present work to literature data shows that the new proposed method enables swift and reliable investigations of LLE.

A new method for noninvasive measurement of grid harmonic impedance with data selection

Summary The paper presents a new, noninvasive method for the measurement of power grid harmonic impedance. The method is a robust variant of transfer function estimation method. Its novelty lays in the way of selecting local harmonic impedance estimates for averaging, based on input–output coherence estimates, which immunizes it against background voltage variations. The method is validated by simulation including varying background voltage harmonics, both for fixed and slowly varying harmonic impedance. It has also been tested with noisy and nonsynchronously sampled signals. The method is compared with another noninvasive method with data selection. Simulation results clearly show that the proposed method returns lower estimation errors. Also, its computational complexity is significantly reduced compared with the reference one. The presented results of a field test conducted at medium-voltage/low-voltage substation prove that the method works well in real conditions. Copyright © 2015 John Wiley & Sons, Ltd.

A New Method for Non-Invasive Measurement of Skin in the Low Frequency Range

ObjectivesThe purpose of our study was to estimate skin structure and conductivity distribution in a cross section of local tissue using non-invasive measurement of impedance data. The present study was designed to evaluate the efficiency of skin depth information through computer simulations. The multilayer tissue model was composed of epidermis, dermis tissues, and subcutaneous.MethodsIn this study, electrical characteristics of skin models were used for conductivity of 0.13 S/m, 0.26 S/m, 0.52 S/m, permittivity of 94,000 F/m, and a frequency of 200 Hz. The effect of the new method was assessed by computer simulations using three-electrode methods. A non-invasive electrical impedance method has been developed for analysis using computer simulation and a skin electrical model with low frequency range. Using the three-electrode method differences through the potentials between measurement electrodes and reference electrodes can be easily detected. The Cole electrical impedance model, which is better suited for skin was used in this study.ResultsIn this study, experiments using three-electrode methods were described by computer simulation based on a simple model. This electrical impedance model was fitted and developed in comparison with our model for measurement of skin impedance.ConclusionsThe proposed electrical model for skin is suitable for use in interpretation of changes in impedance characterization of the skin. Using the computer simulation method, information on skin impedance depth can be more accurately developed and predicted.

A New Method of Non-Invasive Measurement of Left Atrial Function after The Cox-Maze Procedure

A New Method of Non-Invasive Measurement of Left Atrial Function after The Cox-Maze Procedure

A New Method for Noninvasive Measurement of Multilayer Tissue Conductivity and Structure Using Divided Electrodes

This paper outlines a new method for measuring multilayer tissue conductivity and structure by using divided electrodes, in which current electrodes are divided into several parts. Our purpose is to estimate the multilayer tissue structure and the conductivity distribution in a cross section of the local tissue by using bioresistance data measured noninvasively. The effect of the new method is assessed by computer simulations using a typical two-dimensional (2-D) model. In this paper, the conductivity distribution in the model is analyzed based on a finite difference method (FDM) and a steepest descent method (SDM). Simulation results show that the conductivity values of skin, fat, and muscle layers can be estimated with an error of less than 0.1%. When random noise at various levels is added to the measured resistance values, estimates of the conductivity values for skin, fat, and muscle layers are still reasonably precise: their root mean square errors are about 1.06%, 1.39%, and 1.61% for 10% noise. In a 2-D model, increasing the number of divided electrodes permits simultaneous estimates of tissue structure and conductivity distribution. Optimal configuration for divided electrodes is examined in terms of dividing pattern.

Hydration status measurement by radio frequency absorptiometry in young athletes—a new method and preliminary results**US and International Patents pending.

A new method for non-invasive measurement of the human state of hydration is presented. This method is based on frequency-dependent absorptiometry of radio-waves passing through tissues. A device utilizing this method was constructed and applied to 12 young (24 ± 1) male volunteers, who were dehydrated for 1–2.5% of their weight by performance of a physical effort (two 30 min bouts of treadmill walking/running at 2, 3, 4, 5, 6 and 7 mph, 5 min at each speed, separated by 10 min rest), under moderate heat stress (40 °C, 40% RH). Hypohydration level was determined by body weight measurements taken before each session, after 30 min and at the end of each session. Concomitantly, measurements of radio frequency (RF) absorption were taken. Each volunteer underwent the heat stress exercise twice: one in which no drinking was permitted, and another with free drinking. A correlation (R2 = 0.734) between weight loss and a change in the radio-waves absorption pattern was observed in most of the volunteers, in both hypo and euhydration sessions. Further work to establish the reproducibility and validity of the RF methodology in larger and different populations, i.e., females, other age groups and different health conditions, is already being researched.

質量分析計を用いた換気・血流比分布の測定 Ｍｕｌｔｉｐｌｅ Ｃｏｍｐａｒｔｍｅｎｔ伝達関数法

Distribution of ventilation-perfusion ratio (VA/QC distribution) is one of the most important functional parameters of the lung. A new method for noninvasive measurement of VA/QC distribution is described. Based on a multiple compartment model which simulates the lung as an electric RC network, a concept of multiple compartment transfer function (MCTF) is proposed. A system of algebraic equations is derived from MCTF and the VAZQC distribution can be obtained by solving these equations according to the frequency response of the lung which is measured by continuous analysis of respiratory gas during the inspiration of the gas with sinusoidally varied halothane concentration.Simultaneous and instantaneous analysis of physiological and inert gases is essential in this measurement. By employing an improved multicollector mass spectrometer, such measurement was accomplished with comparatively satisfactory sensitivity and stability. Another technical problem was to produce the air flow containing sinusoidally varied halothane concentration with a wider range of frequency components. It was achieved by using a commercially available flow controller combining with computer-controlled frequency modulation and synthesis technique.Experimental results of normal subjects and patients with lung diseases gave physiologically reasonable results of VA/QC distributions. It is demonstrated that the method is useful in physiological studies and clinical diagnoses.

A new method for noninvasive measurement of short-term cerebrospinal fluid pressure changes in humans.

Changes in cerebrospinal fluid (CSF) pressure were shown to be reflected by changes in tympanic membrane (TM) tension. Impedance audiometry measures mechanical tension on the TM and was used to detect changes during jugular vein compression in normal students. CSF and peri-lymph communicate through the cochlear aqueduct, permitting increases in CSF pressure to result in increased pressure on the stapes footplate. This is transmitted to the TM by the ossicles and detected by impedance audiometry. TM tension was also proportional to CSF pressure in cadavers, where CSF pressure was manipulated by saline injection through a lumbar puncture.

Evaluation of Cutaneous Blood Flow Responses by 133Xenon Washout and a Laser-Doppler Flowmeter

A new method for noninvasive measurement of cutaneous blood flow is laser-Doppler flowmetry. The technique is based on the fact that laser light is back-scattered from the moving red blood cells, with Doppler-shifted frequencies; these impulses lead to photodetectors and are converted to flow signals. In this work we used a new system with a low noise level. Comparison was made between this technique and the atraumatic epicutaneous 133Xenon technique for measurement of cutaneous blood flow during reactive hyperemia and orthostatic pressure changes. The laser-Doppler flowmeter seems to measure blood flow in capillaries as well as in arteriovenous anastomoses, while the 133Xe method probably measures only capillary flow. A calibration of the laser-Doppler method against the 133Xe method would appear to be impossible in skin areas where arteriovenous anastomoses are present. The changes in blood flow during reactive hyperemia, orthostatic pressure changes, and venous stasis were found to be parallel as measured by the two methods in skin areas without shunt vessels. The laser-Doppler flowmeter would appear to be a useful supplement to the 133Xe washout method in cutaneous vascular physiology, but it is important to keep in mind that different parameters may be measured.