scholarly journals Contactless Impedance Cardiography Using Embedded Sensors

2013 ◽  
Vol 13 (3) ◽  
pp. 157-164 ◽  
Author(s):  
E. Pinheiro ◽  
O. Postolache ◽  
P. Girão
Keyword(s):  
Cardiac Output ◽  
Impedance Cardiography ◽  
Left Ventricular ◽  
Embedded Sensors ◽  
Left Ventricular Ejection ◽  
Ejection Time ◽  
Left Ventricular Ejection Time ◽  
Non Invasive ◽  
Impedance Cardiogram ◽  
Ventricular Ejection Time

Impedance cardiography is a technique developed with the intent of monitoring cardiac output. By inspecting a few properties of the obtained signal (impedance cardiogram (ICG), the left ventricular ejection time can be derived with certainty, and an estimate of cardiac output is available. This signal is nowadays used in non-invasive monitoring, requiring the placement of electrodes over the subject’s skin, either ECG-type or in the form of encircling bands. The work here reported describes the implementation steps and the results obtained when embedding the ICG circuitry in a wheelchair’s backrest. The subject is seated normally, is normally dressed, and is completely unaware that monitoring is taking place. That means that the variation of tenths of ohm produced due to the cardiac cycle has to be detected with electrodes having substantial coupling impedance. Contactless ICG with embedded sensors was developed and tested on fourteen healthy subjects. The signal was always acquired, although respiratory activity is also important, constituting a noteworthy innovation in the area.

scholarly journals Improvement of Left Ventricular Ejection Time Measurement in the Impedance Cardiography Combined with the Reflection Photoplethysmography

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 3036 ◽  
Author(s):  
Shing-Hong Liu ◽  
Jia-Jung Wang ◽  
Chun-Hung Su ◽  
Da-Chuan Cheng
Keyword(s):  
Impedance Cardiography ◽  
Left Ventricular ◽  
Ventricular Ejection ◽  
Left Ventricular Ejection ◽  
Artificial Noise ◽  
Ejection Time ◽  
Left Ventricular Ejection Time ◽  
Noise Interference ◽  
Non Invasive ◽  
Ventricular Ejection Time

Cardiac stroke volume (SV) is an essential hemodynamic indicator that can be used to assess whether the pump function of the heart is normal. Non-invasive SV measurement is currently performed using the impedance cardiography (ICG). In this technology, left ventricular ejection time (LVET) is an important parameter which can be determined from the ICG signals. However, the ICG signals are inherently susceptible to artificial noise interference, which leads to an inaccurate LVET measurement and then yields an error in the calculation of SV. Therefore, the goal of the study was to measure LVETs using both the transmission and reflection photoplethysmography (PPG), and to assess whether the measured LVET was more accurate by the PPG signal than the ICG signal. The LVET measured by the phonocardiography (PCG) was used as the standard for comparing with those by the ICG and PPG. The study recruited ten subjects whose LVETs were simultaneously measured by the ICG using four electrodes, the reflection PPG using neck sensors (PPGneck) and the transmission PPG using finger sensors (PPGfinger). In each subject, ten LVETs were obtained from ten heartbeats selected properly from one-minute recording. The differences of the measured LVETs between the PCG and one of the ICG, PPGneck and PPGfinger were −68.2 ± 148.6 ms, 4.8 ± 86.5 ms and −7.0 ± 107.5 ms, respectively. As compared with the PCG, both the ICG and PPGfinger underestimated but the PPGneck overestimated the LVETs. Furthermore, the measured LVET by the PPGneck was the closest to that by the PCG. Therefore, the PPGneck may be employed to improve the LVET measurement in applying the ICG for continuous monitoring of SV in clinical settings.

Dynamics of cardiac output and systolic time intervals in supine and upright exercise

1983 ◽  
Vol 55 (6) ◽  
pp. 1674-1681 ◽  
Author(s):  
Y. Miyamoto ◽  
J. Higuchi ◽  
Y. Abe ◽  
T. Hiura ◽  
Y. Nakazono ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Response Times ◽  
Systolic Time Intervals ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Upright Posture ◽  
Ejection Time ◽  
Left Ventricular Ejection Time ◽  
Supine Posture ◽  
Ventricular Ejection Time

Transient and steady-state responses of stroke volume (SV), heart rate (HR), cardiac output (Q), left ventricular ejection time (LVET), preejection period (PEP), and the ratio of LVET to PEP during bicycle exercises of 50 and 100 W were studied in four healthy male subjects in supine and upright postures. A computer-based system in which impedance cardiography was incorporated served to determine the above parameters on a 10-s interval basis. SV remained almost unchanged in response to exercises in a supine posture, whereas it increased significantly in an upright posture, although the individual differences among subjects were found to be large. The half-response times of variables to a step work load were determined. An approximate accordance was observed among the response times for HR, Q, and LVET/PEP. There was an inverse relationship between LVET and HR, the slope of which was found to be steeper in the supine posture than in the upright posture, reflecting the difference between the SV responses in both postures. LVET fell shortly after the cessation of exercise despite the decreasing HR. Inasmuch as the paradoxical reduction of LVET was also found in the case where SV remained unchanged in response to exercise, no changes in SV can be the cause thereof. Thus, a transient increase in ejection rate, which is due to either the increased myocardial contractility or decreased peripheral vascular resistance, may be responsible for the phenomenon.

Left ventricular ejection time index in man

1963 ◽  
Vol 18 (5) ◽  
pp. 919-923 ◽  
Author(s):  
Arnold M. Weissler ◽  
Leonard C. Harris ◽  
George D. White
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Left Ventricular ◽  
Ventricular Ejection ◽  
Left Ventricular Ejection ◽  
Ejection Time ◽  
Left Ventricular Ejection Time ◽  
Time Index ◽  
Normal Individuals ◽  
Ventricular Ejection Time

The present studies were undertaken in an attempt to formulate an accurate expression of the relationship between the duration of left ventricular ejection and heart rate in man. On the basis of regression equations relating the duration of left ventricular ejection and heart rate in normal individuals, the index LVET + .0016 HR was derived and tested in normal adults and prepubertal children. The left ventricular ejection time index (ETI) remained constant and reproducible over the range of heart rate from 50 to 150 and yielded more consistent values in this range of heart rate than did previously derived equations. A slight but significantly higher value of the ETI was present in the adult females when compared to the adult males, while no significant difference according to sex was apparent in the children. A decrease in ETI was found when cardiac output was diminished in normal individuals during 60° head-up tilt and in patients with congestive heart failure. Of note was the finding of a significant correlation between the level of the ETI and the cardiac output in these situations. Submitted on December 13, 1962

scholarly journals Comparability of Spot Versus Band Electrodes for Impedance Cardiography

2005 ◽  
Vol 19 (3) ◽  
pp. 195-203 ◽  
Author(s):  
Jennifer J. McGrath ◽  
William H. O'Brien ◽  
Hilary J. Hassinger ◽  
Purvi Shah
Keyword(s):  
Cardiac Output ◽  
Stroke Volume ◽  
Mental Arithmetic ◽  
Statistical Tests ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Ejection Time ◽  
Left Ventricular Ejection Time ◽  
Advantages And Disadvantages ◽  
Ventricular Ejection Time

Abstract. Although band and spot electrodes have been compared in prior research, they have not been evaluated (a) at identical anatomical locations, (b) during a single laboratory session, (c) with measures taken in close temporal proximity, (d) using a single impedance cardiograph unit, or (e) using sufficiently powerful statistical tests. Thirty-one healthy young adults completed a psychophysiological assessment which consisted of baseline, mental arithmetic stressor, and recovery conditions. Data from spot and band electrodes were collected by alternating between electrode types every minute of the experiment. Correlations between spot and band electrodes at absolute levels of all cardiovascular measures (cardiac output, impedance derivative, basal impedance level, Heather index, heart rate, left ventricular ejection time, pre-ejection period, stroke volume) were of high magnitude (ravg = .78), while the correlations for difference scores were lower (ravg = .50). Analyses of mean levels indicated spot electrodes yielded significantly lower values for the impedance derivative, Heather index, and basal impedance, and higher values for cardiac output and stroke volume, than band electrodes. The advantages and disadvantages associated with spot and band electrode configurations, as well as their use in ambulatory recording, are discussed.

Reliability of noninvlasive methods for measuring cardiac function in exercise

1978 ◽  
Vol 44 (1) ◽  
pp. 55-58 ◽  
Author(s):  
L. A. Wolfe ◽  
D. A. Cunningham ◽  
G. M. Davis ◽  
P. A. Rechnitzer
Keyword(s):  
Cardiac Output ◽  
Systolic Time Intervals ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Ejection Time ◽  
Time Intervals ◽  
Left Ventricular Ejection Time ◽  
Ejection Rate ◽  
Systolic Time ◽  
Ventricular Ejection Time

Externally recorded systolic time intervals (STI's), indirect (CO2 re-breathing) cardiac output, and auscultatory blood pressures were measured during upright bicycle ergometer work in 20 healthy men, aged 24–56 yr. The subjects were studied on 2 separate days at steady-state work loads chosen to represent light (mean heart rate (HR) = 96 beats.min-1), moderate (HR = 118 beats.min-1) and heavy (HR = 147 beats.min-1) exercise. In addition to determinations of cardiac output, systolic time intervals, and blood pressure, the individual's mean systolic ejection rate (stroke volume/left ventricular ejection time) was calculated as a measure of left ventricular function. In general, heart-rate-corrected STI's were found to be reliable and reproducible. Reliability coefficients for total electromechanical systole and left ventricular ejection time ranged from 0.93 to 0.96 while those for the preejection period and its subcomponents were between 0.63 and 0.88. The reliability of cardiac output, stroke volume, mean systolic ejection rate, and systolic blood pressure was also considered to be acceptable but tended to be higher during moderate and heavy work (r = 0.85–0.95) compared to light exercise (r = 0.60–0.83).

Responses of peak ear-pulse derivative to changing left ventricular function

1980 ◽  
Vol 238 (3) ◽  
pp. H355-H359 ◽  
Author(s):  
Y. Nakamura ◽  
B. G. Haffty ◽  
D. H. Spodick ◽  
D. Paladino ◽  
K. Moreau ◽  
...  
Keyword(s):  
Ventricular Function ◽  
Cycle Length ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Ejection Time ◽  
Pressure Derivative ◽  
Left Ventricular Ejection Time ◽  
Ejection Rate ◽  
Ventricular Ejection Time ◽  
Technical Reliability

The ear densitograph displacement pulse derivative (dD/dtear) is the analog of the arterial pressure derivative (dP/dt) and behaves comparably under a variety of cardiocirculatory challenges. Technical reliability and uniform application of the transducer are advantages that make it ideal for intrasubject monitoring. With atrial fibrillation as a model of functional variability in eight subjects, peak dD/dtear (P) tracked echocardiographic stroke volume, ejection fraction, ejection rate, and velocity of circumferential fiber shortening quite closely with the exception of some values in three subjects, two of whom had mitral regurgitation and one paradoxic septal movement. In all subjects, P showed good to excellent correlations with cycle length, preejection period (PEP), LVET (left ventricular ejection time), and PEP/LVET. The method appears to be ideally suited to intrasubject monitoring for changing ventricular function.

Abstract 17298: Validation of Beat-to-Beat Blood Pressure and Left Ventricular Ejection Time by the Caretaker Physiological Monitor Against Invasive Central Aortic Measurement

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Evan Harmon ◽  
Younghoon Kwon ◽  
Patrick Stafford ◽  
Martin Baruch ◽  
Sung-Hoon Kim ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Unmet Need ◽  
Aortic Pressure ◽  
Left Ventricular ◽  
Ventricular Ejection ◽  
Left Ventricular Ejection ◽  
Ejection Time ◽  
Left Ventricular Ejection Time ◽  
Monitoring Technologies ◽  
Ventricular Ejection Time

Objective: There is an unmet need for noninvasive continuous blood pressure (BP) monitoring technologies in various clinical settings. We examined the accuracy of noninvasive Caretaker device against invasively measured central aortic BP. Methods: Beat-to-beat BP by Caretaker was recorded simultaneously with central aortic BP measured in patients undergoing cardiac catheterization. We derived correlations and Bland-Altman comparisons, after calibrating the Caretaker with 20 seconds of the initial catheter readings, as well as trend analyses for both systolic (SBP) and diastolic BP (DBP). We also measured left ventricular ejection time (LVET) from both aortic pressure tracing and Caretaker and compared the two. Results: A total of 47 patients were included in the study. A total of 31,369 beats obtained during the diagnostic portion of coronary angiogram were used for analysis. The correlations for SBP and DBP were 0.89 and 0.78, respectively (p < 0.001 for both). The Bland-Altman comparison yielded overall mean differences of 2.11 mmHg (SD 7.40) for SBP and 1.46 mmHg (SD 6.12) for DBP respectively (p <0.001 for all comparisons). The trend analysis yielded concordances of 86% and 85% for SBP and DBP, respectively. The correlation and Bland-Altman analyses for the LVET comparison yielded 0.89 (p< 0.001) with a mean difference of 13.9 ms (SD 14.4 ms). Conclusion: Beat-to-beat BP by Caretaker showed excellent agreement and high concordance in the direction and the degree of BP change with central aortic BP. This study supports the satisfactory performance of the Caretaker device in continuous tracking of beat-to-beat BP and LVET measurements.

scholarly journals Wearable Cardiorespiratory Monitoring Employing a Multimodal Digital Patch Stethoscope: Estimation of ECG, PEP, LVET and Respiration Using a 55 mm Single-Lead ECG and Phonocardiogram

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 2033 ◽  
Author(s):  
Michael Klum ◽  
Mike Urban ◽  
Timo Tigges ◽  
Alexandru-Gabriel Pielmus ◽  
Aarne Feldheiser ◽  
...  
Keyword(s):  
Cause Of Death ◽  
Left Ventricular ◽  
Noncommunicable Diseases ◽  
Left Ventricular Ejection ◽  
Ejection Time ◽  
Left Ventricular Ejection Time ◽  
Respiratory Parameters ◽  
Respiratory Signal ◽  
Ventricular Ejection Time ◽  
The Impact

Cardiovascular diseases are the main cause of death worldwide, with sleep disordered breathing being a further aggravating factor. Respiratory illnesses are the third leading cause of death amongst the noncommunicable diseases. The current COVID-19 pandemic, however, also highlights the impact of communicable respiratory syndromes. In the clinical routine, prolonged postanesthetic respiratory instability worsens the patient outcome. Even though early and continuous, long-term cardiorespiratory monitoring has been proposed or even proven to be beneficial in several situations, implementations thereof are sparse. We employed our recently presented, multimodal patch stethoscope to estimate Einthoven electrocardiogram (ECG) Lead I and II from a single 55 mm ECG lead. Using the stethoscope and ECG subsystems, the pre-ejection period (PEP) and left ventricular ejection time (LVET) were estimated. ECG-derived respiration techniques were used in conjunction with a novel, phonocardiogram-derived respiration approach to extract respiratory parameters. Medical-grade references were the SOMNOmedics SOMNO HDTM and Osypka ICON-CoreTM. In a study including 10 healthy subjects, we analyzed the performances in the supine, lateral, and prone position. Einthoven I and II estimations yielded correlations exceeding 0.97. LVET and PEP estimation errors were 10% and 21%, respectively. Respiratory rates were estimated with mean absolute errors below 1.2 bpm, and the respiratory signal yielded a correlation of 0.66. We conclude that the estimation of ECG, PEP, LVET, and respiratory parameters is feasible using a wearable, multimodal acquisition device and encourage further research in multimodal signal fusion for respiratory signal estimation.

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