Explore the vast range of titles available.

Objective: To investigate the accuracy of electrical cardiometry (EC) to measure stroke volume (SV) and cardiac output (CO) and to provide gestational age (GA) and birth weight (BW)-based reference data for SV and CO in hemodynamically stable preterm neonates. Study Design: Prospective observational blinded study. Paired measurements of SV and CO on stable preterm infants without any hemodynamic compromise were carried out using EC (SV EC ) and echocardiography (SV ECHO ). Results: Seventy-nine preterm neonates (mean GA: 31±3.2 weeks) were enrolled. A good correlation was found for SV ( r =0.743; P <0.0001) and CO ( r =0.7; P <0.0001) measured by EC and echocardiography. These correlations remained significant after adjusting for GA, patent ductus arteriosus and type of respiratory support (SV: St.β=0.48, P <0.0001 and CO: St.β=0.69, P <0.0001). Mean biases (and variabilities) were −1.1 (from 0.7 to −2.9) ml and −0.21 (from 0.15 to −0.55) l min −1 for SV and CO, respectively. Local regression shows a tendency for EC to overestimate SV and CO especially at higher values (at about >2 ml and >0.4 l min −1 , respectively). Coefficient of variation of SV was 48.9% and 52%, for EC and echocardiography. SV and CO rose with increasing GA and BW following an exponential equation ( R 2 >0.8). Conclusion: Measuring SV and CO with EC in hemodynamically stable preterm infants shows good correlation and variability similar to that of echocardiography. A trend to overestimation exists at highest values, but it is unlikely to be clinically significant. Reference GA and BW-based nomograms for SV and CO are provided.

The ‘strength–endurance continuum’ is a key concept in strength training (ST). Although cardiopulmonary responses have seldom been reported in conjunction with ST, this repeated‐measurement study examined acute blood pressure and haemodynamic responses continuously depending on the number of repetitions but without changing the intensity. Fifteen healthy male participants (21.6 (2.0) years; mean (SD)) performed an incremental exercise test and a 3‐repetition maximum test (3‐RM) on a Smith machine. They were then randomly assigned to three ST sessions involving 10, 20 and 30 repetitions at 50% of their 3‐RM. Blood pressure (vascular unloading technique) and cardiopulmonary responses (spirometry and impedance cardiography) were continuously monitored. Heart rate (121 (10) vs. 139 (22) vs. 153 (13) bpm, P = 0.001, respectively), cardiac output (10.4 (1.9) vs. 13.6 (3.8) vs. 14.6 (3.1) L/min, P = 0.001, respectively) and diastolic blood pressure (113 (8) vs. 116 (21) vs. 135 (22) mmHg, P = 0.001, respectively) increased in the training sessions with higher repetitions. Stroke volume, systolic blood pressure and end‐diastolic volume indicated no change in peak values between training sessions. Total peripheral resistance (13.6 (2.8) vs. 11.3 (3.6) vs. 11.2 (3.1) mmHg min/L, P = 0.002, respectively) was significantly lower with 20 and 30 repetitions, while oxygen uptake (V̇O2 ${\\dot V_{{{\\mathrm{O}}_{\\mathrm{2}}}$ : 15.5 (1.9) vs. 20.5 (4.1) vs. 20.6 (4.4) mL/min/kg, P = 0.001, respectively) was significantly higher. ST of moderate intensity with an exhausting number (>20) of repetitions induces strong haemodynamic responses, especially high cardiac afterload and a compensatory heart rate acceleration, which may also create a strong stimulus for cardiopulmonary adaptation. What is the central question of this study? What are the haemodynamic effects of different numbers of repetitions in strength training when investigated independently of intensity? What is the main finding and its importance? Performing an exhaustive number of repetitions (>20) in strength training elicits intense, primarily chronotropic cardiac responses, similar to isometric strength exercises.

Accurate and reliable determination of the characteristic points of the impedance cardiogram (ICG) is an important research problem with a growing range of applications in the cardiological diagnostics of patients with heart failure (HF). The shapes of the characteristic waves of the ICG signal and the temporal location of the characteristic points B, C, and X provide significant diagnostic information. On this basis, essential diagnostic cardiological parameters can be determined, such as, e.g., cardiac output (CO) or stroke volume (SV). Although the importance of this problem is obvious, we face many challenges, including noisy signals and the big variability in the morphology, which altogether make the accurate identification of the characteristic points quite difficult. The paper presents an effective method of ICG points identification intended for conducting experimental research in the field of impedance cardiography. Its effectiveness is confirmed in clinical pilot studies.

Accurate cardiac output (CO) estimation from impedance cardiography (ICG) signals is vital for non-invasive monitoring of cardiovascular disorders, including heart failure, arrhythmias, and hemodynamic instability. However, the reliability of ICG-based assessment is often limited by noise artifacts that obscure clinically relevant features. This study introduces a novel three-stage denoising framework integrating Variational Mode Decomposition (VMD), Non-Local Means (NLM), and Discrete Wavelet Transform (DWT) to enhance ICG signal quality for robust CO estimation. The method was validated on the publicly available ReBeatICG dataset, which includes annotated signals from 24 subjects and reflects real-world noise sources such as motion artifacts and baseline drift. Experimental results demonstrate that the proposed VMD-NLM-DWT approach achieves a maximum of 1.2 dB improvement in signal-to-noise ratio (SNR), an average 13% reduction in mean squared error (MSE), and 9% lower percent root mean square difference (PRD) compared to leading two-stage denoising methods. The framework also enhances fiducial point detection (F1-score increase up to 4.4%) and preserves high heart rate variability (HRV) fidelity (correlation coefficient 0.91), with the highest denoising robustness index (DRI) observed across a wide range of noise conditions. These findings confirm that the proposed method outperforms state-of-the-art alternatives in preserving both signal fidelity and clinically significant features under both stationary and non-stationary noise. Furthermore, all performance improvements are statistically validated using paired t -tests and effect size analysis ( , Cohen’s ) and achieves top scores in PSNR and SSIM compared to all baselines. Computational profiling demonstrates feasibility for real-time, continuous cardiac output monitoring in clinical and ambulatory care, supporting its broader application in cardiovascular diagnostics.

The accurate detection of fiducial points in the impedance cardiography signal (ICG) has a decisive impact on the proper estimation of diagnostic parameters such as stroke volume or cardiac output. It is, therefore, necessary to find an algorithm that is able to assess their positions with great precision. The solution to this problem is, however, quite challenging with regard to the high sensitivity of the ICG technique to the noise and varying morphology of the acquired signals. The aim of this study is to propose a novel method that allows us to overcome these limitations. The developed algorithm is based on Empirical Mode Decomposition (EMD)—an effective technique for processing and analyzing various types of non-stationary signals. We find high correlations between the results obtained from the algorithm and annotated by an expert. This, in turn, implies that the difference in estimation of the diagnostic-relevant parameters is small, which suggests that the method can automatically provide precise clinical information.

Measurement of internal thoracic impedance (ITI) is sensitive and accurate in detecting acute pulmonary edema even at its preclinical stage. We evaluated the suitability of the highly sensitive and noninvasive RS-207 monitor for detecting pleural effusion and for demonstrating increased ITI during its resolution. This prospective controlled study was performed in a single department of internal medicine of a university-affiliated hospital between 2012-2013. One-hundred patients aged 25–96 years were included, of whom 50 had bilateral or right pleural effusion of any etiology (study group) and 50 had no pleural effusion (controls). ITI, the main component of which is lung impedance, was continuously measured by the RS-207 monitor. The predictive value of ITI monitoring was determined by 8 measurements taken every 8 hours. Pleural effusion was diagnosed according to well-accepted clinical and roentgenological criteria. During treatment, the ITI of the study group increased from 32.9±4.2 ohm to 42.8±3.8 ohm (p<0.0001) compared to non-significant changes in the control group (59.6±6.6 ohm, p = 0.24). Prominent changes were observed in the respiratory rate of the study group: there was a decrease from 31.2±4.0 to 19.5±2.4 ohm (35.2%) compared to no change for the controls, and a mean increase from 83.6± 5.3%-92.5±1.6% (13.2%) in O2 saturation compared to 94.2±1.7% for the controls. Determination of ITI for the detection and monitoring of treatment of patients with pleural effusion enables earlier diagnosis and more effective therapy, and can prevent hospitalization and serious complications, such as respiratory distress, and the need for mechanical ventilation. The study is registered at ClinicalTrials.gov NCT01601444.

Impedance cardiography (ICG) is a low-cost, non-invasive technique that enables the clinical assessment of haemodynamic parameters, such as cardiac output and stroke volume (SV). Conventional ICG recordings are taken from the patient’s thorax. However, access to ICG vital signs from the upper-arm brachial artery (as an associated surrogate) can enable user-convenient wearable armband sensor devices to provide an attractive option for gathering ICG trend-based indicators of general health, which offers particular advantages in ambulatory long-term monitoring settings. This study considered the upper arm ICG and control Thorax-ICG recordings data from 15 healthy subject cases. A prefiltering stage included a third-order Savitzky–Golay finite impulse response (FIR) filter, which was applied to the raw ICG signals. Then, a multi-stage wavelet-based denoising strategy on a beat-by-beat (BbyB) basis, which was supported by a recursive signal-averaging optimal thresholding adaptation algorithm for Arm-ICG signals, was investigated for robust signal quality enhancement. The performance of the BbyB ICG denoising was evaluated for each case using a 700 ms frame centred on the heartbeat ICG pulse. This frame was extracted from a 600-beat ensemble signal-averaged ICG and was used as the noiseless signal reference vector (gold standard frame). Furthermore, in each subject case, enhanced Arm-ICG and Thorax-ICG above a threshold of correlation of 0.95 with the noiseless vector enabled the analysis of beat inclusion rate (BIR%), yielding an average of 80.9% for Arm-ICG and 100% for Thorax-ICG, and BbyB values of the ICG waveform feature metrics A, B, C and VET accuracy and precision, yielding respective error rates (ER%) of 0.83%, 11.1%, 3.99% and 5.2% for Arm-IG, and 0.41%, 3.82%, 1.66% and 1.25% for Thorax-ICG, respectively. Hence, the functional relationship between ICG metrics within and between the arm and thorax recording modes could be characterised and the linear regression (Arm-ICG vs. Thorax-ICG) trends could be analysed. Overall, it was found in this study that recursive averaging, set with a 36 ICG beats buffer size, was the best Arm-ICG BbyB denoising process, with an average of less than 3.3% in the Arm-ICG time metrics error rate. It was also found that the arm SV versus thorax SV had a linear regression coefficient of determination (R2) of 0.84.

The long-term hypercortisolemia of Cushing disease (CD) may lead to hemodynamic disorders by increasing subclinical cardiac and vascular dysfunction. The purpose of this observational cohort study was to assess the relationship between hemodynamic parameters evaluated via impedance cardiography (ICG) and echocardiographic parameters reflecting left ventricular function in 54 patients newly diagnosed with CD. The parameters assessed via ICG included stroke volume index (SI), cardiac index (CI), acceleration index (ACI), velocity index (VI), systemic vascular resistance index (SVRI), total artery compliance index (TACI). The echocardiographic parameters included left ventricular mass index (LVMI) and left ventricular systolic and diastolic parameters. Higher LVMI values were associated with lower SI (p = 0.003), CI (p = 0.001), VI (p = 0.048), TACI (p < 0.001), and with higher SVRI (p < 0.001). Poorer parameters of left ventricular diastolic function corresponded to the parameters assessed via ICG: (1) lower ratio E/A was associated with lower SI (p = 0.002), VI (p = 0.001), ACI (p = 0.01), TACI (p = 0.001); (2) lower average e’ was associated with lower SI ( p  = 0.017), CI ( p  = 0.009), VI ( p  = 0.004), TACI ( p  = 0.001), and with higher SVRI ( p  = 0.002); (3) higher ratio E/e’ corresponded to lower TACI ( p  = 0.01). Decreased global longitudinal strain corresponded to lower TACI ( p  = 0.046). CD is associated with impaired pumping function of the heart and higher afterload.

Background Impedance Cardiography (ICG) is a non-invasive tool for continuous hemodynamic monitoring. Aims of our study were to assess the utility of ICG to evaluate the hemodynamic impact of 6 mg (GL6) vs 8 mg (GL8) levobupivacaine combined with fentanyl in healthy patients undergoing elective cesarean section; secondary, to compare the duration and quality of analgesia and anesthesia. Methods Sixty-two women receiving combined spinal-epidural (CSE) for elective cesarean delivery were randomly allocated to GL6 or GL8 groups. Mean arterial pressure (MAP), cardiac index (CI), systemic vascular resistance index (SVRI), heart rate (HR), stroke volume index (SVI) were recorded from Tbaseline to 31 min after CSE by ICG. Sensory and motor blocks, patients and surgeons satisfaction, neonatal data were also recorded. Results Fifteen of 32 patients in GL6 and 15 of 30 patients in GL8 experienced hypotension at T2 vs Tbaseline ( P  < .001) and SVRI reduction ( P  = .035 and P < .001 respectively). MAP, CI and SVRI were always slightly higher in GL6 vs GL8. HR and SVI remained stable until the end of surgery in all patients. Total ephedrine requirements was higher in GL8 ( P  = .010). The onset and offset time of sensory and motor block were similar in both groups, but the number of patients with motor block was lower in GL6 vs GL8 ( P  = .001). Patients and surgeon satisfaction scores, the number of patients needed systemic rescue doses, neonatal data were similar in both groups. Conclusions ICG is a useful noninvasive tool to monitor continuously hemodynamics during cesarean section. The hemodynamic stability, the satisfying sensory block and rapid mobilization provided by low levobupivacaine dose may be particularly advantageous in obstetric patients. Trial registration ClinicalTrials.gov: NCT03170427 . Retrospectively Registered (Date of registration: May 2017).

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.