Thoracic Bioimpedance Research Articles

Towards personalized fluid monitoring in haemodialysis patients: thoracic bioimpedance signal shows strong correlation with fluid changes, a cohort study

BackgroundHaemodialysis (HD) patients are burdened by frequent fluid shifts which amplify their comorbidities. Bioimpedance (bioZ) is a promising technique to monitor changes in fluid status. The aim of this study is to investigate if the thoracic bioZ signal can track fluid changes during a HD session.MethodsPrevalent patients from a single centre HD unit were monitored during one to six consecutive HD sessions using a wearable multi-frequency thoracic bioZ device. Ultrafiltration volume (UFV) was determined based on the interdialytic weight gain and target dry weight set by clinicians. The correlation between the bioZ signal and UFV was analysed on population level. Additionally regression models were built and validated per dialysis session.Results66 patients were included, resulting in a total of 133 HD sessions. Spearman correlation between the thoracic bioZ and UFV showed a significant strong correlation of 0.755 (p < 0.01) on population level. Regression analysis per session revealed a strong relation between the bioZ value and the UFV (R2 = 0.982). The fluid extraction prediction error of the leave-one-out cross validation was very small (56.2 ml [− 121.1–194.1 ml]) across all sessions at all frequencies.ConclusionsThis study demonstrated that thoracic bioZ is strongly correlated with fluid shifts during HD over a large range of UFVs. Furthermore, leave-one-out cross validation is a step towards personalized fluid monitoring during HD and could contribute to the creation of autonomous dialysis.

Combining Bioimpedance and Myographic Signals for the Assessment of COPD During Loaded Breathing.

Chronic Obstructive Pulmonary Disease (COPD) is one of the most common chronic conditions. The current assessment of COPD requires a maximal maneuver during a spirometry test to quantify airflow limitations of patients. Other less invasive measurements such as thoracic bioimpedance and myographic signals have been studied as an alternative to classical methods as they provide information about respiration. Particularly, strong correlations have been shown between thoracic bioimpedance and respiratory volume. The main objective of this study is to investigate bioimpedance and its combination with myographic parameters in COPD patients to assess the applicability in respiratory disease monitoring. We measured bioimpedance, surface electromyography and surface mechanomyography in forty-three COPD patients during an incremental inspiratory threshold loading protocol. We introduced two novel features that can be used to assess COPD condition derived from the variation of bioimpedance and the electrical and mechanical activity during each respiratory cycle. These features demonstrate significant differences between mild and severe patients, indicating a lower inspiratory contribution of the inspiratory muscles to global respiratory ventilation in the severest COPD patients. In conclusion, the combination of bioimpedance and myographic signals provides useful indices to noninvasively assess the breathing of COPD patients.

Impedance Cardiography Signal Enhancement through Block Based Adaptive Cancellers for Distant Medical Care

The impedance Cardiography (ICG) assists the impedance occurred in the heart. The ICG also known as Thoracic Electro Bio-Impedance (TEB).This projects various flexible and mathematical reduced adaptive methods to visualize the extreme clear TEB modules. In the medical premises, TEB wave notifies the several physiological and non-physiological incidents, that covers small characteristics which are predominant for finding the volume of the stroke. In addition, mathematical difficulty is a significant constraint to novel healthcare observing tool. Therefore, the paper project novel wave working methods for TEB improvement in isolated arrangements. So that we selected higher preference adaptive eliminator as a fundamental constituent in the procedure. To recover the original signal, convergence rate, to minimize mathematical difficulty of the wave working method, we relate the data normalization to extract the ideal wave. The projected realizations are simulated with practical TEB waves. At last, outcomes proves projected extracted normalized higher order filter is appropriate to realistic medical arrangement.

Electrode Positioning to Investigate the Changes of the Thoracic Bioimpedance Caused by Aortic Dissection - A Simulation Study.

Impedance cardiography (ICG) is a non-invasive method to evaluate several cardiodynamic parameters by measuring the cardiac-synchronous changes in the dynamic transthoracic electrical impedance. ICG allows us to identify and quantify conductivity changes inside the thorax by measuring the impedance on the thorax during a cardiac cycle. Pathologic changes in the aorta, like aortic dissection, will alter the aortic shape as well as the blood flow and consequently, the impedance cardiogram. This fact distorts the evaluated cardiodynamic parameters, but it could lead to the possibility to identify aortic pathology. A 3D numerical simulation model is used to compute the impedance changes on the thorax surface in case of the type B aortic dissection. A sensitivity analysis is applied using this simulation model to investigate the suitability of different electrode configurations considering several patient-specific cases. Results show that the remarkable pathological changes in the aorta caused by aortic dissection alters the impedance cardiogram significantly.

Hemodynamic profile of Spanish adults with Down syndrome

ObjectivesAlthough the reasons are unknown, the prevalence of arterial hypertension and atherosclerotic cardiovascular events in the adult population with Down syndrome (SD) is anecdotal. To better understand this finding, we evaluated the haemodynamic characteristics of a cohort of adults with SD. MethodsWe conducted a cross-sectional study of adults with SD recruited consecutively from the outpatient clinics of an internal medicine department between June and November 2018. We collected demographic, clinical and laboratory variables and employed a thoracic bioimpedance device (HOTMAN® System) for the haemodynamic measures. Outpatient blood pressure monitoring (OBPM) was conducted on a subgroup of participants. ResultsTwenty-six participants (mean age, 45±11 years) participated in the study (50 % men). The sample’s mean blood pressure (BP) was 109/69±11/9mm Hg, with a mean heart rate of 60±12 bpm. None of the participants had hypertension. The predominant haemodynamic profile consisted of normal dynamism (65 %), normal BP (96 %), hypochronotropism (46 %), normal inotropism (50 %) and hypervolaemia (54 %), with normal peripheral vascular resistance values (58 %). Twelve participants underwent OBPM (46 %). The mean 24-h systolic BP, diastolic BP, mean BP and mean heart rate were 105±11mm Hg, 67±11mm Hg, 80±11mm Hg and 61±6 bpm, respectively. ConclusionsThe most common haemodynamic profile observed in adults with SD consisted of hypochronotropism and hypervolaemia, with normal values for peripheral vascular resistance and optimal mean BP values. There were no participants with hypertension in our sample.

Standalone IoT Bioimpedance Device Supporting Real-Time Online Data Access

The use of electrical bioimpedance methods in medical and personalized healthcare applications requires sophisticated hardware and measurement settings. Here, we describe Zink , a standalone bioimpedance analyzer with Internet of Things (IoT) monitoring features. Zink can be connected to a secure wireless or local area network and accessed using any device with a Web browser and Internet access. Through a user-friendly Web-based access able to handle multiple simultaneous connections, the user(s) can perform single or multiple bioimpedance measurement(s) remotely. Zink supports the measurement of bioimpedance in both time and frequency domains using stepped-sine and multisine excitation signals. Embedded signal processing calculates bioimpedance from voltage and current signals using a coherent demodulation and the fast Fourier transform. Zink can also measure bioimpedance synchronized with either electrocardiogram (ECG) or electromyogram signals. The data is displayed on the user’s Web client from where it can be downloaded for further analysis. Zink full bandwidth is 100 mHz to 10 MHz and the average signal-to-noise ratio tested from 1 kHz to 1 MHz is 56 dB. The extended calibration method proposed here reduces the average magnitude error with respect to the existing three-parameter calibration approach by $0.6~\Omega $ (0.3%) measuring phantoms. Thoracic bioimpedance and ECG measurements on volunteers demonstrate the feasibility of detecting respiration changes while showing the results in real time on the user device’s Web browser. The performance, portability, and integration of Zink makes it a suitable standalone platform for medical and personalized health IoT monitoring applications.

Chest Movement and Respiratory Volume both Contribute to Thoracic Bioimpedance during Loaded Breathing

Bioimpedance has been widely studied as alternative to respiratory monitoring methods because of its linear relationship with respiratory volume during normal breathing. However, other body tissues and fluids contribute to the bioimpedance measurement. The objective of this study is to investigate the relevance of chest movement in thoracic bioimpedance contributions to evaluate the applicability of bioimpedance for respiratory monitoring. We measured airflow, bioimpedance at four electrode configurations and thoracic accelerometer data in 10 healthy subjects during inspiratory loading. This protocol permitted us to study the contributions during different levels of inspiratory muscle activity. We used chest movement and volume signals to characterize the bioimpedance signal using linear mixed-effect models and neural networks for each subject and level of muscle activity. The performance was evaluated using the Mean Average Percentage Errors for each respiratory cycle. The lowest errors corresponded to the combination of chest movement and volume for both linear models and neural networks. Particularly, neural networks presented lower errors (median below 4.29%). At high levels of muscle activity, the differences in model performance indicated an increased contribution of chest movement to the bioimpedance signal. Accordingly, chest movement contributed substantially to bioimpedance measurement and more notably at high muscle activity levels.

Perfil hemodinámico de los adultos españoles con síndrome de Down

ObjectivesAlthough the reasons are unknown, the prevalence of arterial hypertension and atherosclerotic cardiovascular events in the adult population with Down syndrome (SD) is anecdotal. To better understand this finding, we evaluated the haemodynamic characteristics of a cohort of adults with SD. MethodsWe conducted a cross-sectional study of adults with SD recruited consecutively from the outpatient clinics of an internal medicine department between June and November 2018. We collected demographic, clinical and laboratory variables and employed a thoracic bioimpedance device (HOTMAN® System) for the haemodynamic measures. Outpatient blood pressure monitoring (OBPM) was conducted on a subgroup of participants. ResultsTwenty-six participants (mean age, 45±11years) participated in the study (50% men). The sample's mean blood pressure (BP) was 109/69±11/9mmHg, with a mean heart rate of 60±12bpm. None of the participants had hypertension. The predominant haemodynamic profile consisted of normal dynamism (65%), normal BP (96%), hypochronotropism (46%), normal inotropism (50%) and hypervolaemia (54%), with normal peripheral vascular resistance values (58%). Twelve participants underwent OBPM (46%). The mean 24-h systolic BP, diastolic BP, mean BP and mean heart rate were 105±11mmHg, 67±11mmHg, 80±11mmHg and 61±6bpm, respectively. ConclusionsThe most common haemodynamic profile observed in adults with SD consisted of hypochronotropism and hypervolaemia, with normal values for peripheral vascular resistance and optimal mean BP values. There were no participants with hypertension in our sample.

Performance of Electrical Velocimetry for Noninvasive Cardiac Output Measurements in Perioperative Patients After Subarachnoid Hemorrhage

Fluid therapy guided by cardiac output measurements is of particular importance for adequate cerebral perfusion and oxygenation in neurosurgical patients. We examined the usefulness of a noninvasive electrical velocimetry (EV) device based on the thoracic bioimpedance method for perioperative hemodynamic monitoring in patients after aneurysmal subarachnoid hemorrhage. In total, 18 patients who underwent surgical clipping or endovascular coiling for ruptured aneurysms were examined prospectively. Simultaneous cardiac index (CI) measurements obtained with EV (CIEV) and reference transpulmonary thermodilution (CITPTD) were compared. A total of 223 pairs of data were collected. A significant correlation was found between CIEV and CITPTD (r=0.86; P<0.001). Bland and Altman analysis revealed a bias between CIEV and CITPTD of -0.06 L/min/m, with limits of agreement of ±1.14 L/min/m and a percentage error of 33%. Although the percentage error for overall data was higher than the acceptable limit of 30%, subgroup analysis during the postoperative phase showed better agreement (23% vs. 42% during the intraprocedure phase). Four-quadrant plot and polar plot analyses showed fair-to-poor trending abilities (concordance rate of 90% to 91%, angular bias of +17 degrees, radial limits of agreement between ±37 and ±40 degrees, and polar concordance rate of 72% to 75%), including the subgroup analysis. Absolute CI values obtained from EV and TPTD are not interchangeable with TPTD for perioperative use in subarachnoid hemorrhage patients. However, considering the moderate levels of agreement with marginal trending ability during the early postoperative phase, this user-friendly device can provide an attractive monitoring option during neurocritical care.

HEMODYNAMIC PROFILES IN TREATMENT-NAIVE ARTERIAL HYPERTENSION AND THEIR CLINICAL IMPLICATION FOR CHOICE OF TREATMENT – A PILOT STUDY

Objective: Arterial Hypertension (AHT) is characterised by different hemodynamic modulators, which can be non-invasively assessed using the HOTMAN® System, a very low-current thoracic bioimpedance method to estimate modulators such as volemia, inotropy, chronotropy and vasoactivity, and express them as a hemodynamic map. The aim of the present study was to characterise hemodynamic patterns in newly diagnosed treatment-naive hypertensive patients and to assess the advantages of hemodynamic profiling in clinical decision making regarding choice of an antihypertensive therapy. Design and method: Between April 2015 and March 2018, 80 outpatients with newly diagnosed AHT were randomized to antihypertensive monotherapy with either an ACE inhibitor, an angiotensin receptor blocker, a calcium channel blocker, or hydrochlorothiazide. Hemodynamic profiles and 24h-blood pressure (BP) measurements were done at baseline and after one month of treatment. Three hypertension experts (blinded to treatment assignment) retrospectively determined the most appropriate treatment according to the hemodynamic maps at baseline. The randomized patients were post-hoc categorised as having received concordant or discordant treatment. Three hemodynamic profiles could not be analyzed due to technical problems. Results: Mean age, body mass index and gender proportion were 48.9(±14.3) years, 26.5(±3.7) kg/m2 and 74% males, respectively. The mean 24 h average BP at baseline was 141.8(±9.1)/87.7(±7.6) mmHg. The predominant hemodynamic profiles at baseline were 45% hypervolemia without vasoconstriction and 48% hypervolemia with vasoconstriction (mixed) (Figure 1).After one month of treatment, the BP control rate was 53.7%(43/80) among all, 57.7%(30/52) in the discordant group and 48%(12/25) in the concordant group. The overall 24 h average BP was 131.3(±11.3)/82.2(±8.3) mmHg, respectively with a BP reduction of −10.5(±11.7)/−5.6(±6.5) mmHg. The average 24 h BP systolic and diastolic reductions in the concordant treatment group (n = 25) and the discordant group (n = 52) were −12.4(±14.8)/−6.9 (±6.9) mmHg and −9.7(±10.1)/−5.0(±6.2) mmHg, respectively. The differences were statistically not significant (p = 0.496 and 0.322) (Figure 2). Conclusions: Our data does not support the hypothesis that treatment initiation based on hemodynamic patterns improves blood pressure control in newly diagnosed hypertensive outpatients.

Validation of intracardiac shunt using thoracic bioimpedance and inert gas rebreathing in adults before and after percutaneous closure of atrial septal defect in a cardiology research unit: study protocol

IntroductionIntrathoracic shunt quantification is a major factor for appropriate clinical management of heart and pulmonary diseases. Intracardiac shunts quantified by pulmonary to systemic output ratio (Qp/Qs) are generally assessed by...

Processing of impedance cardiogram differential for non-invasive cardiac function detection

The precise recognition of feature points of impedance cardiogram (ICG) is the precondition of calculating hemodynamic parameters based on thoracic bioimpedance. To improve the accuracy of detecting feature points of ICG signals, a new method was proposed to de-noise ICG signal based on the adaptive ensemble empirical mode decomposition and wavelet threshold firstly, and then on the basis of adaptive ensemble empirical mode decomposition, we combined difference and adaptive segmentation to detect the feature points, A, B, C and X, in ICG signal. We selected randomly 30 ICG signals in different forms from diverse cardiac patients to examine the accuracy of the proposed approach and the accuracy rate of the proposed algorithm is 99.72%. The improved accuracy rate of feature detection can help to get more accurate cardiac hemodynamic parameters on the basis of thoracic bioimpedance.

Non-invasive stroke volume estimation by transthoracic electrical bioimpedance versus Doppler echocardiography in healthy volunteers

Thoracic electrical bioimpedance (TEB) and transthoracic echocardiography (TTE) are non-invasive methods to estimate stroke volume (SV) and cardiac output (CO). Thoracic electrical bioimpedance is not in widespread clinical use with reports of inaccurate cardiac output estimation compared to invasive monitors, particularly in non-healthy populations. We explore its use as a trend monitor by comparing it against thoracic echocardiography in fifteen healthy volunteers undergoing two physical challenges designed to vary cardiac output. Of all paired values, 54.6% showed gross trend agreement and only 1.9% showed direct disagreement between the two monitors. Our results show thoracic bioimpedance may have a role as a non-invasive cardiac output trend monitor in healthy volunteer studies.

A novel technique to assess the quality of ventilation during pre-hospital cardiopulmonary resuscitation

BackgroundDevices that measure ventilation in the pre-hospital setting are deficient especially during early cardiopulmonary resuscitation (CPR) before placement of an advanced airway. Consequently, evidence is limited regarding the role of ventilation during early CPR and its effect on outcomes. ObjectiveTo develop software that automatically identifies ventilation waveforms recorded by defibrillators based on changes in transthoracic impedance during standard CPR. MethodsThis was an observational, retrospective analysis of non-traumatic pre-hospital cardiac arrest patients who received 30:2 CPR by emergency medical service rescuers. Data was collected from 550 cases recorded by the bioimpedance channel of defibrillators. Two expert clinicians independently assessed all episodes from the time of initial CPR until placement of an advanced airway, defined acceptable ventilation waveforms, and annotated the pauses between compressions with ventilation waveforms. We then developed software that incorporated the expert criteria and automatically annotated pauses with acceptable ventilations. ResultsA total of 7396 pauses were analyzed, mean(SD) duration of 30:2 CPR was 13 (8) min, with 13 (10) pauses/patient, and mean pause duration of 6 (3) s. Reviewer 1 and reviewer 2 identified 2375 and 2249 pauses with any acceptable ventilation, respectively, with an inter-rater reliability of 0.94. The novel software program reproduced expert annotation with excellent agreement (>0.8) and high accuracy, both sensitivity and specificity above 90%, compared to two reviewers. The software presented a substantial agreement with the reviewers (κ > 0.73) for ventilation counts in the pauses. ConclusionWe developed a novel and reliable strategy that enables investigation of ventilation quality during standard CPR using thoracic bioimpedance. This strategy would allow a timely and reliable automatic annotation of large scale resuscitation datasets.

Non-invasive cardiac output monitoring device "ICON" in trauma patients: a feasibility study.

Assessment of hemodynamics is crucial for the evaluation of major trauma patients. Cardiac output (CO) monitoring provides additional information and may improve volume resuscitation. The goal of this prospective pilot study was to evaluate the feasibility of a new non-invasive CO monitoring (NICOM) device in the emergency department (ED). Single-center prospective observational pilot study including 20 trauma patients admitted to a level 1 trauma center. CO was continuously monitored for 60min after ED admission using the new NICOM device ICON®. This device measures changes of the thoracic bioimpedance to calculate CO. Conventional vital signs were recorded simultaneously. Feasibility, safety, reliability, user-friendliness, and impact of the device on standard ED procedures were assessed. Thirteen (65%) patients were male, median age was 57.5 (IQR 25), and median ISS was 10.5 (IQR 14.8). Median CO over time was 9.8l/min (IQR 4.6). No adverse effects were recorded. The device proved to be user-friendly with no negative impact on routine ED care. In four patients, detachment of electrodes was observed, and in four patients, the CO recording was temporary discontinued. Short-term changes of the CO were observed 44 times after the placement of electrodes and during patient transfers. Non-invasive CO monitoring proved to be feasible and safe for the initial hemodynamic evaluation of trauma patients. Problems with the NICOM device were detachment of electrodes and temporary signal loss. Due to the small sample size and relatively low injury burden of the patients included in this study, further prospective investigation is warranted.

Latest Advances in Cardiac Output Monitoring from High-Definition Impedance Cardiography

Cardiac output (CO) and hemodynamic parameters, and specifically the noninvasive approach to their measurement, have been the subject of continuous technological developments and lengthy debates. The challenge remains to measure these parameters in a user friendly and cost-effective way, without compromising accuracy and with few limitations in the real clinical environment. The industry might have solved the issue with the latest development of thoracic bioimpedance, called high-definition impedance cardiography (HD-ICG) and based on the direct analysis of morphology of the heart impedance signals. It may offer improvements in accuracy, inter-operator reproducibility, sensitivity, and parameters management, and also simplifies the understanding of the etiology of cardiac dysfunctions. HD-ICG might have the potential to make hemodynamic measurements in anesthesia come of age and become a clinical standard.

Meta-analyses on measurement precision of non-invasive hemodynamic monitoring technologies in adults

An ideal non-invasive monitoring system should provide accurate and reproducible measurements of clinically relevant variables that enables clinicians to guide therapy accordingly. The monitor should be rapid, easy to use, readily available at the bedside, operator-independent, cost-effective and should have a minimal risk and side effect profile for patients. An example is the introduction of pulse oximetry, which has become established for non-invasive monitoring of oxygenation worldwide. A corresponding non-invasive monitoring of hemodynamics and perfusion could optimize the anesthesiological treatment to the needs in individual cases. In recent years several non-invasive technologies to monitor hemodynamics in the perioperative setting have been introduced: suprasternal Doppler ultrasound, modified windkessel function, pulse wave transit time, radial artery tonometry, thoracic bioimpedance, endotracheal bioimpedance, bioreactance, and partial CO2 rebreathing have been tested for monitoring cardiac output or stroke volume. The photoelectric finger blood volume clamp technique and respiratory variation of the plethysmography curve have been assessed for monitoring fluid responsiveness. In this manuscript meta-analyses of non-invasive monitoring technologies were performed when non-invasive monitoring technology and reference technology were comparable. The primary evaluation criterion for all studies screened was aBland-Altman analysis. Experimental and pediatric studies were excluded, as were all studies without anon-invasive monitoring technique or studies without evaluation of cardiac output/stroke volume or fluid responsiveness. Most studies found an acceptable bias with wide limits of agreement. Thus, most non-invasive hemodynamic monitoring technologies cannot be considered to be equivalent to the respective reference method. Studies testing the impact of non-invasive hemodynamic monitoring technologies as atrend evaluation on outcome, as well as studies evaluating alternatives to the finger for capturing the raw signals for hemodynamic assessment, and, finally, studies evaluating technologies based on aflow time measurement are current topics of clinical research.

Determination of Arterial Compliance Using Thoracic Bioimpedance to Predict the Presence of Heart Diseases

Introduction: Thoracic bioimpedance is a simple, cost-effective, and non-invasive tool used generally to determine several hemodynamic parameters. Based on this technique, the cardiac output and the stroke volume are the most common parameters used for diagnosing heart diseases. This study aims to investigate the ability of the arterial compliance parameter to predict or detect the presence of heart diseases. Methods: two groups of young subjects participated in this study: a control group consisted of 10 subjects including 2 athletes and a group of 10 patients with various heart diseases. The thoracic bioimpedance recordings are used to determine the arterial compliance for the 2 groups of subjects. Statistical analyses are performed using the Student’s t-test and the ROC curve analysis. Results: Experimental results show that the arterial compliance is significantly lower in patients with heart diseases compared to control subjects (P < 0.001). Conclusions: The arterial compliance is a potentially useful hemodynamic parameter which could be successfully used to predict or detect the presence of heart diseases.

Exercise intolerance in adolescents born preterm associated with left ventricular diastolic dysfunction

IntroductionPreterm birth disrupts the development of vital organ systems, and places significant challenges on these systems to function in an underdeveloped state. Physiological challenges have been well documented in the preterm infant, and recent evidence suggests that young adults born preterm have higher incidence of hypertension, cardiac dysfunction, and exercise intolerance. However, it is unclear whether adolescent children who received modern neonatal care, including surfactant therapy and lower mechanical ventilation pressures, express these same impairments. Our study sought to determine exercise capacity in adolescents born preterm, as well as resting blood pressure (BP), stroke volume (SV) during exercise, and left ventricular (LV) function using a cardiac MRI.MethodsAdolescent children born preterm in 2003 and 2004 weighing &lt;1500g with an average gestational age of 28 weeks, and healthy age‐matched controls with an average gestational age of 40 weeks were studied. Participants filled out a self‐reported physical activity questionnaire (PAQ) and underwent progressive maximal exercise testing on the upright cycle ergometer, where maximal aerobic capacity (VO2max), maximal power (Pmax), and time to exhaustion (Tmax) were determined. SV throughout exercise was determined using thoracic bioimpedance (PhysioFlow). Average resting BP was recorded during a 10‐minute supine rest, and resting cardiac structure and function measurements were acquired by cardiovascular magnetic resonance by a 3‐T GE scanner. Statistics were performed using Mann‐Whitney tests, and significance was determined as p&lt;0.05. Results are reported as mean±SD.ResultsPreterm adolescents had lower absolute VO2max than controls (2.1±0.5 vs 2.5±0.5 L/min, respectively, p=0.01), lower Pmax, (124±27 watts vs 151±29, p&lt;0.01), lower Tmax, (8.3±2.6 minutes vs 10.4±2.1, p&lt;0.01), with no difference in PAQ scores. Mean BP was higher in preterms than controls (82.2±3.7 vs 76.6±4.0 mmHg, p&lt;0.01), and sex‐, age‐ and height‐adjusted median z‐scores for systolic BP (SBP) and diastolic BP (DBP) were significantly higher in preterms than controls (SBP 0.60±0.57 vs −0.09±0.38, p&lt;0.01), (DBP 0.22±0.46 vs −0.42±0.51, p&lt;0.01). At rest, preterms had lower end diastolic volume (EDVi) (72.9±9.5 vs 84.2±7.2 ml/m2, p=0.02), with a higher LV ejection fraction (EF; 64.1±3.5 vs 58.1±5.5%, p=0.02). The change in SV from rest to maximal exercise was significantly lower in preterms (ΔSV; 4.8±12.7 vs 26.2±18.7 ml, p&lt;0.01).DiscussionWhile the underlying mechanisms of exercise impairment in our population are unclear, we found that preterm adolescents have higher resting BP, lower EDVi, elevated EF, and a blunted SV response to maximal exercise. A lower EDVi suggests diastolic dysfunction, and combined with an elevated EF at rest suggests a hyperdynamic heart. Taken together, our data suggest that there may be a cardiac function limitation in conjunction with cardiovascular autonomic dysfunction causing exercise intolerance in this young population. Our findings, together with blunted stroke volume reserve during exercise, resemble those seen in early stage heart failure with preserved EF, and suggest further study in this population.Support or Funding InformationNIH‐NHLBI R01–HL115061This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The timeline of blood pressure changes and hemodynamic responses during an experimental noise exposure

BackgroundNoise exposure increases blood pressure and peripheral vascular resistance in both genders in an experimental setting, as previously reported by the authors. ObjectivesThe aim of this re-analysis was to present the minute-by-minute timeline of blood pressure changes and hemodynamic events provoked by traffic noise in the young and healthy adults. MethodsThe experiment consisted of three 10-min phases: rest in quiet conditions before noise (Leq = 40 dBA), exposure to recorded road-traffic noise (Leq = 89 dBA), and rest in quiet conditions after noise (Leq = 40 dBA). Participants’ blood pressure, heart rate, and hemodynamic parameters (cardiac index and total peripheral resistance index) were concurrently measured with a thoracic bioimpedance device. The raw beat-to-beat data were collected from 112 participants, i.e., 82 women and 30 men, aged 19–32 years. The timeline of events was created by splitting each experimental phase into ten one-minute intervals (30 intervals in total). Four statistical models were fitted to answer the six study questions what is happening from one minute to another during the experiment. ResultsBlood pressure decreased during quiet phase before noise, increased in the first minute of noise exposure and then decreased gradually toward the end of noise exposure, and continued to decline to baseline values after noise exposure. The cardiac index showed a gradual decrease throughout the experiment, whereas total vascular resistance increased steadily during and after noise exposure. ConclusionsThe timeline of events in this 30-min experiment provides insight into the hemodynamic processes underlying the changes of blood pressure before, during and after noise exposure.