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In this paper, we propose the use of black box models for the system identification of the cardiopulmonary baroreflex control of arterial resistance and of ventricular contractility and of arterial baroreflex control of heart rate (HR) from invasive, continuous measurements of arterial blood pressure (ABP) and central venous pressure (CVP), and non invasive, continuous recordings of ECG and respiration...
This paper presents the analysis of the autonomic nervous system (ANS) control and cardiac baroreflex sensitivity in patients undergoing general anesthesia for major surgery, with the goal of evaluating the effects of anesthesia bolus induction with propofol on autonomic control of heart rate (HR) and arterial blood pressure (ABP). The increase in baroreflex gain in the LF band observed through two...
In this paper Heart Rate Variability (HRV) and Blood Pressure Variability (BPV) were analyzed before the onset of cardiac arrhythmia in order to derive markers for short-term forecasting. The (a) coherence between systolic blood pressure (SBP) and cardiac oscillations in low-frequency (LF) and high-frequency (HF) band; (b) fluctuations of phase; (c) HRV and BPV as a LF power and HF power in frequency...
Periodic breathing patterns known as Central Sleep Apnea (CSA) are often observed in congestive heart failure. This phenomenon is associated with increased risk of sudden cardiac death, but the mechanism for that outcome has not been exposed. Endocardial electrograms were recorded during spontaneous episodes of CSR and PB in patients in conscious and unconscious states. Analysis exposed a regular...
Some diseases, such as hypertension, require a close control of the patient's blood pressure. This is even more critical when that patient is going through — or has just underwent — a surgical procedure In such situations, reducing blood pressure to normal levels is of paramount importance. Usually, this demanding and time consuming monitoring is done manually by clinical personnel and are subject...
The arterial baroreflex stabilizes arterial pressure by modulating the mechanical properties of cardiovascular system. We previously demonstrated that the baroreflex impairment makes the circulatory system extremely sensitive to volume overload and predisposes to pulmonary edema irrespective of left ventricular systolic function. To overcome the volume intolerance, we developed an artificial baroreflex...
This paper presents a novel systematic approach to the stability analysis of the cardiovascular (CV) baroreflex. The proposed approach determines the equilibrium state and the system stability in its neighbourhood with computational efficiency, once the parameters of the CV baroreflex model are specified for an individual. We first propose a linearization-based analytical method for determining the...
Regular aerobic exercise is a recommended treatment for elevated blood pressure (BP). However, making permanent lifestyle changes is not easy. Having personally relevant information about the treatment, about its effects and importance, is a precondition for motivation. Thus, the first step towards a successful lifestyle change is appropriate education. This paper describes a Sugeno-type Fuzzy Inference...
With increasing interest in the effect of postural changes on arterial blood pressure and vascular properties, it is important to understand effects of pressure-dependent arterial compliance. This study investigates effects of pressure-dependent compliance on pulse wave velocity (PWVar), pressure wave shape, and transmission characteristics in an arterial model of the human arm from heart to radial...
We compared pulse arrival time (PAT) and pulse transit time (PTT) in terms of their ability to track diastolic pressure (DP). We performed the comparison using high fidelity, invasive arterial waveforms recorded from six dogs during multiple interventions. On average, DP ranged from 40 to 106 mmHg and therefore varied widely. PAT and PTT were able to predict DP with average root-mean-squared-errors...
Sympathetic nerve activity is an important regulator of blood pressure and blood flow in humans. Our understanding about how sympathetic neurons are recruited during baroreflex stress is limited. This paper investigates the sympathetic neural recruitment patterns during the Valsalva maneuver. Using microneurography, muscle sympathetic nerve activity was recorded in seven healthy subjects during baseline...
In this paper cross time-frequency (TF) analysis is used to estimate the phase differences and the phase locking between cardiovascular signals. Phase differences give a measure of the changes in the synchronization between two oscillations, while phase locking measures the degree of similarity of these changes across subjects. The methodology is based on the smoothed pseudo Wigner-Ville distribution...
We present a comprehensive probabilistic point process framework to estimate and monitor the instantaneous heartbeat dynamics as related to specific cardiovascular control mechanisms and hemodynamics. Assessment of the model's statistics is established through the Wiener-Volterra theory and a multivariate autoregressive (AR) structure. A variety of instantaneous cardiovascular metrics, such as heart...
Predicting major adverse events following surgery remains a significant problem. Currently, the perioperative period is too often considered a black box, with risk assessment and prediction largely based on static pre-surgical parameters. Here, we review the problem of intraoperative hypotension and outline some of the opportunities for improved monitoring during surgery
Up to now, we have successfully carried out the non-invasive beat-by-beat measurement of blood pressure (BP) in the root of finger, superficial temporal and radial artery based on the volume-compensation technique with reasonable accuracy. The present study concerns with improvement of control method for this beat-by-beat BP measurement. The measurement system mainly consists of a partial pressurization...
The concept of tailored bioinstrumentation using rapid prototyping and three-dimensional CAD (3D-CAD) was proposed. This concept is to make individually designed and fabricated sensor unit to attach human body. Within the proposed concept, cuff-units for continuous blood pressure measurement were individually designed using 3D-CAD and fabricated automatically. As the result, blood pressure wave forms...
Congestive heart failure (CHF) is a leading cause of death in the United States. WANDA is a wireless health project that leverages sensor technology and wireless communication to monitor the health status of patients with CHF. The first pilot study of WANDA showed the system's effectiveness for patients with CHF. However, WANDA experienced a considerable amount of missing data due to system misuse,...
The study aimed to investigate baroreceptor reflex sensitivity in a patient with head injury for whom plateau waves of intracranial pressure (ICP) were recorded. Baroreflex sensitivity index was separately estimated on top of plateau waves and during intermediate intervals between two consecutive waves. The EuroBaVar data set was utilized to verify and validate the results. A very high baroreflex...
Carotid-femoral pulse wave velocity (PWV) has emerged as the gold standard for non-invasive evaluation of aortic stiffness. However, the absence of standardized methodologies of study and lack of normal and references values have limited wider implementation of PWV in clinical practice. In this work normal PWV levels were determined in a Uruguayan population and the obtained values were analyzed taking...
A model-based approach that integrates known portion of the cardiovascular system and unknown portion through a parameter estimation to predict evolution of the mean arterial pressure is considered. The unknown portion corresponds to the neural portion that acts like a controller that takes corrective actions to regulate the arterial blood pressure at a constant level. The input to the neural part...
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