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The Valsalva maneuver (VM) provokes strong changes in the cardiovascular system and is therefore well suited to study the cardiac-coronary interaction in humans. In 12 patients undergoing catheterization we simultaneously recorded aortic pressure, left ventricular pressure, and intracoronary pressure (Pd) and flow velocity (U) while the patients were performing a VM. Coronary wave intensity was calculated...
Intradyalitic exercise programas are important to improve patient's hemodynamic stability. Blood pressure and metabolic changes are correlated when heat accumulation is due to increment of the body core temperature (+1.0°C). However, increase in temperature could be controlled by lowering dialysate's temperature using two main modalities techniques (isothermic and thermoneural) with different patient's...
Hemodynamic monitoring provides vital information for diagnosing and treating patients in acute clinical settings. A method is investigated to non-invasively monitor changes in the hemodynamic state. The approach utilizes short-axis ultrasound color flow imaging and processing methods to produce simultaneous waveforms for the arterial area and flow. Beat-to-beat measurements of the mean area, peak...
A low cost multimodal monitoring and signal processing platform is presented. A modular and flexible system was developed, aimed to continuous acquisition of several biological variables at patient bed-head and further processing with application specific algorithms. System hardware is made of a six-channel isolation and signal conditioning front-end along with a high resolution analog-to-digital...
The study presents a method for quantification of the respiratory effect on the thoracic impedance signal. We used measurements with 18 simultaneously scanning impedance signal locations. Elimination of breathing is based on the assumption that the neck and limb impedance signal measures only the variability in systemic blood pressure and is not affected by respiration. The results show approximately...
Accurate measurement of blood pressure (BP) is important for diagnosis and treatment of hypertension. Noninvasive BP measurements performed manually or automatically are subject to errors. We developed an experimental system that uses two cuffs in order to improve accuracy of noninvasive BP measurement. The system consists of a compact module with pneumatic and electronic circuits, two detachable...
To explore the grey relation between hemodynamic parameters and the diversity of non-invasive systolic blood pressure (NISBP) and invasive systolic blood pressure (INSBP), NISBP-INSBP diversity and hemodynamic parameters were measured in 16 female hypertensive patients. Grey analysis was performed to explore their relations. The diversity of NISBP and INSBP was -29.94??20.815 mmHg. The radial perk...
A proven implantable device is now available for long-term ambulatory monitoring of the right ventricular pressure (RVP) waveform of congestive heart failure patients. However, cardiac output (CO) and left atrial pressure (LAP) are far more useful for assessing cardiac function and managing volume status. We developed a new technique to monitor both CO and LAP by analysis of the RVP waveform based...
The ultimate hemodynamic sensor for an implantable device would provide information about cardiovascular performance including systolic function, diastolic function, preload, and afterload. We examined the potential clinical utility of simultaneous measurement of left ventricular pressure and continuous intrathoracic impedance in a group of 20 patients undergoing acute intravenous ablation for atrial...
Quantitative flow measurements with volumetric coverage and three directional flow encoding are technically feasible with magnetic resonance imaging yet prohibitively long in clinical settings. Data reconstruction from three dimensional angular undersampled MR acquisitions allows for dramatic reductions in scan time with tolerable imaging artifacts in many clinical applications. This approach provides...
The esophageal Doppler monitor (EDM) is a minimally-invasive device to measure aortic blood flow and quantify hemodynamics in patients. A modified dual-Doppler EDM, combined with pressure measurements, allows for measurement of aortic volume via the Bramwell-Hill equation. An in-vitro flow system was developed to model the cardioaortic circulation. This system consists of a pump to expel a viscous...
The aim of this study was to evaluate and compare changes of arterial blood pressure, heart rate and thoracic impedance cardiography parameters during head-up tilt table test and to discuss possible negative-positive influence to diagnostic contribution. Results demonstrate that blood pressure parameters do not drop dramatically while tilting within healthy subjects. On the contrary, thoracic impedance...
The compliance and stiffness of artery are closely related to the disease of arteries. Pulse wave velocity (PWV) in the blood vessel is a basic and common parameter in the hemodynamic. Blood pressure (BP) and blood flow wave traveling in arteries are important because the PWV is affected directly by the condition of blood vessels. However, there is no standardized method to measure the PWV and it...
One of the chief factors, incriminated for the formation of intimal hyperplasia at the venous side of an arteriovenous shunt (AVS), is the disturbed hemodynamic condition in that region. Owing to the difficulty of properly measuring the local flow field in AVS, numerical computation has been extensively used for its assessment. The purpose of this study was to examine the flow field in AVS with computational...
The aim of this study was to assess the cardiopulmonary baroreflex contribution to the maintenance of arterial pressure stability. Twelve young healthy subjects were examined (mean age -25.7 plusmn 4.9 years). Cardiac rhythm and arterial pressure were continuously recorded with the use of finapress technique at rest and in the course of low pressure area receptors deactivation due to lower body negative...
To examine the effects of heart failure on beat-to beat arterial blood pressure (ABP) variability, four adult mongrel dogs (20-25 kg) were chronically instrumented for ventricular pacing and continuous measurements of central ABP and cardiac output (CO). Five minutes recordings with the dogs conscious and at rest took place after recovery from surgery (control) and after a 30 days long period of pacing...
In this communication, we estimated the Lempel-Ziv complexity (LZC) on over 40 h of arterial blood pressure (ABP) recordings corresponding to 18 mechanically ventilated animal subjects. In this study, all subjects underwent a period of abrupt hemodynamic changes after an induced injury involving severe blood loss leading to hemorrhagic shock, followed by fluid resuscitation using either lactated ringers...
Wave intensity (WI) is a hemodynamics index, which is the product of changes in pressure and velocity across the wave-front. Wave Intensity Analysis, which is a time domain technique allows for the separation of running waves into their forward and backward directions and traditionally uses the measured pressure and velocity waveforms. However, due to the possible difficulty in obtaining reliable...
We describe a novel algorithm to estimate the pulse pressure variation index (PPV) from arterial blood pressure signals (ABP). PPV has been shown to be one of the best predictors of fluid responsiveness in mechanically ventilated subjects. Our PPV algorithm uses a non-linear technique for envelope estimation, eliminating the need for automatic beat detection. Additionally, the algorithm makes use...
We describe a novel algorithm to estimate the pulse pressure variation index (PPV) from arterial blood pressure signals (ABP). PPV has been shown to be one of the best predictors of fluid responsiveness in mechanically ventilated subjects. Our PPV algorithm uses a non-linear technique for envelope estimation, eliminating the need for automatic beat detection. Additionally, the algorithm makes use...
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