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Comparison of peripheral venous and central venous (CVP) waveforms, time-synced with EKG. CVP consists of three peaks (a,c,v) and two descents (x,y).
Source publication
The peripheral venous system serves as a volume reservoir due to its high compliance and can yield information on intravascular volume status. Peripheral venous waveforms can be captured by direct transduction through a peripheral catheter, non-invasive piezoelectric transduction, or gleaned from other waveforms such as the plethysmograph. Older an...
Contexts in source publication
Context 1
... CVP is one measure frequently used to estimate intravascular volume and guide fluid resuscitation in intensive care unit (ICU) settings. The CVP waveform consists of three peaks and two descents (Figure 1) related to different stages of the cardiac cycle. The various peaks and troughs of the CVP tracing represent forward and backward waves as blood flows through the heart. ...
Context 2
... waves are easily seen on a CVP tracing, but the backward compression waves are not prominent in the peripheral venous system. Thus, the peripheral venous waveform morphology differs from that of the central venous system (Figure 1). The differences in the peripheral venous waveform may be due to the direction of the waveform (forward vs. backward compression wave), dampening related to the presence of valves, increased compliance, and/or distance from the heart. ...
Similar publications
Pulse pressure variation (PPV) is a dynamic cardiac preload variable used to predict fluid responsiveness. PPV can be measured non-invasively using innovative finger-cuff systems allowing for continuous arterial pressure waveform recording, e.g., the Nexfin system [BMEYE B.V., Amsterdam, The Netherlands; now Clearsight (Edwards Lifesciences, Irvine...
Citations
... , which depends on the regularity of s . However, for the PVP signal we focus on, it is commonly found that unlike the CVP or arterial blood pressure waveforms, PVP waveforms oscillate with a more dampened sinusoidal pattern [4], which might come from the presence of valves, increased compliance, and/or distance from the heart [24]. As a result, its oscillatory pattern is smooth without spiky behavior. ...
Develop a signal quality index (SQI) for the widely available peripheral venous pressure waveform (PVP). We focus on the quality of the cardiac component in PVP. We model PVP by the adaptive non-harmonic model. When the cardiac component in PVP is stronger, the PVP is defined to have a higher quality. This signal quality is quantified by applying the synchrosqueezing transform to decompose the cardiac component out of PVP, and the SQI is defined as a value between 0 and 1. A database collected during the lower body negative pressure experiment is utilized to validate the developed SQI. All signals are labeled into categories of low and high qualities by experts. A support vector machine (SVM) learning model is trained for practical purpose. The developed signal quality index coincide with human experts’ labels with the area under the curve 0.95. In a leave-one-subject-out cross validation (LOSOCV), the SQI achieves accuracy 0.89 and F1 0.88, which is consistently higher than other commonly used signal qualities, including entropy, power and mean venous pressure. The trained SVM model trained with SQI, entropy, power and mean venous pressure could achieve an accuracy 0.92 and F1 0.91 under LOSOCV. An exterior validation of SQI achieves accuracy 0.87 and F1 0.92; an exterior validation of the SVM model achieves accuracy 0.95 and F1 0.96. The developed SQI has a convincing potential to help identify high quality PVP segments for further hemodynamic study. This is the first work aiming to quantify the signal quality of the widely applied PVP waveform.
... Alternatively, a ROI could be placed at the superior sagittal sinus. A damped and complex waveform could potentially impair the phase sorting [44]. However, this has not been evaluated systematically yet. ...
Purpose
Brain perfusion imaging is of enormous importance for various neurological diseases. Fast gradient-echo sequences offering flow-related enhancement (FREE) could present a basis to generate perfusion-weighted maps. In this study, we obtained perfusion-weighted maps without contrast media by a previously described postprocessing algorithm from the field of functional lung MRI. At first, the perfusion signal was analyzed in fast low-angle shot (FLASH) and balanced steady-state free precession (bSSFP) sequences. Secondly, perfusion maps were compared to pseudo-continuous arterial spin labeling (pCASL) MRI in a healthy cohort. Thirdly, the feasibility of the new technique was demonstrated in a small selected group of patients with metastases and acute stroke.
Methods
One participant was examined with bSSFP and FLASH sequences at 1.5T and 3T, different flip angles and slice thicknesses. Twenty-five volunteers had bSSFP imaging and pCASL MRI. Three patients with cerebral metastases and one with acute ischemic stroke had bSSFP imaging and were compared to T1 post-contrast images and CT perfusion. Frequency analyses, SNR and perfusion contrast were compared at different flip angles and slice thicknesses. Regional correlations and Sorensen-Dice overlap were calculated in the healthy cohort. Dice overlap of the pathologies in the patient cohort were calculated.
Results
The bSSFP sequence presented detectable perfusion signal within brain vessel and parenchyma together with superior SNR compared to FLASH. Perfusion contrast and its corticomedullary differentiation increased with flip angle. Mean regional correlation was 0.36 and highly significant between FREE maps and pCASL and grey and white matter Dice match were 72% and 60% in the healthy cohort. Pathologies presented good overlap between FREE perfusion-weighted and T1 post-contrast images.
Conclusion
The feasibility of FREE brain perfusion imaging has been shown in a healthy cohort and selected patient cases with brain metastases and acute stroke. The study demonstrates a new approach for non-contrast brain perfusion imaging.
In recent years, several works have addressed the problem of modeling blood flow phenomena in veins, as a response to increasing interest in modeling pathological conditions occurring in the venous network and their connection with the rest of the circulatory system. In this context, one-dimensional models have proven to be extremely efficient in delivering predictions in agreement with in-vivo observations. Pursuing the increase of anatomical accuracy and its connection to physiological principles in haemodynamics simulations, the main aim of this work is to describe a novel closed-loop Anatomically-Detailed Arterial-Venous Network (ADAVN) model. An extremely refined description of the arterial network consisting of 2,185 arterial vessels is coupled to a novel venous network featuring high level of anatomical detail in cerebral and coronary vascular territories. The entire venous network comprises 189 venous vessels, 79 of which drain the brain and 14 are coronary veins. Fundamental physiological mechanisms accounting for the interaction of brain blood flow with the cerebro-spinal fluid and of the coronary circulation with the cardiac mechanics are considered. Several issues related to the coupling of arterial and venous vessels at the microcirculation level are discussed in detail. Numerical simulations are compared to patient records published in the literature to show the descriptive capabilities of the model. Furthermore, a local sensitivity analysis is performed, evidencing the high impact of the venous circulation on main cardiovascular variables.
The main purpose of cardiopulmonary bypass is to fulfil the functions of the heart or of both the heart and lungs, whose functions have been stopped in parallel with the application requirement and to keep patients alive until the heart and lungs function at full capacity again. While extracorporeal circulation takes over heart and/or lung functions with full or partial circulatory and respiratory supports, the physiopathology of cardiopulmonary bypass requires very sensitive monitoring due to the biomechanical and biocompatible properties of extracorporeal circulation devices, the contact of blood with non-physiological surfaces, and highly complex, dynamic and variable extracorporeal circulation processes. In these critical processes, monitoring the vital functions of patients and applying the necessary interventions to all problems should be managed by a multidisciplinary team, including cardiac surgeon, cardiovascular anesthesiologist and perfusionist. The main purpose of monitoring vital functions is to observe with full accuracy that end-organ perfusion and oxygenation are fully achieved. First, circulatory, respiratory and coagulation monitoring should be provided to maintain extracorporeal circulation; second, vital functions of other organs such as kidney, brain and metabolism should be monitored. Monitoring during extracorporeal circulation must be a multi-level, multi-variate and very dynamic process. By adding new parameters, continuous monitoring of several invasive or non-invasive parameters can be relatively practical for the entire team.
PurposePeripheral venous pressure (PVP) waveform analysis is a novel, minimally invasive, and inexpensive method of measuring intravascular volume changes. A porcine cohort was studied to determine how venous and arterial pressure waveforms change due to inhaled and infused anesthetics and acute hemorrhage.Methods
Venous and arterial pressure waveforms were continuously collected, while each pig was under general anesthesia, by inserting Millar catheters into a neighboring peripheral artery and vein. The anesthetic was varied from inhaled to infused, then the pig underwent a controlled hemorrhage. Pearson correlation coefficients between the power of the venous and arterial pressure waveforms at each pig’s heart rate frequency were calculated for each variation in the anesthetic, as well as before and after hemorrhage. An analysis of variance (ANOVA) test was computed to determine the significance in changes of the venous pressure waveform means caused by each variation.ResultsThe Pearson correlation coefficients between venous and arterial waveforms decreased as anesthetic dosage increased. In an opposing fashion, the correlation coefficients increased as hemorrhage occurred.Conclusion
Anesthetics and hemorrhage alter venous pressure waveforms in distinctly different ways, making it critical for researchers and clinicians to consider these confounding variables when utilizing pressure waveforms. Further work needs to be done to determine how best to integrate PVP waveforms into clinical decision-making.
Teaching traditionally asserts that the arterial pressure pulse is dampened across the capillary bed to the extent that pulsatility is non-existent in the venous circulation of the lower limbs. Herein, we present evidence of transmission of arterial pulsations across the capillary network into perforator veins in the lower limbs of healthy, heat-stressed humans. Perforator veins are connections from the superficial veins that drain into the deep veins. When assessed using ultrasound at rest, they infrequently demonstrate flow and a pulsatile flow waveform is not described. We investigated perforator vein pulsatility in ten young, healthy volunteers who underwent passive heating by +2 ºC deep body temperature via a hot-water-perfused suit, and five who also underwent active heating by +2 ºC via low-intensity cycling while wearing the hot-water-perfused suit. At +0.5 ºC increments in temperature, blood velocity in an ankle perforator vein was measured using duplex ultrasound. In all perforators with heating, sustained flow was demonstrated, with a pulsatile waveform that was synchronous with the cardiac cycle. The maximum velocity was 29 ± 14 cm/s with passive heating and approximately half with active heating (P=0.04). The small veins of the skin at the ankle also demonstrated increased perfusion with pulsatility, seen with low-velocity microvascular imaging technology. We consider explanations for this pulsatility and conclude that it is propagated from the arterial inflow through the skin microcirculation as a result of increased dilatation and flow volume, and that this a normal response to increased skin blood flow.
Background:
Heart failure is the leading cause of hospitalization in the elderly and readmission is common. Clinical indicators of congestion may not precede acute congestion with enough time to prevent hospital admission for heart failure. Thus, there is a large and unmet need for accurate non-invasive assessment of congestion. Non-Invasive Venous waveform Analysis in heart failure (NIVAHF) is a novel, non-invasive technology that monitors intravascular volume status and hemodynamic congestion. The objective of this study was to determine the correlation of NIVAHF with pulmonary capillary wedge pressure (PCWP) and the ability of NIVAHF to predict 30-day admission after right heart catheterization (RHC).
Methods:
The prototype NIVAHF device was compared to PCWP in 106 subjects undergoing RHC. The NIVAHF algorithm was developed and trained to estimate PCWP. NIVA Scores and central hemodynamic parameters [(PCWP, pulmonary artery diastolic pressure (PAD), and cardiac output (CO)] were evaluated in 84 patients undergoing outpatient RHC. Receiver Operating Characteristic (ROC) curves were used to determine whether a NIVA Score predicted 30-day hospital admission.
Results:
The NIVA Score demonstrated a positive correlation with PCWP (r=0.92, n=106, p<0.0001). NIVA Score at time of hospital discharge predicted 30-day admission with an AUC of 0.84, a NIVA Score >18 predicted admission with a sensitivity of 91% and specificity of 56%. Residual analysis suggested that no single patient demographic confounded the predictive accuracy of the NIVA Score.
Conclusions:
NIVAHF is a non-invasive monitoring technology that is designed to provide an estimate of PCWP. A NIVA Score >18 indicated increased risk for 30-day hospital admission. This non-invasive measurement has potential for guiding decongestive therapy and prevention of hospital admission in heart failure patients.
