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![Pressure profiles of the central venous pressure Pcv\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$P_{\mathrm{cv}}$$\end{document} (simulation of two complete breathing cycles after starting the heart from rest is reported). Solid line refers to the simulation of normal breathing, while dashed line refers to the simulation of deep breathing](publication/327350017/figure/fig2/AS:960131944689664@1605924702948/Pressure-profiles-of-the-central-venous-pressure-Pcvdocumentclass12ptminimal.png)
Pressure profiles of the central venous pressure Pcv\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$P_{\mathrm{cv}}$$\end{document} (simulation of two complete breathing cycles after starting the heart from rest is reported). Solid line refers to the simulation of normal breathing, while dashed line refers to the simulation of deep breathing
Source publication
![Percent variation of Q vs. PaCO2\documentclass[12pt]{minimal}...](publication/327350017/figure/fig4/AS:960131948900352@1605924703268/Percent-variation-of-Q-vs-PaCO2documentclass12ptminimal-usepackageamsmath_Q320.jpg)
![Effect of PaCO2\documentclass[12pt]{minimal} \usepackage{amsmath}...](publication/327350017/figure/fig5/AS:960131948896257@1605924703408/Effect-of-PaCO2documentclass12ptminimal-usepackageamsmath-usepackagewasysym_Q320.jpg)
Purpose
Brain hemodynamics is fundamental for the functioning of the human being. Many biophysical factors affect brain circulation, so that a satisfactory understanding of its behavior is challenging. We developed a mathematical model to simulate cerebral and extracerebral flows and pressures in humans.
Methods
The model is composed of an anatomi...
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Background:
Within the field of plastic surgery, free tissue transfer is common practice for knee and lower leg defects. Usually, after such free flap reconstruction, patients undergo a dangling protocol in the postoperative phase. A dangling protocol is designed to gradually subject the free flap to increased venous pressure resulting from gravit...
Peripheral venous pressure (PVP) waveform analysis is a novel, minimally invasive method of measuring intravascular volume, especially during hemorrhage. We hypothesized that inhaled anesthetics directly affect PVP waveforms and are a potential confounding factor in the waveform analysis.
Citations
... Obviously, it is not possible to properly simulate this condition on Earth. Moreover, the model takes into account the breathing effect on the central venous pressure 40 . Breathing effect on the hydraulic properties of the IJV and VV leads to an increase in flow, even if the intracranial autoregulation mechanisms prevent alterations of cerebral perfusion due to breathing 33,41,42 . ...
Cardiovascular haemodynamics alters during posture changes and exposure to microgravity. Vascular auto-remodelling observed in subjects living in space environment causes them orthostatic intolerance when they return on Earth. In this study we modelled the human haemodynamics with focus on head and neck exposed to different hydrostatic pressures in supine, upright (head-up tilt), head-down tilt position, and microgravity environment by using a well-developed 1D-0D haemodynamic model. The model consists of two parts that simulates the arterial (1D) and brain-venous (0D) vascular tree. The cardiovascular system is built as a network of hydraulic resistances and capacitances to properly model physiological parameters like total peripheral resistance, and to calculate vascular pressure and the related flow rate at any branch of the tree. The model calculated 30.0 mmHg (30%), 7.1 mmHg (78%), 1.7 mmHg (38%) reduction in mean blood pressure, intracranial pressure and central venous pressure after posture change from supine to upright, respectively. The modelled brain drainage outflow percentage from internal jugular veins is 67% and 26% for supine and upright posture, while for head-down tilt and microgravity is 65% and 72%, respectively. The model confirmed the role of peripheral veins in regional blood redistribution during posture change from supine to upright and microgravity environment as hypothesized in literature. The model is able to reproduce the known haemodynamic effects of hydraulic pressure change and weightlessness. It also provides a virtual laboratory to examine the consequence of a wide range of orthostatic stresses on human haemodynamics.
... Most of the numerical studies were dedicated to computational fluid dynamics investigation in modeling the cardiovascular and pulmonary vessel diseases while less attention has been paid to the study of the neck and brain vascular diseases [6,10]. Models are regulated on the basis of physics and mechanics rules to understand the influences of the involved biological factors [11][12][13]. Moreover, pathological cases can be simulated starting from a model previously calibrated to mimic healthy subjects [14]. ...
... In this study, the mathematical model built by Gadda et al. [11,14,21] is modified to investigate more precisely the human brain drainage. The model considers the cardiovascular system as an electrical circuit where blood flow rate and pressure at the x anatomical level represent the electrical current and voltage, respectively. ...
... The model consists of a 0-D and 1-D algorithm [11]. In the 0-D algorithm, the intracranial autoregulation mechanisms and cerebral outflow were modeled according to the model by Ursino et al. [12,23]. ...
Background:
Congenital vascular disease is one of the leading causes of death in paediatric age. Despite the importance of paediatric haemodynamics, large investigations have been devoted to the evaluation of circulation in adults. The novelty of this study consists in the development of a well calibrated mathematical model of cardiovascular circulation in paediatric subjects. To reach the purpose, a model for adult circulation was modified and recalibrated with experimental data and literature from children to be able to calculate the flow rates and pressures in the brain and neck.
Methods:
The haemodynamic model simulates the 76 main arteries, together with the main veins in brain and neck. A proper magnetic resonance imaging (MRI) dataset of 29 volunteers aged 12 ± 5 years (mean ± standard deviation) was used to extract age-dependent physiological and clinical parameters such as heart rate, flow rate, vessel cross section area, and blood pressure. The computational model was calibrated using such experimental data. The paediatric and adult model results were compared.
Results:
Increase of the vessels stiffness due to aging contributes to a flow rate decrease while blood pressure increases. In accordance, our simulation results show about 16% decrease in mean pressure of internal jugular vein in paediatric rather than adult subjects. The model outcomes indicated about 88% correlation with MRI data.
Conclusions:
The mathematical model simulates the paediatric head and neck blood circulation. The model provides detailed information of human haemodynamics including arterial and venous network to study both paediatric and adult blood circulation.
... Balloon angioplasty causes significant reduction in pressure in the jugular vein and venous sinuses. [23][24][25] Lowering of this fundamental circulatory parameter facilitates glymphatic drainage. [26][27][28] This might explain the reduced accumulation of gadolinium-enhanced T1 lesions found in the present study, particularly evident immediately after the procedure in the subgroup with favorable venography. ...
Purpose
To evaluate if jugular vein flow restoration in various venographic defects indicative of chronic cerebrospinal venous insufficiency (CCSVI) in multiple sclerosis (MS) patients can have positive effects on cerebral lesions identified using magnetic resonance imaging (MRI).
Materials and Methods
The Brave Dreams trial ( ClinicalTrials.gov identifier NCT01371760) was a multicenter, randomized, parallel group, double-blind, sham-controlled trial to assess the efficacy of jugular venoplasty in MS patients with CCSVI. Between August 2012 and March 2016, 130 patients (mean age 39.9±10.6 years; 81 women) with relapsing/remitting (n=115) or secondary/progressive (n=15) MS were randomized 2:1 to venography plus angioplasty (n=86) or venography (sham; n=44). Patients and study personnel (except the interventionist) were masked to treatment assignment. MRI data acquired at 6 and 12 months after randomization were compared to the preoperative scan for new and/or >30% enlargement of T2 lesions plus new gadolinium enhancement of pre-existing lesions. The relative risks (RR) with 95% confidence interval (CI) were estimated and compared. In a secondary assessment, venograms of patients who underwent venous angioplasty were graded as “favorable” (n=38) or “unfavorable” (n=30) for dilation according to the Giaquinta grading system by 4 investigators blinded to outcomes. These subgroups were also compared.
Results
Of the 130 patients enrolled, 125 (96%) completed the 12-month MRI follow-up. Analysis showed that the likelihood of being free of new cerebral lesions at 1 year was significantly higher after venoplasty compared to the sham group (RR 1.42, 95% CI 1.00 to 2.01, p=0.032). Patients with favorable venograms had a significantly higher probability of being free of new cerebral lesions than patients with unfavorable venograms (RR 1.82, 95% CI 1.17 to 2.83, p=0.005) or patients in the sham arm (RR 1.66, 95% CI 1.16 to 2.37, p=0.005).
Conclusion
Expanded analysis of the Brave Dreams data that included secondary/progressive MS patients in addition to the relapsing/remitting patients analyzed previously showed that venoplasty decreases new cerebral lesions at 1 year. Secondary analysis confirmed the efficacy of the Giaquinta grading system in selecting patients appropriate for venoplasty who were more likely to be free from accumulation of new cerebral lesions at MRI.
... Proper pressure outputs from the arterial 1-D model are used as input to the 0-D models, together with the contribution to venous pressure due to breathing that simulates the drainage effect of the thoracic pump. The model is able to evaluate the effects of reduced/elevated carbon dioxide in the blood (hypo/hypercapnia) [8], and to compare adult and pediatric circulation through a straightforward calibration of the parameters. Proper MRI and ultrasound datasets were used to extract information about blood rheology (e.g., blood velocity and flow), and vessel status (hydraulic resistance and capacitance, inner pressure and cross section area). ...
Many biophysical factors affect human circulation, so that. [...]
... In silico experimentation with this model has specifically linked genes to phenotypes. In mammals, multiscale models are available for simulation of cerebral and extracerebral blood flows [91], the olfactory system [92], thrombogenesis [93] and skin [94]. Fully integrated cellular models that have mechanistic details about biochemical pathways have been used for predicting the onset of disease [95], risk prognosis [96], patient stratification [97], treatment responses and mechanism of drug action [98,99] and drug sensitivity [100]. ...
For decades, plant geneticists have attempted to link crop genes to phenotypes of interest. Advanced technologies in molecular biology, biochemistry and high-performance computing have provided unprecedented depth of knowledge about biological systems, and have accelerated molecular breeding and bioengineering of crop species. Single-omic level technologies that explore genomes, transcriptomes, proteomes and metabolomes have led to gene discovery and have revealed important signalling and regulatory mechanisms that influence crop response to the environment. Data from individual biological scales have been used in mathematical models to predict how crops will respond to untested environmental conditions. However, many of these models are empirical and lack predictive capability that can extrapolate beyond the conditions used to optimize the model. There is a need to move beyond modelling at single-scales to achieve integrative, multiscale modelling that takes full advantage of our understanding of molecular mechanisms and the wealth of genomewide data that has been generated over the last three decades. In this review, we survey the most recent literature exploring the collection and analysis of multi-omic data, and provide examples of attempts to integrate these data in various ways. It is apparent that integrative and multiscale modelling improve crop model prediction accuracy, and it is anticipated that the movement towards in silico crops will aid in the development of crop ideotypes that can thrive under challenging environmental conditions.
Intact, coordinated, and precisely regulated cerebrovascular responses are required for the maintenance of cerebral metabolic homeostasis, adequate perfusion, oxygen delivery, and acid‐base balance during deviations from homeostasis. Increases and decreases in the partial pressure of arterial carbon dioxide (PaCO2) lead to robust and rapid increases and decreases in cerebral blood flow (CBF). In awake and healthy humans, PaCO2 is the most potent regulator of CBF, and even small fluctuations can result in large changes in CBF. Alterations in the responsiveness of the cerebral vasculature can be detected with carefully controlled stimulus‐response paradigms and hold relevance for cerebrovascular risk in steno‐occlusive disease. As changes in PaCO2 do not typically occur in isolation, the integrative influence of physiological factors such as intracranial pressure, arterial oxygen content, cerebral perfusion pressure, and sympathetic nervous activity must be considered. Further, age and sex, as well as vascular pathologies are also important to consider. Following a brief summary of key historical events in the development of our understanding of cerebrovascular physiology and an overview of the measurement techniques to index CBF this review provides an in‐depth description of CBF regulation in response to alterations in PaCO2. Cerebrovascular reactivity and regional flow distribution are described, with further consideration of how differences in reactivity of parallel networks can lead to the “steal” phenomenon. Factors that influence cerebrovascular reactivity are discussed and the mechanisms and regulatory pathways mediating the exquisite sensitivity of the cerebral vasculature to changes in PaCO2 are outlined. Finally, topical avenues for future research are proposed. © 2019 American Physiological Society. Compr Physiol 9:1101‐1154, 2019.
A look at the history of science supports this statement. Harvey's discovery of the blood circulation, published in 1628, is undoubtedly among the most important events in the history of physiology. Although Harvey's concept of blood circulation was brilliant at that time, it was far away from a comprehensive insight into the circulatory system.
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