hydrostatic pressure in blood vessels

Several methods have been developed for generating 3D, in vitro , organ-on-chip models of human vasculature to study vascular function, transport, and tissue engineering. However, many of these existing models lack the hierarchical nature of the arterial-to-capillary-to-venous architecture that is key to capturing a more comprehensive view of the human microvasculature. Here, we present a perfusable, multi-compartmental model that recapitulates the three microvascular compartments to assess various physiological properties such as vessel permeability, vasoconstriction dynamics, and circulating cell arrest and extravasation...

Central serous chorioretinopathy (CSCR) is a relatively common retinal disease involving the localized serous detachment of the neurosensory retina from the retinal pigment epithelium (RPE). Research suggests that individuals with a Type A personality, exhibiting traits such as competitiveness, urgency, aggression, and hostility, are significantly more prone to developing CSCR. Several studies have confirmed that a propensity to stress as well as different stressful events may predispose subjects to the development and recurrence of CSCR...

The Starling principle is a model that explains the transvascular distribution of fluids essentially governed by hydrostatic and oncotic forces, which dynamically allow vascular refilling according to the characteristics of the blood vessel. However, careful analysis of fluid physiology has shown that the principle, while correct, is not complete. The revised Starling principle (Michel-Weinbaum model) provides relevant information on fluid kinetics. Special emphasis has been placed on the endothelial glycocalyx, whose subendothelial area allows a restricted oncotic pressure that limits the reabsorption of fluid from the interstitial space, so that transvascular refilling occurs mainly from the lymphatic vessels...

OBJECTIVE: To figure out the timing of zeroing and the location of the zero line in the central venous pressure (CVP) monitoring and invasive arterial blood pressure (IBP) monitoring, and to provide scientific and accurate data for patients management. METHODS: The liquid vessel models were used to simulate the pressure measurement process of the continuous pressure monitoring system. Based on the theory of fluid mechanics and the knowledge of blood pressure physiology and cardiovascular anatomy, the composition and influencing factors of the pressure in the fluid-filled catheter system during the zeroing and placing the transducer in the zero line of CVP and IBP, were analyzed...

Solid tumors contain hypoxic regions that contribute to anticancer therapy resistance. Thus, mitigating tumor hypoxia may enhance the efficacy of radiation therapy which is commonly utilized for patients with prostate cancer. Increasing perfusion pressure in the prostate with head-up tilt (HUT) may augment prostate tumor perfusion and decrease hypoxia. The purpose of this study was to determine if an increase in the vascular hydrostatic gradient via 70° HUT increases tumor perfusion and decreases tumor hypoxia in a preclinical orthotopic model of prostate cancer...

In this article, the CHIVA and ASVAL methods are assessed from the hemodynamic point of view. The CHIVA method comprises complicated, unusual terminology and new perceptions, such as closed and open shunts, fractionation of the hydrostatic pressure, subdivision of the venous network. The principal part of the CHIVA theory is the drainage of venous blood from the thigh saphenous system into the deep lower leg veins through the preserved saphenous trunk after high ligation at the saphenofemoral junction, which is considered as a beneficial, physiological phenomenon...

Background: Performance and durability of arterio-venous grafts depend on their ability to mimic the mechanical behavior of the anastomized blood vessels. To select the most suitable synthetic graft, in vivo evaluation of the radial deformability of peripheral arteries and veins could be crucial; however, a standardized non-invasive strategy is still missing. Herein, we sought to define a novel and user-friendly clinical protocol for in vivo assessment of the arm vessel deformability...

Intracranial blood pressure can directly reflect the status of blood vessels in real time. However, it can only be estimated invasively using a microcatheter during craniotomy. Subharmonic-aided pressure estimation (SHAPE) is a promising technique for estimating cardiac pressures but mainly uses Sonazoid, whereas SHAPE using SonoVue is still in the early stages of development. The aim of this study was to optimize transcranial SHAPE using SonoVue by investigating the relationship between subharmonic signals and middle cerebral artery pressure (MCAP) (20-160 mmHg) in vitro...

The neurovascular unit (NVU) consists of cells intrinsic to the vessel wall, the endothelial cells and pericytes, and astrocyte endfeet that surround the vessel but are separated from it by basement membrane. Endothelial cells are primarily responsible for creating and maintaining blood-brain-barrier (BBB) tightness, but astrocytes contribute to the barrier through paracrine signaling to the endothelial cells and by forming the glia limitans. Gap junctions (GJs) between astrocyte endfeet are composed of connexin 43 (Cx43) and Cx30, which form plaques between cells...

We use a three-dimensional (3D) microvascular platform to measure the elasticity and membrane permeability of the endothelial cell layer. The microfluidic platform is connected with a pneumatic pressure controller to apply hydrostatic pressure. The deformation is measured by tracking the mean vessel diameter under varying pressures up to 300 Pa. We obtain a value for the Young's modulus of the cell layer in low strain where a linear elastic response is observed and use a hyperelastic model that describes the strain hardening observed at larger strains (pressure)...

Cells are constantly exposed to various mechanical forces, including hydrostatic pressure, cyclic stretch, fluid shear stress, and extracellular matrix stiffness. Mechanical cues can be translated into the cell-specific transcriptional process by a cellular mechanic-transducer. Evidence suggests that mechanical signals assist activated intracellular signal transduction pathways and the relative phenotypic adaptation to coordinate cell behavior and disease appropriately. The Hippo/yes-associated protein (YAP) signaling pathway is regulated in response to numerous mechanical stimuli...

KEY POINTS: Microvascular network architecture defines coupling of fluid and protein exchange. Network arrangements markedly reduce capillary hydrostatic pressures and resting fluid movement while increasing the capacity for change The presence of vascular remodelling or angiogenesis puts constraints of network behaviour The sites of fluid and protein exchange can be segregated to different portions of the network Although there is a net filtration of fluid from a network of exchange vessels, there are specific areas where fluid moves into the circulation (reabsorption) and while protein is moving into tissue the amount is insufficient under basal conditions to result in changes in oncotic pressure...

In reptiles, exposure to hypoxia during embryonic development affects several cardiovascular parameters. These modifications may impose different mechanical stress to the arterial system, and we speculated that the arterial wall of major outflow vessels would be modified accordingly. Since non-crocodilian reptiles possess a partially divided ventricle, ensuing similar systemic and pulmonary systolic pressures, we investigated how morphological and mechanical properties of segments from the left aortic arch (LAo) and the proximal and distal segments of the left pulmonary artery (LPAp and LPAd, respectively) change as body mass (Mb ) increases...

Hydrostatic pulmonary edema is a well-known complication of veinoarterial extracorporeal membrane oxygenation (VA-ECMO) caused by increased left ventricle afterload due to reverse blood flow in the aorta. Several techniques are commonly used for left ventricle venting such as intra-aortic balloon pump, Impella® (Abiomed, Danvers, MA), central surgical cannulation or Rahskind atrial septostomy. We reported two cases of hydrostatic pulmonary edema in patients under VA-ECMO for whom it was decided to perform Rashkind technique...

Given the increased recognition of the importance of physiologically relevant microenvironments when designing in vitro assays, microphysiological systems (MPS) that mimic the critical function and structure of tissues and organs have gained considerable attention as alternatives to traditional experimental models. Accordingly, the field is growing rapidly, and some promising MPS are being tested for use in pharmaceutical development and toxicological testing. However, most MPS are complex and require additional infrastructure, which limits their successful translation...

Microvascular fluid exchange is primarily dependent on Starling forces and both the active and passive myogenic response of arterioles and post-capillary venules. Arterioles are classically considered resistance vessels, while venules are considered capacitance vessels with high distensibility and low tonic sympathetic stimulation at rest. However, few studies have investigated the effects of modulating interstitial hydrostatic pressure, particularly in the context of hemorrhagic shock. The objective of this study was to investigate the mechanics of arterioles and functional capillary density (FCD) during application of negative tissue interstitial pressure after 40% total blood volume hemorrhagic shock...

The endothelium responds to numerous chemical and mechanical factors in regulating vascular tone, blood pressure, and blood flow. The endothelial volume-regulated anion channel (VRAC) has been proposed to be mechanosensitive and thereby sense fluid flow and hydrostatic pressure to regulate vascular function. Here, we show that the leucine-rich repeat-containing protein 8a, LRRC8A (SWELL1), is required for VRAC in human umbilical vein endothelial cells (HUVECs). Endothelial LRRC8A regulates AKT-endothelial nitric oxide synthase (eNOS) signaling under basal, stretch, and shear-flow stimulation, forms a GRB2-Cav1-eNOS signaling complex, and is required for endothelial cell alignment to laminar shear flow...

The high incidence of vascular ulcers and the difficulties encountered in their healing process require the understanding of their multiple etiologies to develop effective strategies focused on providing different treatment options. This work provides a description of the principles of the physics of fluid dynamics related to vascular ulcers. The morphological characteristics of the cardiovascular system promote blood flow. The contraction force of the left ventricle is enhanced by its ability to reduce its radius of curvature and by increasing the thickness of the ventricular wall (Laplace's Law)...

Purpose: Two diabetic case reports of serous retinal detachment (SRD) accompanied by pachychoroid in hypotony maculopathy after trabeculectomy for neovascular glaucoma (NVG). Observations: Case 1: A 66-year-old female with stage 3 NVG and decreased vision acuity in the left eye. After trabeculectomy, postoperative laser suture lysis (LSL) resulted in development of hypotony maculopathy, followed by pachychoroid and SRD. Injection of C3F8 gas in the anterior chamber was unsuccessful and transconjunctival scleral re-suturing was performed...

Lymph nodes (LN) are crucial for immune function, and comprise an important interface between the blood and lymphatic systems. Blood vessels (BV) in LN are highly specialized, featuring high endothelial venules across which most of the resident lymphocytes crossed. Previous measurements of overall lymph and BV flow rates demonstrated that fluid also crosses BV walls, and that this is important for immune function. However, the spatial distribution of the BV in LN has not been quantified to the degree necessary to analyse the distribution of transmural fluid movement...