Search results for "Dynamics"
showing 10 items of 9782 documents
Computational fluid dynamics simulation to evaluate aortic coarctation gradient with contrast-enhanced CT
2014
Coarctation of aorta (CoA) is a narrowing of the aorta leading to a pressure gradient (Delta P) across the coarctation, increased afterload and reduced peripheral perfusion pressures. Indication to invasive treatment is based on values of maximal (systolic) trans-coarctation Delta P. A computational fluid dynamic (CFD) approach is herein presented for the non-invasive haemodynamic assessment of Delta P across CoA. Patient-specific CFD simulations were created from contrast-enhanced computed tomography (CT) and appropriate flow boundary conditions. Computed Delta P was validated with invasive intravascular trans-CoA pressure measurements. Haemodynamic indices, including pressure loss coeffic…
Epidemiología de la transfusión sanguínea en los Servicios de Medicina Intensiva en España: «Transfusion Day»
2022
Objective To describe the transfusion practice in the ICUs in Spain, according to national and international recommendations (guidelines).DesignProspective, cross-sectional, multi-centre study.ScopeData collection was carried out by means of a questionnaire sent electronically to the Heads of Service of 111 ICUs in Spain.Participants1,448 patients were included, aged 61.8 (SD 15.7) years, 66.2% male, with an SOFA of 4.7 ± 3.8 and average stay of 10.62 ± 17.49 days.VariablesDemographic and clinical variables of the patients were collected, as well as variables related to the transfusion act.ResultsOf the 1,448 patients, 9.9% received al least one transfusion of any blood product, 3.7% fresh …
Simulation of left ventricular outflow tract (LVOT) obstruction in transcatheter mitral valve-in-ring replacement.
2020
Left ventricular outflow tract (LVOT) obstruction is a feared complication of transcatheter mitral valve replacement (TMVR). This procedure leads to an elongation of LVOT in the left ventricle (namely, the neoLVOT), ultimately portending hemodynamic impairment and death. This study sought to understand the biomechanical implications of LVOT obstruction in two patients who underwent TMVR as an "off-label" application of the Edwards SAPIEN 3 (S3) Ultra transcatheter heart valve (THV). A computational framework of TMVR was developed to assess the neoLVOT area and quantify the sub-aortic flow structure. We observed that the annuloplasty ring serves as the key anchor zone of S3 Ultra THV. A good…
A Nonlinear Circulatory Model for Artificial Heart Studies
1983
Animals with total artificial heart replacement (TAH) have survived for up to 9 months with manually controlled driving systems. A certain physiological control is provided by the animals intact peripheral regulation resulting in pathological venous hemodynamics, expressing the needs for a technical automatic control system, replacing the natural sympathetic stimulation and Starlings Law of the heart. A nonlinear dynamic mathematical model of the human cardiovascular system (CVSM) containing the systemic and pulmonary components was outlined and verified, which is employable to analyse the hemodynamic behaviour under normal and abnormal states. By modifying this model, assuming that cardiac…
A mathematical model of cardiovascular dynamics for the diagnosis and prognosis of hemorrhagic shock
2020
Abstract A variety of mathematical models of the cardiovascular system have been suggested over several years in order to describe the time-course of a series of physiological variables (i.e. heart rate, cardiac output, arterial pressure) relevant for the compensation mechanisms to perturbations, such as severe haemorrhage. The current study provides a simple but realistic mathematical description of cardiovascular dynamics that may be useful in the assessment and prognosis of hemorrhagic shock. The present work proposes a first version of a differential-algebraic equations model, the model dynamical ODE model for haemorrhage (dODEg). The model consists of 10 differential and 14 algebraic e…
Standardized Hemorrhagic Shock Induction Guided by Cerebral Oximetry and Extended Hemodynamic Monitoring in Pigs.
2019
Hemorrhagic shock ranks among the main reasons for severe injury-related death. The loss of circulatory volume and oxygen carriers can lead to an insufficient oxygen supply and irreversible organ failure. The brain exerts only limited compensation capacities and is particularly at high risk of severe hypoxic damage.This article demonstrates the reproducible induction of life-threatening hemorrhagic shock in a porcine model by means of calculated blood withdrawal. We titrate shock induction guided by near-infrared spectroscopy and extended hemodynamic monitoring to display systemic circulatory failure, as well as cerebral microcirculatory oxygen depletion. In comparison to similar models tha…
The influence of dopamine on hemodynamics, microcirculation and renal function in patients with hypnotic drug intoxication
1976
The effect of dopamine on hemodynamics (CO, AoPm, TPR, SV, SW, CVP, PAPm, PAEDP), microcirculation (MBF, PS-product) and renal function (VU, CKI, CNa, CK, Cosm, TcH2O) was studied in 8 patients with hypnotic drug poisoning. With increasing doses of dopamine, cardiac output and heart rate increased and the peripheral resistance decreased. An augmentation of stroke volume and left ventricular stroke work was observed in the low dose range only (200--400 mug/min). With increasing doses, central venous pressure as well as mean pulmonary artery pressure and enddiastolic pulmonary artery pressure decreased. No vasoconstriction was found in muscle tissue vessels even with large doses of dopamine. …
Hemodynamic monitoring and management in patients undergoing high risk surgery: a survey among North American and European anesthesiologists
2011
Abstract Introduction Several studies have demonstrated that perioperative hemodynamic optimization has the ability to improve postoperative outcome in high-risk surgical patients. All of these studies aimed at optimizing cardiac output and/or oxygen delivery in the perioperative period. We conducted a survey with the American Society of Anesthesiologists (ASA) and the European Society of Anaesthesiology (ESA) to assess current hemodynamic management practices in patients undergoing high-risk surgery in Europe and in the United States. Methods A survey including 33 specific questions was emailed to 2,500 randomly selected active members of the ASA and to active ESA members. Results Overall,…
Assessment of the cardiostimulant action of propionyl-L-carnitine on chronically volume-overloaded rat hearts.
1993
Chronic volume overload was induced in young rats of Wistar strain by surgical opening of the aorto-caval fistula. Three months later, during in vitro perfusion with exogenous palmitate, left ventricular function and energy turnover (QO2) of hypertrophied hearts were severely depressed. This seemed to be related to impaired long-chain fatty acid utilization, as reflected by decreased 14CO2 production from U-14C-palmitate and decreased tissue levels of L-carnitine. Another group of rats exposed to chronic volume overload was pretreated for 2 weeks before sacrifice with propionyl-L-carnitine (250 mg/kg/day), and the hearts were perfused with 1.2 mM palmitate and 10 mM propionyl-L-carnitine. I…
Blood flow velocity waveforms of the middle cerebral artery and abnormal neurological evaluations in live-born fetuses with absent or reverse end-dia…
1992
Abstract We studied 37 fetuses with absent or reverse end-diastolic flow velocities (AREDFV) of the umbilical arteries with respect to the mode of delivery, fetal acidosis, resistance index of the middle cerebral arteries, and abnormal neurological evaluation at the time of discharge from the department of pediatrics. A control group with normal umbilical artery flow velocity waveforms was matched for gestational age. Fetuses with AREDFV were delivered almost exclusively by cesarean section, in most cases due to fetal distress. Metabolic changes with decreased base excess values were found more often in fetuses with AREDFV, but no difference could be detected with respect to severe fetal ac…