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Stomach Microcirculation
Published in John H. Barker, Gary L. Anderson, Michael D. Menger, Clinically Applied Microcirculation Research, 2019
The rate of dissipation of a highly diffusible, biologically inert gas such as H2 from a homogeneously perfused tissue is determined by the rate of blood flow that carries the gas away. Assuming that H2 in the tissue is in an instantaneous diffusion equilibrium with H2 in venous blood flowing through that tissue, the Fick principle can be applied to determine the blood flow.
Analysis and interpretation of Fick and thermodilution cardiac output determinations
Published in John Edward Boland, David W. M. Muller, Interventional Cardiology and Cardiac Catheterisation, 2019
Gary J. Gazibarich, John Edward Boland, Louis W. Wang
Assumptions of the Fick principle (with oxygen as the indicator substance): The circulation is in a steady-state with equal pulmonary and systemic flows and no intracardiac shunt.Correct anatomical sampling and analysis of blood samples.Correct collection and analysis of the exhaled volume and gas fractions.
Cardiac catheterization for pediatric patients
Published in Debabrata Mukherjee, Eric R. Bates, Marco Roffi, Richard A. Lange, David J. Moliterno, Nadia M. Whitehead, Cardiovascular Catheterization and Intervention, 2017
The Fick principle is used to calculate pulmonary and system blood flows. To calculate right-to-left and left-to- right shunts, the concept of effective pulmonary blood flow must be used. Effective pulmonary blood flow (Q) is defined as the desaturated blood that flows to the lungs. In the absence of a right-to-left shunt, effective blood flow equals pulmonary blood flow. The equation to calculate effective pulmonary blood flow is
Percutaneous ASD closure of children weighing less than 10 kg
Published in Acta Cardiologica, 2020
Nazmi Narin, Osman Baspinar, Ozge Pamukcu, Suleyman Sunkak, Aydin Tuncay, Onur Tasci, Ali Baykan
The ratio of pulmonary blood flow to systemic blood flow (Qp/Qs) was calculated based on the Fick principle. Percutaneous ASD closure was done by the technique that has been published previously [4]. Successful implantation was defined as the device being properly placed and deployed without malposition or embolisation in the catheterisation laboratory. Major complications were defined as any life-threatening event and/or need for immediate surgical intervention like cardiac arrest, device embolisation, cardiac tamponade, cardiac arrhythmia, hypotension, bleeding (requiring blood transfusion), vascular complications (femoral arteriovenous fistula, femoral haematoma, and femoral thrombosis), and stroke. Minor complications were defined as transient complication with no long-term sequela. Physical examination, ECG, TTE examinations were done in all patients immediately after procedure, at 24th hour, 1st and 6th months after procedure. After the 6th month control, it was done annually. All patients routinely received aspirin therapy (3–5 mg/kg) for 6 months after the procedure.
Cardiopulmonary exercise testing – refining the clinical perspective by combining assessments
Published in Expert Review of Cardiovascular Therapy, 2020
Ross Arena, Justin M. Canada, Dejana Popovic, Cory R. Trankle, Marco Giuseppe Del Buono, Alexander Lucas, Antonio Abbate
Of the numerous measures that can be derived from CPX, measures of exercise capacity and ventilatory efficiency garner the greatest focus in the clinical and research settings. With respect to exercise capacity, maximal VO2 (VO2max) obtained during exercise defines the upper limits of the cardiopulmonary system as illustrated through the Fick principle wherein VO2max is the product of cardiac output (CO) and the arteriovenous oxygen content difference [C(a-v)O2] at peak exercise. However, it is important to note that aerobic capacity is more commonly defined as peak VO2 (highest level obtained during exercise) versus VO2max as the latter implies attainment of a physiologic plateau not often observed in clinical populations. Peak VO2 reflects both central and peripheral functioning of the cardiopulmonary system and is influenced by age, sex, disease states, genetics, and physical activity levels[6]. The VE/VCO2 slope has been the most widely used index of ventilatory efficiency [5] and is attractive due to its high test–retest reliability [40]. Like peak VO2, although inversely, VE/VCO2 broadly reflects disease severity with higher values indicating worse prognosis in cardiopulmonary disease populations[2]. Moreover, the OUES has independent value in the prognostication of patients with cardiopulmonary disease [41–44] Furthermore, it has high reliability, is independent of exercise intensity, and is sensitive to therapeutic interventions such as exercise training regimens [45–47].
Preventing disease progression in Eisenmenger syndrome
Published in Expert Review of Cardiovascular Therapy, 2021
Ana Barradas-Pires, Andrew Constantine, Konstantinos Dimopoulos
The direct Fick method is recommended for the calculation of Qp in cardiac catheterization laboratories but requires ‘direct’ measurement of oxygen consumption with equipment that may not be widely available. The thermodilution method is considered a reliable technique in PH practice but should be avoided in patients with cardiac shunts. The less accurate indirect Fick method (that uses nomograms to obtain oxygen consumption) is commonly used in patients with simple cardiac defects, despite its limitations. Cardiovascular magnetic resonance (in a hybrid catheterization laboratory) can provide accurate estimates of Qp and Qs, especially in patients with complex cardiac anatomy in whom the Fick principle may be difficult to apply.