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Inert gas rebreathing

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https://www.readbyqxmd.com/read/29474844/early-and-late-preeclampsia-are-characterized-by-high-cardiac-output-but-in-the-presence-of-fetal-growth-restriction-cardiac-output-is-low-insights-from-a-prospective-study
#1
Jasmine Tay, Lin Foo, Giulia Masini, Phillip R Bennett, Carmel M McEniery, Ian B Wilkinson, Christoph C Lees
BACKGROUND: Preeclampsia and fetal growth restriction are considered to be placentally mediated disorders. The clinical manifestations are widely held to relate to gestation age at onset with early- and late-onset preeclampsia considered to be phenotypically distinct. Recent studies have reported conflicting findings in relation to cardiovascular function, and in particular cardiac output, in preeclampsia and fetal growth restriction. OBJECTIVE: We conducted this study to examine the possible relation between cardiac output and peripheral vascular resistance in preeclampsia and fetal growth restriction...
May 2018: American Journal of Obstetrics and Gynecology
https://www.readbyqxmd.com/read/29396582/comparative-noninvasive-measurement-of-cardiac-output-based-on-the-inert-gas-rebreathing-method-innocor%C3%A2-and-mri-in-patients-with-univentricular-hearts
#2
Miriam Kuhn, Andreas Hornung, Heidi Ulmer, Christian Schlensak, Michael Hofbeck, Gesa Wiegand
There are many complex cardiac malformations that are characterized by a functionally univentricular physiology. Staged surgical repair according to the Fontan principle separates the systemic and pulmonary circulations by connecting the systemic venous return to the pulmonary arteries. However, long-term follow-up studies demonstrate a gradual deterioration of cardiac function, particularly from the second or third decade. Noninvasive evaluation of the cardiac function is, therefore, important in the follow-up of these patients...
April 2018: Pediatric Cardiology
https://www.readbyqxmd.com/read/29368399/do-interindividual-differences-in-cardiac-output-during-submaximal-exercise-explain-differences-in-exercising-muscle-oxygenation-and-ratings-of-perceived-exertion
#3
Robert F Bentley, Joshua H Jones, Daniel M Hirai, Joel T Zelt, Matthew D Giles, James P Raleigh, Joe Quadrilatero, Brendon J Gurd, J Alberto Neder, Michael E Tschakovsky
Considerable interindividual differences in the Q˙-V˙O2 relationship during exercise have been documented but implications for submaximal exercise tolerance have not been considered. We tested the hypothesis that these interindividual differences were associated with differences in exercising muscle deoxygenation and ratings of perceived exertion (RPE) across a range of submaximal exercise intensities. A total of 31 (21 ± 3 years) healthy recreationally active males performed an incremental exercise test to exhaustion 24 h following a resting muscle biopsy...
January 2018: Physiological Reports
https://www.readbyqxmd.com/read/29301460/inert-gas-rebreathing-helpful-tool-in-the-management-of-left-ventricular-assist-device-patients
#4
Nils Reiss, Thomas Schmidt, Stephanie Mommertz, Christina Feldmann, Jan Dieter Schmitto
In patients with left ventricular assist devices (LVAD), exercise capacity is a decisive factor regarding the quality of life. When evaluating exercise capacity, precise information about the total cardiac output generated is crucial. To date, complex measurements using a right-heart catheter were necessary in order to determine total cardiac output. The inert gas rebreathing method facilitates non-invasive, direct and valid measurement of total cardiac output as well as associated parameters, like the difference in arteriovenous oxygen saturation, both at rest and during exercise...
January 1, 2018: Perfusion
https://www.readbyqxmd.com/read/29171164/exercise-performance-haemodynamics-and-respiratory-pattern-do-not-identify-heart-failure-patients-who-end-exercise-with-dyspnoea-from-those-with-fatigue
#5
Marco Morosin, Stefania Farina, Carlo Vignati, Emanuele Spadafora, Susanna Sciomer, Elisabetta Salvioni, Gianfranco Sinagra, Piergiuseppe Agostoni
AIMS: The two main symptoms referred by chronic heart failure (HF) patients as the causes of exercise termination during maximal cardiopulmonary exercise testing (CPET) are muscular fatigue and dyspnoea. So far, a physiological explanation why some HF patients end exercise because of dyspnoea and others because of fatigue is not available. We assessed whether patients referring dyspnoea or muscular fatigue may be distinguished by different ventilator or haemodynamic behaviours during exercise...
February 2018: ESC Heart Failure
https://www.readbyqxmd.com/read/28942874/contribution-of-central-and-peripheral-factors-at-peak-exercise-in-heart-failure-patients-with-progressive-severity-of-exercise-limitation
#6
Alberico Del Torto, Nicoletta Corrieri, Carlo Vignati, Piero Gentile, Gaia Cattadori, Stefania Paolillo, Piergiuseppe Agostoni
BACKGROUND: A reduced cardiac output (CO) response during exercise is a major limiting factor in heart failure (HF). Oxygen consumption (VO2 ) is directly proportional to CO. Peripheral mechanisms via arteriovenous oxygen difference (Δ(a-v)O2 ) play a pivotal role in chronic HF. We hypothesized a weak correlation between peak VO2 and peak CO with a greater Δ(a-v)O2 variability in most severe HF. METHODS: We analyzed 278 HF patients (NYHA II-III) who performed maximal cardiopulmonary exercise test with non-invasive CO measurement by inert gas rebreathing...
December 1, 2017: International Journal of Cardiology
https://www.readbyqxmd.com/read/28757153/hemodynamic-determinants-of-the-biologic-variation-of-n-terminal-pro-b-type-natriuretic-peptide-in-patients-with-stable-systolic-chronic-heart-failure
#7
Tobias Täger, Ann-Kathrin Wiedergruen, Hanna Fröhlich, Rita Cebola, Anna Corletto, Andrea Horsch, Georg Hess, Karen Slottje, Dietmar Zdunek, Hugo A Katus, Frank H Wians, Lutz Frankenstein
BACKGROUND CONTEXT: Biologic variation of N-terminal pro-B-type natriuretic peptide (NT-proBNP) in chronic heart failure (CHF) may affect blood levels and risk stratification. The sources of NT-proBNP variation are unknown. METHODS AND RESULTS: We performed NT-proBNP measurements and clinical and hemodynamic assessments in 50 patients with heart failure with reduced ejection fraction (HFrEF) who met criteria for clinical stability over 2 time intervals. Hemodynamic variables were measured with the use of inert gas rebreathing and impedance cardiography...
December 2017: Journal of Cardiac Failure
https://www.readbyqxmd.com/read/28574213/comparison-of-cardiac-output-estimates-by-bioreactance-and-inert-gas-rebreathing-methods-during-cardiopulmonary-exercise-testing
#8
Nduka C Okwose, Shakir Chowdhury, David Houghton, Michael I Trenell, Christopher Eggett, Matthew Bates, Guy A MacGowan, Djordje G Jakovljevic
PURPOSE: This study assessed the agreement between cardiac output estimated by inert gas rebreathing and bioreactance methods at rest and during exercise. METHODS: Haemodynamic measurements were assessed in 20 healthy individuals (11 females, nine males; aged 32 ± 10 years) using inert gas rebreathing and bioreactance methods. Gas exchange and haemodynamic data were measured simultaneously under rest and different stages (i.e. 30, 60, 90, 120, 150 and 180 W) of progressive graded cardiopulmonary exercise stress testing using a bicycle ergometer...
June 2, 2017: Clinical Physiology and Functional Imaging
https://www.readbyqxmd.com/read/28552098/cardiopulmonary-exercise-testing-in-aortic-stenosis
#9
Van Doan Tuyet Le
Patients with moderate to severe aortic stenosis (AVA <1.3 cm(2)) who were judged, by a referring cardiologist, as asymptomatic or equivocal symptomatic from the aortic stenosis were included in the study. Patients with left ventricular ejection fraction <50% were not included. Twenty-nine percent of the referred patients were judged asymptomatic and 71% equivocal symptomatic from their valve disease. The mean age was 72 years and 90% of the patients had an AVA-index <0.6 cm(2)/m(2). By clinical evaluation in the outpatient clinic, 48% were judged as having functional limitation corresponding to NYHA≥II...
May 2017: Danish Medical Journal
https://www.readbyqxmd.com/read/28283502/validation-of-noninvasive-measurement-of-cardiac-output-using-inert-gas-rebreathing-in-a-cohort-of-patients-with-heart-failure-and-reduced-ejection-fraction
#10
COMPARATIVE STUDY
Mohamed Hassan, Kerolos Wagdy, Ahmed Kharabish, Peter Philip Selwanos, Ahmed Nabil, Ahmed Elguindy, Amr ElFaramawy, Mahmoud F Elmahdy, Hani Mahmoud, Magdi H Yacoub
BACKGROUND: Cardiac output (CO) is a key indicator of cardiac function in patients with heart failure. No completely accurate method is available for measuring CO in all patients. The objective of this study was to validate CO measurement using the inert gas rebreathing (IGR) method against other noninvasive and invasive methods of CO quantification in a cohort of patients with heart failure and reduced ejection fraction. METHODS AND RESULTS: The study included 97 patients with heart failure and reduced ejection fraction (age 42±15...
March 2017: Circulation. Heart Failure
https://www.readbyqxmd.com/read/28108178/reference-values-for-peak-exercise-cardiac-output-in-healthy-individuals
#11
Piergiuseppe Agostoni, Carlo Vignati, Piero Gentile, Costanza Boiti, Stefania Farina, Elisabetta Salvioni, Massimo Mapelli, Damiano Magrì, Stefania Paolillo, Nicoletta Corrieri, Gianfranco Sinagra, Gaia Cattadori
BACKGROUND: Cardiac output (Q˙) is a key parameter in the assessment of cardiac function, its measurement being crucial for the diagnosis, treatment, and prognostic evaluation of all heart diseases. Until recently, Q˙ determination at peak exercise has been possible through invasive methods, so that normal values were obtained in studies based on small populations. METHODS: Nowadays, peak Q˙ can be measured noninvasively by means of the inert gas rebreathing (IGR) technique...
June 2017: Chest
https://www.readbyqxmd.com/read/27997255/emphysema-on-thoracic-ct-and-exercise-ventilatory-inefficiency-in-mild-to-moderate-copd
#12
Joshua H Jones, Joel T Zelt, Daniel M Hirai, Camilla V Diniz, Aida Zaza, Denis E O'Donnell, J Alberto Neder
There is growing evidence that emphysema on thoracic computed tomography (CT) is associated with poor exercise tolerance in COPD patients with only mild-to-moderate airflow obstruction. We hypothesized that an excessive ventilatory response to exercise (ventilatory inefficiency) would underlie these abnormalities. In a prospective study, 19 patients (FEV1 = 82 ± 13%, 12 Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage 1) and 26 controls underwent an incremental exercise test. Ventilatory inefficiency was assessed by the ventilation ([Formula: see text]E)/CO2 output ([Formula: see text]CO2 ) nadir...
April 2017: COPD
https://www.readbyqxmd.com/read/27834447/physical-capacity-in-lvad-patients-hemodynamic-principles-diagnostic-tools-and-training-control
#13
REVIEW
Nils Reiss, Thomas Schmidt, Anke Workowski, Detlev Willemsen, Jan D Schmitto, Axel Haverich, Birna Bjarnason-Wehrens
Over time left ventricular assist devices (LVAD) have become an alternative to heart transplantation because of enormous technical development and miniaturization. Most patients present a significant improvement in clinical conditions and exercise capacity. Nevertheless, exercise tolerance remains markedly limited even after LVAD implantation compared to a control group. The complex physiological and hemodynamic changes in LVAD patients, both at rest and during exercise, are not yet understood, or at least not completely...
November 11, 2016: International Journal of Artificial Organs
https://www.readbyqxmd.com/read/27730167/closed-circuit-rebreathing-to-achieve-inert-gas-wash-in-for-multiple-breath-wash-out
#14
Alex R Horsley, Katherine O'Neill, Damian G Downey, J Stuart Elborn, Nicholas J Bell, Jaclyn Smith, John Owers-Bradley
Multiple breath wash-out (MBW) testing requires prior wash-in of inert tracer gas. Wash-in efficiency can be enhanced by a rebreathing tracer in a closed circuit. Previous attempts to deploy this did not account for the impact of CO2 accumulation on patients and were unsuccessful. We hypothesised that an effective rebreathe wash-in could be delivered and it would not alter wash-out parameters. Computer modelling was used to assess the impact of the rebreathe method on wash-in efficiency. Clinical testing of open and closed circuit wash-in-wash-out was performed in healthy controls and adult patients with cystic fibrosis (CF) using a circuit with an effective CO2 scrubber and a refined wash-in protocol...
January 2016: ERJ Open Research
https://www.readbyqxmd.com/read/27499214/noninvasive-cardiac-output-estimation-by-inert-gas-rebreathing-in-mechanically-ventilated-pediatric-patients
#15
COMPARATIVE STUDY
Amanda M Perak, Alexander R Opotowsky, Brian K Walsh, Jesse J Esch, James A DiNardo, Barry D Kussman, Diego Porras, Jonathan Rhodes
OBJECTIVE: To assess the feasibility and accuracy of inert gas rebreathing (IGR) pulmonary blood flow (Qp) estimation in mechanically ventilated pediatric patients, potentially providing real-time noninvasive estimates of cardiac output. STUDY DESIGN: In mechanically ventilated patients in the pediatric catheterization laboratory, we compared IGR Qp with Qp estimates based upon the Fick equation using measured oxygen consumption (VO2) (FickTrue); for context, we compared FickTrue with a standard clinical short-cut, replacing measured with assumed VO2 in the Fick equation (FickLaFarge, FickLundell, FickSeckeler)...
October 2016: Journal of Pediatrics
https://www.readbyqxmd.com/read/27090042/noninvasive-measurement-of-cardiac-output-during-6-minute-walk-test-by-inert-gas-rebreathing-to-evaluate-heart-failure
#16
Suping Zhou, Peng Chen, Huijie Li, Chunyu Zeng, Yuqiang Fang, Weibin Shi, Chengming Yang
OBJECTIVE: The objective of this study was to assess the clinical value of cardiac output (CO) measurements using the inert gas rebreathing (IGR) method during the 6-minute walk test (6MWT) in evaluation of chronic heart failure (CHF). METHODS AND RESULTS: A total of 56 CHF patients in our hospital who conformed to the Framingham CHF diagnostic criteria were recruited to this study from October 2007 to February 2009. Subjects were asked to complete a 6MWT and a bicycle exercise test...
April 2016: Acta Cardiologica
https://www.readbyqxmd.com/read/26995373/noninvasive-cardiac-output-estimation-by-inert-gas-rebreathing-in-pediatric-and-congenital-heart-disease
#17
COMPARATIVE STUDY
Amanda K Marma, Alexander R Opotowsky, Brian S Fromm, Ana Ubeda-Tikkanen, Diego Porras, Jonathan Rhodes
BACKGROUND: Inert gas rebreathing (IGR) techniques provide rapid, reliable estimates of cardiac output in adults with structurally normal hearts. Data on IGR reliability in pediatric and congenital heart disease populations are lacking. Our objective was to validate pulmonary blood flow (Qp) measurement by IGR compared with clinical reference tests, cardiovascular magnetic resonance (CMR), and indirect Fick. METHODS: Pulmonary blood flow was measured by IGR and CMR or indirect Fick in 80 patients grouped by presence and type of shunt lesion...
April 2016: American Heart Journal
https://www.readbyqxmd.com/read/26961172/positive-effects-of-aggressive-vasodilator-treatment-of-well-treated-essential-hypertensive-patients
#18
M Engholm, M J Mulvany, A Eftekhari, O N Mathiassen, N H Buus, K L Christensen
Increased systemic vascular resistance and coronary microvascular dysfunction are well-documented in essential hypertension (EH). We investigated the effect of additional vasodilating treatment on coronary and peripheral resistance circulation in EH patients with high systemic vascular resistance index (SVRI) despite well-treated blood pressure (BP). We enroled patients on stable antihypertensive treatment that were given intensified vasodilating therapy (ACE inhibitor, angiotensin II receptor blocker or calcium channel blocker)...
November 2016: Journal of Human Hypertension
https://www.readbyqxmd.com/read/26869330/-hemodynamics-and-physical-capacity-in-patients-with-left-ventricular-assist-devices-an-overview
#19
REVIEW
N Reiss, M Altesellmeier, S Mommertz, T Schmidt, S Schulte-Eistrup, D Willemsen
In the course of time implantation of left ventricular assist devices (LVAD) has become an alternative to heart transplantation due to the enormous technical developments and miniaturization of these systems. Following implantation most patients show a significant improvement in their clinical condition and exercise capacity as measured by the New York Heart Association (NYHA) classification; nevertheless, exercise tolerance remains clearly limited even after LVAD implantation. The complex physiological and hemodynamic changes in LVAD patients both at rest and during exercise are ultimately not completely understood...
September 2016: Herz
https://www.readbyqxmd.com/read/26808510/the-prognostic-value-of-peak-cardiac-power-output-in-chinese-patients-with-chronic-heart-failure
#20
Yuqin Shen, Haoming Song, Wenlin Ma, Zhu Gong, Yi Ni, Xiaoyu Zhang, Wenjun Xu, Jinfa Jiang, Lin Che, Jiahong Xu, Wenwen Yan, Lin Zhou, Guanghe Li, Qiping Zhang, Lemin Wang
BACKGROUND: Cardiopulmonary exercise testing has been widely used to risk stratify patients with chronic heart failure (CHF). Peak oxygen consumption (peakVO2) was regarded as a powerful predictor of survival, as it is a surrogate for peak cardiac output (CO), which by most is considered the "true" measure of heart failure. Therefore, it is reasonable to hypothesize that CO is an even stronger predictor than peak VO2. The present study is aimed to investigate the prognostic value of peak cardiac power output (peak CPO) in comparison with peakVO2 in Chinese patients with CHF...
2016: PloS One
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