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Inert gas rebreathing

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
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...
November 24, 2017: ESC Heart Failure
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
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: Biological variation of amino-terminal probrain 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, clinical and hemodynamic assessment in 50 patients with HFrEF who met criteria for clinical stability at 2 time intervals. Hemodynamic variables were measured using inert gas rebreathing and impedance cardiography...
July 27, 2017: Journal of Cardiac Failure
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
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
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
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
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...
December 20, 2016: COPD
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
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
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
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
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
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
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
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
Victoria L Meah, John R Cockcroft, Karianne Backx, Rob Shave, Eric J Stöhr
OBJECTIVE: Cardiac output, a fundamental parameter of cardiovascular function, has consistently been shown to increase across healthy pregnancy; however, the time course and magnitude of adaptation remains equivocal within published literature. The aim of the present meta-analyses was to comprehensively describe the pattern of change in cardiac output during healthy pregnancy. METHOD: A series of meta-analyses of previously published cardiac output data during healthy, singleton pregnancies was completed...
April 2016: Heart: Official Journal of the British Cardiac Society
Catherine Kiely, Joel Rocha, Eamonn O'Connor, Donal O'Shea, Simon Green, Mikel Egaña
We investigated if the magnitude of the Type 2 diabetes (T2D)-induced impairments in peak oxygen uptake (V̇O2) and V̇O2 kinetics was affected by menopausal status. Twenty-two women with T2D (8 premenopausal, 14 postmenopausal), and 22 nondiabetic (ND) women (11 premenopausal, 11 postmenopausal) matched by age (range = 30-59 yr) were recruited. Participants completed four bouts of constant-load cycling at 80% of their ventilatory threshold for the determination of V̇O2 kinetics. Cardiac output (CO) (inert gas rebreathing) was recorded at rest and at 30 s and 240 s during two additional bouts...
October 15, 2015: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
Thomas Radtke, Daniel Poerschke, Matthias Wilhelm, Lukas D Trachsel, Hansueli Tschanz, Friederike Matter, Daniel Jauslin, Hugo Saner, Jean-Paul Schmid
BACKGROUND: The haemodynamic response to Finnish sauna and subsequent cold-water immersion in heart failure patients is unknown. METHODS: Haemodynamic response to two consecutive Finnish sauna (80℃) exposures, followed by a final head-out cold-water immersion (12℃) was measured in 37 male participants: chronic heart failure (n = 12, 61.8 ± 9.2 years), coronary artery disease (n = 13, 61.2 ± 10.6 years) and control subjects (n = 12, 60.9 ± 8...
April 2016: European Journal of Preventive Cardiology
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