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Inert gas rebreathing

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
AIMS: 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 AND RESULTS: Nowadays, peak Q can be measured noninvasively by means of inert gas rebreathing technique (IGR)...
January 17, 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
Eamonn O'Connor, Simon Green, Catherine Kiely, Donal O'Shea, 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 age. Thirty-three men with T2D (15 middle-aged, 18 older), and 21 nondiabetic (ND) men (11 middle-aged, 10 older) matched by age were recruited. Participants completed four 6-min bouts of constant-load cycling at 80% ventilatory threshold for the determination of V̇o2 kinetics. Cardiac output (inert-gas rebreathing) was recorded at rest and 30 and 240 s during two additional bouts...
April 15, 2015: Journal of Applied Physiology
Jean-Paul Schmid, Daniel Nobel, Nicolas Brugger, Jan Novak, Patricia Palau, Anja Trepp, Matthias Wilhelm, Hugo Saner
AIMS: High altitude exposure for the purpose of tourism is very popular in mountainous regions and is considered to be safe for patients with stable CAD and preserved LV function. The purpose of this study was to evaluate the haemodynamic response to exercise and electrical stability by Holter monitoring in patients with chronic heart failure (HF) and an EF <40%. METHODS AND RESULTS: We studied 29 HF patients with a peak VO2 >50% of the predicted (25 men, age 60...
February 2015: European Journal of Heart Failure
Louise W Sturesson, Jan O Frennström, Marcella Ilardi, Peter Reinstrup
BACKGROUND: A modified heat-moisture exchanger that incorporates a reflecting filter for use with partial rebreathing of exhaled volatile anaesthetics has been commercially available since the 1990 s. The main advantages of the device are efficient delivery of inhaled sedation to intensive care patients and reduced anaesthetic consumption during anaesthesia. However, elevated arterial CO2 values have been observed with an anaesthetic conserving device compared with a conventional heat and moisture exchanger, despite compensation for larger apparatus dead space...
August 2015: European Journal of Anaesthesiology
C Siebenmann, P Rasmussen, H Sørensen, M Zaar, M Hvidtfeldt, A Pichon, N H Secher, C Lundby
Several techniques assessing cardiac output (Q) during exercise are available. The extent to which the measurements obtained from each respective technique compares to one another, however, is unclear. We quantified Q simultaneously using four methods: the Fick method with blood obtained from the right atrium (Q(Fick-M)), Innocor (inert gas rebreathing; Q(Inn)), Physioflow (impedance cardiography; Q(Phys)), and Nexfin (pulse contour analysis; Q(Pulse)) in 12 male subjects during incremental cycling exercise to exhaustion in normoxia and hypoxia (FiO2  = 12%)...
February 2015: Scandinavian Journal of Medicine & Science in Sports
U Limper, P Gauger, P Beck, F Krainski, F May, L E J Beck
PURPOSE: Commercial parabolic flights accessible to customers with a wide range of health states will become more prevalent in the near future because of a growing private space flight sector. However, parabolic flights present the passengers' cardiovascular system with a combination of stressors, including a moderately hypobaric hypoxic ambient environment (HH) and repeated gravity transitions (GT). Thus, the aim of this study was to identify unique and combined effects of HH and GT on the human cardiovascular, pulmonary and fluid regulation systems...
June 2014: European Journal of Applied Physiology
Thomas C Bonne, Gregory Doucende, Daniela Flück, Robert A Jacobs, Nikolai B Nordsborg, Paul Robach, Guillaume Walther, Carsten Lundby
With this study we tested the hypothesis that 6 wk of endurance training increases maximal cardiac output (Qmax) relatively more by elevating blood volume (BV) than by inducing structural and functional changes within the heart. Nine healthy but untrained volunteers (Vo2max 47 ± 5 ml·min(-1)·kg(-1)) underwent supervised training (60 min; 4 times weekly at 65% Vo2max for 6 wk), and Qmax was determined by inert gas rebreathing during cycle ergometer exercise before and after the training period. After the training period, blood volume (determined in duplicates by CO rebreathing) was reestablished to pretraining values by phlebotomy and Qmax was quantified again...
May 15, 2014: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
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