Reproducibility of Inert Gas Rebreathing Method to Estimate Cardiac Output at Rest and During Cardiopulmonary Exercise Stress Testing

Abstract

ABStR AC tThe present study evaluated reproducibility of the inert gas rebreathing method to estimate cardiac output at rest and during cardiopulmonary exercise testing. Thirteen healthy subjects (10 males, 3 females, ages 23-32 years) performed maximal graded cardiopulmonary exercise stress test using a cycle ergometer on 2 occasions (Test 1 and Test 2). Participants cycled at 30-watts/ 3-min increments until peak exercise. Hemodynamic variables were assessed at rest and during different exercise intensities (i. e., 60, 120, 150, 180 watts) using an inert gas rebreathing technique. Cardiac output and stroke volume were not significantly different between the 2 tests at rest 7.4 (1.6) vs. 7.1 (1.2) liters min − 1 , p = 0.54; 114 (28) vs. 108 (15) ml beat − 1 , p = 0.63) and all stages of exercise. There was a significant positive relationship between Test 1 and Test 2 cardiac outputs when data obtained at rest and during exercise were combined (r = 0.95, p < 0.01 with coefficient of variation of 6.0 %), at rest (r = 0.90, p < 0.01 with coefficient of variation of 5.1 %), and during exercise (r = 0.89, p < 0.01 with coefficient of variation 3.3 %). The mean difference and upper and lower limits of agreement between repeated measures of cardiac output at rest and peak exercise were 0.4 ( − 1.1 to 1.8) liter min − 1 and 0.5 ( − 2.3 to 3.3) liter min − 1 , respectively. The inert gas rebreathing method demonstrates an acceptable level of test-retest reproducibility for estimating cardiac output at rest and during cardiopulmonary exercise testing at higher metabolic demands.

Fate Tracing of Isl1+Cells in Adult Mouse Hearts under Physiological and Exercise Conditions

“…Other studies have shown that exercise promotes cardiomyocyte cell division in response to specific stimuli [2,3,15,16,22]. In preliminary analyses, we found that regular moderate aerobic exercise could induce improvement in cardiac structure and physiological function in wild-type mice and has substantial effects on morphological indices, such as heart size, weight, ventricular wall thickness, and angiogenesis [17].…”

“…Current treatment strategies do not address the problem of myocardial tissue loss and repair. Recent studies indicated that the adult mammalian heart retains regeneration ability in normal conditions or in response to specific stimuli, such as exercise [1][2][3]. However, the optimal cell types for this approach remain elusive.…”

Non-Invasive Cardiac Output Measurement Using Inert Gas Rebreathing Method during Cardiopulmonary Exercise Testing—A Systematic Review

“…The use of IGR has been shown to produce pulmonary blood flow measurements that are comparable to those obtained by various other methods such as thermodilution, direct Fick, and modified Fick methods during rest as well as graded exercise [46][47][48][49]. Furthermore, this method offers high reproducibility for CO measurements during rest and exercise for both healthy individuals and those with cardiac indications [50,51].…”

“…The IGR method has high repeatability, reproducibility, and its reliability is not compromised by atrial fibrillation or pulmonary diseases [45,51,55,56,63,76,84]. The IGR method is, therefore, ideally suitable for determining CO in LVAD (Left Ventricular Assist Device) patients at rest and during exercise.…”

“…The presented systematic review includes several limitations. Firstly, some of the studies included in this review were based on small patient groups [31,51,59,66,76,79], and most of the studies focused on patients with either healthy conditions or heart failure. There were few studies available that focused on other disease entities [85,89,[95][96][97][98][99].…”