Noninvasive Determination of Cardiac Output by the Inert-Gas-Rebreathing Method – Comparison with Cardiovascular Magnetic Resonance Imaging

Abstract

Background: An easy, noninvasive and accurate technique for measuring cardiac output (CO) would be desirable for the diagnosis and therapy of cardiac diseases. Innocor, a novel inert-gas-rebreathing (IGR) system, has shown promising results in smaller studies. An extensive evaluation in a larger, less homogeneous patient collective is lacking. Methods: We prospectively assessed the accuracy and reproducibility of CO measurements obtained by IGR in 305 consecutive patients as compared to the noninvasive gold standard, cardiovascular magnetic resonance (CMR) imaging. Results: Bland-Altman analysis showed a good correspondence of the two methods for CO measurement with an average deviation of 0.2 ± 1.0 liters/min (mean ± SD) and a good reproducibility with a mean bias of 0.2 ± 0.5 liters/min. The accuracy of the present measurements at rest was significantly better in the physiological range than in higher or lower CO ranges. The error levels set forth by current recommendations were exceeded. Conclusion: The data show that IGR measurements are easy to perform and show good agreement with CMR; however, the technique appears to be less accurate in extreme CO ranges at rest. The clinical importance of the IGR method remains to be proven by further studies.

Non-Invasive Measurement of Cardiac Output during Atrial Fibrillation: Comparison between Cardiac Magnetic Resonance Imaging and Inert Gas Rebreathing

“…Short measurement cycles may lead to inaccuracies in beat-based methods such as CMR. IGR proved promising in previous investigations [4,5,6,7,8,9,10]. Measurement of CO over a range of consecutive heart beats may provide a realistic representation of the patient’s cardiac function in AF.…”

“…AF leads to a decrease in stroke volume and cardiac output (CO) according to Frank and Starling’s law of the heart [3]. The novel inert gas rebreathing (IGR) device (Innocor; Innovision, Odense, Denmark) based on the Fick principle obtained promising results when compared to other invasive [4,5,6,7,8] and non-invasive techniques [9,10,11]. The Fick principle is based on the observation that the total uptake of a substance by the peripheral tissues is equal to the product of blood flow to the peripheral tissues and the arterial-venous concentration difference in the substance.…”

“…Since extreme circulatory states are known to potentially affect the accuracy of CO measurements [10,23,24], we stratified the data in quartiles by CO CMR . The IGR system showed very good agreement for CO in the physiological range between 2.0 and 5.4 l/min.…”

“…Third, IGR measurements require active collaboration and thus are problematic in uncooperative patients. When performed correctly, validity and reproducibility are high [7,10]. …”

Fator de diferenciação de crescimento 15: um novo biomarcador em pacientes com disfunção diastólica?

“…Cardiac output (CO) was measured using an inert gas rebreathing (IGR) device (Innocor™, Innovision A/S, Denmark) in a subgroup with either normal diastolic function or asymptomatic mild LVDD (LVDD grade I, n = 10) and patients with HFnEF (LVDD grade II or III, n = 10). The method has been described in details elsewhere 18 and has been validated in heart failure patients at rest and exertion 19,20 . For the IGR method, O 2 -enriched test gas with 0.5% N 2 O (blood soluble gas) and 0.1% SF6 (blood insoluble gas) was used.…”