Department of Cardiology, Hvidovre Hospital, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
Scand J Clin Lab Invest. 2011 Jul;71(4):304-13. doi: 10.3109/00365513.2011.563790. Epub 2011 Mar 10.
Atrial fibrillation (AF) is associated with significant morbidity and mortality. To test the effect of interventions, knowledge of cardiac output (CO) is important. However, the irregular heart rate might cause some methods for determination of CO to have inherent weaknesses. Objective. To assess the validity of these methods in AF, a new inert gas rebreathing device and impedance cardiography was tested with echocardiography as reference.
Using a cross-sectional design, 127 patients with AF and 24 in SR were consecutively recruited. Resting CO was measured using inert gas rebreathing (n = 62) or impedance measurement of intrathoracic blood flow (n = 89) in separate studies with echocardiographic measurement as reference.
CO determined with impedance cardiography was mean 4.77 L/min ± 2.24(SD) compared to 4.93 L/min ± 1.17 by echocardiography (n = 89, n.s.) in patients with AF. CO by inert gas rebreathing was 4.98 L/min ± 2.49(SD) compared to 5.70 L/min ± 2.49 by echocardiography (n = 62, n.s.) in patients with AF and SR (AF 5.42 ± 2.9 vs. 6.27, n.s. and SR 4.09 ± 1.08 vs. 4.35 ± 0.86, n.s.). Mean bias between impedance cardiography and echocardiography was 0.14 ± 0.95 L/min and -0.13 ± 0.98 L/min between inert gas rebreathing and echocardiography. Inert gas rebreathing showed larger intra-patient variation than impedance cardiography (0.11 vs. 0.054). Correlation between inert gas rebreathing and echocardiography was r = -0.060 and between impedance cardiography and echocardiography was r = 0.128. Impedance cardiography and inert gas rebreathing both underestimated CO compared to echocardiography.
Variation between the inert gas rebreathing and the reference method for AF patients was less than desired. Impedance cardiography was superior to inert gas rebreathing and showed acceptable agreement with echocardiography and variability similar to echocardiography.
心房颤动（AF）与显著的发病率和死亡率相关。为了测试干预措施的效果，了解心输出量（CO）很重要。然而，不规则的心率可能会导致一些用于确定 CO 的方法存在固有弱点。目的：为了评估这些方法在 AF 中的有效性，我们使用新型惰性气体再呼吸装置和电抗血流图，并以超声心动图作为参考进行了测试。
采用横断面设计，连续招募了 127 例 AF 患者和 24 例窦性心律（SR）患者。在单独的研究中，使用惰性气体再呼吸（n = 62）或阻抗法测量胸腔内血流（n = 89）测量静息 CO，并以超声心动图测量作为参考。
在 AF 患者中，阻抗心输出量测定法的 CO 平均值为 4.77 L/min ± 2.24（SD），而超声心动图为 4.93 L/min ± 1.17（n = 89，无统计学意义）。在 AF 和 SR 患者中，惰性气体再呼吸法的 CO 为 4.98 L/min ± 2.49（SD），而超声心动图为 5.70 L/min ± 2.49（n = 62，无统计学意义）。AF 患者的平均偏差为 0.14 ± 0.95 L/min，SR 患者的平均偏差为 0.13 ± 0.98 L/min。惰性气体再呼吸法的患者内变异大于阻抗心输出量测定法（0.11 对 0.054）。惰性气体再呼吸法与超声心动图之间的相关性为 r = -0.060，而阻抗心输出量测定法与超声心动图之间的相关性为 r = 0.128。与超声心动图相比，惰性气体再呼吸法和阻抗心输出量测定法均低估了 CO。
AF 患者的惰性气体再呼吸法和参考方法之间的差异小于预期。阻抗心输出量测定法优于惰性气体再呼吸法，与超声心动图具有可接受的一致性，且变异性与超声心动图相似。
