Trinkmann F, Papavassiliu T, Kraus F, Leweling H, Schoenberg Stefan O, Borggrefe M, Kaden J J, Saur J
First Department of Medicine - Cardiology, Angiology, Pneumology, Intensive Care, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany.
Clin Physiol Funct Imaging. 2009 Jul;29(4):255-62. doi: 10.1111/j.1475-097X.2009.00861.x. Epub 2009 Mar 16.
Cardiac output (CO) is an important cardiac parameter, however its determination is difficult in clinical routine. Non-invasive inert gas rebreathing (IGR) measurements yielded promising results in recent studies. It directly measures pulmonary blood flow (PBF) which equals CO in absence of significant pulmonary shunt flow (Q(S)). A reliable shunt correction requiring the haemoglobin concentration (c(Hb)) as only value to be entered manually has been implemented. Therefore, the aim of the study was to evaluate the effect of various approaches to Q(S) correction on the accuracy of IGR.
Cardiac output determined by cardiac magnetic resonance imaging (CMR) served as reference values. The data was analysed in four groups: PBF without correcting for Q(S) (group A), shunt correction using the patients' individual c(Hb) values (group B), a fixed standard c(Hb) of 14.0 g dl(-1) (group C) and a gender-adapted standard c(Hb) for male (15.0 g dl(-1)) and female (13.5 g dl(-1)) probands each (group D).
147 patients were analysed. Mean CO(CMR) was 5.2 +/- 1.4 l min(-1), mean CO(IGR) was 4.8 +/- 1.3 l min(-1) in group A, 5.1 +/- 1.3 in group B, 5.1 +/- 1.3 l min(-1) in group C and 5.1 +/- 1.4 l min(-1) in group D. The accuracy in group A (mean bias 0.5 +/- 1.1 l min(-1)) was significantly lower as compared to groups B, C and D (0.1 +/- 1.1 l min(-1); P<0.01).
IGR allows a reliable non-invasive determination of CO. Since PBF significantly increased the measurement bias, shunt correction should always be applied. A fixed c(Hb) of 14.0 g dl(-1) can be used for both genders if the exact c(Hb) value is not known. Nevertheless, the individual value should be used if any possible.
心输出量（CO）是一项重要的心脏参数，然而在临床常规中其测定较为困难。近期研究表明，无创惰性气体再呼吸（IGR）测量取得了有前景的结果。它直接测量肺血流量（PBF），在无显著肺分流（Q(S)）时，肺血流量等于心输出量。已实施一种可靠的分流校正方法，该方法仅需手动输入血红蛋白浓度（c(Hb)）这一数值。因此，本研究的目的是评估不同的Q(S)校正方法对IGR准确性的影响。
通过心脏磁共振成像（CMR）测定的心输出量作为参考值。数据分为四组进行分析：未校正Q(S)的PBF（A组）、使用患者个体c(Hb)值进行分流校正（B组）、固定标准c(Hb)为14.0 g dl(-1)（C组）以及分别针对男性（15.0 g dl(-1)）和女性（13.5 g dl(-1)）受试者的性别适应性标准c(Hb)（D组）。
对147例患者进行了分析。A组的平均CO(CMR)为5.2±1.4 l min(-1)，平均CO(IGR)为4.8±1.3 l min(-1)；B组为5.1±1.3 l min(-1)；C组为5.1±1.3 l min(-1)；D组为5.1±1.4 l min(-1)。与B、C、D组（0.1±1.1 l min(-1)；P<0.01）相比，A组的准确性显著更低（平均偏差为0.5±1.1 l min(-1)）。
IGR可实现可靠的无创心输出量测定。由于PBF显著增加了测量偏差，应始终进行分流校正。如果不知道确切的c(Hb)值，固定的14.0 g dl(-1)的c(Hb)值可用于男女两性。不过，如有可能应使用个体值。
