Department of Internal Medicine I, Cardiology Division, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080, Würzburg, Germany.
Department of Clinical Research & Epidemiology, Comprehensive Heart Failure Center, University Hospital Würzburg, Am Schwarzen Berg 26, 97078, Würzburg, Germany.
Herz. 2024 Feb;49(1):50-59. doi: 10.1007/s00059-023-05196-0. Epub 2023 Jul 13.
Invasive cardiac output (CO) is measured with the thermodilution (TD) or the indirect Fick method (iFM) in right heart catheterization (RHC). The iFM estimates CO using approximation formulas for oxygen consumption ([Formula: see text]O), but there are significant discrepancies (> 20%) between both methods. Although regularly applied, the formula proposed by Krakau has not been validated. We compared the CO discrepancies between the Krakau formula with the reference (TD) and three established formulas and investigated whether alterations assessed in cardiac magnetic resonance imaging (CMR) determined the extent of the deviations.
This retrospective study included 188 patients aged 63 ± 14 years (30% women) receiving both CMR and RHC. The CO was measured with TD or with the iFM using the formulas by Krakau, LaFarge, Dehmer, and Bergstra for [Formula: see text]O2 estimation (iFM-K/-L/-D/-B). Percentage errors were calculated as twice the standard deviation of the difference between two CO methods divided by their means; a cut-off of < 30% was regarded as acceptable. The iFM and TD-derived CO ratio was built, and deviations > 20% were counted. Logistic regression analyses were performed to identify determinants of a deviation of > 20%.
The TD-derived CO (5.5 ± 1.7 L/min) was significantly different from all iFM (K: 4.8 ± 1.6, L: 4.3 ± 1.6; D: 4.8 ± 1.5 L/min; B: 5.4 ± 1.8 L/min all p < 0.05). The iFM-K-CO differed from all methods (p < 0.001) except iFM‑D (p = 0.19). Percentage errors between TD-CO and iFM-K/-L/-D/-B were all beyond the acceptance limit (44/45/44/43%), while percentage errors between iFM‑K and other iFM were all < 16%. None of the parameters measured in CMR was predictive of a discrepancy of > 20% between both methods.
The Krakau formula was comparable to other iFM in estimating CO levels, but none showed satisfactory agreement with the TD method. Improved derivation cohorts for [Formula: see text]O estimation are needed that better reflect today's patients undergoing RHC.
在右心导管检查（RHC）中，通过热稀释（TD）或间接 Fick 方法（iFM）测量有创心输出量（CO）。iFM 使用氧消耗的近似公式（[Formula: see text]O）来估计 CO，但两种方法之间存在显著差异（>20%）。尽管经常应用，但 Krakau 提出的公式尚未得到验证。我们比较了 Krakau 公式与参考（TD）和三种已建立公式之间的 CO 差异，并研究了心脏磁共振成像（CMR）中评估的变化是否确定了偏差的程度。
这项回顾性研究纳入了 188 名年龄 63±14 岁（30%为女性）的患者，他们同时接受了 CMR 和 RHC 检查。CO 通过 TD 或使用 Krakau、LaFarge、Dehmer 和 Bergstra 用于 [Formula: see text]O2 估计的公式（iFM-K/-L/-D/-B）进行 iFM 测量。百分比误差计算为两种 CO 方法之间差异的两倍除以它们的平均值的标准差；<30%被认为是可以接受的。构建了 iFM 和 TD 衍生的 CO 比值，并计算了>20%的偏差。进行逻辑回归分析以确定偏差>20%的决定因素。
TD 衍生的 CO（5.5±1.7 L/min）与所有 iFM 均显著不同（K：4.8±1.6，L：4.3±1.6；D：4.8±1.5 L/min；B：5.4±1.8 L/min，均 p<0.05）。iFM-K-CO 与所有方法均不同（p<0.001），除了 iFM-D（p=0.19）。TD-CO 与 iFM-K/-L/-D/-B 之间的百分比误差均超过可接受的范围（44/45/44/43%），而 iFM-K 与其他 iFM 之间的百分比误差均<16%。CMR 中测量的任何参数均不能预测两种方法之间>20%的差异。
Krakau 公式在估计 CO 水平方面与其他 iFM 相当，但与 TD 方法相比均无令人满意的一致性。需要更好地反映当前接受 RHC 治疗的患者的 [Formula: see text]O 估计的改进推导队列。
