Department of Emergency Medicine, Massachusetts General Hospital, Boston, MA, USA.
Br J Anaesth. 2011 Jan;106(1):23-30. doi: 10.1093/bja/aeq295. Epub 2010 Nov 4.
Multiple methods for non-invasive measurement of cardiac output (CO) and stroke volume (SV) exist. Their comparative capabilities are not clearly established.
Healthy human subjects (n=21) underwent central hypovolaemia through progressive lower body negative pressure (LBNP) until the onset of presyncope, followed by termination of LBNP, to simulate complete resuscitation. Measurement methods were electrical bioimpedance (EBI) of the thorax and three measurements of CO and SV derived from the arterial blood pressure (ABP) waveform: the Modelflow (MF) method, the long-time interval (LTI) method, and pulse pressure (PP). We computed areas under receiver-operating characteristic curves (ROC AUCs) for the investigational metrics, to determine how well they discriminated between every combination of LBNP levels.
LTI and EBI yielded similar reductions in SV during progressive hypovolaemia and resuscitation (correlation coefficient 0.83) with ROC AUCs for distinguishing major LBNP (-60 mm Hg) vs resuscitation (0 mm Hg) of 0.98 and 0.99, respectively. MF yielded very similar reductions and ROC AUCs during progressive hypovolaemia, but after resuscitation, MF-CO did not return to baseline, yielding lower ROC AUCs (ΔROC AUC range, -0.18 to -0.26, P < 0.01). PP declined during hypovolaemia but tended to be an inferior indicator of specific LBNP levels, and PP did not recover during resuscitation, yielding lower ROC curves (P < 0.01).
LTI, EBI, and MF were able to track progressive hypovolaemia. PP decreased during hypovolaemia but its magnitude of reduction underestimated reductions in SV. PP and MF were inferior for the identification of resuscitation.
存在多种用于非侵入性测量心输出量（CO）和每搏量（SV）的方法。它们的比较能力尚不清楚。
健康人体受试者（n=21）通过逐渐施加下体负压（LBNP）导致中心性低血容量，直至出现先兆晕厥，然后终止 LBNP，以模拟完全复苏。测量方法包括胸部的电生物阻抗（EBI）和源自动脉血压（ABP）波形的 CO 和 SV 的三种测量：Modelflow（MF）方法、长时间间隔（LTI）方法和脉压（PP）。我们计算了研究指标的受试者工作特征曲线（ROC AUC）下面积，以确定它们在每个 LBNP 水平组合之间的区分程度。
LTI 和 EBI 在逐渐低血容量和复苏过程中产生了相似的 SV 减少（相关系数 0.83），ROC AUC 用于区分主要 LBNP（-60mmHg）与复苏（0mmHg）的分别为 0.98 和 0.99。MF 在逐渐低血容量期间产生了非常相似的减少和 ROC AUC，但在复苏后，MF-CO 并未恢复到基线水平，导致 ROC AUC 降低（ΔROC AUC 范围为-0.18 至-0.26，P < 0.01）。PP 在低血容量期间下降，但倾向于成为特定 LBNP 水平的较差指标，并且在复苏期间没有恢复，导致 ROC 曲线降低（P < 0.01）。
LTI、EBI 和 MF 能够跟踪逐渐低血容量。PP 在低血容量期间下降，但降低幅度低估了 SV 的减少。PP 和 MF 对识别复苏的能力较差。
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