Haites N E, McLennan F M, Mowat D H, Rawles J M
Lancet. 1984 Nov 3;2(8410):1025-7. doi: 10.1016/s0140-6736(84)91118-8.
Measurement of volumetric cardiac output is technically difficult and poorly reproducible, and the technique is unsuitable for use in the majority of patients in whom a knowledge of overall cardiovascular function would be desirable. Interpretation of a single measurement in a patient is difficult because little is known about volumetric cardiac output in normal subjects and the available techniques of measurement are very complex or invasive. Linear cardiac output, in contrast, can be simply, non-invasively, and reproducibly measured at the bedside by doppler ultrasound. The systolic-velocity integral of a single heart beat (stroke distance) multiplied by the heart rate gives minute distance; this may be envisaged as the distance travelled by mid-stream blood in the aorta in a minute. Providing there is no aortic disease, minute distance may be used as an absolute indication of cardiac output and for following serial changes.
测量心脏每搏输出量在技术上具有难度且重复性较差，并且该技术不适用于大多数需要了解整体心血管功能的患者。由于对正常受试者的心脏每搏输出量了解甚少，且现有的测量技术非常复杂或具有侵入性，因此很难对患者的单次测量结果进行解读。相比之下，线性心输出量可以通过多普勒超声在床边简单、无创且可重复地进行测量。单次心跳的收缩期速度积分（搏出距离）乘以心率得出每分钟距离；这可以想象为主动脉中流血液在一分钟内所行进的距离。如果没有主动脉疾病，每分钟距离可作为心输出量的绝对指标并用于跟踪连续变化。
