Ligas J R, Moslehi F, Epstein M A
Surgical Research Center, University of Connecticut School of Medicine, Farmington 06030.
Ann Biomed Eng. 1993 Jul-Aug;21(4):361-5. doi: 10.1007/BF02368628.
Continuous measurement of arterial blood density after bolus injection of fluids of different density into the right atrium has been used to measure cardiac output and mean transit time through the central circulation. The transit time distribution for density, however, differs from that for plasma-phase tracers such as indocyanine green. This difference may yield important information about red cell transit times through the microcirculation. We analyzed the potential of the density technique to resolve small changes in transit time distributions. Rayleigh's Method was used to calculate the relationship between density distribution within the U-tube and frequency of oscillation. Fourier integral transformation of a functional representation of indocyanine green dye curves provided an estimate of amplitude versus frequency for likely input density signals. We found that the ability of the densitometer to accurately follow blood density changes depends upon physiologic parameters associated with the experimental animal and upon the physical characteristics of the densitometer itself. Even for small animals, such as a rabbit, the densitometer theoretically has the ability to accurately follow rapid density changes over time.
在向右心房推注不同密度的液体后，连续测量动脉血密度已被用于测量心输出量和通过中心循环的平均转运时间。然而，密度的转运时间分布与诸如吲哚菁绿等血浆相示踪剂的转运时间分布不同。这种差异可能会产生有关红细胞通过微循环的转运时间的重要信息。我们分析了密度技术分辨转运时间分布微小变化的潜力。瑞利方法用于计算U形管内密度分布与振荡频率之间的关系。吲哚菁绿染料曲线功能表示的傅里叶积分变换提供了可能的输入密度信号的幅度与频率的估计。我们发现，密度计准确跟踪血液密度变化的能力取决于与实验动物相关的生理参数以及密度计本身的物理特性。即使对于小动物，如兔子，理论上密度计也有能力准确跟踪随时间快速的密度变化。
