Sarelius I H, McKinlay S M
Am J Physiol. 1985 Apr;248(4 Pt 2):H577-86. doi: 10.1152/ajpheart.1985.248.4.H577.
We show that two separate estimators of microvessel hematocrit (H) using the same fluorescent cell technique are not equally precise. The precision of H (indicated by the coefficient of variation, CV) depends on in vivo labeled cell counts (m), the labeled fraction (p), and for time-averaged H estimates, the mean cell velocity (v). Thus, for length-dependent estimates of H, CV2(HL) = 1/E(m) + CV2(p) and for time-averaged H estimates, CV2(Ht) = 1/E(m) + CV2(p) + CV2(v). Because CV(p) can be made small arbitrarily and independently, the precision of H is principally dependent on the expected value of m. Practical sampling constraints and minimum sampling intervals are identified and used to define strategies to minimize CV(H). We show that Ht is preferable to HL because it is more precise and the useful in vivo sampling range of m and p is more flexible. In addition, Ht allows simultaneous determination of cell flux and mean cell velocity.
我们发现，使用相同荧光细胞技术的两种独立微血管血细胞比容（H）估计方法的精度并不相同。H的精度（由变异系数CV表示）取决于体内标记细胞计数（m）、标记比例（p），对于时间平均H估计值，还取决于平均细胞速度（v）。因此，对于长度依赖性H估计，CV2(HL) = 1/E(m) + CV2(p)；对于时间平均H估计，CV2(Ht) = 1/E(m) + CV2(p) + CV2(v)。由于CV(p)可以任意且独立地减小，H的精度主要取决于m的期望值。确定了实际采样限制和最小采样间隔，并用于定义使CV(H)最小化的策略。我们表明，Ht比HL更可取，因为它更精确，并且m和p的体内有用采样范围更灵活。此外，Ht允许同时测定细胞通量和平均细胞速度。
