Glenny R W, McKinney S, Robertson H T
Department of Medicine, University of Washington, Seattle 98195, USA.
J Appl Physiol (1985). 1997 Mar;82(3):902-7. doi: 10.1152/jappl.1997.82.3.902.
Despite the heterogeneous distribution of regional pulmonary perfusion over space, local perfusion remains stable over short time periods (20-100 min). The purpose of this study was to determine whether the spatial distribution of pulmonary perfusion remains stable over longer time periods (1-5 days). Regional blood flow was measured each day for 5 days in five awake standing dogs. Fluorescent microspheres of different colors were injected into a limb vein over 30 s on each day. After the last microsphere injection, the dogs were killed, and lungs were flushed free of blood, excised, dried at total lung capacity, and diced into approximately 2-cm3 pieces (n = 1,296-1,487 per dog). Relative blood flow to each piece on each day was determined by extracting the fluorescent dyes and determining the concentrations of each color. We established that blood flow is spatially heterogeneous with a coefficient of variation of 29.5 +/- 2%. Blood flow to each piece is highly correlated with flow to the same piece on all days (r = 0.930 +/- 0.006). The temporal heterogeneity of regional perfusion as measured by the coefficient of variation is 6.9 +/- 0.7% over the 5 days and is nonrandom. The magnitude of spatial and temporal variation is significantly less than previously reported in a study in which anesthetized and mechanically ventilated dogs were used. We conclude that spatial distribution of pulmonary blood flow remains stable over days and we speculate that in the normal awake dog regional perfusion is determined primarily by a fixed structure such as the geometry of the pulmonary vascular tree rather than by local vasoactive regulators. Anesthesia and/or mechanical ventilation may increase the temporal variability in regional perfusion.
尽管肺部区域灌注在空间上分布不均，但局部灌注在短时间内（20 - 100分钟）保持稳定。本研究的目的是确定肺部灌注的空间分布在较长时间段（1 - 5天）内是否保持稳定。对5只清醒站立的狗连续5天每天测量其局部血流量。每天在30秒内将不同颜色的荧光微球注入一条肢体静脉。在最后一次微球注射后，处死狗，冲洗肺部使其无血，切除后在肺总量下干燥，然后切成约2立方厘米的小块（每只狗n = 1296 - 1487块）。通过提取荧光染料并测定每种颜色的浓度来确定每天每块组织的相对血流量。我们确定血流量在空间上是不均匀的，变异系数为29.5±2%。每天每块组织的血流量与同一天同一组织块的血流量高度相关（r = 0.930±0.006）。通过变异系数测量的区域灌注的时间异质性在5天内为6.9±0.7%，且是非随机的。空间和时间变化的幅度明显小于先前一项使用麻醉和机械通气狗的研究中所报道的。我们得出结论，肺部血流的空间分布在数天内保持稳定，并且我们推测在正常清醒的狗中，区域灌注主要由固定结构如肺血管树的几何形状决定，而不是由局部血管活性调节剂决定。麻醉和/或机械通气可能会增加区域灌注的时间变异性。
