Baumbach G L, Heistad D D
Ann Biomed Eng. 1985;13(3-4):303-10. doi: 10.1007/BF02584248.
Autoregulation of cerebral blood flow is heterogeneous in several ways: regional, segmental, and temporal. We have found regional heterogeneity of the autoregulatory response during both acute reductions and increases in systemic arterial pressure. Changes in blood flow are less in brain stem than in cerebrum during decreases and increases in cerebral perfusion pressure. Segmental heterogeneity of autoregulation has been demonstrated in two ways. Direct determination of segmental cerebral vascular resistance indicates that, while small cerebral vessels (less than 200 micron in diameter) make a major contribution to autoregulation during acute increases in pressure between 80 and 100 mm Hg, the role of large cerebral arteries (greater than 200 micron) becomes increasingly important to the autoregulatory response at pressures above 100 mm Hg. Measurement of changes in diameter of pial vessels has shown that, during acute hypotension, autoregulation occurs predominantly in small resistance vessels (less than 100 micron). Finally, there is temporal heterogeneity of autoregulation. Sudden increases in arterial pressure produce transient increases in blood flow, which are not observed under steady-state conditions. In addition, the blood-brain barrier is more susceptible to hypertensive disruption after rapid, compared to step-wise, increases in arterial pressure. Thus, when investigating cerebral vascular autoregulation, regional, segmental, and temporal differences in the autoregulatory response must be taken into consideration.
区域、节段和时间方面。我们发现在全身动脉压急性降低和升高期间，自动调节反应存在区域异质性。在脑灌注压降低和升高时，脑干中的血流量变化小于大脑中的变化。自动调节的节段异质性已通过两种方式得到证实。对节段性脑血管阻力的直接测定表明，虽然在压力急性升高至80至100毫米汞柱之间时，小脑血管（直径小于200微米）对自动调节起主要作用，但在压力高于100毫米汞柱时，大脑大动脉（直径大于200微米）对自动调节反应的作用变得越来越重要。对软脑膜血管直径变化的测量表明，在急性低血压期间，自动调节主要发生在小阻力血管（小于100微米）中。最后，自动调节存在时间异质性。动脉压突然升高会导致血流量短暂增加，而在稳态条件下不会观察到这种情况。此外，与逐步升高相比，动脉压快速升高后血脑屏障更容易受到高血压破坏。因此，在研究脑血管自动调节时，必须考虑自动调节反应在区域、节段和时间上的差异。
