Cerebral venous steal: Blood flow diversion with increased tissue pressure
Cerebral venous steal: Blood flow diversion with increased tissue pressure
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DOI：
10.1097/00006123-200211000-00023
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发表时间：
2002-11-01
期刊：
影响因子：
4.8
通讯作者：
Pranevicius, O
中科院分区：
文献类型：
--
作者：
Pranevicius, M;Pranevicius, O
目得：在组织压力增加的区域中，血流由Starling电阻器描述，并由流入压力（P-i）、外部压力（P-e）和流出或静脉压力（P-v）确定。流量在区域1中处于P-e > P-i > P-v，在区域2中处于P-i > P-e > P-v，并且在区域3中处于P-i > P-v > P-e。中风或创伤后局灶性组织压力增加可能导致从中心的1区或2区过渡到周边的3区。我们假设不同区域的共存可能导致盗血样血流。概念：我们使用了一个集总参数模型的两个平行的斯特林电阻与共同流入。具有较高P-e的第一电阻器表示具有增加的组织压力的区域。第二个电阻; P-e（'）= 0，代表周围区域。我们评估了静脉压对两个Starling resistors.RATIONALE之间的流量分配的影响：该模型证明了血流转向第二个Starling resistors与低外部压力。高流入阻力促进了这种“偷流”。“分流是由Starling电阻器的有效流出压差引起的（第一个电阻器为P-e，第二个电阻器为P-v）：静脉压增加平衡了有效背压，减少了分流。当静脉压力等于外部组织压力时，血流转向（脑静脉盗血）被废除。虽然静脉压力增加会导致全球流量减少，它可能会恢复流量超过50%的基线值在增加组织pressure.DISCUSSION地区：脑静脉盗血是一个潜在的原因，继发性脑损伤的组织压力增加的地区。它可以通过增加静脉压来消除。静脉压升高可使塌陷的血管网恢复并纠正病灶周围灌注分布不均。这类似于呼气末正压如何招募塌陷的气道并减少通气/灌注不匹配。
PURPOSE: Flow, in areas with increased tissue pressure is described by a Starling resistor and is determined by the inflow pressure (P-i), the external pressure (P-e); and the outflow or venous pressure (P-v). Flow is in Zone 1 at P-e > P-i > P-v, Zone 2 at P-i > P-e > P-v, and Zone 3 at P-i > P-v > P-e. A focal tissue pressure increase after stroke or trauma may lead to a transition from Zone 1 or 2 in the center to Zone 3 in the periphery. We hypothesize that the coexistence of different zones may lead to steal-like, blood flow. diversion in the perifocal area.CONCEPT: We used a lumped-parameter model of two parallel Starling resistors with a common inflow. The first resistor,with higher P-e, represented the area with increased tissue pressure. The second resistor; with P-e(') = 0, represented the surrounding area. We evaluated the effects of venous pressure on the flow distribution between the two Starling resistors.RATIONALE: The model demonstrated blood flow diversion toward the second Starling resistor with low external pressure. High inflow resistance facilitates this "steal." Flow diversion is caused by effective outflow pressure differences for the Starling resistors (P-e for the first and P-v for the second): The venous pressure increase equilibrates the effective backpressure and decreases flow diversion. When the venous pressure equals the external tissue pressure, blood flow diversion (cerebral venous steal) is abolished. Although increased venous pressure causes global flow reduction, it may restore flow to more than 50% of baseline values in areas of increased tissue pressure.DISCUSSION: Cerebral venous steal is a potential cause of secondary brain injury in areas of increased tissue pressure. It can be eliminated with increased venous pressure. Increased venous pressure may recruit the collapsed vascular network and correct perifocal perfusion maldistribution. This resembles how positive end expiratory pressure recruits collapsed airways and decreases the ventilation/perfusion mismatch.