Kastrup A, Hagendorff A, Dettmers C, Lüderitz B, Hartmann A
Department of Neurology, University of Bonn, Germany.
Neurol Res. 1998 Sep;20(6):549-54. doi: 10.1080/01616412.1998.11740562.
The present experiments were designed to compare the behavior of cerebral blood flow (CBF) during acute moderate and severe hypotensive episodes induced by either ventricular tachycardias (VT) or by hemorrhage. Using the microsphere method CBF was determined in 20 Sprague-Dawley rats during sinus rhythm (Group A), in 28 animals during high-rate VT (Group B) and in 10 animals after hemorrhage (Group C). According to the decrease in blood pressure and with respect to the lower threshold of cerebral autoregulation Group B was divided into 2 subgroups (B1: 80-130 mmHg; B2: 50-80 mmHg) retrospectively. While CBF remained constant in Group B1 (0.98 +/- 0.3 ml g-1 min-1 vs. 1.01 +/- 0.32 in controls, NS), CBF decreased markedly during severely hypotensive VT in Group B2 (0.52 +/- 0.2 ml g-1 min-1, p < 0.001 vs. A; p < 0.05 vs. C) and during hypovolemic hypotension in Group C (0.77 +/- 0.22 ml g-1 min-1 vs. A; NS). Cerebrovascular resistance and autoregulation indices indicated a maintenance of CBF regulation during hypovolemic hypotension and a failure during normovolemic hypotension. These findings indicate that the autoregulatory ability of the brain is substantially more stable during hypovolemic hypotension than during normovolemic hypotension. Therefore, the hemodynamic sequelae of acute hypotensive episodes on CBF depend on the underlying cause of hypotension.
本实验旨在比较由室性心动过速（VT）或出血诱发的急性中度和重度低血压发作期间脑血流量（CBF）的变化情况。采用微球法，分别在20只处于窦性心律的Sprague-Dawley大鼠（A组）、28只处于高速率室性心动过速的动物（B组）和10只出血后的动物（C组）中测定脑血流量。根据血压下降情况以及脑自动调节的下限，B组被回顾性地分为2个亚组（B1：80 - 130 mmHg；B2：50 - 80 mmHg）。在B1组中，脑血流量保持恒定（0.98±0.3 ml g-1 min-1，对照组为1.01±0.32，无显著差异），而在B2组严重低血压性室性心动过速期间（0.52±0.2 ml g-1 min-1，与A组相比p < 0.001；与C组相比p < 0.05）以及C组低血容量性低血压期间（0.77±0.22 ml g-1 min-1，与A组相比；无显著差异），脑血流量显著下降。脑血管阻力和自动调节指数表明，在低血容量性低血压期间脑血流量调节得以维持，而在血容量正常性低血压期间则出现调节失败。这些发现表明，在低血容量性低血压期间，大脑的自动调节能力比在血容量正常性低血压期间要稳定得多。因此，急性低血压发作对脑血流量的血流动力学后遗症取决于低血压的潜在原因。
