培训课件-脑出血血肿扩大机制和防范.pptVIP

* * * * * * 高血压对脑出血的发生无疑起着非常重要的作用 ,然而其对活动性出血的发生有无影响仍无定论 * * * * * * Autoregulation refers to the inherent regulation of arterial diameter to allow maintenance of a relatively constant amount of blood flow in different vascular beds and is most frequently discussed in terms of cerebral tissue.1 Autoregulation is lost in ischemic tissue. In patients with chronic hypertension, the structure of the arterioles thickens and entire autoregulatory curve is shifted to the right. When BP is increased beyond the upper limits of autoregulation, “breakthrough” hyperperfusion occurs. In previously normotensive patients, whose vessels have not been altered by prior exposure to high pressures, breakthrough typically occurs at a MAP of about 120 mm Hg. In chronic hypertensive patients, the breakthrough may occur at 160 mm Hg.2 As such, a normotensive patient would be expected to develop end-organ damage at a lower BP than a chronic hypertensive. Lowering BP into the normal range in a poorly controlled, chronic hypertensive patient may actually accelerate end-organ damage.2 This difference in autoregulatory set points has important implications for the management of hypertensive urgency and emergency. The majority of the complications seen in the management of hypertensive emergency are actually from overly aggressive BP reductions. Care should be exercised in patients with chronic hypertension, or patients whose previous BP status is unknown, that their MAP is not lowered to the point where they suffer from ischemia (“fall off the left side of the curve”).2 1. Berne RM, Levy MN. Cardiovascular Physiology. 8th ed. Philadelphia, Pa: Mosby; 2001. 2. Strandgaard S. Circulation. 1976;53:720-727. * * Treatment of Acute Intracerebral Hemorrhage with epsilon-Aminocaproic Acid: A Pilot Study.Piriyawat P, Morgenstern LB, H Yawn D, Hall CE, Grotta JC.Stroke Program, Department of Neurology, University of Texas at Houston, Houston,TX.Introduction: Up to 40% of primary intracerebr