Studies on the effects of alpha-agonist and Ca antagonist for maintaining cerebral blood flow after cardiopulmonary resuscitation.

心肺复苏(CPR)期间和术后的脑保护是关键问题之一。维持脑血流灌注对保护脑损伤可能具有重要意义。最近的报道表明，右美托咪定改善了缺血后的神经学转归。本研究的目的是阐明心肺复苏期间应用右旋美托咪定是否能改善脑血流灌注。(1)确定右旋美托咪定对正常脑血管的直接影响。采用颅窗方法，测量局部应用右美托咪定后软脑膜小动脉和小静脉的直径。右旋美托咪定以剂量依赖的方式收缩软脑膜小动脉和小静脉。(2)探讨右旋美托咪定维持脑血流灌注的作用。采用开颅窗法测量心肺复苏后硬膜微动脉和小静脉直径。加入右旋美托咪定并不能从脑皮质直径的变化来观察脑血流灌注的明显改善。然而，右美托咪定减少了CPR后严重心律失常的发生率。结论，我们不能澄清右美托咪定可以改善CPR后脑血流灌注的确凿证据，但加入右美托咪定后血流动力学的稳定性可能有助于改善CPR后的预后。

Brain protection during and after CPR (cardiopulmonary resuscitation) is one of the critical problems. Maintaining of the cerebral perfusion might be important to protect the brain damage. Recent reports have demonstrated that dexmedetomidine improves neurologic outcomes from ischemia. The aim of this study was to clarify whether the administration of dexmedetomidine during CPR resulted in improved cerebral perfusion.(1) To determine the direct effects of dexmedetomidine on normal cerebral vessels.Using cranial window method, we measured the diameters of pial arterioles and venules following the topical administration of dexmedetomidine. Dexmedetomidine constricted both pial arterioles and venules in dose-dependent manner.(2) To determine the effect of dexmedetomidine for maintaining the cerebral perfusion.Using cranial window method, we measured the diameter of pial arterioles and venules after CPR with or without dexmedetomidine. The addition of dexmedetomidine did not demonstrated the apparent improvement of cerebral perfusion fro point of the changes of diameters of cerebral bessels. However, dexmedetomidine reduced the incidence of serious dysrhythmia after CPR.In conclusion, we could not clarify the conclusive evidence that dexmedetomidine could improve cerebral perfusion after CPR.However, the stability of hemodynamics by the addition of dexmedetomidine might contribute to improved outcome after CPR.