Central blood pressure is really the  pressure that the heart， the brain， and  the kidney experience because it is the pressure in the aorta. And because the aorta is a big tube and its pumping blood out into smaller tubes， the smaller tubes are of course going to have higher resistance. So if you are measuring brachial blood pressure which is a much smaller tube than the central large artery and the more pliable the vessel is the less likely there is to be a difference. The stiffer the vessel the more likelihood of a difference. And of course these people using wrist cuffs that are measuring blood pressure at the radial artery are going to get even more inaccurate data. And actually inaccurate in the sense that those pressures are going to be higher than what the central pressure is. The danger is that if you start treating those pressures， especially in the elderly or people with very stiff vessels， you are going to further reduce the central pressure which already may be lower. And by doing so， the brain may not see the pressure it is normally expecting and the patient may get lightheaded or dizzy.

    中心动脉压实际是心脏、大脑和肾脏的血压，为主动脉的压力。主动脉是大血管，当它将血液泵入较小的血管时，小血管可产生较高阻力。因此，如果在检测肱动脉（一个远小于中心大动脉的血管）血压时，血管越柔韧，产生压力误差的可能性就越小。血管越僵硬，可能性就越大。当然那些采用腕袖即在桡动脉处检测血压者获得的数据误差更大。事实上，压力值的不准确是指这些测量值将高于中心血压。如果按照这些血压进行干预，对于老年患者或血管僵硬的患者，有可能进一步降低已经较低的中心血压。并且，这种干预可使脑部压力不足，引起出血、眩晕或类似症状。

crackcrack