Stewart Julian M
Department of Pediatric, The Center for Pediatric Hypotension, New York Medical College, Valhalla 10595, USA.
J Pediatr. 2002 Apr;140(4):418-24. doi: 10.1067/mpd.2002.122643.
We hypothesized that transient hypotension associated with the symptom of lightheadedness with standing is a common phenomenon in healthy adolescents but may be mistaken for orthostatic intolerance.
We studied 23 healthy adolescents, combining upright tilt to 70 degrees and to 35 degrees (in 12 patients) with continuous heart rate and blood pressure (BP) measurements. We measured peripheral blood flow and venous pressure in the arms and legs by using venous plethysmography.
Healthy subjects with normal vasoconstrictive responses to sustained upright tilt uniformly have a transient fall in BP during 70 degrees upright tilt that varies from almost undetectable to large decreases in BP easily exceeding the 20-mm Hg threshold for orthostatic hypotension. Large decreases are associated with short-lived symptoms of lightheadedness and are most marked in those with the largest calf blood flow. The higher the flow, the lower the BP falls. There is appropriate reflex tachycardia.
We conclude that transient orthostatic hypotension is common in many healthy adolescents, especially after prolonged recumbency, and is related to dependent vascular tone.
我们推测，与站立时头晕症状相关的短暂性低血压在健康青少年中是一种常见现象，但可能被误诊为直立不耐受。
我们对23名健康青少年进行了研究，将其倾斜至70度和35度（12名患者），同时持续测量心率和血压（BP）。我们使用静脉体积描记法测量手臂和腿部的外周血流量和静脉压。
对持续直立倾斜具有正常血管收缩反应的健康受试者在70度直立倾斜期间血压均会出现短暂下降，下降幅度从几乎无法检测到大幅下降，很容易超过直立性低血压20毫米汞柱的阈值。大幅下降与短暂的头晕症状相关，在小腿血流量最大的受试者中最为明显。血流量越高，血压下降越低。存在适当的反射性心动过速。
我们得出结论，短暂性直立性低血压在许多健康青少年中很常见，尤其是在长期卧床之后，并且与依赖性血管张力有关。
