His systolic reading was high, so the doctor advised him to cut down on salt.

systolic 是形容词，来自名词 systole（心脏收缩期）。在医学中，systolic 特指"收缩期的"，systolic reading 指心脏收缩时测得的血压值，即"收缩压"。 reading 在这里指"读数、测量值"，特指血压计上显示的数值。