How can you get an accurate blood pressure reading in someone with panic disorder? i always feel panicked at the doc which will raise blood pressure

That is accurate: A person with a panic disorder may have a high blood pressure reading because he is anxious at that time. That reading is his real blood pressure at that time, and therefore is accurate. Furthermore, if he is anxious most of the day, then his high blood pressure truly reflects his usual state of being. To try to get a lower pressure might give lower numbers, but there will be less reality.