How do you know your having a panic attack when you're in the middle of one?

Panic. You suddenly feel apprehensive & fearful, feel urge to escape, feel like u r having a heart attack or going crazy, feel nauseated or like passing out, u shake & sweat & breath fast, feel numb & like choking.
Panic symptoms. During a panic attack you are experiencing a peak of anxiety that will usually last from 20 to 30 minutes. Physical symptoms: rapid pulse, difficulty breathing, sweating, tremulousness, hot and/or cold flashes, light-headedness. Thoughts: sense of impending doom, sense of helplessness, fear of dying, loss of control, etc. Behavior: avoiding places or events, escaping, restlessness, pacing, etc.
You may not! For a lot of people, the first panic attack feels like you are dying! so the first doc to see that person is frequently an er doc.