How to Diagnose Resistant Hypertension

Joanne is prescribed three anti-heperotensive agents from three different classes. She comes back to the clinic in a month and her blood pressure is still high, it's 146 over 92. Is this resistant hypertension or pseudo resistant hypertension? We have to know do we trust the blood pressures we're getting. It has to be someone actually resting for five minutes before their blood pressure is checked.