IMO, if the patient is coming in for a BP check, he/she should not be billed.
1. It's good PR to have the patient come in for a BP check for free. With the high cost of health care and patients always looking for a bargain, why would you charge them for something they can receive for free at a fire station, pharmacy or drug store?
2. Keeps the patient in contact with his/her MD office. If the patient returns to your office for BP checks and there is a problem, zip them in to see the MD. Your office has his/her history.
For 99211, you need a chief complaint, vitals and medical necessity.
Good luck,