The research protocol will involve a prospective, observational analysis. Participants will include acutely ill COPD patients having an AE-COPD who are enrolled during an ER evaluation or hospitalization at Ann Arbor VA Hospital or the University of Michigan Health Systems ER, clinic, or wards. All non-study diagnostic testing, decisions to discharge from the ER or admit to hospital, prescription of medications, and non-study follow-up will be left to the discretion of the primary caregivers.