Dr. O'Brien has been with Overlake Internal Medicine Associates (OIMA) since 2000. He is a graduate of the University of Minnesota Medical School and he did his Internal Medicine Residency at Hennepin County Medical Center in Minneapolis. After completing residency he joined the Internal Medicine Department at Hennepin County Medical Center and was a Clinical Instructor of Medicine at the University of Minnesota. In 1993 he went on to do a pulmonary medicine fellowship at New York University and the Bellevue Hospital Chest Service in New York City. In 1996 to 1997 he did a critical care fellowship at Stanford University. His first position in the Pacific Northwest was in Bellingham, WA where he practiced for three years before moving to OIMA.

Dr. O'Brien is currently board certified in Pulmonary, Critical Care and Sleep Medicine. He has been certified in Internal Medicine. He is a fellow in the American College of Chest Physicians, and a member of the American College of Physicians and the American Thoracic Society. He has been a member of the American Association for the Advancement of Science.

His clinical interests are sleep medicine, tuberculosis and lung infections, blood clots of the lungs, asthma, COPD/emphysema, lung cancer, and critical care medicine.

In his free time he enjoys reading, sporting events, and travel. He has worked in India and traveled extensively in Europe, Asia and the United States.