He is board-certified in emergency medicine, critical care medicine, and neurocritical care. He cares for patients at Harborview Medical Center in the following locations: Emergency Department, Medical Intensive Care Unit, Trauma/Surgical Intensive Care Unit, Neurocritical Care Service, and the Extracorporeal Life Support service. Dr. Johnson strives to improve the care of critically ill patients in the prehospital and emergency department settings, and ensure safe transitions to the intensive care unit.

Dr. Johnson studies cardiac arrest and early critical illness. He is interested in determining how ventilation strategies might impact outcome during and after cardiac arrest, in developing brain-protective resuscitation strategies, and extracorporeal support. He also participates in trials examining the early identification and treatment of ARDS, sepsis, and COVID-19. He has received funding from the National Institutes of Health, the Centers for Disease Control and Prevention, the Department of Defense, the Medic One Foundation, and the UW Royalty Research Fund.