You’re a doctor 11 hours into your shift, and you’ve just walked into a waiting area packed with patients. There’s an elderly man complaining of mild chest pain, a teenage girl whose arms are swollen with bee stings, and an ambulance that is bringing in two unresponsive kids from a car crash. What do you do next?

Welcome to a typical day on the job for doctors in emergency departments: the most intense department in any hospital, and home to the kind of split-second decision making, high-stress troubleshooting, and rapid medical detective work that can make the difference between a patient’s life and death.