NYU Langone Medical Center announced on Wednesday significant changes in its procedures after the death by septic shock of a 12-year-old boy who was sent home. Three hours after the boy, Rory Staunton, left the emergency room, a laboratory test showed that his blood had extraordinarily high levels of cells associated with bacterial infections. He subsequently went into shock and experienced organ failure, and died three days later, on April 1. The hospital has developed a new checklist to ensure that a doctor and nurse have conducted "a final review of all critical lab results and patient vital signs" before a patient leaves, Lisa Greiner, a spokeswoman, said in the statement.