Snapshot An infant is brought to the emergency room for increasing cyanosis around the lips. His mother’s pregnancy was uncomplicated and he was born at 39 weeks without complications. His parents started feeding him water from their backyard well, which they have been using for years. A pulse oximetry reading shows oxygen saturation of 86%, despite supplemental oxygen administration. He is also found to be tachycardic. A CO-oximetry shows methemoglobinemia level of 15%. The patient is started on methylene blue. (Well water contaminated with nitrates) Introduction Clinical definition login to view 3 more bullets Epidemiology Demographics login to view 1 more bullet Risk factors login to view 9 more bullets ETIOLOGY Pathogenesis login to view 7 more bullets Presentation Symptoms login to view 7 more bullets Physical exam login to view 6 more bullets Studies Diagnostic testing login to view 9 more bullets Differential Cyanide poisoning login to view 4 more bullets DIAGNOSIS Making the diagnosis login to view 2 more bullets Treatment Management approach login to view 2 more bullets First-line login to view 10 more bullets Other treatments login to view 4 more bullets Complications End-organ failure Acute respiratory distress syndrome