Superior mediastinal syndrome: emergency management.

Superior Vena Cava Syndrome (SVCS) refers to signs and symptoms caused by obstruction of the superior vena cava. Superior mediastinal syndrome (SMS) is the term used when SVCS coexists with obstruction of trachea. In children, a mediastinal pathology causing SVCS generally results in SMS as well, due to the limited chest volume. Hence, the two terms are often used interchangeably in children. SMS is a medical emergency that can be challenging, albeit often rewarding to manage. The common causes in a patient presenting to pediatric emergency room include non-Hodgkin lymphoma and acute lymphoblastic leukemia. Patients with SMS are at a very high risk for adverse cardio-respiratory events in case they are administered any kind of anesthetic agents, anxiolytics or sedatives. Investigations, including tissue diagnosis are desirable, though not mandatory, before initiating emergency management. The patient's clinical condition should dictate the speed, requirement and sequence of investigations and the specific treatment. The least invasive procedure should be performed to confirm the diagnosis. As the most common cause of SMS in children is lymphoma/leukemia, the administration of systemic steroids is often the front line therapy. Diagnosis, monitoring and management of SMS in relevance to the pediatric emergency room are outlined.