False-negative capnographic reading caused by a malfunctioning bag-valve-mask device resulting in a pneumomediastinum.

Bag-valve-mask ventilation is generally a safe, and often a life-saving procedure for children who are unable to oxygenate or ventilate by themselves. A case is presented which describes a malfunctioning expiratory valve in a disposable manual bag-valve-mask device resulting in a pneumomediastinum in a child. This is a rare cause of a false-negative colorimetric end-tidal carbon dioxide (ETCO2) reading after endotracheal intubation. However, it is important to recognize so that further adverse outcomes can be prevented.