A "steeple sign" capnogram occurs during positive pressure ventilation when there is a leak in the sample line of a sidestream capnography monitor. This occurs because air entrained through the leak dilutes the sampled carbon dioxide, and the magnitude of the leak varies with phasic pressure changes in the breathing circuit.
From: Kodali BS. Capnography outside the operating rooms. Anesthesiology 2013; 118:192. DOI:
10.1097/ALN.0b013e318278c8b6. Copyright © 2013 American Society of Anesthesiologists. Reproduced with permission from Lippincott Williams & Wilkins. Unauthorized reproduction of this material is prohibited.
