End-tidal carbon dioxide (EtCO2) monitoring is a noninvasive method used to measure the concentration of carbon dioxide at the end of an exhaled breath. This measurement provides valuable information about a patient's ventilation and metabolism. EtCO2 monitoring is commonly used in various medical settings, such as during anesthesia, in intensive care units, and in emergency medicine, to help monitor a patient's respiratory status and make clinical decisions. It is often used in conjunction with other vital signs monitoring to provide a comprehensive assessment of a patient's respiratory function.