To analyze a multi-center observational study database. to select adult non-traumatic in-hospital cardiac arrest. Review and recored end-tidal carbon dioxide in per minute. Arrange them in different time line. one is in resuscitation time. The other is the time line which the beginning time is the time of starting appearing stable end-tidal carbon dioxide wave.To compare predictive power of end-tidal carbon dioxide between different time line during resuscitation.

Inclusion Criteria:

adult non-traumatic in-hospital cardiac arrest patients Exclusion Criteria:1) surrogate decision of Do-Not-Resuscitate (DNR) during CPR; 2) out-of-hospital cardiac arrest (OHCA) patient; 3) trauma as the main reason for medical treatment; 4) child or adolescent patients; 5) Petco2 value was not recorded effectively; 6) delay from initial CPR to starting to record Petco2 exceeded 30 min; and 7) screening by qualified experts. More than three experienced physicians thought that the patient's Petco2 value was too extreme to agree with his/her medical history, and the value was seen as an error and was excluded

CPR patient being treated in the emergency department