End-tidal carbon dioxide physiology and monitoring during resuscitation

This article discusses the measurement, physiology, and clinical use of end-tidal CO₂, especially during low blood flow states. End-tidal CO₂ concentration depends on both pulmonary blood flow and minute ventilation. CO₂, if present, is helpful in confirming tracheal intubation, even in cardiac arrest. Poor blood flow during CPR is associated with a low end- tidal CO₂ concentration and a poor chance for resuscitation and survival from cardiac arrest. The limitation of end-tidal CO₂ monitoring is that levels are affected by perfusion, ventilation, and CO₂ production.