Several methods are used to monitor concentrations of O₂, CO₂, and anesthetic gases in the breathing system. The oxygen analyzer is the most important monitor for detecting a hypoxic gas mixture. Capnometry, the measurement of CO₂, has many uses, including monitoring the adequacy of ventilation and detecting breathing system faults. Breath-to-breath monitoring of anesthetic concentrations provides tracking of anesthetic uptake and distribution. Most gas analyzers incorporate alarms. Among the techniques for measurement are the following: