The proper application and monitoring of patients under anesthesia is a crucial component in patient care. The first ever carbon dioxide measuring and recording device was first used by Luft in 1943 and since then, the technology involved in the device has grown enormously. The device with its mask called Capnography is to detect and help prevent situations caused by the harmful effects of hypoxia. Anaesthetists' main aim is to prevent hypoxia and if there are circumstances leading up to it, provide immediate correction with Capnography. Hypoxia can cause irreversible brain damage. Capnography is now used in not only emergency rooms and operation theaters, but its utility extends to X-ray rooms, endoscopy unit and even on mobile emergency units.