Capnography
Capnography, the window to the airway, has its origins in John Tyndall’s 1860s discovery that carbon dioxide absorbs infrared radiation. The first clinical analyser appeared in the 1940s, but capnography only became routine in the 1990s. It confirms endotracheal tube placement, detects hypoventilation, and reveals airway obstruction—essential monitoring that has transformed the safety of anaesthesia.
