Two elderly women died recently at Saint Raphael Hospital in New Haven, Connecticut after they were accidentally given nitrous oxide rather than oxygen while undergoing surgical procedures. A hose was mistakenly plugged into a receptacle for the poisonous gas. Safety prongs that were designed to prevent such mishaps had broken off. When the patients' blood oxygen levels began to plunge during both operations, doctors administered more of what they thought was oxygen. The excessive levels of nitrous oxide killed the women. Health officials are currently investigating the machinery and medical procedures used at the hospital.