Cyclopropane is a cycloalkane, consisting of three carbon atoms, linked to each other to form a ring. Cyclopropane was used as an anesthetic gas since the 1920s, due to being non-irritant, giving rapid induction, excellent relaxation, quiet respiration, and speedy recovery. However, the prolonged administration of cyclopropane may induce a reaction known as "cyclopropane shock", which manifests in a sudden decrease in blood pressure, potentially leading to cardiac dysrhythmia. Because of the toxicity and extreme flammability, cyclopropane was used only for the induction of anesthesia and was gradually superseded by more safe anesthetics. Cyclopropane works by blocking NMDA and AMPA receptors and activating K2P channels, kainate ion channels and glycine receptors at clinical concentrations.