The concentration effect refers to the rapid rise in Fa(alveolar concentration)/Fi(inspired concentration) of an inhaled gas. In simple terms, the higher the concentration of gas used the faster the alveolar concentration of that gas. This theoretically only happens with nitrous oxide.
- Korman B, Mapleson WW (May 1997). "Concentration and second gas effects: can the accepted explanation be improved?". Br J Anaesth 78 (5): 618–25. PMID 9175984.