Pulmonary, Respiratory, and Blood Gas Terminology
Standardization of symbols in respiratory physiology dates from at least 1950.1
Despite the familiarity of abbreviations in pulmonary and respiratory medicine, authors and editors are encouraged to expand all terms at first mention, except as noted.
Symbols and abbreviations are both used. Symbols consist of separate elements in various combinations whose letters may differ from the initial letters of the expansion, eg, (perfusion). Abbreviations are usually initialisms.