肺胞気式
肺胞の空気を計算する他の形態の式も存在する。例えば、
P A O 2 = F I O 2 ( P B − P H 2 O ) − P A C O 2 ( F I O 2 + 1 − F I O 2 R ) = P I O 2 − P A C O 2 ( F I O 2 + 1 − F I O 2 R ) = P I O 2 − V T V T − V D ( P I O 2 − P E O 2 ) = P E O 2 − P I O 2 ( V D V T ) 1 − V D V T {\displaystyle {\begin{aligned}P_{A}{\ce {O2}}&=F_{I}{\ce {O2}}\left(PB-P{\ce {H2O}}\right)-P_{A}C{\ce {O2}}\left(F_{I}{\ce {O2}}+{\frac {1-F_{I}{\ce {O2}}}{R}}\right)\\&=P_{I}{\ce {O2}}-P_{A}C{\ce {O2}}\left(F_{I}{\ce {O2}}+{\frac {1-F_{I}{\ce {O2}}}{R}}\right)\\&=P_{I}{\ce {O2}}-{\frac {V_{T}}{V_{T}-V_{D}}}\left(P_{I}{\ce {O2}}-P_{E}{\ce {O2}}\right)\\&={\frac {P_{E}{\ce {O2}}-P_{I}{\ce {O2}}\left({\frac {V_{D}}{V_{T}}}\right)}{1-{\frac {V_{D}}{V_{T}}}}}\end{aligned}}}