透析患者の透析効率を計算するには日本透析医学会の推奨する新里式があります．原著論文を見ると積分方程式を解く必要があり，一般的な数学の知識では歯が立ちません．ここでは Daugirdas による Kt/V をデータベース内で計算する方法を述べます．新里自身も Daugirdas による Kt/V と新里式による Kt/V とはかなり一致していると述べており，ほぼ代用可能ではないかと思われます．(1) が Daugirdas の方法で (2) と (3) を解くと新里式になります．
![\displaystyle \mathrm{Kt/V} = - LN( R - 0.008 \times t ) + \left[ 4 - \left( 3.5 \times R \right) \right] \times\frac{\mathrm{UF}}{\mathrm{W}}\\ = - LN \left( \frac{\mathrm{postBUN}}{\mathrm{preBUN}} - 0.008 \times t \right) + \left[ 4 - \left( 3.5 \times \frac{\mathrm{postBUN}}{\mathrm{preBUN}} \right) \right] \times \frac{\mathrm{preWeight} - \mathrm{postWeight}}{\mathrm{postWeight}} \cdots(1)](https://s0.wp.com/latex.php?latex=%5Cdisplaystyle+%5Cmathrm%7BKt%2FV%7D+%3D+-+LN%28+R+-+0.008+%5Ctimes+t+%29+%2B+%5Cleft%5B+4+-+%5Cleft%28+3.5+%5Ctimes+R+%5Cright%29+%5Cright%5D+%5Ctimes%5Cfrac%7B%5Cmathrm%7BUF%7D%7D%7B%5Cmathrm%7BW%7D%7D%5C%5C++%3D+-+LN+%5Cleft%28+%5Cfrac%7B%5Cmathrm%7BpostBUN%7D%7D%7B%5Cmathrm%7BpreBUN%7D%7D+-+0.008+%5Ctimes+t+%5Cright%29+%2B+%5Cleft%5B+4+-+%5Cleft%28+3.5+%5Ctimes+%5Cfrac%7B%5Cmathrm%7BpostBUN%7D%7D%7B%5Cmathrm%7BpreBUN%7D%7D+%5Cright%29+%5Cright%5D+%5Ctimes+%5Cfrac%7B%5Cmathrm%7BpreWeight%7D+-+%5Cmathrm%7BpostWeight%7D%7D%7B%5Cmathrm%7BpostWeight%7D%7D+%5Ccdots%281%29&bg=T&fg=000000&s=0 "\displaystyle \mathrm{Kt/V} = - LN( R - 0.008 \times t ) + \left[ 4 - \left( 3.5 \times R \right) \right] \times\frac{\mathrm{UF}}{\mathrm{W}}\\ = - LN \left( \frac{\mathrm{postBUN}}{\mathrm{preBUN}} - 0.008 \times t \right) + \left[ 4 - \left( 3.5 \times \frac{\mathrm{postBUN}}{\mathrm{preBUN}} \right) \right] \times \frac{\mathrm{preWeight} - \mathrm{postWeight}}{\mathrm{postWeight}} \cdots(1)")
![\displaystyle \mathrm{Ce} = \mathrm{Cs} Exp\left( - \frac{\mathrm{Kt}}{\mathrm{V}} \right) + \frac{\mathrm{G}}{\mathrm{K}}\left[ 1 - Exp\left( - \frac{\mathrm{Kt}}{\mathrm{V}} \right) \right] \cdots(3)](https://s0.wp.com/latex.php?latex=%5Cdisplaystyle+%5Cmathrm%7BCe%7D+%3D+%5Cmathrm%7BCs%7D+Exp%5Cleft%28+-+%5Cfrac%7B%5Cmathrm%7BKt%7D%7D%7B%5Cmathrm%7BV%7D%7D+%5Cright%29+%2B+%5Cfrac%7B%5Cmathrm%7BG%7D%7D%7B%5Cmathrm%7BK%7D%7D%5Cleft%5B+1+-+Exp%5Cleft%28+-+%5Cfrac%7B%5Cmathrm%7BKt%7D%7D%7B%5Cmathrm%7BV%7D%7D+%5Cright%29+%5Cright%5D+%5Ccdots%283%29&bg=T&fg=000000&s=0 "\displaystyle \mathrm{Ce} = \mathrm{Cs} Exp\left( - \frac{\mathrm{Kt}}{\mathrm{V}} \right) + \frac{\mathrm{G}}{\mathrm{K}}\left[ 1 - Exp\left( - \frac{\mathrm{Kt}}{\mathrm{V}} \right) \right] \cdots(3)")
下記プロシージャを実行して関数を作成します．
CREATE FUNCTION Function_KtV ( @preBUN DEC(4, 1) , @postBUN DEC(4, 1) , @preWeight DEC(4, 1) , @postWeight DEC(4, 1) , @DialysisDuration int ) RETURNS DEC(3,2) AS BEGIN DECLARE @KtV DEC(3, 2) SELECT @KtV = - LOG(@postBUN / @preBUN - 0.008 * @DialysisDuration / 60) + (4 - (3.5 * @postBUN / @preBUN)) * ((@preWeight - @postWeight) / @postWeight) RETURN @KtV END GO
参照：透析会誌 29 (12): 1511-1516, 1996
Second Generation Logarithmic Estimates of Single-Pool Variable Volume