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Kokyu to Junkan Volume 36, Issue 10 （October 1988）

呼吸と循環 36巻10号（1988年10月発行）

Japanese English

研究

一側肺低酸素換気時の分離肺血流量比算出の理論式 Determination of differential pulmonary blood flow in hypoxic challenge Test:Theory 松下芙佐子 ¹ Fusako Matsushita ¹ ¹東京大学医学部麻酔学教室 ¹Department of Anesthesiology, Faculty of Medicine, University of Tokyo pp.1113-1117

発行日 1988年10月15日 Published Date 1988/10/15

DOI https://doi.org/10.11477/mf.1404205347

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Abstract 文献概要
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　左右肺を分離換気した場合の左右肺の血流比を求めるには，難溶性指示ガスを静脈系に投与し左右肺からの呼出量比を測定するのが一般的な方法である^1）。炭酸ガスを血流の指示ガスとして利用する場合にも，左右肺からの呼出量比を測定してそれより血流比を計算できる可能性がある^2）が，炭酸ガスの場合は混合静脈血の炭酸ガスが肺胞へ全て呼出されるわけではなくかなりの割合で肺胞終末毛細管血（end capillary blood）に残るために，血流比算出のためには左右肺各々の終末毛細管血の炭酸ガス含量を知る必要がある。その場合，血液炭酸ガス含量は血液酸素飽和度の影響を受ける（いわゆるホールデン効果）ため，低酸素換気側の肺胞終末毛細管血炭酸ガス含量の計算に酸素飽和度の数値が必要である^3）。

　この報告は低酸素換気側肺の肺胞終末毛細管血の酸素飽和度の算出法を示し，ホールデン効果の補正を含めた血流比の理論算式系を提出するものである。

In this paper present author proposes a new me-thod to determine per cent blood flow to the lung challenged hypoxic (%Q) and oxygen saturation in end capillary blood of the lung (S_ecO₂),, simultaneo-usly when one lung is normoxic (ventilated with 100% O₂) and the other hypoxic.

There are two well-known relations, relation between %Q and CO₂ content in end capillary blood (C_ecco₂) and relation between %Q and O₂ content in end capillary blood (C_ecO₂), that is, so-called mass balance equations. I found that the rela-tion between %Q and C_ecco₂ can theoretically be transformed to the relation between %Q and S_ecO₂. This relation is given as a group of curves that shift with changes in end tidal CO₂ partial pressure (P_ETCO₂). The relation between %Q and C_ecO₂ also can theoretically be transformed to the another rela-tion between %Q and S_ecO₂. And also, this relation is given as a group of curves that shift with chan-ges in P_ETco₂. In these transformations I used the KELMAN' program, CO₂ equilibration curve, BE curve and ADAIR' equation. In the KELMAN's program the coefficients from VAN SLYKE & SENDROY' nomogram were employed. CO₂ equili-bration curve and BE curve were derived from SIGGAARD-ANDERSEN' curve nomogram. These two relations between %Q and S_ecO₂ are mutually independent, and so determine a point in S_ecO₂- %Q plane, if P_ETCO₂ is fixed. And this is the point wanted to be known.

Applying this method, for example, to the case in which one lung is ventilated with 100% O₂2 (me-asured P_ETco₂=30 mmHg) and the other with 100% N₂ (measured P_ETco₂= 17 mmHg), a pair of values, 72. 3% for S_ecO₂ and 24.3% for %Q, was determi-ned.