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はじめに
肺におけるO2—uptake,CO2—elminationは生存の基本的条件であり,各種心肺疾患ではこれらのうちのいずれか,とくにしばしばO2—uptakeが障害され,全身に循環する動脈血の酸素不飽和を惹起して生命に危険をもたらすことが知られている。胸部X線写真,従来の理学的検査法などでは,かかる障害の指摘が不可能なことは衆知の通りであり,したがって最近ではspirogramの普及とともに呼吸機能検査全般に対する必要性の認識が急速に深まりつつある。しかしながら,spi—rogramによる肺活量,1秒量,1秒率,最大換気量などの測定では,肺全体への空気の出入りを人為的な呼吸法で観察することによりその予備能力を判定するのに止まり,さらに,安静呼吸時の換気量測定,呼気ガス分析などを加えたとしても,呼吸機能本来の目的である"O2—uptake,CO2—elmination"の障害度とその性質を明らかにし,診断と治療に役立てることは不可能である。にも拘らず,spirogramを始めとする換気力学的検査の成績が過大に評価され,それのみをもって呼吸機能検査を代表させる傾向にあるが,かかる観点のみでは,患者の生命に対する危険度を適確に判断することができない場合もありうる。
In many obstructive airway diseases, alveolar functions, especially a-ADco2, A-aDo2, shuntlike effects and VA/Q were studied. They were compared with other parameters of cardio-pulmonary functions. The "mean alveolar Po2" was calculated from the alveolar air equation using the end-tidal Pco2 determined by an infra-red CO2 analyser, in place of the Paco2were measured by a combianalyser simultane-ously.
1) a-ADco2 were 2.0±1.9, 12.3±6.7, 12.4±8.9 and 13.7±5.6 mmHg, in normal, bronchial asthma, chronic bronchitis and chronic pul-monary emphysema, respectively.
2) Since the a-ADco2 exists, the "mean alveolar PO2" thus obtained was found approx. 15mmHg higher than the PAo2 which was calculated using the Pacp2 in chronic obstructive air way diseases. Thus obtained A-aDo2 were 9.0±4.6, 40.5±15.8, 39.6±19.1 and 47.0±12.6 mmHg in normal, bronchial asthma, chronic bronchitis and chronic pulmonary emphysema, respec-tively.
3) The A-aDo2 had negative correlation with the Pao2(r=-0.765), while the a-ADco2 were roughly correlative with the Paco2 (r=0.643) at rest, or after administration of bronchodi-lator.
4) Neither the A-aDo2 nor the a-ADco2 corre-lated with the FEV1/VC at rest, or after administration of bronchodilator. In some cases, decreases in A-aDo2 and the a-ADco2 were found without any increase in the FEV1/VC.
5) The a-ADco2 were correlative with the alveolar dead space ventilation ratio 〔r= 0.927, VDalv・/VTalv・=3(a-ADco2)0.9〕 at rest, or after admi-nistration of bronchodilator.
6) The A-aDo2 and a-ADco2 tended to correlate with the total pulmonary resistance (r=0.522, r=0.660). Furthermore, VA/Q in slow space had rough negative correation with the total pulmonary resistance (r=-0.663).
7) In all cases, anatomical shunts were within 10%, but the shuntlike effects due to uneven-ness of VA/Q distribution were more than 10%. The later was exponential correlative with the A-aDo2(QS/QT=1.5e0.047(A-aDo2))at rest, or after administration of bronchodilator.
Authors make up the alveolar function dia-gram consisted with both a-ADco2 (ordinate) and A-aDo2 (abscissa). This diagram may give a clinical estimation of the severity in chronic obstructive air way diseases.
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