間質性肺炎の呼吸機能検査

Pulmonary function tests in interstitial

間質性肺炎の呼吸機能的特徴というと，拘束性換気障害(肺活量の低下)，動脈血酸素分圧の低下，肺拡散能の低下になる．呼吸機能検査所見のみから，間質性肺炎の病態評価はできない．間質性肺炎の診断は画像所見，病理所見で下される．しかし画像・病理所見のみでは，患者の臨床症状(労作時呼吸困難など)を含めた肺全体の機能の把握はできない．間質性肺炎患者のQOLおよび予後には，呼吸機能が大きく関与している．①％FVC，％DLcoの低値，②％FVC，％DLco，AaDO₂の経時的変化，③6分間歩行距離，労作時SpO₂低下の程度，④肺高血圧症の存在，⑤労作時呼吸困難の程度，など呼吸機能指標を，画像・病理所見とともに把握する必要がある．

IIPs (idiopathic interstitial pneumonias) have undergone repeated redefinition over 30 years, based largely on revised histopathologic classification criteria.　Among them, IPF (idiopathic pulmonary fibrosis) has been defined as a poor response subgroup to traditional therapies and has a significantly worse prognosis than other forms of IIPs.　However, there is substantial heterogeneity in survival among IPF patients.　Clinical and physiological variables including pulmonary function tests are partly able to explain this heterogeneity.　In addition, these variables may affect prognosis and QOL.　The rate of progression as well as baseline variables of FVC, FEV₁, DLco, PaO₂, SpO₂ during exercise and so on, should be evaluated in patients with IIPs including IPF.