Contribution of multiple inert gas elimination technique to pulmonary medicine. 2. Chronic pulmonary diseases: chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis.

The multiple inert gas elimination technique (MIGET) was first described by Wagner et al in 1974.' It allows quantitation of the ventilation- perfusion (VA/Q) distribution and a precise analysis of the intrapulmonary and extra- pulmonary factors that govern gas exchange in humans. This review discusses how this technique has facilitated a better understanding of the mechanisms underlying gas exchange in two common chronic lung diseases -chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis. The methodo- logical aspects ofthe MIGET are not discussed, and the interested reader is referred to the first review in this series (Thorax 1994;49:815-824) or to some comprehensive reviews published recently on this subject.