Multiple inert gas elimination technique in interstitial lung disease: analysis of ventilation - perfusion relationship

There aerI.' stilI few studies on the mechanisms underlying arterial hypoxemia in interstitial lung disease , From these studies arterial hypoxemia was suggested to be a result of various mechanisms: the thickening of alveolar interstitium which reduces the diffusing capacity for oxygen (l, 2); the reduction of alvleolar capillary bed(3); the alteration of alveolar capillary membranes in a non uniform manner, thus causing a ventilation-perfusion mismatching (4); the low mixed venous oxygen tension due to low values of cardiac output and the short,ned timI.' available for diffusion of oxygen across the alveolar-capillary membrane due to pulmonary vascular involvement present in advanced interstitial lung disease (:5, 6). Our pr.sent study was therefore performed with the aim to analyse the probable causes of hypoxemia in patient with interstitial lung disease by the assessment of ventilation-plerfusion relationships from multiple inert gas technique (4). This method is a useful approach for the evaluation of pulmonary gas exchange and, in particular, for the analysis of the relationships between the distribution of ventilation (V) and perfusion (Q) in respect to their V/Q ratio. In this brief paper the preliminary results on three patients have been reported.