Summary:The time-dependent concentrations of hyaluronan, aminoterminal propeptide of type III procollagen, and laminin were determined in sera of 16 patients with severe adult respiratory distress syndrome during treatment with an extracorporeal CO 2 removal device. Patients were classified according to lung Parameters äs responders (n = 10) and non-responders (n = 6) to extracorporeal CO 2 removal. At the beginning of treatment strongly elevated serum concentrations of all studied extracellular matrix components were found. During the first 6-11 days of treatment the concentrations of aminoterminal propeptide of type III procollagen and hyaluronan increased further in non-responders but decreased in the majority of responders, while laminin decreased in both groups. No significant correlations were found between the serum concentrations of connective tissue components and the parameters of lung function. By non-parametric analysis of variance, significant differences between responders and non-responders according to treatment time could be established. By analysing the time course of the serum concentrations of hyaluronan and aminoterminal propeptide of type III procollagen, a total differentiation between responders and nonresponders was made pössible by the trends of these analytes äs early äs three days after the Start of treatment. The determination of aminoterminal propeptide of type III procollagen and hyaluronan in serum of patients with adult respiratory distress syndrome might therefore have prognostic significance in extracorporeal CO 2 removal. unfavourable rapid development of pulmonary fibroThe adult respiratory distress syndrome is a severe sis within about 2 weeks (5, 6), characterized by an condition of life-threatening organ failure, character-increase in fibroblast numbers and accelerated collaized by tachypnoea, hypoxaemia, diffuse interstitial gen metabolism (7,8). mfiltrates, alveolar oedema, and loss of lung compliance (l, 2). The syndrome develops in response to a Components of the extracellular matrix have been primary attack on lung cells like inhalation of toxins, determined in blood of patients with fibrotic lung aspiration of gastric contents (3) or äs a consequence diseases, but in contrast to e. g. liver fibrosis there of systemicdisorders like septicshock and multiorgan seems to be only a weak association between the trauma. Severe, progressive cases are associated with concentrations of such analytes in blood and the a mortality rate of up to 90% (4). One sequel of adult activity and/or grade of the fibrosing process in the respiratory distress syndrome is the prognostically lung (9).