Although fibroblasts are key cells in the lung repair/fibrosis process, their characteristics are poorly studied in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). The aims of our study were to: 1) determine the biological behaviour of alveolar fibroblasts during ALI; and 2) to evaluate the clinical relevance of positive alveolar fibroblast culture from patients with ALI/ARDS. Cells were cultured from bronchoalveolar lavage (BAL) obtained from 68 critically ill, ventilated patients: ALI n517; ARDS n531; and ventilated controls n520. Patients were followed for 28 days and clinical data was recorded. We studied proliferation, migration and collagen-1 synthesis capacities of fibroblasts.Cells expressing fibroblast markers were cultured from BAL obtained in six (35%) ALI patients and six (19%) ARDS patients, but never from ventilated controls. Alveolar fibroblasts exhibited a persistent activated phenotype with enhanced migratory and collagen-1 production capacities, with hyporesponsiveness to prostaglandin E 2 compared to normal lung fibroblasts (pf0.04). Positive fibroblast culture was associated with both an increased collagen-1 concentration and monocyte/macrophage percentage in BAL fluid (pf0.01), and with a reduced duration of mechanical ventilation (p,0.001).We conclude that activated alveolar fibroblasts can be cultured either in ALI or ARDS and that their presence might reflect the initiation of the organising phase of ALI.

Fibrocytes are detectable in bronchoalveolar lavage during acute lung injury and acute respiratory distress syndrome. A bronchoalveolar lavage fibrocyte percentage >6% provides an additive prognostic value to clinical predictors and may be useful to identify patients with acute lung injury and acute respiratory distress syndrome at highest risk of an adverse outcome.

duplex scan, if validated, appears to be a reliable means for excluding the presence of endoleak after EAAR.

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