Relative frequencies of conditions contributing to Pulmonary–renal syndrome in the intensive care unit. Relative frequencies of conditions contributing to Pulmonary–renal syndrome in the intensive care unit based on mean values from data on patients' characteristics provided by [69,70] (shown in detail in Table 2). Perinuclear antineutrophil cytoplasmic antibodies (P-ANCA) vasculitis is the most frequent cause of Pulmonary–renal syndrome for patients admitted to the intensive care unit. 'Other' includes systemic lupus erythematosus, catastrophic antiphospholipid syndrome, polyarteritis nodosa, HIV-related vasculitis, cryoglobulinaemic vasculitis and Henoch–Schönlein purpura. C-ANCA, cytoplasmic antineutrophil cytoplasmic antibodies; anti-GBM, antiglomerular basement membrane.