Clinical review: Vasculitis on the intensive care unit – part 1: diagnosis

The first part of this review addresses the diagnosis and differential diagnosis of the primary vasculitides Wegener's granulomatosis, microscopic polyangiitis, Churg–Strauss syndrome and polyarteritis nodosa. Prompt diagnosis and treatment of these conditions ensures an optimal prognosis. The development of assays for antineutrophil cytoplasmic antibodies has aided the diagnosis of Wegener's granulomatosis and microscopic polyangiitis. However, even in cases where there is high clinical likelihood that these conditions are present, up to 20% may be antibody negative, whereas alternative diagnoses may be antibody positive. The final diagnosis rests on a balance of clinical, laboratory, radiological and histological features. The exclusion of alternative diagnoses is important in assuring appropriate therapy. Particular attention is paid to the more fulminant presentations of these conditions and the role of the critical care physician in their diagnosis and management.