Bench-to-bedside review: pulmonary-renal syndromes--an update for the intensivist

Abstract

The term Pulmonary-renal syndrome refers to the combination of diffuse alveolar haemorrhage and rapidly progressive glomerulonephritis. A variety of mechanisms such as those involving antiglomerular basement membrane antibodies, antineutrophil cytoplasm antibodies or immunocomplexes and thrombotic microangiopathy are implicated in the pathogenesis of this syndrome. The underlying pulmonary pathology is small-vessel vasculitis involving arterioles, venules and, frequently, alveolar capillaries. The underlying renal pathology is a form of focal proliferative glomerulonephritis. Immunofluorescence helps to distinguish between antiglomerular basement membrane disease (linear deposition of IgG), lupus and postinfectious glomerulonephritis (granular deposition of immunoglobulin and complement) and necrotizing vasculitis (pauci-immune glomerulonephritis). Patients may present with severe respiratory and/or renal failure and require admission to the intensive care unit. Since the syndrome is characterized by a fulminant course if left untreated, early diagnosis, exclusion of infection, close monitoring of the patient and timely initiation of treatment are crucial for the patient's outcome. Treatment consists of corticosteroids in high doses, and cytotoxic agents coupled with plasma exchange in certain cases. Renal transplantation is the only alternative in end-stage renal disease. Newer immunomodulatory agents such as those causing TNF blockade, B-cell depletion and mycophenolate mofetil could be used in patients with refractory disease.

Figure 1

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.