Pulmonary-renal syndromes: an update for respiratory physicians.

Pulmonary-renal syndromes are a group of disorders characterised by necrotising glomerulonephritis and pulmonary haemorrhage. Small vessel systemic vasculitis is the most common cause of pulmonary-renal syndromes presenting to respiratory physicians. Rarer causes include systemic lupus erythematosus and connective tissue diseases though severe pneumonia or cardiac failure may mimic their presentation. Some forms of small vessel vasculitides have a predilection for the pulmonary and renal vascular beds and if left untreated can result in fulminant organ failure. Whilst the aetiology of these syndromes remains unclear, much is known about the disease mechanisms including the pathogenic role of autoantibodies, immune-complex mediated inflammation and microangiopathic in-situ thrombosis. Despite established treatments achieving successful remission induction, patient tolerability and side effect profiles have limited their use which has led to searches for more targeted treatments. Consequently newer biological therapies have gained wider acceptance despite little being known about their long term safety and efficacy. The European Vasculitis Study Group (EUVAS) have recently formulated guidelines to provide consensus on diagnosis and management in this area and work to define survival rates in these conditions with longer term follow-up studies is ongoing. This review summarises the current aetiopathogenesis thought to underlie these complex diseases, the diagnostic definitions and classification criteria currently in use and the evidence base for modern therapies. Though unusual for respiratory specialists to coordinate overall management of these patients, an update on their current management is regarded as important to their practice given the recently changing trends in treatments.