Pulmonary hemorrhage, characterized by diffuse intra-alveolar bleeding, is an uncommon but life-threatening manifestation of SLE. It is likely that clinically insignificant or undetectable intra-alveolar hemorrhage occurs in many patients. One retrospective study of 76 autopsy cases of SLE collected over a period of 20 years observed that, even though pulmonary hemorrhage was clinically suspected or noted in less than 2 per cent of patients, it was the primary cause of death in 14 per cent. In another series of 57 patients pulmonary bleeding was the cause of death in 10.5 per cent. The mechanism of pulmonary hemorrhage is unclear, although pulmonary vasculitis and capillaritis are probably responsible. Other mechanisms include the activation of the complement system leading to deposition of immune-complex deposits in the capillary basement membrane of the lungs. The end result is a break in the integrity of the alveolar-capillary basement membranes. The presence of uremia, hemorrhagic diathesis, oxygen toxicity, and infection may increase the risk of pulmonary hemorrhage. Viral infection may lead to hemorrhagic pneumonia. Pathological analysis of the lungs in cases of intra-alveolar hemorrhage has shown abnormalities similar to those of lupus pneumonitis (see below) as well as distinctive vasculitis of small vessels.
Pulmonary hemorrhage is almost never encountered in patients whose primary disease is quiescent. As a rule, it is more likely in those with active and progressive disease. The presence of renal failure as a result of SLE increases the risk of pulmonary hemorrhage. A clinical caveat is that pulmonary hemorrhage can be the presenting manifestation of SLE. Pulmonary hemorrhage may vary from subclinical to massive in quantity. Clinically significant hemorrhage will present as cough with hemoptysis and progressive dyspnea. Significant hemoptysis is noted in about 10 per cent of patients with these symptoms. The onset of hemoptysis and progressive respiratory distress can be abrupt, and the clinical presentation frequently resembles that of acute lupus pneumonitis. Chest radiographs usually reveal bibasilar patchy alveolar infiltrates that are predominantly central (perihilar) in location. The degrees of hypoxia, respiratory distress, and respiratory failure are directly proportional to the extent of intra-alveolar bleeding. Bronchoscopy may reveal diffuse oozing of blood from many segmental bronchi, and the effluent from the bronchoalveolar lavage will be bloody throughout the procedure. Chronic subclinical pulmonary alveolar hemorrhage occurs less commonly than the acute variety and may occur intermittently. It may lead to a clinical and pathological picture of pulmonary hemosiderosis. A diagnostic bronchoalveolar lavage is likely to show a large number of hemosiderin-laden macrophages, although this finding alone is not diagnostic.
Pulmonary hemorrhage caused by SLE requires immediate therapy if the bleeding is significant enough to cause respiratory failure. The initial management of the respiratory disease may require supplemental oxygen therapy, endotracheal intubation and ventilation, and diagnostic bronchoscopy. The medical treatment consists of high-dose prednisone therapy (1.5-2.0 mg/kg/day) supplemented by a cytotoxic agent such as cyclophosphamide (2 mg/kg/day). Plasmapheresis has been used successfully to clear the circulating immune complexes. The mortality from SLE-induced pulmonary alveolar hemorrhage is in excess of 50 per cent, with many patients dying within a few days of the onset of hemoptysis.
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