12

The clinical correlate of alveolar hemorrhage is hemoptysis, or expectoration of blood (Table 12–1). Hemoptysis may be acute, massive, and exsanguinating, or a chronic process with trivial production of bloody sputum. Expectorated blood may derive from other sites than the lung, including the stomach and upper air passages, and exclusion of these sites of origin is essential. In evaluating hemoptysis, the clinician frequently attempts to determine whether it has a localized source or is a diffuse bilateral process. Chest radiographs can be helpful in making this determination. The color of the blood is also of some clinical importance. Dark venous blood derives from the pulmonary arteries. Bright red blood has a bronchial vein or bronchial artery origin; clotted blood often suggests to the clinician that the hemorrhage has been present for some time. Examination of the bloody expectorant by cytology is important to exclude neoplasias and hemorrhagic pneumonias.

From a management perspective, localized bleeding sites are treated first with bronchoscopy with local tamponade by lodging the bronchoscope into sites of bleeding. If unsuccessful, surgery may be needed to resect the affected area because it is vital to avoid the risk of “drowning” the unaffected lung through secondary aspiration. Diffuse lung hemorrhage usually requires immediate surgical lung biopsy to determine its etiology, if it is not clinically obvious.

Once the patient is identified as having hemoptysis and alveolar hemorrhage, several questions need to be answered:

1. Is the alveolar hemorrhage due to a localized lesion or a diffuse process?

The clinical and pathologic differential diagnosis of alveolar hemorrhage is strongly tied to the intrapulmonary distribution of the hemorrhage. Localized lesions that cause pulmonary hemorrhage are often related to bronchiectasis, arteriovenous malformations, hemorrhagic pneumonias, pulmonary infarcts, and mycetomas/cavities. Widespread bilateral alveolar hemorrhage, on the other hand, is frequently referred to as diffuse alveolar hemorrhage (DAH)^1–3 (Table 12–2). This condition represents a distinct subset of cases of pulmonary hemorrhage presumably related to diffuse microvascular injury usually with an immunologic/autoimmune etiology. DAH patients most often present acutely with hemoptysis, rapidly progressive bilateral airspace consolidation, and anemia, although the latter is not always present. Nonspecific elevations of the sedimentation rate and white blood cell count may be present.² A minority of patients with DAH present with more chronic and less dramatic signs and symptoms with episodes of blood-tinged sputum occurring over months or years. From a morphologic perspective, many of these cases, although not all, have vasculitis as the basis for alveolar hemorrhage.

2. Is the alveolar hemorrhage isolated to the lung or part of a systemic process?

This point harkens to the etiology of the hemorrhage. Specifically, is the hemorrhage part of a systemic condition, often vasculitis or toxin exposure, that affects many organs (especially skin and kidney), or is the process isolated to the lung? Because the morphologic findings of alveolar hemorrhage with vasculitis are often nonspecific, a determination of the distribution of the disease in the affected patient is required to ascribe etiology. To this end, a complete serologic profile is essential including an extensive workup for connective tissue disorders with antineutrophil antibodies, antinuclear antibodies, anti-DNA antibodies, rheumatoid factor, antiglomerular basement membrane antibodies, serum complement, cryoglobulins, urinalysis, and serum creatinine. The integration of these clinical, serologic data with physical examination often allows one to determine the cause of the alveolar hemorrhage. On the other hand, a localized zone of infiltration of the lung may represent a non-specific region of bronchiectasis on arteriovenous malformation.

3. What is the etiology of the alveolar hemorrhage?

As indicated earlier, systemic conditions may often be the cause of alveolar hemorrhage. Many of these conditions are autoimmune diseases that require an extensive rheumatologic and serologic evaluation of the patient. Others, however, are not tied to immune status. For example, the most common cause of diffuse alveolar hemorrhage relates to coagulopathies and thrombocytopenia, uremia, mitral valve disease, and drug therapy. Such nonimmunologic causes must be excluded before suspecting an immunologic origin.

Clinical Evaluation of Pulmonary Hemorrhage

The most common manifestation of alveolar hemorrhage clinically is hemoptysis. Chest radiographs demonstrate alveolar consolidation manifested by ground-glass alveolar infiltrates that, on high-resolution computed tomography (CT) scans, are densely consolidated. On chest radiographs, these infiltrates undergo a characteristic progression over time with alveolar infiltrates becoming finely nodular within several weeks, and if bleeding is repetitive, the radiographs may develop a fine interstitial fibrosis associated with patchy zones of alveolar hemorrhage.⁴ Laboratory studies may demonstrate an anemia as a consequence of intrapulmonary blood loss. In patients with low-grade bleeding, such an anemia may mimic anemia of chronic disease, whereas hemoglobin levels in active diffuse alveolar hemorrhage may fall 2 to 4 g/dL or more over a 24-hour period. In fact, stable hemoglobin levels in the face of rapidly progressive pulmonary infiltrates would argue against diffuse alveolar hemorrhage. Because extravascular erythrocytes will bind inhaled carbon monoxide, single-breath pulmonary function techniques for measuring carbon monoxide uptake have been used to monitor alveolar hemorrhage. An increase of KCO to more than 30% of that predicted is a reliable indicator of recent hemorrhage.^2,4 Bronchoalveolar lavage (BAL) may also demonstrate a bloody effluent. Successive BAL fluid aliquots yielding bright red blood support the diagnosis of diffuse alveolar hemorrhage. The presence of hemosiderin-laden macrophages has also been emphasized as a marker for alveolar hemorrhage. Although they are helpful in confirming alveolar hemorrhage in a specific clinical setting, such “heart failure cells” are extremely nonspecific and may be seen in a wide variety of inflammatory states, not specific to hemorrhage syndromes. Because of this, a diagnostic lung biopsy may be needed. The role of transbronchial biopsy in alveolar hemorrhage is somewhat controversial. In acute diffuse alveolar hemorrhage, transbronchial biopsy is probably of limited use, and if a diagnostic biopsy is needed in this setting, transbronchial biopsy should be superseded by open biopsy. By contrast, patients with chronic symptoms of alveolar hemorrhage may benefit from a transbronchial biopsy in that some known causes of alveolar hemorrhage can be diagnosed by this method, for example, Goodpasture’s syndrome and lymphangioleiomyomatosis. When open lung biopsy is required, it is recommended that more than one site be biopsied as the underlying vasculitis may be patchy in its distribution in the lung. Portions of the transbronchial or open lung biopsy can be saved for immunofluorescence and ultrastructural studies to perform specialized evaluations unique to some of the causes of alveolar hemorrhage. To this end, it is important to emphasize that open lung biopsy should be approached as a last resort in patients with alveolar hemorrhage. In particular, kidney biopsies are less morbid than open lung biopsies, and if a pulmonary-renal syndrome is suspected at the time of clinical presentation, renal biopsies may be more helpful than pulmonary ones because the extensive hemorrhage and fibrin exudation associated with alveolar hemorrhage leads to nonspecific immunofluorescence and ultrastructural studies.

*All hemorrhage syndromes with capillaritis may have areas without vascular damage and must be included in the differential diagnosis.

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