Acute interstitial pneumonia

Abstract

In the late 1930's and early 1940's a great deal of interest was generated by the description of four young adults who died from a relatively acute interstitial pulmonary disease process. This entity, which ultimately became known as the 'Hamman-Rich syndrome' or 'alveolar capillary block syndrome,' was characterized by rapid clinical deteriroation, progressive dyspnea, and severe hypoxemia. It lasted from a few weeks to several months, ultimately culminating in right ventricular failure and death. At autopsy, interstitial fibrosis was a prominent feature. The interstitial pneumonias, as we now recognize them, are either acute or chronic processes with a pathologic spectrum that allows for some overlay. As a sequela of acute interstitial pneumonias, many patients develop interstitial fibrosis. This pulmonary response to many insults, occurring either via the inhalation or the vascular route, results in early inflammatory involvement of the pulmonary interstitium, with the subsequent formation of interstitial edema leading to alveolar wall edema, hyaline membrane formation, and eventual fibrosis. The acute interstitial pneumonias generally have a guarded prognosis and seldom remain isolated to the interstitial space. Progression to involve the alveoli is frequently seen. This may be associated with the presence of severe tachypnea, hypoxemia, and respiratory alkalosis. Early diagnosis with aggressive biopsy techniques remains important in decreasing the over-all mortality rate, especially for patients who are immunologically incompetent. Aggressive chemotherapeutic measures, when indicated, and various forms of respiratory support can be life-saving.