Back to the future: the Hamman-Rich syndrome and acute interstitial pneumonia

Acute interstitial pneumonia (hamman-rich syndrome) as a cause of idiopathic acute respiratory distress syndrome

Hamman-Rich syndrome, also known as acute interstitial pneumonia, is a rare and fulminant form of idiopathic interstitial lung disease. It should be considered as a cause of idiopathic acute respiratory distress syndrome. Confirmatory diagnosis requires demonstration of diffuse alveolar damage on lung histopathology. The main treatment is supportive care. It is not clear if glucocorticoid therapy is effective in acute interstitial pneumonia. We report the case of a 77-year-old woman without pre-existing lung disease who initially presented with mild upper respiratory tract infection and then progressed to rapid onset of hypoxic respiratory failure similar to acute respiratory distress syndrome with unknown etiology. Despite glucocorticoid therapy, she did not achieve remission and expired after 35 days of hospitalization. The diagnosis of acute interstitial pneumonia was supported by the histopathologic findings on her lung biopsy.

Diffuse alveolar damage: a common phenomenon in progressive interstitial lung disorders

It has become obvious that several interstitial lung diseases, and even viral lung infections, can progress rapidly, and exhibit similar features in their lung morphology. The final histopathological feature, common in these lung disorders, is diffuse alveolar damage (DAD). The histopathology of DAD is considered to represent end stage phenomenon in acutely behaving interstitial pneumonias, such as acute interstitial pneumonia (AIP) and acute exacerbations of idiopathic pulmonary fibrosis (IPF). Acute worsening and DAD may occur also in patients with nonspecific interstitial pneumonias (NSIPs), and even in severe viral lung infections where there is DAD histopathology in the lung. A better understanding of the mechanisms underlying the DAD reaction is needed to clarify the treatment for these serious lung diseases. There is an urgent need for international efforts for studying DAD-associated lung diseases, since the prognosis of these patients has been and is still dismal.

Early intervention can improve clinical outcome of acute interstitial pneumonia

Study objectives:

To report on our experience with acute interstitial pneumonia (AIP) in which patients underwent early diagnostic procedures and received mechanical ventilation with a “lung-protective” strategy and early institution of immunosuppressive therapy.

Design:

A retrospective chart review.

Setting:

A tertiary referral hospital.

Participants:

Ten patients with AIP who presented with idiopathic ARDS and showed diffuse alveolar damage on surgical lung biopsy specimens from July 1995 to March 2004.

Measurements and results:

The median age of patients was 65.5 years (age range, 38 to 73 years). Patients presented with a median duration of severe dyspnea of 9.5 days (range, 2 to 34 days) at the hospital visit. All patients required mechanical ventilation beginning at median time of hospital day 1 (range, hospital day 0 to 5), which continued for a median duration of 9.5 days (range, 4 to 98 days). Patients received ventilation in the pressure assist-control mode with a median tidal volume of 6.97 mL/kg (range, 6.05 to 8.86 mL/kg) and median positive end-expiratory pressure of 11 cm H₂O (range, 8 to 16 cm H₂O). An aggressive diagnostic workup for respiratory infection, including BAL at a median time of hospital day 2 (range, hospital day 1 to 5) was performed. High-dose steroid pulse therapy was initiated on median hospital day 3.5 (range, hospital day 1 to 8), while surgical lung biopsy was performed on median hospital day 4 (range, hospital day 2 to 7). Eight patients (80%) survived to hospital discharge.

Conclusion:

Earlier intervention, such as an aggressive diagnostic approach, mechanical ventilation with lung-protective strategy, and the early institution of immunosuppressive may improve clinical outcome in patients with AIP.

Acute interstitial pneumonia

The idiopathic interstitial pneumonias have unknown etiology and are characterized by diffuse parenchymal lung involvement and the potential to develop pulmonary fibrosis. Most portend a reduction in life expectancy due, in part, to the absence of effective therapies. The symptoms of idiopathic interstitial pneumonia develop insidiously. In contradistinction, acute interstitial pneumonia (AIP, also known as acute interstitial pneumonitis) is unique in that it has a very rapid to fulminant onset, leading to early hospitalization and a high initial case fatality ratio but, potentially, a more favorable long-term prognosis for survivors. Despite its contemporary description nearly 20 years ago, knowledge of this disease has increased little. This review focuses on AIP and its current place among the idiopathic interstitial pneumonias.

Acute interstitial pneumonitis. Case series and review of the literature

Acute interstitial pneumonitis (AIP) is an acute, idiopathic interstitial lung disease characterized by rapidly progressive diffuse pulmonary infiltrates and hypoxemia requiring hospitalization. The case-fatality ratio is high. Previous reports suggested that survivors of the acute event have a favorable outcome. We undertook this study to examine the natural history of survivors. We had observed several patients who experienced recurrent episodes of AIP and chronic progressive interstitial lung disease. We sought to determine longitudinal survival in these patients and to compare our experience with that in the medical literature. Overall, we identified 13 biopsy-proven cases of AIP. The mean patient age was 54 years in our review, which is identical to previous reports. Twelve patients were hospitalized and all 12 required mechanical ventilation. Overall hospital survival was 67%. All patients demonstrated abnormalities in gas exchange at presentation. Radiographs typically demonstrated bilateral patchy densities that progressed to a diffuse alveolar filling pattern in nearly all cases. All biopsy specimens showed organizing diffuse alveolar damage. Longitudinal data were available for 7 patients. Two died of AIP recurrences. A third died of complications of heart failure shortly after hospital discharge. One patient progressed to end-stage lung disease and required lung transplantation. Two patients experienced persistent pulmonary symptoms, accompanied in 1 by progressive lung fibrosis. One patient had nearly complete recovery of lung function 2 years following AIP. (Follow-up information was unavailable for 2 survivors.) In our literature review, 5 of 7 patients reported experienced some recovery of lung function. One case of progressive interstitial lung disease requiring lung transplantation was reported. The reported mortality was much higher than in our experience (74% versus 33%). The mean time from symptom onset to death was 26 days, compared with 34 days in our experience. The use of corticosteroids did not appear to influence survival, although this has not been tested in a rigorous manner. The better survival in our series may be related in part to a survivor selection bias. In contrast to previous reports, we found that survivors of AIP may experience recurrences and chronic, progressive interstitial lung disease. We did not identify any clinical or pathologic features that predict mortality in these patients. Likewise, there were no features that predicted the longitudinal course in survivors. Further study to identify causal factors is required in the hope of preventing morbidity and mortality related to this disease.

Partial resolution of acute interstitial pneumonia in native lung after single lung transplantation

The case of a 49 year old man presenting with rapidly progressive interstitial lung disease is described. Radiological findings and the lung biopsy specimen were compatible with an acute interstitial pneumonia, as was the relentless clinical course culminating in hypoxic respiratory failure. After right single lung transplantation there was considerable improvement in lung function and radiographic clearing of disease in the native left lung.