Pulmonary Manifestations of the Acquired Immunodeficiency Syndrome

The lungs are the most frequent site of involvement for the infectious processes that are associated with AIDS. In addition, non-infectious disorders, such as Kaposi’s sarcoma and lymphoid interstitial pneumonia, occur in the lungs and must be considered in the differential diagnosis in patients with respiratory symptoms or findings.

The diagnostic evaluation of a patient with or suspected of having AIDS and pulmonary involvement is founded in a knowledge of the epidemiology and pathophysiology of the process so that the proper risk groups are targeted and the types of problems can be anticipated. The sequence of studies should proceed in an orderly fashion from less to more invasive. Non-invasive studies including chest radiography, pulmonary function testing and gallium lung scanning assist in identifying patients who should have further diagnostic testing. Examination of sputum induced by inhalation of 3% saline can make the diagnosis of P. carinii pneumonia in more than 50% of patients with the disease. Bronchoscopy with bronchoalveolar lavage and transbronchial lung biopsy is a highly accurate means of establishing diagnoses thereby making open lung biopsy rarely necessary.

P. carinii is by far the most frequent pathogen causing pulmonary disease in patients with AIDS. Treatment is successful in 75-80% of initial episodes of P. carinii pneumonia using TMP-SMX or pentamidine. These drugs are equally effective, but both have a high frequency of adverse reactions. The survival rate in patients who require mechanical ventilation because of P. carinii pneumonia is approximately 15%.

Tuberculosis is the other important treatable infection in patients with AIDS. This disease occurs most commonly among groups such as Haitians or intravenous drug abusers, that have increased risks of tuberculosis even without AIDS. Tuberculosis in patients with AIDS responds to conventional antituberculosis drugs.

M. avium complex, an organism isolated frequently from patients with AIDS, is very resistant to treatment. The role of this organism in causing significant disease in AIDS patients is not clear, however.

Intensive care for patients with AIDS is most commonly indicated for respiratory failure caused by P. carinii pneumonia. However, because of the poor short-term and worse long-term prognoses, critical care is used less commonly than in the past. Nevertheless, critical care may be of extreme value in some instances and should not be withheld.

Infection control measures for patients with AIDS are essentially the same as those for hepatitis B. In patients with respiratory disease infection control should also take the possibility of tuberculosis into account until a diagnosis is established.