Many AIDS patients develop PCP, but the effectiveness of early diagnosis and treatment of PCP is not known. The effectiveness of PEN may be improved if treatment is begun when the parasite burden (the number of organisms in the lung) is still small, and before respiratory symptoms appear. If PFT of HIV-infected patients is able to identify patients in the early stages of infection, outpatient treatment of these patients offers a possible alternative to the expense and toxicity of continuous preventive therapy of all high-risk patients.~Patients are treated with aerosolized PEN on an outpatient basis. The aerosol therapy is given by a respiratory therapist 5 times a week, for a total of 21 days of treatment. In addition, patients participate in two radioactive aerosol studies in which the patient inhales a radioactive gas while sitting with his/her back against a gamma camera. The resulting picture outlines the lungs. Then the gas is exhaled and the patient breathes an aerosol of PEN. This mist contains a single dose of PEN mixed with a small amount of radioactivity (99mTc-pertechnetate). The gamma camera determines where the particles deposit in the lungs. The radioactive exposure is equivalent to a typical x-ray of the ribs. Patients also undergo diagnostic bronchoscopy with lavage, and PFT. Blood is drawn to measure the blood level of PEN. Patients are followed (clinical exams and PFT's) for 6 months after the end of therapy. Prophylaxis for PCP is allowed during the 6-month follow-up.
To confirm the ability of pulmonary (lung) function testing (PFT) to detect Pneumocystis carinii pneumonia (PCP) before the development of clinical symptoms and to determine if pentamidine (PEN), a drug used in treating PCP, can be given effectively as an aerosol (inhaled mist). Other goals include the measurement of the actual amount of PEN that reaches the lung, and to determine if close clinical observation is safer and as effective as drug therapy for the prevention of subsequent episodes of PCP.~Many AIDS patients develop PCP, but the effectiveness of early diagnosis and treatment of PCP is not known. The effectiveness of PEN may be improved if treatment is begun when the parasite burden (the number of organisms in the lung) is still small, and before respiratory symptoms appear. If PFT of HIV-infected patients is able to identify patients in the early stages of infection, outpatient treatment of these patients offers a possible alternative to the expense and toxicity of continuous preventive therapy of all high-risk patients.