Pulmonary Alveolar Proteinosis

Pulmonary alveolar proteinosis (PAP) is a rare lung disorder in which the tiny air sacs of the lungs (alveoli) fill up with a secreted material known as surfactant. Surfactant is normally necessary for the air sacs to remain open, however, patients with PAP accumulate surfactant abnormally. This accumulation of surfactant interferes with the ability of oxygen to diffuse from the alveoli into the capillaries of the lung producing symptoms. The cause of most cases of PAP is unknown (see below), and the only treatment proven to relieve symptoms is removal of the excessive surfactant material from the alveoli. This is accomplished using a procedure known as whole lung lavage. During this procedure, one lung is repeatedly washed out with a mild salt solution while the other lung is ventilated with pure oxygen. Over the past 30 years, the Center for Hyperbaric Medicine at Duke has been a referral center for treatment of PAP because of the availability of Hyperbaric chambers large enough to support the PAP patient and the physicians, nurses and attendants needed to perform the whole lung lavage procedure. The use of a Hyperbaric chamber insures that an adequate amount of oxygen can always be delivered to the body through one lung while the other lung is being washed out. The Hyperbaric chamber also makes it possible to complete the lavage procedure on both lungs in a single day, one lung in the morning and the other in the afternoon, saving the patient the risk of a second period of general anesthesia, shortening the hospital stay, and decreasing the cost of the procedure.

Clinical Features of Pulmonary Alveolar Proteinosis

• Age of onset typically 20 to 50 years old with a slight male predominance
• Often confused with chronic pneumonia
• Mild to moderate shortness of breath (dyspnea)
• Persistent dry cough (or scant sputum)
• Weight loss
• Low grade fever and/or night sweats
• Bilateral air space opacities on chest radiograph

Types of Pulmonary Alveolar Proteinosis

Primary

• Idiopathic (cause unknown)
• Hereditary

Secondary

• HIV infection (AIDS)
• Lymphoproliferative disorders
• Exposure to silica, aluminum, or titanium dust
• Insecticides
• Tuberculosis

Pathophysiology of Pulmonary Alveolar Proteinosis

• No evidence for production of abnormal alveolar phospholipids (surfactant)
• Some evidence for an imbalance between phospholipid production and clearance
• Cellular function of macrophages recovered from the alveolar spaces is abnormal in patients with PAP
• Genetically altered mice develop PAP that do not express the gene for the hormone GM CSF
• Mice with severe combined immunodeficiency (SCID mice), which have non-functional lymphocytes, accumulate surfactant abnormally in the airspaces
• Genetically altered mice that do not express the gene for Surfactant Apoprotein-D develop a PAP-like disease
• None of the abnormalities found to produce similar diseases in mice have been found in humans with PAP

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The Course of Pulmonary Alveolar Proteinosis

• 1/3 of patients have spontaneous remission (no specific therapy)
• 1/3 of patients need whole lung lavage to relieve symptoms
• 1/3 of patients have progressive disease despite multiple lavages including pulmonary fibrosis
• All PAP patients have increased risk of developing unusual forms of pneumonia
• Indications for Whole Lung Lavage
• Relief of severe symptoms such as intractable cough or shortness of breath
• Severe hypoxemia (PaO2 < 60mmHg or oxygen saturation< 90%)
• Prevention of lung infections?
• Prevention of lung fibrosis?

Registry for Patients with Pulmonary Alveolar Proteinosis

The Duke Center For Hyperbaric Medicine And Environmental Physiology is building a database of Pulmonary Alveolar Proteinosis patient information. The data will be used for the study of Pulmonary Alveolar Proteinosis and possibly a way for PAP patients to communicate with each other.

If you are interested in participating, please email the following information to the webmaster at: boso0001@mc.duke.edu

Name: (First, Last)

Address: (Street, City, State, Zipcode)

Birthdate: (MM/DD/YYYY)

Sex: (Male/Female)

Phone Number: (###-###-####)

Email Address:

Smoker (Non/Past/Present):

Date of onset of PAP: (MM/YYYY))

Number of Lung Lavages: (##))

Interested in future studies: (Yes/No)