Systems AffectedAlthough PAP is a disease caused by the autoimmune system, it directly affects the respiratory system. This is a rare lung disease characterized by the build up of a grainy material in the alveoli. The substance is composed of phospholipids and protein, which are key components of the lung surfactant, which coats the alveoli to prevent lung collapse and promotes oxygen absorption by the lungs. Build up of this surfactant blocks the airways, making it difficult to breathe.
It is caused by the body producing an antibody that inhibits the growth of alveolar macrophages, or in this case the lung surfactant. In normal lungs, specialized immune cells called alveolar macrophages swallow and remove inhaled particles and excess surfactant from the alveoli. In PAP, it is suggested that the alveolar macrophages don't function properly and consequently cannot break down and remove the material they swallow. They become inefficient at clearing material from the lungs. SymptomsPAP is a disease that occurs gradually. Once it becomes noticlable however, symptoms include:
DiagnosisPAP is only diagnosable only after the symptoms present themselves. When they do, however, these tests can determine if a person truly has the disease.
Physical Examination: Breathlessness or crackles heard when listening to the lungs. CT Scan: An x-ray to reveal the internal organs of the body. Used to reveal extensive white patches within the lungs with superimposed angular lines. This pattern is known as ‘crazy paving’ and is a characteristic of PAP. Bronchoscopy: Using a bronchoscope, a doctor will be able to travel through the airways and examine from the throat to the lungs. Used to obtain lung liquids or tissue that will be examined for signs of PAP.
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TreatmentsTreatment of PAP depends on how progressed the disease is in the individual. Usual care includes the mechanical removal of the lipoproteinaceous material by whole-lung lavage. Patients in the past would have been treated with systemic steroids, mucolytics, and proteinase, but were mostly unsuccessful.
Secondary PAP will require whole-lung lavage which is performed with a double-lumen endotracheal tube designed to allow simultaneous ventilation and lavage. Lung lavage is performed under general anesthesia, and the lesser infected lung is ventilated briefly with 100% oxygen before lavage with isotonic sodium chloride solution for the other lung. The standard amount of fluid used is 10-20 L, with up to 50 L for the more sever cases. Upon completion of the procedure, the lung is suctioned of most of the isotonic sodium chloride solution and allowed to recover before lavaging the other lung. Lung lavages have been performed in hyperbaric chambers, which has made lavage of both lungs possible on the same day. Lung lavage may require several hours. This is to wash out the excess surfactant and reestablish oxygenation to the lungs. Life ExpectancyUp to twenty five percent of people who are diagnosed with Pulmonary Alveolar Proteinosis die withing five years of the diagnosis. Patients who receive a full-lung lavage improve greatly, although relapses can occur.
Case StudyA 34 year old man with PAP
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