Interstitial+Lung+Disease

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 * other names: Interstitial lung disease, restirctive lung disease, pulmonary fibrosis, fibrotic lung disease, interstitial pneumonia

>* fluid >* blood >* infllammatory cells >* ECM components
 * most interstitial diseases affect both airspace, interstitium
 * expand the interstitium with:

>* variable types, locations >* cytokines, lipid mediators >* interstitium or alveolar space >* death, hyperstrophy
 * Common Features**
 * widespread changes
 * increased bumbers of inflammatory cells
 * increased fibroblasts
 * incread collaagen deposition
 * alveolar changes

>* alveolar epithelial cells >* fibroblasts >* inflammatory cells
 * Theme**
 * injyr with disordered repair
 * many causes of injry
 * histology may vary depending on pattern of repair
 * CellCell comunicaiton is citicial

>* Pneumoconiosis >>* Asbestos, silica >* Hypersensitivity pneumonitis >>* immune response to organic dusts >* radiation indced fibrosis >* drug9induced fborsis >* infection >* lympangitic carinomatosis
 * Classification**
 * Diseases of known etiology

>* systemic >>* collagen vascular diseases >>>* Rheumatoid Arthritis, SLE >>* Sarcoidosis
 * Diseases of unknown etiology

>* isolated >>* IPF, Idiopathic Pulmonary Fibrosis >>* lots of rare stuff

=Symptoms= >* first with exertion, then at rest >* 'cold that will not go away' >* acute or subtle progression
 * Dyspnea
 * Cough
 * fatigue
 * subacute or chronic presentation

=Signs=
 * Tachypnea
 * Rales
 * Finger clubbing

>* Reticular >* nodular >* reticulonodular >* linear >* normal
 * CXR**
 * icnreased linear and small nodular shadows
 * Honeycombing
 * Unusual distribution
 * progression when compared with old CXRs

>* optimized contrast >* reduces spatioal resolution >* volume averaging/smoothing >* better resolution >* visualize secondary plmonary lobules >* more senstive that CXR in detecting ILD >* patterns of disease helpful in differential diagnosis >* localise active disease >* monitor porgresson or response to treatment
 * Computed Tomography**
 * 8-10mm slices
 * low-spacial frequency algorhithm to reconstruct image
 * Thin section high resoltuion CT (HRCT)
 * 1-2mm slces
 * taken every 10mm
 * high-spactial frequency alorithm

=Physiology= >* increaed interstitial collagen >* alveolar exudates >* id est, volumes are smaller
 * decreased lung compliance
 * spirometry shows decreased forced vital capacity
 * narrowed flow-volume loop
 * curve shifted to right and smaller...


 * Total Lunc Copacity decreased
 * functional residual capacity reduced
 * residual volume may be reduced

>* Reduced DLCO >* Widened A-a gradient >>* destruction of alveolar capillary membrane >>* small airways abnormalitiies >>* not due to diffusion limitation >>* largely due to V/Q mismatch
 * Gas Exchange

>* Ventilatory limitation >>* cannot increase tidal volume >* rapid shallow breathing >* Increased A-a gradient
 * Exercise Physiology

=Specific Interstitial Diseases=

Hypersensitivity Pneumonitis
>* Transient infiltrates >* 'ground-glass' acute infiltration, alveolar filling >* late fibrotic changes >* temporal pattern >* exposure >* late-stage biopsy indistinguishable from other ILD >* Corticosteroid >* Remove from contact with allergen!
 * Response to inhaled organic dusts--Farmer's lung, Pigeon Breeder's Lung, etc
 * Classic acute, subacute, chronic phases
 * restrictive physiology
 * Radiology
 * History is key
 * compatable CXR, physiology
 * biopsy may be unnecessary, may aid diagnosis
 * Treatment:

Sarcoidosis

 * immunologic disorder with noncaseating granulomas in multiple organs
 * lung commonly inovled, almost all other organs possible
 * diagnosis of exclusion
 * most require no treatment
 * those with visceral involvement respond well to corticosteroids

Idiopathic Pulmoanry Fibrosis

 * 65% OF CASES OF ILD
 * commonly presents 40S-60S
 * Insidious onset, slow progression
 * 50% 5year survival
 * poor thereapy response
 * HRCT biopsy may predit surviaval, response to therapy
 * HRCT may predit histological pattern

=Evaluation of suspected ILD= >* best approach >* focus on exposures >* focus on chronicity >* look fo revidence of systemic process >* primary, secondary pulmonary >* confirm restriciton >* identify confounding processes >* gauge severity, progression >* confirm intistitial process >* support specific diagnosis >* severity, progression
 * History is critical!
 * exam
 * Pulmonary Function Tests
 * Radiology--HRCT

>* Safe, quick >* no general anaesthesia >* Small peice of tissue >>* smpling error >>* can't see normal architecture >>* definiteive diagnosis not always possible-- >>>* except with sarcoidosis, malignancy, TB
 * Transbionchial Biopsy

>* Large peice of tissue >* diffferential diagnosis often possible >* get some didea of mprognosis, treatment >* requires general anaestheia >* may not change treatment
 * Surgical lung Biopsy

=treatment= >* exposure >* source of injury >* systemic illness >* steroids >* cytotoxic drugs >>* azathioprine, methotrexate, cyclphosphamide >>* combination therapy: Steroids, azathioprine, antioxidantes >* manipulate cytokines growth factors?
 * Fix problem
 * try to treat pulmonary inflammation
 * lungntrnsplantation
 * The future: