Term
| what is the definition of interstitial lung disease (ILD)? |
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Definition
| a heterogeneous group of inflammatory and fibrotic disorders of the lower respiratory tract, involving the interstitial, and occasionally alveolar and bronchial structures. they are classified together b/c of common clinical, x-ray. physiologic and pathologic features. |
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Term
| how should the lungs look on a healthy CXR? |
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Definition
| there should be clear black spaced between the ribs |
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Term
| how do the lungs look on a CXR of a pt with interstitial lung disease? |
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Definition
| spider webby opacities criss-crossing usually bilateral and diffuse. this is even more obvious on a CT scan |
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Term
| how would alveolar disease, such as ARDS appear on a CXR compared to interstitial lung disease? |
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Definition
| ARDS will appear more cottony, fluffy white diffuse type of pattern not spider webbed/reticulated like interstitial lung disease |
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Term
| what are the clinical features of insterstitial lung disease? |
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Definition
| insidious onset of dyspnea or cough - usually nonproductive . *spontaneous pneumothorax may occur with peripheral fibrosis (*esp w/eosinophilic granulomas/pulm histiocytosis) as well as manifestations of *extrathoracic disease (sarcoidosis, collagen vascular - arthritis, skin changes, erythema nodosum, ocular changes), and pts may present with systemic symptoms (fever, wt loss, arthralgias) |
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Term
| what would be seen on a physical exam for a interstitial lung disease pt? |
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Definition
| bibasilar crackles (dry popping velcro sound heard at the end of inspiration), clubbing (bulbous changes), signs of pulmonary HTN (NVD, ventricular lift, peripheral edema, hepatojugular reflux), and signs of systematic involvement (may be cutaneous findings of sclerodema) |
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Term
| can a CXR help ID specific causes of ILD? what is the common pattern? |
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Definition
| yes - the common pattern is usually *bilateral, linear and usually symetrical. ground glass haze is usually the *first manifestation before discrete lesions, *nodular patterns may also be present along with the classic lines which often reflects bloodstream dissemination (miliary TB, talcosis) |
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Term
| what is the reticular pattern seen on CXRs of pts w/ILD? what is a reticulonodular pattern? |
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Definition
| the linear pattern can coalesce to form a reticulum, which is basically the entire network of spider-webbing lines. a reticulonodular pattern is when there are "too many" lines and nodules seen on a CXR of a pt with ILD |
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Term
| what is the pattern seen on CXRs for pts with end stage fibrosis? |
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Definition
| honeycombing, which represents the development of tiny air containing cysts (5-10 mm in diameter) that indicate the lung becoming more fibrotic with constriction/contraction of the scars around the airspaces tearing open large cystic areas, creating a "honey combed" appearance |
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Term
| how does the volume level of the lungs appear on CXRs of pts with ILD? |
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Definition
| over time as the lungs become scarred and fibrosed, the lung volume shrinks down |
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Term
| what is most importantly seen physiologically for pts with ILD? (*exam question*) |
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Definition
| ILD pts will have *restrictive lung patterns, meaning their *total lung capacity (TLC) will be decreased, (therefore forced vital capacity will be low and residual vol will be low). this is not a disease of obstruction: therefore the FEV1/FVC ratio should be normal or increased - *airflow is normal. |
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Term
| how will CO (carbon monoxide) diffusion capacity be affected by ILD? |
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Definition
| CO diffusion capacity will be low - due to the thickened fibrosed membrane between the alveolus and bloodstream (this may actually predate the development of shrunken lung volumes where you see the TLC and all the other lung volumes decrease) |
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Term
| what are typical blood gas findings for ILD pts? (*exam question*) |
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Definition
| oxygenation is usually preserved, and pCO2 is mildly decreased, (which may lead to a mild alkalosis in the absence of normal oxygenation) **classic finding for ILD blood gas: exercise oxygen desaturation** |
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Term
| how does exercise cause oxygen desaturation in ILD pts? |
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Definition
| in normal individuals, tidal volume increases as you exercise to match increased pulmonary artery perfusion in a 1:1 ratio. pts with interstitial fibrosis can't increase their tidal volume b/c their lungs are fibrosed/scarred but their perfusion still increases w/exercise. this results in a ventilation/perfusion (V/Q) mismatch that results in O2 desaturation. this can also lead to development of diffusion membrane abnormalities (increased pulmonary blood flow is passing by the alveolar capillary unit much faster than in normal situations; so there is less time for the oxygenation gas to be picked up by the blood flowing by it) which further the O2 desaturation problem |
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Term
| can the exercise O2 desaturation seen in ILD pts predate other pulmonary function abnormalities? |
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Definition
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Term
| what happens histologically with ILD? |
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Definition
| the insterstium is inflammed, which leads to collagen fibrosis, the BM of the type I pneumocytes eventfully ruptures - allowing the inflammatory debris to spill into the alveolar airspace. the type I pneumocytes are also replaced by type II pneumocytes - which further impairs gas exchange |
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Term
| what is the generally pathologic progression of ILD? |
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Definition
| 1) interstitial pneumonitis (alveolitis), which consists of a mixed population of cells depending on the disease (sarcoid may be lymphocyte predominate, idiopathic pulmonary fibrosis may be neutrophil predominate) and if there are granulomas you can narrow the disease down to sarcoidosis, TB, fungal disease, and hypersensitivity pneumonitis. -> 2)fibrosis -> 3) bronchiectasis/honeycombing |
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Term
| how does fibrosis cause honeycombing/bronchiectasis? |
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Definition
| the inflammation gets replaced with fibrosis and fibrosis around airways can tether the airways to a wider diameter as well and that can give you bronchiectasis or scarring from “sicco trico bronchiectasis” (scarring bronchiectasis from the fibrosis) |
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Term
| what is one way of classifying the causes of ILD? |
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Definition
| occupational and environmental, drugs/poisons, connective tissue associated, idiopathic, infectious, and other |
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Term
| what are the occupational and environmental causes of ILD? |
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Definition
| occupational and environmental: 1) pneumoconiosis (in organic silica, *asbestos, beryllium, coal) 2) hypersensitivity pneumonitis (organic - thermophilic actinomyces, bacteria, amoebae, fungi). |
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Term
| what are the drugs/poison causes of ILD? |
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Definition
| drugs/poisons: 1)chemo agents (bleomycin, busulfan, methotrexate, chroambucil, melphalan) 2) antibx (nitrofurantion) 3) gold 4) methylsergide 5) paraquat 6) hexamethonium, mecamylamine, pentolinium 7)talc 8) HCTZ 9) cromolyn 10) amiodarone 11) rapeseed oil |
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Term
| what are the connective tissue associated causes of ILD? |
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Definition
| * RA (most common), progressive systemic sclerosis (scleroderma is an important cause), *mixed connective tissue disease, polymyositis/dermatomyositis, SLE, anklosing spondylitis, and sjogren's. (a serologic evaluation for these is often warranted ) |
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Term
| what are the idiopathic causes of ILD? |
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Definition
| sardoidosis, vasculitis (lung primarily involved: **wegener's, *lymphomatoid granulomatosis, and *churg-strauss vasculitis. secondary: systemic leukocytoclastic vasculitis), histiocytosis X (*eosinophilic granuoma or langerhans - young male smokers, *pnuemothorax), idiopathic pulm fibrosis, idiopathic pulm hemosiderosis, chronic pulm alveolar proteinosis, tuberous sclerosis, and familial pulm fibrosis |
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Term
| what are the infectious causes of ILD? |
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Definition
| most common: pneumocystis pneumonia in HIV pts. also, viral pneumonias can cause ILD in immunocompetent pts |
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Term
| what are the "other" causes of ILD? |
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Definition
| lymphatic CA (when tumor goes into lymphatics, it thickens the lymphatic vessels and makes them thick and bulky), chronic aspiration, and uremia |
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Term
| how do the numbers of ILD due to known vs unknown etiology compare? |
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Definition
| there are more causes of unknown etiology leading to ILD than known |
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Term
| what is the general approach to pts w/interstitial lung disease? |
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Definition
| establish a dx, evaluate extent/severity of pulmonary/nonpulmonary involvement, evaluate inflammatory activity, and tx |
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Term
| what does a diagnostic evaluation of interstitial lung disease consist of? |
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Definition
| H+P (v important, ask about occupation - asbestos?), CXR, CR chest (hi-res), pulmonary function test (look for restrictive pattern), arterial blood gas/exercise oximetry, and various serology, gallium scan (helps assess inflammation), bronchoscopy w/bronchoalveolar lavage and transbronchial bx, and an open lung bx (not usually needed) |
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Term
| what should you think of right away if you see hilar lymphadenopathy? |
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Definition
| sarcoidosis (esp especially if the pt is a young african-american female ) |
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Term
| what is the mnemonic for remembering what ILD diseases are upper lobe predominant? (*exam question*) |
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Definition
| ASSET: Ankylosing spondylitis, Sarcoidosis, Silicosis, Eosinophilic granuloma, and Tuberculosis |
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Term
| what is the mnemonic for lower lobe predominant ILD? (*exam question*) |
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Definition
| BADBASS: Bronchiectasis, Asbestosis, DIP/UIP/IPF (desquamative interstitial pneumonia, usual and idiopathic), Breast (shadows can mimic IDL pattern - look at lateral view), Aspiration, Sarcoidosis, Sclerodema |
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Term
| what is the mnemonic for mid lobe predominant ILD? (*exam question*) |
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Definition
| "suck up" or SUCGP: Sarcoidosis, Uremia, Chf, Goodpasture's, Pulmonary alveolar proteinosis |
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Term
| what is the definitive study that will show you the presence of interstitial disease and document the extent of involvement? |
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Definition
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Term
| what are some ILD where pulmonary histology is unnecessary? |
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Definition
| collagen vascular disease (if the pt presents with classic joint manifestations and classic serologic markers and classic chest x-ray, then probably don’t have to do a lung bx) and asbestosis (if someone has lower lobe interstitial disease, have pleural plaques, pleural calcifications and worked in shipyard for 20 years, they have asbestosis and generally don’t have to do a lung bx) |
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Term
| what are the 2 ways of getting a lung bx? |
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Definition
| 1) transbronchial bx: done w/a bronchoscope, and bx is limited b/c it is done blind and disease can be missed. 2) open bx/video assisted thoracoscopy: advantage is bx can be visually directed: gold standard |
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Term
| when would an esophageal manometric study be useful? |
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Definition
| if there are indications of scleroderma |
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Term
| when are serologic studies useful in collagen vascular disease? what diseases match up with which positive results? |
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Definition
| collagen vascular disease: sed rate, ANA, rheumatoid factor, anti scl-70 is positive in scleroderma/anti centromere antibody also for scleroderma, ANCA (anti neutrophil cytopmastic antibody) positive for wegener’s vasculitis, anti Jo, anti PM 1 seen in polymyositis, and antiglomerular basement membrane antibody is positive in goodpasture’s |
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Term
| when would a serologic test for IgG precipitating antibodies be useful? |
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Definition
| IgG precipitating antibodies are positive in 90% of pt w/acute hypersensitivity pneumonitis |
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Term
| when would a serologic test for ACE (angiotensin converting) be useful in light of ILD? |
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Definition
| ACE levels are often high in pts w/sarcoidosis - but its not diagnostic |
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Term
| how can evaluation of extent/severity of organ impairment be conducted? |
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Definition
| PFTs, exercise ABG/O2 saturation. extrathoracic sites also need to be checked to make a dx (if someone has scleroderma, you want to follow BP and kidney function) |
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Term
| what is important to check for pts w/IDL in terms of systemic factors? how is this checked? what does quantification of inflammatory activity indicate? |
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Definition
| level of inflammation. checking for this varies on the specific disease - for ex, ACE levels are inflammatory indicators w/sarcoidosis, and gallium scans are useful in evaluating inflammation in idiopathic pulmonary fibrosis. quantification of inflammatory activity can help indicate the amount of reversibility of the defect and the risk of subsequently developing pulm fibrosis. |
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Term
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Definition
| a kind of nuclear medicine scan, where the pt is injected with gallium, which is distributed through the body where it is avidly taken up by neutrophils and inflammatory cells - if a pt has ongoing inflammation in the lung, the lung will take up gallium and when scan over lung, will see blackness representing gallium uptake |
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Term
| is there tx for asbestosis? |
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Definition
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Term
| is there tx for eosinophilic granumomas? |
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Definition
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Term
| what is the first line of tx for most of the (inflammatory) interstitial lung diseases? what if that doesn't work? |
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Definition
| usually, if non-infectious, the first therapeutic attempted is systemic steroids. if steroids don’t work, other cytotoxic agents may be indicated (ie. ciclofosfamide). gamma IFN can be used w/mild idiopathic pulmonary fibrosis, and may prevent progression |
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Term
| what is indicated for wegener's and goodpasture's? |
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Definition
| cytotoxins ie. cyclofosfamide, cytoxin and for goodpasture's: have to do plasmapheresis to remove bad antibodies from blood stream extracorporeally |
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Term
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Definition
| pts who are polycythemic or have paO2 <55 |
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Term
| why should pts with ILD get pneumovax/flu vaccine? |
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Definition
| they are at a higher risk for contracting these diseases |
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Term
| who is considered for lung transplant? |
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Definition
| pts who have severe disease who are young and healthy otherwise |
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