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interstitial lung disease clinical
RPM II
49
Medical
05/19/2010

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Term
what is the definition of interstitial lung disease (ILD)?
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.
Term
how should the lungs look on a healthy CXR?
Definition
there should be clear black spaced between the ribs
Term
how do the lungs look on a CXR of a pt with interstitial lung disease?
Definition
spider webby opacities criss-crossing usually bilateral and diffuse. this is even more obvious on a CT scan
Term
how would alveolar disease, such as ARDS appear on a CXR compared to interstitial lung disease?
Definition
ARDS will appear more cottony, fluffy white diffuse type of pattern not spider webbed/reticulated like interstitial lung disease
Term
what are the clinical features of insterstitial lung disease?
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)
Term
what would be seen on a physical exam for a interstitial lung disease pt?
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)
Term
can a CXR help ID specific causes of ILD? what is the common pattern?
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)
Term
what is the reticular pattern seen on CXRs of pts w/ILD? what is a reticulonodular pattern?
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
Term
what is the pattern seen on CXRs for pts with end stage fibrosis?
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
Term
how does the volume level of the lungs appear on CXRs of pts with ILD?
Definition
over time as the lungs become scarred and fibrosed, the lung volume shrinks down
Term
what is most importantly seen physiologically for pts with ILD? (*exam question*)
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.
Term
how will CO (carbon monoxide) diffusion capacity be affected by ILD?
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)
Term
what are typical blood gas findings for ILD pts? (*exam question*)
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**
Term
how does exercise cause oxygen desaturation in ILD pts?
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
Term
can the exercise O2 desaturation seen in ILD pts predate other pulmonary function abnormalities?
Definition
yes
Term
what happens histologically with ILD?
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
Term
what is the generally pathologic progression of ILD?
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
Term
how does fibrosis cause honeycombing/bronchiectasis?
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)
Term
what is one way of classifying the causes of ILD?
Definition
occupational and environmental, drugs/poisons, connective tissue associated, idiopathic, infectious, and other
Term
what are the occupational and environmental causes of ILD?
Definition
occupational and environmental: 1) pneumoconiosis (in organic silica, *asbestos, beryllium, coal) 2) hypersensitivity pneumonitis (organic - thermophilic actinomyces, bacteria, amoebae, fungi).
Term
what are the drugs/poison causes of ILD?
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
Term
what are the connective tissue associated causes of ILD?
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 )
Term
what are the idiopathic causes of ILD?
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
Term
what are the infectious causes of ILD?
Definition
most common: pneumocystis pneumonia in HIV pts. also, viral pneumonias can cause ILD in immunocompetent pts
Term
what are the "other" causes of ILD?
Definition
lymphatic CA (when tumor goes into lymphatics, it thickens the lymphatic vessels and makes them thick and bulky), chronic aspiration, and uremia
Term
how do the numbers of ILD due to known vs unknown etiology compare?
Definition
there are more causes of unknown etiology leading to ILD than known
Term
what is the general approach to pts w/interstitial lung disease?
Definition
establish a dx, evaluate extent/severity of pulmonary/nonpulmonary involvement, evaluate inflammatory activity, and tx
Term
what does a diagnostic evaluation of interstitial lung disease consist of?
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)
Term
what should you think of right away if you see hilar lymphadenopathy?
Definition
sarcoidosis (esp especially if the pt is a young african-american female )
Term
what is the mnemonic for remembering what ILD diseases are upper lobe predominant? (*exam question*)
Definition
ASSET: Ankylosing spondylitis, Sarcoidosis, Silicosis, Eosinophilic granuloma, and Tuberculosis
Term
what is the mnemonic for lower lobe predominant ILD? (*exam question*)
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
Term
what is the mnemonic for mid lobe predominant ILD? (*exam question*)
Definition
"suck up" or SUCGP: Sarcoidosis, Uremia, Chf, Goodpasture's, Pulmonary alveolar proteinosis
Term
what is the definitive study that will show you the presence of interstitial disease and document the extent of involvement?
Definition
CT chest scan
Term
what are some ILD where pulmonary histology is unnecessary?
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)
Term
what are the 2 ways of getting a lung bx?
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
Term
when would an esophageal manometric study be useful?
Definition
if there are indications of scleroderma
Term
when are serologic studies useful in collagen vascular disease? what diseases match up with which positive results?
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
Term
when would a serologic test for IgG precipitating antibodies be useful?
Definition
IgG precipitating antibodies are positive in 90% of pt w/acute hypersensitivity pneumonitis
Term
when would a serologic test for ACE (angiotensin converting) be useful in light of ILD?
Definition
ACE levels are often high in pts w/sarcoidosis - but its not diagnostic
Term
how can evaluation of extent/severity of organ impairment be conducted?
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)
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?
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.
Term
what is a gallium scan?
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
Term
is there tx for asbestosis?
Definition
not really
Term
is there tx for eosinophilic granumomas?
Definition
not really
Term
what is the first line of tx for most of the (inflammatory) interstitial lung diseases? what if that doesn't work?
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
Term
what is indicated for wegener's and goodpasture's?
Definition
cytotoxins ie. cyclofosfamide, cytoxin and for goodpasture's: have to do plasmapheresis to remove bad antibodies from blood stream extracorporeally
Term
who needs O2 prescribed?
Definition
pts who are polycythemic or have paO2 <55
Term
why should pts with ILD get pneumovax/flu vaccine?
Definition
they are at a higher risk for contracting these diseases
Term
who is considered for lung transplant?
Definition
pts who have severe disease who are young and healthy otherwise