Interstitial Lung Diseases and Idiopathic Pulmonary Fibrosis Flashcards
interstitial lung diseases
-Diverse group of disorders that involve the distal pulmonary parenchyma (as opposed to the airways)
-Etiology:
-Idiopathic
-Systemic diseases (connective tissue disorders)
-Toxic, radiologic, environmental, occupational exposures
interstitial lung disease are a diverse group of conditions that may result in lung fibrosis
-idiopathic ILDs
-hypersensitivity pneumonitis- inflammatory
-connective tissue disease- ILDs- associated with rheumatologic disease
-sarcoidosis
-other ILDs
interstitial lung diseases: approach to treatment
-Is There an Identifiable Cause or is it Idiopathic? -> If There is an Identifiable Cause, It Should be Specifically Addressed
-Is it Primarily Inflammatory or Fibrotic? ->
-Inflammatory ILD’s are treated with Anti-Inflammatory and Immunosuppressive Medications -> reversible
-Fibrotic ILD’s are treated with Anti-Fibrotic Medications -> scarring that isnt reversible
**Inflammatory ILD’s May Develop Progressive Fibrosis Over Time
-Any ILD With Evidence of Progressive Fibrosis May Be Treated with Anti-Fibrotic Medicationc
challenges to dx interstitial lung diseases
-identifying
-Signs and symptoms are very non-specific (dyspnea and cough)
-More than half of patients will be initially misdiagnosed with more common problems such as COPD and heart disease
-Similar symptoms
-Similar demographic
-75% will consult 3 or more physicians
-34% will have a delay in diagnosis of over 2 years
-Accurate Diagnosis depends on High Resolution CT scan:
-Most CT’s done are not the right type of CT (Low dose for nodules, or CTA for thromboembolic disease)
-you need a high resolution CT
-Most community radiologists are not dedicated Chest Radiologists
-Most radiologists will not give a definitive ILD diagnosis
when should I suspect ILD
-exertional dyspnea*- SOB with exertion
-non productive cough (COPD is productive usually)
-family hx of ILD
-abnormal CXR
-dry crackles** (especially at bases) -> no crackles with COPD
-exertional desaturation-
-spirometry (low FVC) or low DLCO
ILD pathophysiology
-Any process that results in inflammatory-fibrotic infiltration of the alveolar septa resulting in effects on the capillary endothelium and alveolar epithelium
-does not affect the airway!
-Generic term used to describe many conditions that cause breathlessness and/or cough and are associated with radiographic bilateral lung abnormalities
-interstitium- between the capillary and capillary -> with ILD the interstitium is thickened -> lengthens the space for diffusion
-fibrosis- deposition outside alveoli -> thickens
current definition of idiopathic pulmonary fibrosis
-Distinct chronic fibrosing interstitial pneumonia
-Unknown cause
-Limited to the lungs
-Has typical HRCT findings
-Associated with a histologic pattern of usualy interstitial pneumonia (UIP)
-fibrotic disease - little inflammation
-specific pattern on CT
IPF typical presentation
-middle ages 50-70s
-new onset of progressive exertional dyspnea and non-productive cough
-most have symptoms for 12-18 months prior to definitive evaluation
-constitutional symptoms are uncommon
-dry crackles MC physical finding
IPF: dx
-Comprehensive medical history (social history, occupational and environmental exposures [including pets and birds], drug exposures, and family history) -> see if you can find the cause
-PFTs –FVC, DLco, TLC
-6 minute walk test- see if pt desaturates and get a baseline to monitor progression
-Chest Auscultation
-Serologic Testing
-Radiologic Assessment:
-Chest X-Ray
-High Resolution Chest CT*
-Surgical Assessment- Surgical Lung Biopsy (if Necessary)- now this is rarely done
physical exam IPF
-bibasilar late inspiratory fine crackles (velcro rales)
-tachypnea
-clubbing- 40-70% late in disease course
-cardiac exam usually normal until middle late stages -> augmented P2, right sided heave, S3 gallop
-cyanosis
-rash, arthritis, myositis should suggest an alternate dx
look, listen, and walk
-Look at the skin and fingers
Listen carefully for crackles
-Both Lung Bases
-Laterally in mid-axillary line
-Walk the patient in the hallway (or in a staircase):
-Try to elicit exertional dyspnea if possible
-Measure SpO2 before and after walking
-A 3% drop in SpO2 indicates exertional desaturation
-Walk the Patient Again with oxygen titration -> Determine O2 flow that prevents desaturation below 88%
pulmonary function tests
-Spirometry:
-looking for restrictive pattern
-Reduced FVC and TLC
-Normal or increased FEV1/FVC ratio
-Restriction on Lung Volumes
-Impaired gas exchange:
-Decreased DLCO, PaO2
-Desaturation on exercise oximetry
-Increased A-aPO2 gradient
-Normal PFTs do not exclude early ILD
-flow volume loop- restrictive pattern -> normal shape but smaller
serologic evaluation
-Minimum: ANA,CCP, RF (rheumatoid factor), (ATS/ERS guidelines)*
-Based on history & physical exam, consider (dont memorize everything):
-Extractable nuclear antigen (ENA) autoantibody panel (Ro, La, Sm, RNP, Scl-70, Jo)
-Anti-centromere antibody
-ESR & CRP
-MPO/PR3 (ANCA) antibodies
-Anti-cardiolipin antibodies, lupus anticoagulant
-Creatine kinase, aldolase
-Hypersensitivity pneumonitis panel
-Should be performed before a bx
inflammatory disease
diffuse
reticulation
-reticulation results from thickening of the inter-or intralobular septa and appears as linear opacities that resemble a mesh or not on CT
-early signs of fibrosis
honeycombing
-results from deposition of collagen that destroys the characteristic alveolar structure and represents end stage lung disease
-destruction of normal architecture
-advanced stage fibrosis
ground glass opacity
-Hazy areas of increased attenuation with preserved anatomy, including bronchial and vascular markings
-tend to more diffuse
-Indicative of inflammation*
Usual interstitial pneumonia (UIP): hallmark radiologic pattern of IPF
-subpleural, basal predominant, distribution is often heterogenous
-honeycombing with or without traction bronchiectasis or bronchiolectasis
-common at the bases and edges
-common not to see inflammation-> no ground glass
UIP is indicative of IPF
-hallmark criteria of UIP
-subpleural, basal predominance
-reticular abnormality
-honeycombing with or without traction bronchiectasis
-absence of features listed as inconsistent with UIP pattern
advanced IPF HRCT
-Prone HRCT near the lung bases shows extensive reticulation, traction bronchiectasis, and gross honeycombing with a subpleural/basilar predominance
-This appearance indicates advanced IPF
pathologic evaluation: IPF
-Transbronchial biopsy not useful for dx -> Can be used to exclude other dx
-Surgical lung bx (not really helpful):*
-UIP/IPF pattern
-Fibroblastic foci
-Temporal heterogeneity
-Honeycombing appearance
-little to no inflammation
-you should be able to tell everything from the CT
*Necessary if clinical and radiographic findings are atypical for IPF
predictors of disease severity and progression in IPF
-Pts with compromised lung function or respiratory events have worse outcomes
-worser outcomes:
-low DLCO <30% -> lower survival
-pulmonary hypertension
-FVC
-O2 sat < 88% with walk test, small distance walk, HR recovery low
-dyspnea
-hospitalization
known therapy as of 2023
-Nintedanib-Ofev- intracellular inhibitor that targets multiple tyrosine kinases
-Pirfenidone-Esbriet- oral antifibrotic agent
-these drugs have signification GI symptoms -> dont cure but they slow progression
-treating symptoms:
-Oxygen
-Pulmonary rehabilitation
-Treat GERD
-Bronchodilators for cough
-Optimize nutrition
-Immunizations
-Treat cardiac dysfunction
-Lung Transplant
acute exacerbation of IPF
-Unexplained development of worsening of dyspnea within 30 days
-HRCT with new ground-glass abnormalities (usually an inflammatory worsening on top of the IPF)
-Not due to pulmonary infection by ET aspirate or BAL
-Exclusion of alternative causes, e.g. HF, PE
-tx- broad spectrum antibiotics (not usually)
-high dose steroids (prednisone 1mg/kg)**
why do pts die from IPF
-Acute exacerbations
-Cor pulmonale- right heart failure
-Pulmonary infection
-Cardiovascular Disease
-Pulmonary Hypertension
-Lung Cancer
ILD summary
-Diverse group of parenchymal lung diseases
-Idiopathic or Identifiable cause
-Inflammatory or Fibrotic
-Signs and Symptoms are non-specific
-Keep ILD in mind if the patient has a different diagnosis, but is not responding to treatment.
-LISTEN FOR CRACKLES
-Its ok to ask the radiologist to take another look. Pattern is important.
-Early dx and tx may lead to better prognosis
