inpatient / pulmonology and critical care

Interstitial Lung Disease (ILD)

Last Updated: 1/20/2023

# Interstitial Lung Disease

-- Chart Check: previous CT scans, previous rheum abs, previous PFTs, meds (amiodarone, checkpoint inhibitors, MTX, bleo), radiation
-- HPI Intake: timing, smoking, animal/occupational exposures, Rheum ROS, family Hx autoimmune dx
-- Can't Miss: pHTN and RV strain
-- Admission Orders: EKG, consider echo; rheum abs if needed; high res CT non-con inspiratory and expiratory
-- Initial Treatment to Consider: *** need for steroid for acute IPF flares

-- History: *** timing, PFTs, smoking, any below diagnosis in DDx, meds, exposures, family Hx
-- Clinical: *** dyspnea, cough, Rheum ROS (joint pain, thick skin, dry eyes/mouth, etc)
-- Exam: *** mask-like facies, microstomia; crackles, clubbing, pitting, joint disease, raynauds, heliotrope rash, Gottrons papules, mechanics hand, skin fibrosis, sicca
-- Data: *** CXR, CT dry scan, rheum labs (below)

-- Idiopathic Interstitial Pneumonia (IIP) - Chronic - IPF/UIP, NSIP; Acute - AIP, COP; Smoking - RB-ILD, DIP
-- Systemic - sarcoid, amyloid, vasculitis, IBD, malignancy
-- CTD - scleroderma, myositis, RA, SLE, Sigoren’s, MCTD
-- Hypersensitivity Pneumonitis - molds, birds, grains
-- Pneumoconiosis - silicosis, asbestos, coal, berryliosis, metals
-- Drugs - methotrexate, bleomycin, amiodarone, pembro/nivo, nitrofurantoin, radiation
-- Others - LAM, Langerhan’s, IPAF (autoimmune features)

The patient's HPI is notable for ***. Exam showed ***. Labwork and data were notable for ***. Taken together, the patient's presentation is most concerning for ***, with a differential including ***.

-- Initial - CBC/diff, CMP, UA, ESR/CRP
-- if c/f pHTN or RV disease - NT-proBNP, trop, EKG, echo
-- if c/f underlyin g rheumatologic disease - CPK/aldolase, C3/C4, ANA, RF/CCP, RNP, Ro/La, Scl-70, ANCA, hypersensitivity panel, myositis panel, Jo1, MDA-5
-- High-Resolution CT without contrast with inspiratory and expiratory phases
-- Consider Bronch or biopsy based on CT findings (avoid if UIP pattern, only get if will change management or symptoms rapidly progressing)
-- Consider lung transplant eval if candidate

-- O2: currently ***, maintain continuous pulse ox with goal >92-94%
-- Steroids: *** Pulse methylpred 1mg/kd/day with taper for acute IPF exacerbation, NSIP, COP
-- Abx: *** broad spectrum for 7 days if acute IPF exacerbation
-- Continue home *** pifenidone, nintedanib, azathioprine, MMF, cyclophosphamide, prednisone
-- Palliative: low dose opioids, benzos for dyspnea/anxiety

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If You Remember Nothing Else

ILDs are a heterogeneous group of disorders characterized by inflammation and progressive fibrosis. They can be idiopathic (IIPs) like IPF and NSIP or 2/2 known causes like rheum dx, drugs, radiation, and exposures. Patients will most often present with cough and progressive DOE and crackles are common on exam. On PFTs, you will see restrictive physiology (FEV1/FVC normal or increased) with low lung volumes. Treatment includes steroids, immune modulators, and antifibrotics (nintedanib and pirfenidone). Fibrosis can not be reversed and once it leads to end-stage disease, the only treatment is transplant. Otherwise, the goal of treatment is to prevent further decline. ILD can lead to pHTN (Group III) which can lead to RV failure.

Clinical Pearls

  • Interstitial lung disease is fibrosis in the pulmonary interstitium which includes the basement membrane, perivascular, and perilymphatic connective tissue, which supports the lungs and covers the airways
  • When considering the etiologies, think in 4 major buckets - CTD, sarcoid, hypersensitivity, idiopathic (all others are uncommon)
  • UIP (usual interstitial pneumonia) is the radiological correlate of IPF (idiopathic pulmonary fibrosis); from actual fibrosis; will see basilar-predominant disease with bronchiectasis and honeycombing
  • NSIP (non-specific interstitial pneumonia) is from inflammation and eventual fibrosis; will see ground glass, mosaic attenuation from air trapping, increased reticular markings
  • Upper-predominant disease - hypersensitivity, smoking, inhalation
  • Lower-predominant disease - IPF, NSIP - key distinction is IPF has subpleural distribution, whereas NSIP often has immediate subpleural sparing
  • IPF is more common in men, NSIP more common in women and associated with connective tissue disorders, HIV, and hypersensitivity
  • If you see lymphadenopathy - consider sarcoid and malignancy as etiology
  • PFTs will be restrictive (decreased TLC, FRC, RV; FEV1/FVC will be normal or increased); decreased DLCO can be an early sign
  • Hypersensitivity Pneumonitis commonly from bird proteins/feathers, spores from molds or hays
  • ILD can commonly cause pHTN (Group 3 - chronic lung disease with hypoxia)
  • When treating chronic IPF, the goal is to decrease FVC decline since you cannot reverse fibrosis; medications like pirfenidone and nintedanib slow the fibrotic process, but do not reverse it
  • Asbestosis - ship construction workers, plumbers, roofers; ferruginous bodies in alveolar septa, an lead to bronchogenic carcinoma and mesothelioma, calcified pleural plaques, and ILD on imaging
  • Silicosis - miners, quarries, sandblasting, glassmakers; increased risk of TB, eggshell calcifications, many solitary small opacities in upper lobes, GGO
  • Coal Workers - carbon-laden macrophages, chronic bronchitis, Caplan Syndrome (RA and pneumoconiosis), many small nodular opacities in upper lungs
  • Berrylioisis - aerospace engineer, ceramics, electronics, dyes; non-caseating granulomas, hilar lymphadenopathy

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