Interstitial Lung Disease

A CHECKLIST FOR EVALUATING A PATIENT WITH DYSPNEA AND DRY COUGH FOR POTENTIAL ILD¹

• Comprehensive patient history
• Comprehensive physical exam
• Pulmonary function testing
• Laboratory analyses
• Imaging
• Other modalities (as indicated)

A COMPREHENSIVE HISTORY HELPS NARROW THE LIST OF POTENTIAL ILDs

Past Medical History:^3,10

• Gastroesophageal reflux disease
• Cancer, chemotherapy, and/or radiation therapy
• Cardiac arrhythmias and amiodarone use
• Prostate, urinary, kidney infections, and nitrofurantoin use

Current and Past Chronic Medications:^11,12

• Cancer, chemotherapy, and/or radiation therapy
• Amiodarone use
• Nitrofurantoin use

Exposure History:³

• Tobacco use
• Drug use
• Occupational
• Environmental
• Avocational

Family History:^3,10,11

• Pulmonary fibrosis
• ILD
• Sarcoidosis
• Autoimmune disease
• Oxygen use

SPECIFIC SOUNDS AND THEIR TIMING CAN HELP NARROW DOWN POSSIBLE ILDs

Crackles:

• Many ILDs exhibit fine, bibasilar crackles^13,14
• However, crackles are not specific to lLDs¹³
• The timing and location of the crackles can vary, which further distinguishes the specific cause, such as COPD, pneumonia, asbestosis, chronic bronchitis, and pulmonary edema secondary to heart failure¹³
• Crackles may occur alongside other breath sounds, providing further clues to the potential cause(s) of dyspnea and/or cough^13,15,16

Wheezes/Squeaks/Pops/Rhonchi

• Sounds heard at initial inspiration and those heard primarily at the tops of the lungs should prompt investigation of causes other than ILDs, although these can also be characteristic of some forms of ILD^13,17
• Thorough auscultation of all regions is the best way to ensure that the signs of all potential explanations of dyspnea and/or cough are explored¹³

PATIENTS REPORTING DYSPNEA SHOULD UNDERGO COMPLETE PULMONARY FUNCTION TESTS^2,10

• PFTs allow the physician to:¹⁸
  • Evaluate lung function
  • Differentiate among pulmonary disorders
  • Guide initial management strategies

• Pulmonary function can be assessed using parameters such as:^3,10,19
  • Lung volumes – forced expiratory volume in 1 minute (FEV₁), forced vital capacity (FVC)
  • Gas exchange – diffusing capacity of the lungs for carbon monoxide (DL_co)
  • Dyspnea on exertion – 6-minute walking test (6MWT)

PFTS HELP DETERMINE THE TYPE OF RESPIRATORY DEFECT PRESENT¹⁸

Obstructive defect²⁰

• Total lung capacity (TLC) is normal
• Normal FVC
• Lower FEV₁
• Lower FEV₁/FVC ratio
• Flows are lower than expected over the entire volume range

Restrictive defect²⁰

• TLC is low
• Low FVC
• High or normal FEV₁/ FVC ratio
• Flows are higher than expected at a given lung volume

Used with permission from Pellegrino R, Viegi G, Brusasco V, et al. Interpretative strategies for lung function tests. Eur Respir J. 2005;26(5):948-968. doi: 10.1183/09031936.05.00035205.

Restrictive defects are common in ILDs.¹⁸

PFTS HELP DIFFERENTIATE PULMONARY DISORDERS^18,21

Obtaining complete PFTs is important because it allows determination of the nature of the respiratory defect.¹⁸

OTHER INVESTIGATIONS FOR EVALUATING POTENTIAL ILDS^22-24

• Laboratory workups
• Chest X-ray
• High-resolution computed tomography (HRCT)
• Lung biopsy
• Bronchoalveolar lavage (BAL)

LABORATORY WORKUP²⁵

• Basic blood tests [e.g., complete blood count (CBC)] are generally a first step in evaluating a patient, although many ILDs will not have specific abnormalities¹
• Some ILDs — particularly those associated with autoimmune diseases will often exhibit characteristic antibody signatures²

CHEST X-RAYS ARE IMPORTANT TO RULE OUT OTHER POSSIBLE CAUSES OF SHORTNESS OF BREATH

• Chest X-rays cannot solely diagnose most ILDs, but they can help rule out other causes of dyspnea, including heart disease, pneumonia, collapsed lung, emphysema, and lung cancer^3,26
• When possible, previous chest X-rays should be included in the evaluation to determine whether the disease process is acute or chronic²

If an X-ray report states ILD, interstitial findings, or reticulation, the patient should be referred to a pulmonologist for an HRCT scan and further workup.²

HRCTS ARE AN ESSENTIAL PIECE OF DIAGNOSING MANY ILDs

• HRCT creates high-resolution stacked X-ray slices to visualize internal organs^27,28
• HRCT allows physicians to:^3,29
  • Differentiate features that help distinguish among various ILDs
  • Assess progression of disease and to exclude concomitant processes such as emphysema, edema, or infection

PATIENTS WITH DYSPNEA AND/OR COUGH SHOULD HAVE AN HRCT TO LOOK FOR SIGNS OF ILD BECAUSE CHEST X-RAYS MAY APPEAR NORMAL³⁰

Chest X-Ray

HRCT

Images courtesy of and used with permission from the American Thoracic Society.

LUNG BIOPSY CAN ADD ADDITIONAL INFORMATION FOR MAKING AN ACCURATE DIAGNOSIS

Depending on the specific ILD suspected and the outcome of other evaluations, such as serologies and/or HRCT, lung biopsy may be recommended to accurately diagnose the patient’s condition^31,32

Types of lung biopsy procedures:^33,34

• Open lung biopsy
• Video-assisted thoracoscopic surgery
• Cryobiopsy

Patients with suspected acute exacerbations of ILD should not be referred for lung biopsy due to higher risk of mortality.^31,35

BRONCHOALVEOLAR LAVAGE MAY PROVIDE INFORMATION THAT CAN REDUCE THE NEED FOR LUNG BIOPSY²⁴

• Performing BAL can rule out opportunistic infections and is useful in diagnosing hypersensitivity pneumonitis and sarcoidosis²⁴
• However, BAL results are generally nonspecific (consistent with or suggestive of a given condition) rather than pathognomonic for ILD²⁴

Smoking increases the cell count in BAL by approximately 500%.^36,37

DIAGNOSING ILDs INVOLVES A DIVERSE TEAM OF HEALTHCARE PROFESSIONALS^6,32

• Primary care physicians (PCPs) are often the first ones to recognize the initial signs of ILD and/or diseases that have ILD manifestations⁶
• Referral to a pulmonologist, rheumatologist, or other specialist may be required, depending on the presenting symptoms^6,32
• Once interstitial lung disease is suspected, patients should be evaluated and potentially referred to an ILD Center of Excellence⁶

EARLY REFERRAL TO AN ILD CENTER CAN IMPROVE TIME TO DIAGNOSIS⁶

• Multidisciplinary discussions are recommended for diagnosing ILDs^3,6,38
• ILD centers have the resources and experience to manage a multidisciplinary approach to diagnosing ILDs^3,38

An ILD multidisciplinary discussion (MDD) may involve:

Pathologists, pulmonologists, radiologists, nurse practitioners & physician's assistants and rheumatologists