#221 Interstitial Lung Disease with Erin Narewski DO

June 22, 2020 | By Paul Williams

Breathtaking knowledge and other words of inspiration

Throw out your down pillows and join The Curbsiders for this lively discussion on interstitial lung disease. While the hundreds of interstitial lung disease types make this topic a bit overwhelming, breathe easy knowing that pulmonologist, Dr. Erin Narewski @erinnarewski (Temple), can boil things down to an easy to approach framework in less time than it takes to complete a few 6-minute walk tests. In this episode, we walk through the classification, relevant patient history, workup, and management of interstitial lung disease.

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Credits

Written and Produced by: Paul Williams, MD, FACP; Nicole Kus, David Madnick, and Peter Wikoff

Infographic and Cover Art: Edison Jyang

Show Notes: Deborah Gorth

Hosts: Stuart Brigham MD; Matthew Watto MD, FACP; Paul Williams MD, FACP   

Editor: Paul Williams MD, FACP (written materials); Clair Morgan of nodderly.com

Guest: Erin Narewski DO, FCCP

Sponsor

Join the American College of Physicians today! Post-training physicians can take advantage of an exclusive limited-time $100 dues discount. Visit acponline.org/member and use the code ACPDISCOUNT. Discount is only available until June 30, 2020.  

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Time Stamps

• 0:00  Sponsor – Join the ACP community! Be IM Proud Visit acponline.org/member and use the code ACPDISCOUNT
• 00:30 Intro, disclaimer, guest bio
• 03:14 Guest one-liner, career advice, favorite failure, Picks of the Week*: The Strain, FX Horror TV Show; One Hundred Years of Solitude (book) by Gabriel Garcia Marquez; Hypoallergenic pillows; Peanut butter whiskey 
• 10:02 Sponsor – Join the ACP community! Be IM Proud Visit acponline.org/member and use the code ACPDISCOUNT
• 11:00 Case from Kashlak, Definitions
• 16:40 Buckets of ILD
• 32:06 Discussion of testing ILD: Labs and Imaging
• 44:20 Imaging findings in ILD
• 49:44 Basic Management of ILD
• 61:00 Take home points and Outro

Interstitial Lung Disease Pearls

1. Interstitial lung disease (ILD) is a relatively uncommon cause of dyspnea, but due to its severity, ILD should always be on the back of your differential.
2. ILD comprises a diverse family of illnesses that fall into four main buckets: connective tissue disease, sarcoidosis related disease, hypersensitivity pneumonitis, and idiopathic pulmonary fibrosis. 
3. Not all ILD patients report dyspnea, cough, or have restrictive characteristics on pulmonary function tests. 
4. Be careful when evaluating dyspnea; some patients adjust activity for lung function and may not feel short of breath. 
5. Some patients may not know that they received amiodarone while hospitalized for a cardiac condition, so it can be useful to ask about a history of cardiac surgery, arrest, or arrhythmia. 
6. Corticosteroids in idiopathic pulmonary fibrosis  are associated with an increase in mortality, so it is important to understand the etiology of ILD before prescribing this medication class (PANTHER-IPF 2012).
7. The adult oxygen saturation goal is >94%, and too much oxygen can be harmful (Chu et al. 2018). 

Interstitial Lung Disease (ILD)

Defining Pulmonary Interstitium

The pulmonary interstitium comprises the basement membrane, peri-vascular, and perilymphatic fibrous connective tissue, which supports the lung and covers everything including airways and acinar clusters. Nearly all circulating blood passes through this tissue, so any systemic disease can impact the lung interstitium. 

Classifying Interstitial Lung Disease

Although the family of interstitial lung disease refers to a large–some would say overwhelmingly large–family of diseases, these conditions can be simplified by grouping them into four most common causes: connective tissue related diseases, sarcoidosis, hypersensitivity, and idiopathic. Less common causes of ILD include occupational exposures, drug induced, smoking related, and familial ILD.

Does My Patient Have Interstitial Lung Disease?

History for ILD

A comprehensive patient history is the key to unlocking an ILD diagnosis. Questions can be focused on each of the causes of ILD. For a potential connective tissue etiology, questions about changes in skin, hair, dry eyes, or dry mouth can indicate the underlying pathology.  Presence of arthropathy or fatigue could indicate sarcoidosis. Hypersensitivity to antigens could be assessed with questions about wheezing or squeaking sounds in the chest, birds, down products, house age or a  history of water damage at home or work. Possible occupational exposures can be assessed by asking the patient where they work or if they are required to wear ppe at work. Additionally, the Dyspnea 12 Questionnaire can be used to quantify symptomatology. Be careful when evaluating dyspnea; some patients adjust activity for lung function and may not feel short of breath. 

Medications

The CHEST ILD questionnaire covers many medications linked to ILD, but additional history focused on medications can be useful. Some patients may not know that they received amiodarone while hospitalized for a cardiac condition, so it can be useful to ask about a history of cardiac surgery, arrest, or arrhythmia. If the patient has an extensive history of urinary tract infections, they may not remember the name of the medication they took, but nitrofurantoin could be a cause. A cancer history could indicate exposure to chemotherapy or radiation. Methotrexate has also been linked with ILD (Fragoulis et al 2019).

Exposures

Is your patient an avid pigeon racer? While direct bird exposures are becoming less common, beware of luxurious down pillows and encourage patients to switch to fiber filled pillows if this could be contributing to their disease. Unfortunately, microwave popcorn has also been linked to ILD. The possible exposures contributing to ILD are vast, so the CHEST ILD questionnaire is a useful tool for evaluating for possible exposures.  

Physical Exam Findings in ILD

Pulmonary crackles is the classic physical exam finding of ILD. However, many patients with ILD will have a normal lung exam. The crackles of ILD is a dry velcro sound as opposed to the “wet” rales associated with heart failure (Bohadana et al 2014). Digital clubbing is a common non-pulmonary physical exam finding of ILD (Sarkar et al 2012). Right heart strain and pulmonary artery hypertension are also late findings. The mouth, teeth, eyes, skin can also provide important information. Rashes, swollen joints, ulcers, chronic dry mouth leading to tooth or gum erosion can indicate connective tissue disease (Gupta et al 2019). 

Labs for Interstitial Lung Disease

Initial tests for evaluating dyspnea potentially caused by ILD should include a CBC with a differential, basic metabolic panel, urine dipstick, and liver function tests.  Additional tests to consider, depending on the clinical context, include an ESR, CRP, and a urinalysis if there is suspected vasculitis or kidney involvement (Wells and Hirani 2008). Consider scleroderma, myositis, or vasculitis workups if there is a suspicion of these conditions. 

Imaging in ILD

A plain chest x-ray has poor sensitivity for ILD, but remains an initial component of the workup for dyspnea. A high resolution CT scan of the chest without contrast is ideal for characterizing the lung parenchyma and diagnosing interstitial lung disease. This narrow beam approach results in high definition slices that are representative of lung tissue and can illuminate the character of diffuse disease. 

Patterns on high resolution CT can provide an important clue for diagnosis, but it does not determine the diagnosis. Usual interstitial pneumonia (UIP) pattern–honeycombing, peripheral basal distribution, and absence of ground glass opacities–is the pattern most commonly associated with idiopathic pulmonary fibrosis, but you still need to do a full work up for other causes (Distefano et al 2020). 

Pulmonary Function Tests

Normal lung function tests do not rule out ILD. Always order diffusion capacity along with spirometry and lung volumes. There can be mixed obstruction and restriction patterns, especially if there is also a smoking history. 

Six Minute Walk Test

The six minute walk test is easy and can be very useful for the initial work up of dyspnea to evaluate functional capacity. This test can be performed in the office using a 100-ft hallway, marked every 3 meters (ATS Guidelines).  If there is dizziness while walking, consider pulmonary hypertension as part of the diagnosis. Or if they have chest pain, be concerned about cardiovascular disease. 

Biopsy

Biopsy is not necessary for the diagnosis; this procedure can be dangerous, and it is rarely used.

Treatments

Inhaled medications are helpful in a minority of patients who have airway involvement, but systemic medications are typically required. There is mixed evidence suggesting that proton pump inhibitors may have a role in treating interstitial lung disease, but more work is necessary to draw clear conclusions (Johannson et al 2017). 

Antigen Avoidance

Antigen avoidance is the mainstay of treatment for hypersensitivity mediated ILD. Down pillows should be switched for fiber filled alternatives. If your patient is an avid duck hunter, maybe suggest transitioning to Nintendo Duck Hunt along with their nintedanib. 

Anti-fibrotics

Nintedanib, pirfenidone act on cellular signaling cascade that lead to fibrosis inhibiting this process. These medications prevent acute exacerbations of ILD, slow fibrotic progression, and are now being used for early ILD (Maher and Strek 2019). 

Anti-inflammatory Medications

Steroid therapy in idiopathic pulmonary fibrosis is associated with an increase in mortality, so it is important to understand the etiology of ILD before prescribing this medication class (PANTHER-IPF 2012). Anti-inflammatory medications used for ILD include rituximab, mycophenolate mofetil, and azathioprine. 

Pulmonary Rehabilitation

Pulmonary rehabilitation is a lot like boot camp for breathing and can improve short term morbidity, but these interventions need to be maintained. It is an opportunity to learn how to use oxygen. There is not a lot of data on the use of pulmonary rehabilitation for ILD, but pulmonary rehabilitation has been translated from other lung diseases and has been shown to provide benefit (Tonelli et al 2017). 

Palliative Care/Lung Transplant

Long term prognosis of progressive ILD is poor, and early involvement of palliative care can be helpful. When referring patients to a pulmonologist, be sure to refer to a center with lung transplant capabilities.

Links*

1. The Strain, FX Horror TV Show
2. One Hundred Years of Solitude by Gabriel Garcia Marquez
3. Hypoallergenic pillows
4. Peanut butter whiskey 
5. Diagnosis of Idiopathic Pulmonary Fibrosis An Official ATS/ERS/JRS/ALAT Clinical Practice Guideline
6. CHEST Patient Questionnaire

*The Curbsiders participates in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising commissions by linking to Amazon. Simply put, if you click on our Amazon.com links and buy something we earn a (very) small commission, yet you don’t pay any extra.

Goal

Listeners will feel comfortable with the basic pathophysiology, diagnosis, and management of interstitial lung disease. 

Learning objectives

After listening to this episode listeners will…  

1. Be able to define the lung interstitium. 
2. Develop a mental framework for the basic subtypes of interstitial lung disease. 
3. Learn with the types of questions necessary to elucidate the pathophysiology of their patient’s ILD. 
4. Know the steps to initiate a workup for ILD.
5. Become familiar with the treatment strategy for ILD. 

Disclosures

Dr Narewski reports no relevant financial disclosures. The Curbsiders report no relevant financial disclosures.

Citation

Narewski E, Gorth DJ, Kus N, Madnick D, Wikoff P, Williams PN, Jyang E, Brigham SK, Watto MF. “#221 Interstitial Lung Disease with Erin Narewski DO”. The Curbsiders Internal Medicine Podcast. http://thecurbsiders.com/episode-list . June 22, 2020.

References

Bohana A, Izbicki G, and Kraman SS.  2014.  Fundamentals of lung auscultation.  New England Journal of Medicine 370: 744-751.

Chu DK et al.  2018.  Mortality and morbidity in acutely ill patients treated with liberal versus conservative oxygen therapy (IOTA): A systematic review and meta-analysis.  The Lancet 391(10131): 1693-1705.

DiStefano G et al.  2020.  HRCT patterns of interstitial lung diseases: a review.  Diagnostics 10(4): 244.

Fragoulis GE et al.  2019.  Methotrexate-associated pneumonitis and rheumatoid arthritis-interstitial lung disease: Current concepts for the diagnosis and treatment.  Frontiers in Medicine 6:238.

Gupta S, Ferrada MA, and Hasni SA.  2019.  Pulmonary manifestations of Sjogren’s syndrome: Underlying immunologic mechanisms, clinical presentation, and management.  Frontiers in Immunology 10:1327.

Idiopathic Pulmonary Fibrosis Clinical Research Network, Raghu G, et al.  2012.  Prednisone, azathioprine, and N-acetylcysteine for pulmonary fibrosis.  New England Journal of Medicine 366(21): 1968-1977.

Johannson KA et al.  2017.  Antacid therapy in idiopathic pulmonary fibrosis: More questions than answers?  Lancet Respiratory Medicine 5(7): 591-598.

Maher TB and Strek ME.  2019.  Antifibrotic therapy for idiopathic pulmonary fibrosis: Time to treat.  Respiratory Research 20(205).

Sarkar M, Mahesh DM, Madabhavi I.  Digital clubbing.  Lung India 29(4): 354-362.

Tonelli R et al.  2017.  Effectiveness of pulmonary rehabilitation in patients with interstitial lung disease of different etiology: A multicenter prospective study.  BMC Pulmonary Medicine 17(1): 130.

Wells AU and Hirani N.  2008.  Interstitial lung disease guideline.  Thorax 63: v1-v58.