INTERSTITIAL LUNG DISEASE

INTERSTITIAL LUNG DISEASE

WHEN LUNGS STIFFEN, EVERY BREATH BECOMES A CHALLENGE. HENCE UNDERSTANDING INTERSTIAL LUNG DISEASE MAKES A WORLD OF DIFFERENCE!

WHAT IS INTERSTITIAL LUNG DISEASE (ILD)?

Interstitial lung disease (ILD) is a collective term for a large group of chronic lung diseases in which there is inflamation/fibrosis of lung interstitium. Pulmonary interstitium is the tissue which surrounds alveoli or air sacs of lung and is important for absorption of oxygen into the blood capillaries. In ILD, the interstitium becomes inflamed and eventually fibrosed (fibrosis is scarring). This scarring makes the oxygen transfer into blood difficult and due to the stiffness lungs are unable to expand fully,making breathing more difficult.

WHAT CAUSES INTERSTITIAL LUNG DISEASE?

Causes are many,from 'IDIOPATHIC '( cause not known) to 'INFECTIONS'.

1. IDIOPATHIC ILD is called IDIOPATHIC PULMONARY FIBROSIS (IPF):

   Here the cause is not known. IPF is the most common and serious form of ILD, due to an abnormal healing response to alveolar epithelial injury in a genetically susceptible individual.

2. AUTOIMMUNE DISEASES/CONNECTIVE TISSUE DISEASES ( CTD-ILD):

   In certain Connective Tissue Diseases (CTD) like Rheumatoid arthritis, Scleroderma /Systemic Sclerosis (SSc), Systemic Lupus Erythematosus (SLE) and Myopathies (PM_DM), the body's immune system produces specific Auto antibodies which mistakenly attack its own tissues like skin, joints, blood vessels, muscles, kidney, glands etc. When the damage includes lungs, it is called CTD-ILD.

3. HYPERSENSITIVITY PNEUMONITIS (HP): Environmental exposure to organic dusts may cause ILD known as Hypersensitivity Pneumonitis (HP) .The material may be fungal spores (molds), avian ( bird related) proteins like bird droppings, feathers, dander, animal proteins, contaminated water systems like AC/ humidifier with bacteria, dust from farming (Farmer's lung) and chemicals like disiocyanate in paints etc.

4. DRUG INDUCED ILD: Medications like nitrofurantoin, amiodarone, bleomycin, certain cancer immuno therapies including Immune Check Point Inhibitors (ICPI) can lead to development of ILD.

5. POST INFECTIOUS ILD : Infections like Covid-19 may be followed by ILD. Severe Covid -19 infections in some patients may lead to ILD with reversible/ irreversable fibrosis. Other Corona viruses like MERS/SARS can also cause ILD.

   
   

INCIDENCE:

IPF accounts for more than 30% of all cases of ILD.

HP accounts for 15%.

CTD-ILD accounts for 25% of all cases of ILD.

The rest are Drug related and Post infectious ILD.

PROGRESSIVE PULMONARY FIBROSIS (PPF) :

30 to 40 % of people with ILD may develop fibrosis which progresses leading to respiratory failure. It has poor prognosis.

The median survival in PPF patients is 2.5 to 3.5 years.

WHAT ARE THE SYMPTOMS OF ILD?

1.Breathlessness or Dyspnea is the most common symptom. It starts as breathlessness during exertion ( mild exercise) , later progresses to be present even at rest.

The onset of dyspnea in IPF and Rheumatoid Arthritis-ILD (RA-ILD) may take weeks to months.

Organizing Pneumonia (OP) or Acute Interstitial Pneumonia (AIP) takes days to few weeks.

In SSc-ILD and chronic HP dyspnea develops more slowly over many months.

2. Dry, persistent cough in 30 to 50 %.

3. Fatigue, Weight loss occur with progression of ILD.

   
   

SOME OF THE SIGNS THAT MIGHT BE OBSERVED IN CASES OF ILD:

DIGITAL CLUBBING is seen in 7 to 42% of ILD.

In cases of CTD- ILD(Autoimmune diseases), depending on the specific disease certain signs may be observed.

In cases of Rheumatoid Arthritis : Subcutanious nodules, Digital ulcers, Deformities of small joints.

In Systemic Sclerosis: Thickening of the skin, face, fingers and hands (sclerodactyly).

In Systemic Lupus Erythematosis (SLE) : Skin rash, Discoid Lupus, Oral ulcers, Arthritis, Butterfly rash.

In Dermatosis - Myositis cases: Heliotropic rash, Gottron papules are seen.

In Antisythetase Syndrome: Mechanic hands .

70 to 93 % of IPF-ILD cases may reveal VELCRO rales at lung bases.

(VELCRO : pulling apart Velcro strips).

HP cases may have End inspiratory SQUAWKS.

COMMON MANIFESTATIONS IN CONNECTIVE TISSUE DISEASES

MULTI ORGAN INVOLVEMENT AND MANIFESTATIONS OF SLE

SKIN TIGHTENING,THINNING OF MOUTH & RED SPOTS IN SCLERODERMA

HOW DOES A PULMONOLOGIST/CHEST PHYSICIAN ASSESS DIAGNOSIS?

1.CHEST CT SCAN ( HRCT SCAN) is the primary diagnostic test. It provides detailed images which show characterstic appearances of ILDs.

Some of the important descriptions of various types of ILDs:

BIBASAL RETICULATIONS, TRACTION BRONCHIECTASIS & HONEYCOMBING IN IPF

1. Subpleural basal reticulations,honey coombing, traction bronchiectasis seen in UIP/IPF.

2. Basal groundglass opacities (GGO), reticulations and traction bronchiectasis seen in NSIP (Non Specific Interstitial Pneumonitis)

3. Patchy consolidation and Atoll-sign seen in Organizing Pneumonia (OP).

4. Diffuse ground glass opacities or consolidation and cystic spaces seen in

   Diffuse Alveolar Damage(DAD).

5. Centrinobular nodules, patchy groundglass opacities, mosaic attenuation seen in Non Fbrotic HP.

Upperzone and midzone peribronchovascular fibrosis, mosaic attenuation, traction bronchiectasis seen in Fibrotic HP.

2. SEROLOGIC TESTS FOR DETECTING MARKERS IN CTD -ILD:

1. ANA,Anti ds DNA ( + ve in SLE,Sjogrens,MCTD)

2. ANCA ( +ve in ANCA associated vasulitides like GPA,EGPA and MPA)

3. RA factor and ACCP ( key blood tests for Rheumatoid Arthritis)

4. Anti Scl-70 ,ANTI CENTROMERE antibody( +ve in SSc)

5. Anti-Smith antibody ( +ve in SLE)

6. Anti Jo-1, Anti Mi-2,Anti SRP (+ve in Dermatomyositis and Polymyositis)

7. Anti Ro/SSA and Anti La/ SSB ( + ve in Sjogrens syndrome)

8. Sp IgG ab /precipitins (+ve in HP)

3.LUNG BIOPSY:

In difficult cases, for more accurate diagnosis, Lung Biopsy is necessary.

Currently less than 10% cases of ILD require Lung Biopsy.

VATS(Video Assisted Thoracic Surgery) or

TBLC (Trans Bronchial Lung Cryobiopsy)/ BTCB ( Bronchoscopic Transbronchial Cryo Biopsy) are the methods used to obtain tissue samples.

4. PFT ( Pulmonary Function Tests):

To assess severity of the ILD, tests like FVC, DLCO and

6 Minutes walking test ( 6MWT) with Pulse Oxymetry ( SpO2) to assess O2 desaturation are done. These tests are repeated at regular intervals to assess the progress of the disesase and response to medications.

THE ACCEPTED APPROACH TO ILD DIAGNOSIS IS

"MULTIDISCIPLINARY ASSESSMENT" WITH A TEAM CONSISTING OF PULMONOLOGIST, RADIOLOGIST,PATHOLOGIST AND RHEUMATOLOGIST.

WHAT IS THE TREATMENT OF ILD?

Treatment is based on the type of ILD.

ANTIFIBROTICS TO SLOW DOWN FIBROSIS:

The two most important antifibrotics are NINTEDANIB & PIRFENIDONE.

They slow down rate of fibrosis (scarring) of lung and decline of lung funtion(FVC), though they cannot reverse the existing fibrosis. A newer drug, NERANDOMILAST is recently approved by FDA , specifically for IPF & PPF.

NINTEDANIB: It is a TK inhibitor and inhibits >12 growth factor receptors, used in a dose of 150 mg twice a day. Side effects are diarrhea, nausea and weight loss.

PIRFENIDONE: It downregulates TGF Beta,TNF and other cytokines. Used in a dose of 801 mg three times a day. Side effects are nausea, bloating, photosensitive rash and weight loss.

1. In IPF: PIRFENIDONE and NINTEDANIB

2. IN SSC ILD: CYCLOPHOSPHAMIDE, MYCOPHENOLATE MOFETIL, RITUXIMAB, NINTEDANIB, TOCILIZUMAB

3. In PPF: NINTEDANIB

4. In SLE, SSC: IMMUNOSUPPRESSANTS LIKE STEROIDS etc.

5. In HP: IDENTIFING AND AVOIDING THE ANTIGEN (molds, pigeons, parakeets, fowls, dust)

TREATMENT OF DISEASE COMPLICATIONS:

PULMONARY REHABILITATION:

Exercise training, Breathing techniques

PULMONARY HYPERTENSION:

Inhaled TREPROSTINIL

RESPIRATORY FAILURE:

Home Oxygen therapy

END STAGE LUNG DISEASE:

LUNG TRANSPLANTATION

OTHERS: Management of symptoms like cough,breathlessness.

WITH TIMELY EVALUATION ,APPROPRIATE THERAPY & REGULAR FOLLOW-UP BY A PULMONOGIST, LIVING WELL WITH ILD IS NOT ONLY POSSIBLE - IT'S EMPOWERING