RESTRICTIVE LUNG DISEASERESTRICTIVE LUNG DISEASE

ssharma.comssharma.com

By Sat Sharma By Sat Sharma

Assistant ProfessorAssistant Professor

University of ManitobaUniversity of Manitoba

BackgroundBackgroundThe lung volumes are reduced either because of:The lung volumes are reduced either because of:

1.1. Alteration in lung parenchyma.Alteration in lung parenchyma.

2.2. Diseases of the pleura, chest wall or neuromuscular Diseases of the pleura, chest wall or neuromuscular apparatus.apparatus.

Physiologically restrictive lung diseases are Physiologically restrictive lung diseases are defined by reduced total lung capacity, vital defined by reduced total lung capacity, vital capacity and functional residual capacity, but capacity and functional residual capacity, but with preserved air flow.with preserved air flow.

Restrictive lung diseases may be divided Restrictive lung diseases may be divided into the following groups:into the following groups:

Intrinsic lung diseases (diseases of the Intrinsic lung diseases (diseases of the lung parenchyma)lung parenchyma)

Extrinsic disorders (extra-parenchymal Extrinsic disorders (extra-parenchymal diseases)diseases)

Intrinsic Lung DiseasesIntrinsic Lung DiseasesThese diseases cause either:These diseases cause either: Inflammation and/or scarring of lung Inflammation and/or scarring of lung

tissue (interstitial lung disease)tissue (interstitial lung disease)

oror Fill the air spaces with exudate and Fill the air spaces with exudate and

debris (pneumonitis).debris (pneumonitis).

These diseases are classified further These diseases are classified further according to the etiological factor.according to the etiological factor.

Extrinsic DisordersExtrinsic DisordersThe chest wall, pleura and respiratory The chest wall, pleura and respiratory

muscles are the components of muscles are the components of respiratory pump.respiratory pump.

Disorders of these structures will cause lung Disorders of these structures will cause lung restriction and impair ventilatory function.restriction and impair ventilatory function.

These are grouped as:These are grouped as: Non-muscular diseases of the chest wall.Non-muscular diseases of the chest wall. Neuromuscular disorders.Neuromuscular disorders.

PathophysiologyPathophysiologyIntrinsic lung diseases:Intrinsic lung diseases: Diffuse parenchymal disorders cause reduction Diffuse parenchymal disorders cause reduction

in all lung volumes.in all lung volumes. This is produced by excessive elastic recoil of This is produced by excessive elastic recoil of

the lungs.the lungs. Expiratory flows are reduced in proportion to Expiratory flows are reduced in proportion to

lung volumes.lung volumes. Arterial hypoxemia is caused by Arterial hypoxemia is caused by

ventilation/perfusion mismatch.ventilation/perfusion mismatch. Impaired diffusion of oxygen will cause Impaired diffusion of oxygen will cause

exercise-induced desaturation.exercise-induced desaturation. Hyperventilation at rest secondary to reflex Hyperventilation at rest secondary to reflex

stimulation.stimulation.

Extrinsic DisordersExtrinsic Disorders

Diseases of the pleura, thoracic cage, Diseases of the pleura, thoracic cage, decrease compliance of respiratory system.decrease compliance of respiratory system.

There is reduction in lung volumes.There is reduction in lung volumes. Secondarily, atelectasis occurs leading to Secondarily, atelectasis occurs leading to

V/Q mismatch V/Q mismatch hypoxemia. hypoxemia. The thoracic cage and neuromuscular The thoracic cage and neuromuscular

structures are a part of respiratory system.structures are a part of respiratory system. Any disease of these structures will cause Any disease of these structures will cause

restrictive disease and ventilatory restrictive disease and ventilatory dysfunction.dysfunction.

Diseases of the Diseases of the Lung ParenchymaLung Parenchyma

Structure of the Alveolar Structure of the Alveolar WallWall

EM in Pulmonary FibrosisEM in Pulmonary Fibrosis

InterstitiumInterstitium

Diffuse Interstitial Pulmonary Diffuse Interstitial Pulmonary FibrosisFibrosis

Synonyms: idiopathic pulmonary fibrosis, Synonyms: idiopathic pulmonary fibrosis, interstitial pneumonia, cryptogenic fibrosing interstitial pneumonia, cryptogenic fibrosing alveolitis.alveolitis.

PathologyPathology Thickening of interstitium.Thickening of interstitium. Initially, infiltration with lymphocytes and plasma Initially, infiltration with lymphocytes and plasma

cells.cells. Later fibroblasts lay down thick collagen bundles.Later fibroblasts lay down thick collagen bundles. These changes occur irregularly within the lung.These changes occur irregularly within the lung. Eventually alveolar architecture is destroyed – Eventually alveolar architecture is destroyed –

honeycomb lunghoneycomb lung

EtiologyEtiologyUnknown, may be immunological reaction.Unknown, may be immunological reaction.

Clinical FeaturesClinical Features Uncommon disease, affects adults in late Uncommon disease, affects adults in late

middle age.middle age. Progressive exertional dyspnea, later at rest.Progressive exertional dyspnea, later at rest. Non-productive cough.Non-productive cough. Physical examination shows finger clubbing, Physical examination shows finger clubbing,

fine inspiratory crackles throughout both fine inspiratory crackles throughout both lungs.lungs.

Patient may develop respiratory failure Patient may develop respiratory failure terminally.terminally.

The disease progresses insidiously, median The disease progresses insidiously, median survival 4-6 years.survival 4-6 years.

Pulmonary FunctionPulmonary Function Spirometry reveals a Spirometry reveals a

restrictive pattern. restrictive pattern. FVC is reduced, but FVC is reduced, but FEVFEV11/FVC supernormal./FVC supernormal.

All lung volumes – TLC, All lung volumes – TLC, FRC, RV – are reduced.FRC, RV – are reduced.

Pressure volume curve Pressure volume curve of the lung is displaced of the lung is displaced downward and downward and flattened.flattened.

Gas ExchangeGas Exchange Arterial PaOArterial PaO22 and PaCO and PaCO22 are reduced, pH are reduced, pH

normal.normal. On exercise PaOOn exercise PaO22 decreases dramatically. decreases dramatically. Physiologic dead space and physiologic Physiologic dead space and physiologic

shunt and VQ mismatch are increased.shunt and VQ mismatch are increased. Diffuse impairment contributes to Diffuse impairment contributes to

hypoxemia on exercise.hypoxemia on exercise. There is marked reduction in diffusing There is marked reduction in diffusing

capacity due to thickening of blood gas capacity due to thickening of blood gas barrier and VQ mismatch.barrier and VQ mismatch.

DiagnosisDiagnosis Diagnosis is often suggested by history, Diagnosis is often suggested by history,

chest radiograph and high resolution CT chest radiograph and high resolution CT scan of the lungs.scan of the lungs.

If old chest x-rays show classical If old chest x-rays show classical disease, absence of other disease disease, absence of other disease processes on history and no processes on history and no occupational or environmental exposure occupational or environmental exposure – clinical diagnosis can be made.– clinical diagnosis can be made.

In other cases a surgical lung biopsy is In other cases a surgical lung biopsy is obtained.obtained.

TreatmentTreatment Each patient is individually assessed.Each patient is individually assessed. Patients are treated if they have symptoms or Patients are treated if they have symptoms or

progressive dysfunction on pulmonary function progressive dysfunction on pulmonary function tests.tests.

Corticosteroids (Prednisone 1 mg/kg) is standard Corticosteroids (Prednisone 1 mg/kg) is standard therapy.therapy.

Prednisone dose is lowered over 6-8 weeks and Prednisone dose is lowered over 6-8 weeks and continued at 15 mg for 1-2 years.continued at 15 mg for 1-2 years.

Addition of Imuran may benefit survival.Addition of Imuran may benefit survival. Cyclophosphamide occasionally used.Cyclophosphamide occasionally used. Antifibrotics such as colchicine may be used.Antifibrotics such as colchicine may be used. Ancillary therapies such as oxygen, Ancillary therapies such as oxygen,

rehabilitation, psychosocial aspects are helpful.rehabilitation, psychosocial aspects are helpful.

SarcoidosisSarcoidosis A disease characterized by the presence A disease characterized by the presence

of granulomatous tissue.of granulomatous tissue. This is a systemic disease which involves This is a systemic disease which involves

eyes, brain, heart, lungs, bones and eyes, brain, heart, lungs, bones and kidneys, skin, liver and spleen.kidneys, skin, liver and spleen.

On pathology a non-caseating granuloma On pathology a non-caseating granuloma composed of histiocytes, giant cells and composed of histiocytes, giant cells and lymphocytes.lymphocytes.

In advanced lung disease fibrotic changes In advanced lung disease fibrotic changes are seen.are seen.

EtiologyEtiology Unknown, likely immunological basis.Unknown, likely immunological basis.

Clinical FeaturesClinical FeaturesFour stages are identified:Four stages are identified: Stage 0: No obvious intrathoracic involvementStage 0: No obvious intrathoracic involvement Stage 1: Bilateral hilar lymphadenopathy, often Stage 1: Bilateral hilar lymphadenopathy, often

accompanied by arthritis, uveitis and erythema accompanied by arthritis, uveitis and erythema nodosum.nodosum.

Stage 2: Pulmonary parenchyma is also Stage 2: Pulmonary parenchyma is also involved, changes in mid and upper zones.involved, changes in mid and upper zones.

Stage 3: Pulmonary infiltrates and fibrosis Stage 3: Pulmonary infiltrates and fibrosis without adenopathy.without adenopathy.

Non-caseating granulomasNon-caseating granulomasin Sarcoidosisin Sarcoidosis

Stage I Stage I (bilateral hilar (bilateral hilar adenopathy)adenopathy)

Stage IIStage IIReticular nodules and BHLReticular nodules and BHL

HRCT – subpleural nodulesHRCT – subpleural nodules

Pulmonary FunctionPulmonary Function No impairment occurs in stages 0 and 1.No impairment occurs in stages 0 and 1. In stages 2 and 3 restrictive changes are In stages 2 and 3 restrictive changes are

seen.seen.

Treatment and PrognosisTreatment and Prognosis 85% of these patients improve 85% of these patients improve

spontaneously, but 15% may develop spontaneously, but 15% may develop progressive fibrosis and respiratory failure.progressive fibrosis and respiratory failure.

Treatment is other observation, but in Treatment is other observation, but in symptomatic patients or deteriorating PFT’s – symptomatic patients or deteriorating PFT’s – treatment recommended.treatment recommended.

Prednisone 0.5- 1 mg/kg initially, then Prednisone 0.5- 1 mg/kg initially, then tapered and continued for 6 months to 1 tapered and continued for 6 months to 1 year.year.

Hypersensitivity Hypersensitivity PneumonitisPneumonitis

Also known as extrinsic allergic alveolitis.Also known as extrinsic allergic alveolitis. Hypersensitivity reaction in the lung occurs Hypersensitivity reaction in the lung occurs

in response to inhaled organic dust.in response to inhaled organic dust. Example is farmer’s lung.Example is farmer’s lung. The exposure may be occupational or The exposure may be occupational or

environmental.environmental. The disease occurs from type III and type IV The disease occurs from type III and type IV

hypersensitivity reactions.hypersensitivity reactions. Farmer’s lung is due to thermophilic Farmer’s lung is due to thermophilic

actinomyces in moldy hay.actinomyces in moldy hay. Bird fancier’s lung is caused by avian Bird fancier’s lung is caused by avian

antigen.antigen.

PathologyPathology

There is infiltration of alveolar walls with There is infiltration of alveolar walls with lymphocytes, plasma cells and histiocytes.lymphocytes, plasma cells and histiocytes.

There are loosely formed granulomas.There are loosely formed granulomas. Fibrotic changes occur in advanced disease.Fibrotic changes occur in advanced disease.

Clinical FeaturesClinical Features The disease may occur in acute or chronic The disease may occur in acute or chronic

forms.forms.

Acute HPAcute HP Dyspnea, fever, malaise and cough appear 4-6 Dyspnea, fever, malaise and cough appear 4-6

hours after exposure.hours after exposure. These symptoms continue for 24-48 hours.These symptoms continue for 24-48 hours. Physical examination shows fine crackles Physical examination shows fine crackles

throughout the lungs.throughout the lungs. These patients present with progressive These patients present with progressive

dyspnea over a period of years.dyspnea over a period of years. Chest radiograph may be normal, but may show Chest radiograph may be normal, but may show

reticular nodular infiltration.reticular nodular infiltration.

HRCT in Acute HPHRCT in Acute HP

Chronic HPChronic HP

These patients present with progressive These patients present with progressive dyspnea.dyspnea.

Physical examination shows bilateral Physical examination shows bilateral inspiratory crackles.inspiratory crackles.

Chest x-ray shows reticular nodular Chest x-ray shows reticular nodular infiltration and fibrosis predominantly in infiltration and fibrosis predominantly in upper lobes.upper lobes.

Pulmonary function tests – restrictive Pulmonary function tests – restrictive pattern. pattern.

Gas exchange shows hypoxemia which Gas exchange shows hypoxemia which worsens on exercise.worsens on exercise.

Interstitial Disease Caused by Interstitial Disease Caused by Drugs, Poisons and RadiationDrugs, Poisons and Radiation

Various drugs cause acute pulmonary Various drugs cause acute pulmonary reaction – proceeding to interstitial reaction – proceeding to interstitial fibrosis.fibrosis.

These drugs are busulfan, nitrofurantoin, These drugs are busulfan, nitrofurantoin, amiodarone, bleomycin.amiodarone, bleomycin.

High oxygen concentration – interstitial High oxygen concentration – interstitial fibrosis.fibrosis.

Radiation exposure – acute pneumonitis – Radiation exposure – acute pneumonitis – fibrosis.fibrosis.

Collagen Vascular Collagen Vascular DiseasesDiseases

Several collagen vascular diseases Several collagen vascular diseases particularly systemic sclerosis and lupus particularly systemic sclerosis and lupus and rheumatoid arthritis may lead to and rheumatoid arthritis may lead to systemic sclerosis.systemic sclerosis.

Dyspnea is often severe.Dyspnea is often severe. A definite diagnosis requires surgical lung A definite diagnosis requires surgical lung

biopsy.biopsy. Treatment is corticosteroids plus cytotoxic Treatment is corticosteroids plus cytotoxic

therapy.therapy.

Pleural DiseasesPleural Diseases Pneumothorax could be either primary or Pneumothorax could be either primary or

secondary.secondary. Pleural effusion can be acute or chronic.Pleural effusion can be acute or chronic. Pleural effusion is divided into exudate and Pleural effusion is divided into exudate and

transudate.transudate. Pleural thickening – longstanding pleural Pleural thickening – longstanding pleural

effusion results in fibrotic pleura which effusion results in fibrotic pleura which splints the lung and prevents its expansion.splints the lung and prevents its expansion.

If the disease is bilateral – may cause If the disease is bilateral – may cause restrictive lung diease.restrictive lung diease.

Treatment may be decortication.Treatment may be decortication.

Diseases of the Chest WallDiseases of the Chest Wall Deformity of thoracic cage such as kyphoscoliosis Deformity of thoracic cage such as kyphoscoliosis

and ankylosing spondylitis.and ankylosing spondylitis. Scoliosis – lateral curvature of spine, kyphosis – Scoliosis – lateral curvature of spine, kyphosis –

posterior curvature.posterior curvature. Cause is unknown, polio and previous Cause is unknown, polio and previous

tuberculosis.tuberculosis. Patients develop exertional dyspnea, rapid Patients develop exertional dyspnea, rapid

shallow breathing.shallow breathing. Hypoxemia, hypercapnia and cor-pulmonale Hypoxemia, hypercapnia and cor-pulmonale

supervene.supervene. Pulmonary function tests show RVP with normal Pulmonary function tests show RVP with normal

diffusion.diffusion. Cause of death is respiratory failure or Cause of death is respiratory failure or

intracurrent pulmonary infection.intracurrent pulmonary infection. Treatment is non-invasive or invasive chronic Treatment is non-invasive or invasive chronic

ventilation.ventilation.

Neuromuscular DisordersNeuromuscular Disorders Diseases affecting muscles of respiration or their Diseases affecting muscles of respiration or their

nerve supply.nerve supply. Poliomyelitis, Guillain-Barre syndrome, ALS, Poliomyelitis, Guillain-Barre syndrome, ALS,

myasthenia gravis, muscular dystrophies.myasthenia gravis, muscular dystrophies. All these lead to dyspnea and respiratory failure.All these lead to dyspnea and respiratory failure. PFT’s show reduced FVC, TLC and FEVPFT’s show reduced FVC, TLC and FEV11.. The progress of disease can be monitored by FVC The progress of disease can be monitored by FVC

and blood gases.and blood gases. Maximal inspiratory and expiratory pressures are Maximal inspiratory and expiratory pressures are

reduced.reduced. Treatment is either treating the underlying cause or Treatment is either treating the underlying cause or

assisted ventilation.assisted ventilation.

RESTRICTIVE LUNG DISEASERESTRICTIVE LUNG DISEASE

ssharma.comssharma.com

By Sat Sharma By Sat Sharma

Assistant ProfessorAssistant Professor

University of ManitobaUniversity of Manitoba