Restrictive Lung Disease

Updated: Oct 30, 2017
  • Author: Jonathan Robert Caronia, DO; Chief Editor: John J Oppenheimer, MD  more...
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Overview

Background

Restrictive lung diseases are characterized by reduced lung volumes, either because of an alteration in lung parenchyma or because of a disease of the pleura, chest wall, or neuromuscular apparatus. Unlike obstructive lung diseases, such as asthma and chronic obstructive pulmonary disease (COPD), which show a normal or increased total lung capacity (TLC), restrictive disease are associated with a decreased TLC. Measures of expiratory airflow are preserved and airway resistance is normal and the forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) ratio is increased. If caused by parenchymal lung disease, restrictive lung disorders are accompanied by reduced gas transfer, which may be marked clinically by desaturation after exercise.

The many disorders that cause reduction or restriction of lung volumes may be divided into two groups based on anatomical structures.

The first is intrinsic lung diseases or diseases of the lung parenchyma. The diseases cause inflammation or scarring of the lung tissue (interstitial lung disease) or result in filling of the air spaces with exudate and debris (pneumonitis). These diseases can be characterized according to etiological factors. They include idiopathic fibrotic diseases, connective-tissue diseases, drug-induced lung disease, environmental exposures (inorganic and organic dusts), and primary diseases of the lungs (including sarcoidosis).

The second is extrinsic disorders or extrapulmonary diseases. The chest wall, pleura, and respiratory muscles are the components of the respiratory pump, and they need to function normally for effective ventilation. Diseases of these structures result in lung restriction, impaired ventilatory function, and respiratory failure (eg, nonmuscular diseases of the chest wall, neuromuscular disorders).

The mnemonic "PAINT" has been used to divide the causes of restrictive lung disease into pleural, alveolar, interstitial, neuromuscular, and thoracic cage abnormalities.

Table 1. Causes of Restrictive Lung Disease (Open Table in a new window)

Causes Examples Diagnosis PFT Findings
Pleural Trapped lung, pleural scarring, large pleural effusions, chronic empyema, asbestosis Radiography, CT scanning, pleural manometry, pleural biopsy Low RVa, low TLC, low FVC
Alveolar Edema, hemorrhage Radiography, CT scanning, physical examination Increased DLCOb in hemorrhage (Intrapulmonary hemoglobin absorbs the carbon monoxide, thus increasing the DLCO reading.)
Interstitial Interstitial lung disease including IPFc, NSIPd, COPe Radiography, CT scanning, physical examination, echo often shows pulmonary hypertension Low RV, low FVC, low TLC, decreased DLCO, poor lung compliance
Neuromuscular Myasthenia gravis, ALSf, myopathy Physical examination, EMGsg, serology Low RV, low TLC, low NIFh, low MMVi
Thoracic/extrathoracic Obesity, kyphoscoliosis, ascites Physical examination Low ERVj and FRC in obesity, low VCk, TLC, FRCl in kyphoscoliosis
aResidual volume.



bDiffusion capacity of the lungs for carbon monoxide.



cIdiopathic pulmonary fibrosis.



dNonspecific interstitial pneumonitis.



eCryptogenic organizing pneumonia.



fAmyotrophic lateral sclerosis.



gElectromyography.



hNegative inspiratory force.



iMaximal voluntary ventilation.



jExpiratory reserve volume.



kVital capacity.



lFunctional residual capacity.



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Pathophysiology

Air flows to and from the alveoli as lungs inflate and deflate during each respiratory cycle. Lung inflation is accomplished by a contraction of respiratory, diaphragmatic, and external intercostal muscles, whereas deflation is passive at rest. Functional reserve capacity (FRC) is the volume of air in the lungs when the respiratory muscles are fully relaxed and no airflow is present. The volume of FRC is determined by the balance of the inward elastic recoil of the lungs and the outward elastic recoil of the chest wall. Restrictive lung diseases are characterized by a reduction in FRC and other lung volumes because of pathology in the lungs, pleura, or  structures of the thoracic cage.

The distensibility of the respiratory system is called compliance. Compliance is the volume change produced by a change in the distending pressure. Lung compliance is independent of the thoracic cage, which is a semirigid container. The compliance of an intact respiratory system is an algebraic sum of the compliances of both of these structures. Therefore, it is influenced by any disease of the lungs, pleura, or chest wall.

In cases of intrinsic lung disease, the physiological effects of diffuse parenchymal disorders reduce all lung volumes by the excessive elastic recoil of the lungs,  relative to the outward recoil forces of the chest wall. Expiratory airflow is reduced in proportion to lung volume.

Arterial hypoxemia in disorders of pulmonary parenchyma is primarily caused by ventilation-perfusion mismatching, with further contribution from an intrapulmonary shunt. Decreased diffusion of oxygen rarely contributes to hypoxemia because sufficient time still exists for full equilibration of oxygen or carbon dioxide. However, if transit time is significantly shortened, as with exercise, then there can be significant exercise-induced desaturation.

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Etiology

Intrinsic lung diseases

Collagen-vascular diseases, including scleroderma, polymyositis, dermatomyositis, systemic lupus erythematosus, rheumatoid arthritis, and ankylosing spondylitis, are causes of restrictive lung disease.

Other causes may include drugs and other treatments (eg, nitrofurantoin, amiodarone, gold, phenytoin [Dilantin], thiazides, hydralazine, bleomycin, bischloroethylnitrosourea [BCNU or carmustine], cyclophosphamide, methotrexate, radiation). Also see Drug-Induced Pulmonary Toxicity.

Causes related to primary or unclassified diseases may include sarcoidosis, pulmonary Langerhans cell histiocytosis, lymphangioleiomyomatosis (LAM), pulmonary vasculitis, alveolar proteinosis, eosinophilic pneumonia, and cryptogenic organizing pneumonia (COP).

Inorganic dust exposure (eg, silicosis, asbestosis, talc, pneumoconiosis, berylliosis, hard metal fibrosis, coal worker's pneumoconiosis, chemical worker’s lung) may cause restrictive lung disease.

Organic dust exposure can lead to hypersensitivity pneumonitis (eg, farmer's lung, bird fancier's lung, bagassosis, and mushroom worker's lung, humidifier lung, hot tub pneumonitis).

Idiopathic fibrotic disorders

These may include acute interstitial pneumonia, IPF (usually interstitial pneumonitis), lymphocytic interstitial pneumonitis, desquamative interstitial pneumonitis, and nonspecific interstitial pneumonitis.

Extrinsic disorders

Nonmuscular diseases of the chest wall, in which kyphosis can be idiopathic or secondary, may cause restrictive lung disease. The most common cause of secondary kyphoscoliosis is neuromuscular disease (eg, polio, muscular dystrophy). Fibrothorax, massive pleural effusion, morbid obesity, ankylosing spondylitis, and thoracoplasty are other causes.

Neuromuscular diseases manifest as respiratory muscle weakness and are due to myopathy or myositis, quadriplegia, or phrenic neuropathy from infectious or metabolic causes.

Pleural diseases, including trapped lung or asbestos-related pleural plaques, are an underrecognized, and potentially treatable, cause of restrictive lung disease.

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Epidemiology

Frequency

United States

For intrinsic lung diseases, studies cite an overall prevalence of 3-6 cases per 100,000 persons. The prevalence of idiopathic pulmonary fibrosis (IPF) is 27-29 cases per 100,000 persons. [1, 2] The prevalence for adults aged 35-44 years is 2.7 cases per 100,000 persons. Prevalence exceeded 175 cases per 100,000 persons among patients older than 75 years. Exposure to dust, metals, organic solvents, and agricultural employment is associated with increased risk.

In North America, the prevalence of sarcoidosis is 10-40 cases per 100,000 persons. [3]

The incidence of chronic interstitial lung diseases in persons with collagen-vascular diseases is variable, but it is increasing for most diseases. [4]

Kyphoscoliosis is a common extrinsic disorder. It is associated with an incidence of mild deformities amounting to 1 case per 1000 persons, with severe deformity occurring in 1 case per 10,000 persons. [5]

Other nonmuscular and neuromuscular disorders are rare, but their incidence and prevalence are not well known.

According to the US Centers for Disease Control and Prevention (CDC), 35.9% of Americans older than 20 years are obese, and 69% of Americans are at least overweight (body mass index [BMI] 25-30). [6]

International

In Sweden, the prevalence rate for sarcoidosis is 64 cases per 100,000 persons. In Japan, the prevalence rate of sarcoidosis is 10-40 cases per 100,000 persons. The prevalence of sarcoidosis is difficult to determine, and tuberculosis is common. [7]

Pediatric data from England have demonstrated the prevalence of idiopathic scoliosis to be 1 case per 200 patients aged 6-14 years. [8]

The worldwide prevalence of fibrotic lung diseases is difficult to determine because studies have not been performed.

Race

Although a familial variant of IPF exists, a genetic predisposition has not yet been elucidated. [9]

The incidence among black Americans is 35.5 cases per 100,000 persons. In contrast, the incidence among white Americans is 10.9 cases per 100,000 persons. [3]

Sex

LAM and lung involvement in tuberous sclerosis occur primarily in premenopausal women, although a handful of cases of LAM have been reported in men. Sporadic LAM has a prevalence of approximately 4.9 cases per 1,000,000 women. Men are more likely to have pneumoconiosis because of occupational exposure, IPF, and collagen-vascular diseases (eg, rheumatoid lung). Worldwide, sarcoidosis is slightly more common in women. [7]

Age

IPF is rare in children. Some intrinsic lung diseases present in patients aged 20-40 years. These include sarcoidosis, collagen-vascular–associated diseases, and pulmonary Langerhans cell histiocytosis (formerly referred to as histiocytosis X). Most patients with IPF are older than 50 years. [10]

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Prognosis

The natural history of interstitial lung diseases is variable. It depends on the specific diagnosis and the extent and severity of lung involvement based on high-resolution CT scanning and lung biopsy. [10] IPF is typically a relentless progressive disorder, and patients have a mean survival of 3-6 years after diagnosis. [11] Early recognition of IPF is important for directing patient management and predicting prognosis. [12]

Pulmonary sarcoidosis has a relatively benign self-limiting course, with spontaneous recovery or stabilization in most cases. [13] However, up to 20% of patients develop pulmonary fibrosis and disability. [14]

Prognosis for collagen-vascular diseases, eosinophilic pneumonia, cryptogenic organizing pneumonia (COP), and drug-induced lung disease is generally favorable with treatment. [15, 16, 17]

Patients with chest wall diseases and neuromuscular disorders develop progressive respiratory failure and succumb during an intercurrent pulmonary infection. [18]

Mortality/morbidity

The mortality and morbidity from various causes of restrictive lung disease is dependent on the underlying case of the disease process.

The median survival time for patients with IPF is less than 3 years. Factors that predict poor outcome include older age, male sex, severe dyspnea, history of cigarette smoking, severe loss of lung function, appearance and severity of fibrosis on radiologic studies, lack of response to therapy, and prominent fibroblastic foci on histopathologic evaluation. [11]

See the image below.

Gross pathology of small and firm lungs due to res Gross pathology of small and firm lungs due to restrictive lung disease from advanced pulmonary fibrosis.
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