Restrictive pulmonary disease is characterized by reductions in lung volumes. Compared to disorders consistent with an obstructive pulmonary pattern, there is no increase in airway resistance and measures of airflow are within normal limits. Pulmonary function tests (PFTs) in patients with restrictive disease will show a reduction in total lung capacity (TLC) leading to reductions in both forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC). Because both values are reduced, the FEV1/FVC ratio remains normal (Figure 46-1). The flow-volume loop is general normal, but demonstrates reduced lung volumes (Figure 46-2). FRC is decreased. Total pulmonary compliance is also reduced. Patients with restrictive disease increase their work of breathing by taking slow, deep breaths.
Pulmonary function tests in restrictive and obstructive pulmonary disease. (Reproduced, with permission, from Fauci AS, Braunwald E, Kasper DL, et al. Harrison’s Principles of Internal Medicine. 17th ed. New York, NY: McGraw-Hill, Inc.; 2008: Fig. 246-2, p. 1586.)
Flow-volume loop in restrictive disease. (Reproduced with permission from McKean SC, Ross JJ, Dressler DD, Brotman DJ, Ginsberg JS, eds. Principles and Practice of Hospital Medicine. New York, NY: McGraw-Hill Education, Inc.; 2012. Fig. 103-9.)
There are multiple methods for classifying restrictive pulmonary diseases. Based on the temporal history of disease, the disorder can be acute or chronic. Diseases can be further classified as intrinsic, referring to diseases of the lung parenchyma, or extrinsic, which refers to extra-pulmonary diseases. The mnemonic “PAINT” is a helpful aid for remembering the anatomic sites of diseases able to cause restrictive disease (Table 46-1).
TABLE 46-1Causes of Restrictive Pulmonary Diseases |Favorite Table|Download (.pdf) TABLE 46-1 Causes of Restrictive Pulmonary Diseases
|Causes ||Examples ||Diagnosis ||PFT findings |
|Pleural ||Trapped lung, pleural scarring, large pleural effusions, chronic empyema, asbestosis ||Radiography, CT scanning, pleural manometry, pleural biopsy ||Low RV, low TLC, low FVC |
|Alveolar ||Edema, hemorrhage ||Radiography, CT scanning, physical examination ||Increased DLCO in hemorrhage |
|Interstitial ||Interstitial lung disease including idiopathic pulmonary fibrosis (IPF), nonspecific interstitial pneumonia (NSIP), cryptogenic organizing pneumonia (COP) ||Radiography, CT scanning, physical examination, echo often shows pulmonary hypertension ||Low RV, low FVC, low TLC, decreased DLCO, poor lung compliance |
|Neuromuscular ||Myasthenia gravis, ALS, myopathy ||Physical examination, EMGs, serology ||Low RV, low TLC, low NIF, low MMV |
|Thoracic/extrathoracic ||Obesity, kyphoscoliosis, ascites ||Physical examination ||Low ERV and FRC in obesity, low VC, TLC, FRC in kyphoscoliosis |
ACUTE INTRINSIC RESTRICTIVE PULMONARY DISEASE
Disorders with sudden onset and pathophysiology principally affecting alveoli are classified as acute intrinsic pulmonary diseases. They include acute respiratory distress syndrome (ARDS), infectious pneumonia, cardiogenic or noncardiogenic pulmonary edema, aspiration pneumonitis, ...