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Diseases of the lung can be classified into four general categories: (1) obstructive lung disease; (2) restrictive lung disease; (3) infectious disease; and (4) neoplastic disease (Table 13-1). The key clinical difference between obstructive and restrictive lung disease is the forced expiratory volume at one second (FEV1) and the forced vital capacity (FVC) ratio, which is decreased in obstructive lung disease and normal in restrictive lung disease. In obstructive lung disease, air is trapped within the parenchyma; in restrictive lung disease, airway filling is impaired due to fibrosis of alveolar septae. The four main types of obstructive lung disease are emphysema, asthma, bronchiectasis, and chronic bronchitis. Restrictive lung disease can be divided into acute and chronic forms, and chronic forms can be subdivided by etiology (i.e., work related, drug induced, autoimmune, and idiopathic).
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The seven major forms of infectious lung disease (i.e., pneumonia) are (1) community-acquired typical (e.g., bacterial); (2) community-acquired atypical (e.g., viral, others); (3) nosocomial; (4) aspiration; (5) necrotizing pneumonia; (6) chronic pneumonia (e.g., fungal, mycobacterial); and (7) pneumonia in immunocompromised hosts. Neoplastic disease can be divided into small cell lung carcinoma and non–small cell lung carcinoma. The designation of non–small cell carcinoma versus small cell carcinoma is of utmost importance when determining treatment options. Small cell carcinoma is assumed at the time of diagnosis to have already metastasized.
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This chapter will discuss acute respiratory failure, atelectasis, obstructive lung disease, restrictive lung disease, causes of chronic restrictive lung disease, diffuse pulmonary hemorrhage, pulmonary hypertension, pulmonary infections, pulmonary neoplasms, miscellaneous pleural conditions (including pleural effusions and mesothelioma), and upper respiratory tract conditions.
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Overview: There are two types of acute respiratory failure: hypoxemic acute respiratory failure and hypercapnic acute respiratory failure.
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Hypoxemic Acute Respiratory Failure
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Basic description: Respiratory failure with pO2 of < 60 mm Hg.
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Causes: Pulmonary edema, acute respiratory distress syndrome (ARDS), pneumonia.
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Hypercapnic Acute Respiratory Failure
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Basic description: Respiratory failure with pCO2 of > 45 mm Hg.
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Causes: Obstructive lung disease (e.g., chronic obstructive pulmonary disease[COPD], asthma), upper respiratory obstruction, decreased compliance of the chest wall (e.g., kyphoscoliosis), and hypoventilation.
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Overview: Atelectasis is collapse of the pulmonary parenchyma. Because of atelectasis, airways and alveoli are unable to fill, and blood is shunted from the arteries to the veins without adequate oxygenation. The ...