Porth's Essentials of Pathophysiology, 4e

he major function of the lungs is to oxygenate the blood and remove carbon dioxide as a means of supporting the metabolic functions of the body’s tis- sues. Many types of disease are capable of disrupting the normal gas exchange function of the lungs. In some cases the disruption is temporary and in other cases it is marked and disabling. This chapter focuses on disorders that disrupt ventilation and pulmonary gas exchange. It is divided into six sections: the physiologic effects of altered ventilation and gas exchange, disorders of lung inflation, obstructive airway disorders, chronic intersti- tial lung disorders, disorders of the pulmonary circula- tion, and acute respiratory disorders. Disorders of Ventilation and Gas Exchange 23 C h a p t e r The primary function of the respiratory system is gas exchange between the atmospheric air in the alveoli and the blood in the pulmonary circulation. 1–3 In the process, oxygen (O 2 ) from air in the alveoli diffuses into the blood in the pulmonary capillaries and carbon dioxide (CO 2 ) moves from the blood in pulmonary capillaries into the alveoli (discussed in Chapter 21). This section provides a brief overview of two abnormal states (hypoxemia and hypercapnia) that develop as the result of impaired ventilation and gas exchange that occur with many of the disorders discussed in the chapter. Respiration can be divided into three parts: ventila- tion, perfusion, and diffusion. Ventilation involves the movement of air into the lungs. However, not all inspired air reaches the alveoli where gas exchange takes place. Of each 500 mL of air, which is the typical volume of air that is inhaled by the average-sized adult, about 150 mL remains behind in the airways, with the remainder (350 mL) moving into the alveoli. This is called alveolar ventilation and represents the portion of ventilation that participates in gas exchange. The actual movement or diffusion of O 2 and CO 2 takes place in the lung driven by T Physiologic Effects of Ventilation and Diffusion Disorders

Physiologic Effects of Ventilation and Diffusion Disorders Hypoxemia Hypercapnia Disorders of Lung Inflation Disorders of the Pleura Pleuritis

Pleural Effusion Pneumothorax

Atelectasis Obstructive Airway Disorders

Physiology of Airway Disease Bronchial Asthma Etiology and Pathogenesis Manifestations Diagnosis and Treatment Severe Asthma Bronchial Asthma in Children Chronic Obstructive Pulmonary Disease Emphysema Chronic Bronchitis Manifestations Diagnosis and Treatment Bronchiectasis Etiology and Pathogenesis Manifestations Diagnosis and Treatment Cystic Fibrosis Etiology and Pathogenesis Manifestations Diagnosis and Treatment Interstitial Lung Diseases Pathogenesis Clinical Features Idiopathic Pulmonary Fibrosis Sarcoidosis Disorders of the Pulmonary Circulation Pulmonary Embolism Pathogenesis Manifestations Diagnosis and Treatment Pulmonary Hypertension Secondary Pulmonary Hypertension Acute Respiratory Disorders Acute Lung Injury/Acute Respiratory Distress Syndrome Etiology and Pathogenesis Clinical Features Acute Respiratory Failure Hypoxemic Respiratory Failure Hypercapnic/Hypoxemic Respiratory Failure Clinical Features Primary Pulmonary Arterial Hypertension Cor Pulmonale

565