Review of Physiology and Pathophysiology
摘要
Understanding mechanical ventilation begins with learning important physiologic concepts. This chapter reviews the principles behind gas exchange, focusing on oxygenation and ventilation. Considering the five major physiologic causes of hypoxemia: shunt, V/Q mismatch, alveolar hypoventilation, decreased diffusion, and decreased partial pressure of oxygen, allows clinicians to work through a differential diagnosis at the bedside. Other key principles related to hypoxemia include appreciating hypoxemic vasoconstriction and the impact of derecruitment. Resistance and compliance are core concepts in respiratory physiology and directly impact the management of ventilated patients. Recognizing and managing air trapping is essential to preventing untoward outcomes as well.