Lecture Overview

An understanding of blood gases is essential for respiratory management, and this requires familiarity with concepts such as the alveolar gas equation, the alveolar ventilation equation, and the Henderson–Hasselbalch equation.

In addition, respiratory management involves not only monitoring daytime blood gas changes but also ensuring proper blood gas control during sleep, making it important to understand sleep-related breathing disorders.

There are 17 types of sleep-related breathing disorders; however, in practice, it is crucial to understand conditions related to obstructive and central sleep apnea/hypopnea, as well as sleep-related hypoventilation.

Respiration is regulated by both behavioral and chemical (metabolic) control systems, which are influenced by wakefulness and sleep. For example, while few textbooks or reviews list hypoxemia as a clinical symptom of psychogenic hyperventilation syndrome, during wakefulness, hyperpnea and hyperventilation (not identical concepts) typically lead to a decrease in PaCO₂ and an increase in PaO₂. However, once the individual falls asleep, ventilatory drive is lost, ventilation decreases, and apnea may occur (post-hyperventilation apnea). Under conditions of low PaCO₂, hypoxic drive is blunted even during wakefulness, which can result in unexpectedly severe hypoxemia.

As is well known, various medications also affect respiratory control. Therefore, a comprehensive understanding of clinical pulmonary physiology, including respiratory control mechanisms, is indispensable for appropriate respiratory management.