8.2 Oxygenation Basic Concepts
Open Resources for Nursing (Open RN)
Review of Anatomy and Physiology
Several body systems contribute to a person’s oxygenation status, including the respiratory, cardiovascular, and hematological systems. The anatomy and physiology of these systems are reviewed in the following sections.
Respiratory System
The major organs of the respiratory system function primarily to provide oxygen to body tissues for cellular respiration, remove the waste product carbon dioxide, and help maintain acid-base balance.[1] See Figure 8.1 for an illustration of the major structures of the respiratory system.[2]
The purpose of the respiratory system is to perform gas exchange. Gas exchange refers to the exchange of oxygen and carbon dioxide in the alveoli and the pulmonary capillaries, also called respiration. During external respiration, at the alveolar level, oxygen from the air we breathe diffuses into the blood, and carbon dioxide diffuses out of the blood where it can be exhaled. Throughout the rest of the body, gas exchange also occurs between the systemic capillaries and body cells/tissues, called internal respiration. During internal respiration, oxygen diffuses out of the systemic capillaries and into body cells/tissues, and carbon dioxide diffuses from the cells/tissues into the systemic capillaries where it is carried to the lungs. It is through this process that cells in the body are oxygenated and carbon dioxide, the waste product of cellular respiration, is removed from the body.[3] See Figure 8.2a[4] for an illustration of alveoli.
To achieve gas exchange, the structures of the respiratory system create the mechanical movement of air into and out of the lungs called ventilation. Pulmonary ventilation provides air to the alveoli for this gas exchange process.
Lung sounds are caused by the movement of air from the trachea to the bronchioles to the alveoli and can be impacted by the presence of sputum, bronchoconstriction, or fluid in the alveoli. Examples of adventitious sounds are rhonchi (coarse crackles), rales (fine crackles), wheezes, stridor, and pleural rub[5]:
- Rhonchi, also referred to as coarse crackles, are low-pitched, continuous sounds heard on expiration that are a sign of turbulent airflow through mucus in the large airways.
- Rales, also called fine crackles, are popping or crackling sounds heard on inspiration. They are associated with medical conditions that cause fluid accumulation within the alveolar and interstitial spaces, such as heart failure or pneumonia. The sound is similar to that produced by rubbing strands of hair together close to your ear.
- Wheezes are whistling noises produced when air is forced through airways narrowed by bronchoconstriction or mucosal edema. For example, clients with asthma commonly have wheezing.
- Stridor is heard only on inspiration. It is associated with obstruction of the trachea/upper airway.
- Pleural rub sounds like the rubbing together of leather and can be he