Pulmonary Compliance

Definition

Pulmonary compliance is a measure of the lungs' ability to stretch and expand during inhalation. It represents the relationship between changes in lung volume and the pressure required to cause those changes, reflecting the elasticity of the lungs and chest wall.

5 Must Know Facts For Your Next Test

1. Pulmonary compliance is an important determinant of the work of breathing, as it influences the pressure required to inflate the lungs.
2. Decreased pulmonary compliance, as seen in conditions like pulmonary fibrosis, increases the work of breathing and can lead to respiratory distress.
3. Surfactant, a substance produced by alveolar type II cells, plays a crucial role in maintaining normal pulmonary compliance by reducing surface tension within the alveoli.
4. Factors that can affect pulmonary compliance include lung volume, lung elasticity, and the properties of the chest wall and diaphragm.
5. Measurement of pulmonary compliance is an important tool in the clinical assessment of respiratory function and the diagnosis of respiratory disorders.

Review Questions

• Explain how pulmonary compliance is related to the work of breathing.
  • Pulmonary compliance is directly related to the work of breathing. Lower pulmonary compliance, which indicates stiffer or less elastic lungs, requires greater pressure changes to achieve the same volume changes during inhalation and exhalation. This increased pressure change translates to a higher work of breathing, as the respiratory muscles must generate more force to overcome the reduced lung elasticity. Conversely, higher pulmonary compliance allows for easier lung expansion and contraction, reducing the overall work required for breathing.
• Describe the role of surfactant in maintaining normal pulmonary compliance.
  • Surfactant, a complex mixture of phospholipids and proteins produced by alveolar type II cells, plays a crucial role in maintaining normal pulmonary compliance. Surfactant reduces the surface tension within the alveoli, which would otherwise tend to collapse the alveoli during exhalation. By lowering surface tension, surfactant allows the alveoli to expand more easily during inhalation and reduces the pressure required to inflate the lungs. This improvement in lung elasticity, or compliance, directly benefits the work of breathing and overall respiratory function.
• Analyze how changes in lung volume, lung elasticity, and chest wall properties can affect pulmonary compliance.
  • Pulmonary compliance is influenced by a variety of factors, including lung volume, lung elasticity, and the properties of the chest wall and diaphragm. Increased lung volume, as seen in emphysema, can lead to decreased pulmonary compliance due to the loss of elastic recoil in the lungs. Reduced lung elasticity, as observed in pulmonary fibrosis, also decreases pulmonary compliance and increases the work of breathing. Additionally, changes in the chest wall, such as decreased compliance of the rib cage or impaired diaphragmatic function, can negatively impact overall pulmonary compliance. Understanding how these factors interact to influence pulmonary compliance is crucial for the accurate diagnosis and management of respiratory disorders.

Related terms

Lung Compliance:

Lung compliance is the change in lung volume per unit change in transpulmonary pressure, which is the difference between alveolar and pleural pressures.

Chest Wall Compliance: Chest wall compliance is the change in chest wall volume per unit change in pleural pressure, reflecting the elasticity of the chest wall structures.

Transpulmonary Pressure: Transpulmonary pressure is the difference between alveolar pressure and pleural pressure, which drives the expansion and contraction of the lungs during breathing.