Lung Compliance

Definition

Lung compliance is a measure of the lung's ability to stretch and expand during inhalation. It represents the relationship between the change in lung volume and the change in transpulmonary pressure (the difference between alveolar pressure and pleural pressure).

5 Must Know Facts For Your Next Test

1. High lung compliance indicates that the lungs are more distensible and require less pressure to achieve a given change in volume.
2. Low lung compliance, as seen in conditions like pulmonary fibrosis, makes it more difficult to inflate the lungs and requires higher pressures to achieve the same volume change.
3. Surfactant, a substance produced by alveolar type II cells, plays a crucial role in maintaining lung compliance by reducing surface tension within the alveoli.
4. Lung compliance can be affected by various factors, including lung volume, lung elasticity, and the properties of the alveolar-capillary membrane.
5. Measuring lung compliance is important in the assessment and management of respiratory disorders, as it provides insights into the mechanical properties of the lungs.

Review Questions

• Explain the relationship between lung compliance and the change in transpulmonary pressure during inhalation.
  • Lung compliance represents the ease with which the lungs can be stretched and expanded during inhalation. It is defined as the change in lung volume divided by the change in transpulmonary pressure. High lung compliance means the lungs require less pressure to achieve a given change in volume, while low compliance indicates the lungs are stiffer and require higher pressures to achieve the same volume change. This relationship is crucial in understanding the mechanical properties of the lungs and how they affect respiratory function.
• Describe the role of surfactant in maintaining lung compliance.
  • Surfactant, a substance produced by alveolar type II cells, is essential for maintaining lung compliance. Surfactant reduces the surface tension within the alveoli, which would otherwise make it more difficult to inflate the lungs. By lowering surface tension, surfactant allows the alveoli to expand more easily during inhalation, requiring less pressure to achieve a given change in lung volume. Alterations in surfactant production or function, as seen in conditions like respiratory distress syndrome, can lead to decreased lung compliance and impaired respiratory mechanics.
• Analyze how changes in lung compliance can impact respiratory function and the management of respiratory disorders.
  • Variations in lung compliance can have significant implications for respiratory function and the clinical management of respiratory disorders. Low lung compliance, as observed in diseases like pulmonary fibrosis, makes it more difficult to inflate the lungs, requiring higher pressures to achieve the same volume change. This increased work of breathing can lead to respiratory muscle fatigue and impaired gas exchange. Conversely, high lung compliance, as seen in emphysema, can result in over-distension of the alveoli and decreased surface area for gas exchange. Understanding lung compliance is crucial in the assessment and management of respiratory disorders, as it guides the selection of appropriate ventilatory strategies, such as the use of positive end-expiratory pressure (PEEP) or the adjustment of tidal volumes, to optimize respiratory mechanics and gas exchange.

Related terms

Transpulmonary Pressure: The difference between the alveolar pressure and the pleural pressure, which drives the expansion of the lungs during inhalation.

Alveolar Pressure: The pressure within the alveoli of the lungs, which changes during the respiratory cycle.

Pleural Pressure: The pressure within the pleural space, which surrounds the lungs and changes during the respiratory cycle.