Lung Compliance: Difference between revisions
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Revision as of 07:14, 20 September 2020
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Introduction[edit | edit source]
Compliance is defined as the change in lung volume produced by a unit change in transpulmonary pressure. Lung compliance is represented by the gradient of the pressure–volume curve.
Normal Range: The total compliance of both lungs together in normal adult human being average is about 200 millilitres of air per centimetre of water trans-pulmonary pressure. That is every time the trans pulmonary pressure increases one centimetre of water the lung volume after 10 to 20 seconds will expand 200 milliliteres.
Compliance Diagram[edit | edit source]
The diagram relates the lung volume changes to changes in the trans pulmonary pressure. It differs for inspiration and expiration
Compliance Curve[edit | edit source]
The two compliance curves are:
- Inspiratory Compliance curve
- Expiratory Compliance curve
Types of Compliance[edit | edit source]
Dynamic Compliance : This describes the compliance measured during breathing which involves a combination of Lung compliance and air resistance.
Static Compliance : This describes the pulmonary compliance when there is no air flow like an inspiratory pass.
Important Factors[edit | edit source]
The two important factors of Lung compliance :
Elastic Fibers : More fibers in the tissue lead to ease in expand-ability and there for compliance.
Surface tension : It is decrease due to the production of surfactant to prevent collapse.
Hysteresis[edit | edit source]
Hysteresis is the term used to describe the difference between inspiratory and expiratory compliance. Lung volume at any given pressure during inhalation is less than the lung volume at any given pressure during exhalation.
Hysteresis is present in both static and dynamic lung compliance curves
Hysteresis develops due to:
- The effect of surfactant
- Relaxation of lung tissue
- Recruitment and derecruitment of alveoli
- Gas absrption during measurement
- Differences in expiratory and inspiratory air flow (for dynamic compliance)
Factors which affect compliance can be divided into chest wall factors and lung factors:
Lung compliance | Chest wall compliance |
Increased lung compliance
|
Increased chest wall compliance
|
Decreased static lung compliance
Decreased dynamic lung compliance
|
Decreased chest wall compliance
|
Related articles[edit | edit source]
Lung volumes-physiopedia
Lung compliance
References[edit | edit source]
- Iotti, G., & Braschi, A. (1999). Measurements of respiratory mechanics during mechanical ventilation. Rhäzüns, Switzerland: Hamilton Medical Scientific Library.
- Harris, R. Scott. "Pressure-volume curves of the respiratory system." Respiratory care 50.1 (2005): 78-99.
- Rahn, Hermann, et al. "The pressure-volume diagram of the thorax and lung." American Journal of Physiology-Legacy Content 146.2 (1946): 161-178.
- https://www.us.elsevierhealth.com/guyton-and-hall-textbook-of-medical-physiology-9781455770052.html
- https://www.ncbi.nlm.nih.gov/books/NBK554517/
- https://med.libretexts.org/Bookshelves/Anatomy_and_Physiology/Book%3A_Anatomy_and_Physiology_(Boundless)/21%3A_Respiratory_System/21.6%3A_Factors_Affecting_Pulmonary_Ventilation/21.6B%3A_Factors_Affecting_Pulmonary_Ventilation%3A_Compliance_of_the_Lungs