What is hysteresis of the lung?
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.
What are the factors that affect lung compliance?
Two important factors of lung compliance are elastic fibers and surface tension. More elastic fibers in the tissue lead to ease in expandability and, therefore, compliance. Surface tension within the alveoli is decreased by the production of surfactant to prevent collapse.
In which three conditions is lung compliance decreased?
Compliance also increases with increasing age. Both peak inspiratory and plateau pressure increase when elastic resistance increases or when pulmonary compliance decreases (e.g. during abdominal insufflation, ascites, intrinsic lung disease, obesity, pulmonary edema, tension pneumothorax).
What causes increased lung compliance?
Emphysema or COPD: In both of these conditions, the elastic recoil property of the lung suffers damage due to a genetic cause (alfa-1 antitrypsin deficiency) or an extrinsic factor (e.g., smoking). Because of poor elastic recoil, such patients have high lung compliance.
What causes hysteresis in the lungs?
In the lungs, hysteresis is due mainly to surface properties and alveolar recruitment-derecruitment, whereas in the chest wall, it seems mainly related to muscles and ligaments because both skeletal muscles and elastic fibers exhibit hysteresis.
What causes a decrease in lung compliance?
Common causes of decreased lung compliance are pulmonary fibrosis, pneumonia and pulmonary edema. In an obstructive lung disease, airway obstruction causes an increase in resistance. During normal breathing, the pressure volume relationship is no different from in a normal lung.
What is hysteresis law?
When a ferromagnetic material is magnetized in one direction, it will not relax back to zero magnetization when the imposed magnetizing field is removed. The lack of retraceability of the magnetization curve is the property called hysteresis and it is related to the existence of magnetic domains in the material.
How is hysteresis related to expiratory lung compliance?
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:
How is hysteresis related to the transpulmonary pressure curve?
The transpulmonary pressure vs Volume curve of inhalation is different from the Pressure vs Volume curve of exhalation, the difference being described as hysteresis. Lung volume at any given pressure during inhalation is less than the lung volume at any given pressure during exhalation.
How are specific compliance and hysteresis measured?
Specific compliance (sCdyn), specific hysteresis (s η ), and pressure at which the airways collapsed (Pcol) were calculated from each recording. Airway wall dimensions were measured morphometrically. Lung function parameters of airflow obstruction were correlated to sCdyn, s η , and Pcol.
What happens when you measure static lung compliance?
As mentioned above, measurement of static lung compliance has a certain built-in pause in every step, which allows some of the gas to become absorbed in living systems, leading to an apparent change in volume and pressure. In contrast to static compliance]