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Airway resistance can also change over time. During an asthma attack the airways constrict causing an increase in airway resistance. Airway resistance can also vary between inspiration and expiration: In emphysema there is destruction of the elastic tissue of the lungs which help hold the small airways open. Therefore, during expiration ...
The measurement of peak expiratory flow was pioneered by Martin Wright, who produced the first meter specifically designed to measure this index of lung function. Since the original design of instrument was introduced in the late 1950s, and the subsequent development of a more portable, lower cost version (the "Mini-Wright" peak flow meter ...
Lung compliance, or pulmonary compliance, is a measure of the lung's ability to stretch and expand (distensibility of elastic tissue). In clinical practice it is separated into two different measurements, static compliance and dynamic compliance. Static lung compliance is the change in volume for any given applied pressure. [1]
Airway resistance Lung compliance is influenced by a variety of primary abnormalities of lung parenchyma , both chronic and acute. Chest wall compliance can be decreased by fixed abnormalities (e.g. kyphoscoliosis , morbid obesity ) or more variable problems driven by patient agitation while intubated.
When estimating static lung compliance, volume measurements by the spirometer needs to be complemented by pressure transducers in order to simultaneously measure the transpulmonary pressure. When having drawn a curve with the relations between changes in volume to changes in transpulmonary pressure, C st is the slope of the curve during any ...
is the resistance (atkinsons), is the rate of flow of air (thousands of cubic feet per second). One atkinson is defined as the resistance of an airway which, when air flows along it at a rate of 1,000 cubic feet per second, causes a pressure drop of one pound-force per square foot.
Another important parameter, which can be calculated with a body plethysmograph is the airway resistance. During inhalation the chest expands, which increases the pressure within the box. While observing the so-called resistance loop (cabin pressure and flow), diseases can easily be recognized.
Lung volumes. Functional residual capacity (FRC) is the volume of air present in the lungs at the end of passive expiration. [1] At FRC, the opposing elastic recoil forces of the lungs and chest wall are in equilibrium and there is no exertion by the diaphragm or other respiratory muscles.