1/16/2024 0 Comments Cmh2o peep definitionFigure 1 displays the compliance difference between saline-filled and normal air-filled lungs. Surface Tension Elastic Force: One of the important concepts affecting lung compliance is the elastic property of the lung contributed to by the surface tension of the alveolar lining. They could be damaged or affected by specific pulmonary pathologies. Thus the flexibility of these fibers determines the compliance of the lungs. When the lung expands, they elongate and exert even more elastic force, similar to a rubber band. When the lung is outside the body system and in a deflated state, these fibers fully contract due to elasticity. Įlastic Property of the Lung Tissue: These result from the collagen and elastin fibers meshed inside the lung parenchyma. In specific pathologies, continuous monitoring of the lung compliance curve is useful to understand the progression of the condition and to decide on therapeutic settings needed for ventilator management. If the lung has low compliance, it requires more work from breathing muscles to inflate the lungs. Compliance determines 65% of the work of breathing. Any changes occurring to these forces could lead to changes in compliance. This elastic resistance is both due to the elastic property of lung tissue or parenchyma and the surface elastic force. Lung compliance is inversely proportional to elastance. The pressure required to inflate the lungs is higher than the pressure necessary to deflate them. You can see that the lung is not a perfect elastic structure. This curve is also called the Hysteresis curve. The area falling between this line and both the curves represents the excess work required to overcome the airway resistance during inspiration and expiration. The two meeting points are end-inspiratory and end-expiratory points, and the line connecting them provides the measurement of dynamic compliance of the lungs. When different readings of the lung volume are taken at specific measured pressure points and then plotted on a diagram, a pressure-volume curve representing both elastic and airway resistance properties of the lung is obtained Figure 1. Thus, airway resistance can undergo physiologic alteration by changes in the radius of the airway bronchus. Except for the radius of the airway, all other variables are relatively constant. Airway resistance depends on the air viscosity, density, and length, and radius of airways. It monitors both elastic and airway resistance. Pplat = Plateau pressure, PEEP = Positive End Expiratory Pressureĭynamic Compliance: It is the continuous measurement of pulmonary compliance calculated at each point representing schematic changes during rhythmic breathing. Therapeutically, it serves to select the ideal level of positive end-expiratory pressure, which is calculated based on the following formula: In cases of a paralyzed individual as in the operating theatre, it is straightforward to measure static compliance using recordings captured through electrical transducers. But the compliance measurement is considered valid since the static pressure difference is unaffected by any muscle activity. In the conscious individual, it is difficult to achieve complete certainty of respiratory muscle relaxation. Its measurement uses a simple water manometer, but electrical transducers are now more commonly used. This situation takes place when transpulmonary pressure equals the elastic recoil pressure of the lungs. It only measures the elastic resistance. Static Compliance: It represents pulmonary compliance at a given fixed volume when there is no airflow, and muscles are relaxed.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |