End-expiratory lung volume is the volume of lung space after normal expiration and is equal to the sum of expiratory reserve volume and residual volume. A healthy person brings it to values of about 2.7 liters on average. Various lung diseases can pathologically decrease or increase volume.
What is end-expiratory lung volume?
Lung volumes are the various spatial contents of the lungs. The air we breathe occupies them during the various steps of respiration. Lung volumes are the various spatial contents of the lungs. The respiratory air occupies them in the different steps of respiration. Lung volumes play a role in both inspiration and expiration and differ during inhalation from those during exhalation. Combinations of individual lung volumes are understood as lung capacities. End-expiratory lung volume is the volume of space that the lungs have after a normal expiration. It is also referred to as functional residual capacity and thus corresponds to the volume of gas remaining in the lungs after expiration. Other lung volumes include inspiratory reserve volume, respiratory volume, expiratory reserve volume, and residual volume. Lung volumes and all diseases of the lungs are predominantly the subject of pneumology.
Function and task
The paired lung serves air-breathing vertebrates for respiration. The efficiency of the respiratory process is called lung volume. Thus, the individual lung volumes describe the efficiency with which the lungs take in oxygen and expel carbon dioxide. During inspiration, air is drawn into the lungs by active breathing and the associated contraction of the respiratory muscles. Inhalation fills only a fraction of the maximum lung volume, which can be expanded by exertion. During expiration, breath exits the lungs as the diaphragm and chest relax. During expiration, the lungs are only partially emptied of respiratory gas and a volume of gas remains. This volume is the end-expiratory lung volume. This volume is therefore relevant to respiration and plays a role primarily in the form of functional residual capacity. The volume is the sum of the residual volume and the expiratory reserve volume. The residual volume is the volume of gas that remains in the lungs after maximum expiration and cannot be exhaled due to physical relationships. In a healthy lung, this value is 1.5 liters. The expiratory reserve volume, on the other hand, corresponds to the additional lung volume that can be exhaled after normal expiration during forced breathing. On average, it amounts to 1.2 liters for a healthy person. As the sum of the expiratory reserve volume and the residual volume, the end expiratory lung volume of a healthy lung is therefore around 2.7 liters. This functional residual capacity plays a role primarily in pulmonary function diagnostics. The value can be determined, for example, using procedures such as the helium dilution method. In this test method, the physician opens a helium gas supply that is administered to the patient after normal expiration. When he breathes, he uses it to mix the lung volume of the functional residual capacity with the ambient air that he breathes in. This establishes a buffer function that can level out fluctuations in oxygen partial pressure between the breathing steps of inspiration and expiration. Thus, the partial pressure of oxygen in the alveoli of the lungs decreases. The partial pressure of CO2 rises above that of fresh air.
Diseases and medical conditions
Lung volumes assume pathologic values in the setting of various diseases. In asthma, for example, lung volume is severely impaired and requires medical agents to increase its efficiency. End-expiratory lung volume changes mainly in obstructive lung diseases. Diseases from this group make it difficult to exhale by obstructing or narrowing the airways. As a result, breathing is slower and overinflation occurs in the lungs. Insufficient end-expiratory lung volume causes end-expiratory obstruction of the small airways. The downstream alveoli can thus collapse in the worst case. Positive end-expiratory pressure allows the respiratory loop to return to normal.Sometimes, however, lung volumes are decreased not because of actual loss of lung function but because of spinal curvatures. Increased end-expiratory lung volume may indicate obstruction of the lungs. Additional ventilation could be counterproductive in such a circumstance. Interstitial lung diseases have opposite effects on end-expiratory lung volume. They cause respiratory failure of the lungs and thus decrease end-expiratory lung volume. Pulmonary function diagnostics are used in pulmonology to assess pathologic lung volumes. Lung volumes also play a role in the intensive care unit, where decisions must be made about possible ventilation steps. Spirometry or bodyplethysmography can be used to check small and large lung function. Spirometry measures lung volumes and the rate of respiratory activity and can thus be used to assess overall lung function. There are different ways to test lung volumes independently, but they are not very accurate. One of these ways is the candle test, in which a lit candle is placed about one meter away from the test person. Anyone who can blow out the candle from this distance has excellent lung volume. A second test option for private use is the balloon test, in which the test person blows once into a balloon. The level of the balloon primarily provides an indication of expiratory vital capacity, which can be an indicator of individual lung volumes.
