CLOSING VOLUME Meaning and
Definition
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Closing volume (CV) is a term used in pulmonary function testing to describe the volume of gas that remains in the lungs at the end of normal expiration. It represents the amount of air that is trapped in the peripheral airways and does not participate in gas exchange with the alveoli.
During a forced expiration, the closing volume is measured by using a nitrogen washout technique, where the subject breathes 100% oxygen followed by a 100% nitrogen mixture. As the subject exhales, the concentration of nitrogen in the expired gas gradually increases. The point at which the curve of nitrogen concentration levels off represents the closing volume.
The closing volume is influenced by various factors such as age, posture, lung disease, and smoking. In healthy individuals, the closing volume is relatively low and occurs towards the end of expiration. However, in conditions such as chronic obstructive pulmonary disease (COPD) or emphysema, the closing volume is increased, indicating airway obstruction and air trapping.
The measurement of closing volume can provide valuable information about the functionality of the peripheral airways and the extent of ventilation-perfusion (V/Q) mismatch. It can help in diagnosing and monitoring lung diseases, assessing the effectiveness of therapeutic interventions, and evaluating the overall lung function.
In summary, closing volume refers to the volume of gas that remains in the lungs at the end of a normal expiration. It is measured using a nitrogen washout technique and can provide insights into lung function and the presence of airway obstruction.
Common Misspellings for CLOSING VOLUME
- xlosing volume
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Etymology of CLOSING VOLUME
The word "closing volume" is a term used in respiratory physiology to describe a measurement that quantifies the degree of airway collapse during expiration. The etymology of the term can be broken down as follows:
1. Closing: The word "closing" comes from the verb "close", which ultimately derives from the Old French word "clos" meaning "enclosed" or "shut". It entered Middle English as "closen" and later evolved into "close". In the context of respiration, "closing" refers to the point at which small airways in the lungs collapse or close during expiration.
2. Volume: The word "volume" has Latin origins, derived from the Latin word "volumen" meaning "a roll or scroll". It entered English through Middle French as "volume" and has been used to refer to a quantity or amount of something.
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