Lung Volumes: Difference between revisions
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== Measurement of Lung Volumes == | == Measurement of Lung Volumes == | ||
Measurements of lung volume are important for a correct physiological diagnosis, however, its role in the assessment of disease severity, functional disability, the course of disease and response to treatment remains controversial.<ref>Pellegrino R, Viegi G, Enright P, ''et al.'' Interpretative strategies for lung function testing. Eur Respir J 2005; (In press).</ref> | |||
== References == | == References == | ||
<references /> | <references /> | ||
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Description[edit | edit source]
Lung volumes are also known as respiratory volumes. It refers to the volume of gas in the lungs at a given time during the respiratory cycle. Lung capacities are derived from a summation of different lung volumes. The average total lung capacity of an adult human male is about 6 litres of air. Lung volumes measurement is an integral part of pulmonary function test. These volumes tend to vary, depending on the depth of respiration, ethnicity, gender, age and in certain respiratory diseases. A number of the lung volumes can be measured by Spirometry- Tidal volume, Inspiratory reserve volume, and Expiratory reserve volume. However, measurement of Residual volume , Functional residual capacity, and Total lung capacity is through body plethysmography, nitrogen washout and helium dilution.
Lung Volumes[edit | edit source]
- Tidal Volume(TV)
It is the amount of air that can be inhaled and exhaled during normal quiet breathing. Normal adult value is 5ooml.
- Inspiratory Reserve Volume(IRV)
It is the maximum amount of air that can be inhaled after a normal tidal volume. Normal adult value is 1900-3300ml.
- Expiratory Reserve Volume(ERV)
It is the maximum amount of air that can be exhaled after exhalation of normal tidal volume. Normal adult value is 700-1200ml.
- Residual Volume(RV)
It is the amount of air remaining in the lungs after maximal exhalation. Normal adult value is averaged at 1200ml.
Lung capacities[edit | edit source]
- Inspiratory capacity(IC)
It is the maximum volume of air that can be inhaled following a resting state. It is calculated from the sum of inspiratory reserve volume and tidal volume.
IC = IRV+TV
- Total Lung Capacity(TLC)
it is the maximum volume of air the lungs can accommodate. Value is about 6,000mL. It is calculated by summing tidal volume, inspiratory reserve volume, expiratory reserve volume and residual volume
TLC = TV+IRV+ERV+RV
- Vital Capacity(VC)
It is the total amount of air exhaled after maximal inhalation. Value is about 4800mL and it varies according to age and body size. It is calculated by summing tidal volume, inspiratory reserve volume, and expiratory reserve volume.
VC = TV+IRV+ERV
- Function Residual Capacity(FRC)
It is the amount of air remaining in the lungs at the end of a normal exhalation. It is calculated by adding together residual and expiratory reserve volumes. Value is about 1800 – 2200 mL.
FRC = RV+ERV
Measurement of Lung Volumes[edit | edit source]
Measurements of lung volume are important for a correct physiological diagnosis, however, its role in the assessment of disease severity, functional disability, the course of disease and response to treatment remains controversial.[1]
References[edit | edit source]
- ↑ Pellegrino R, Viegi G, Enright P, et al. Interpretative strategies for lung function testing. Eur Respir J 2005; (In press).
