Lung Volumes: Difference between revisions
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== Lung Volumes == | == Lung Volumes == | ||
* '''Tidal Volume(TV)''' | * '''Tidal Volume(TV)''' | ||
It is the amount of air that can be inhaled and exhaled during normal | It is the amount of air that can be inhaled and exhaled during one respiratory cycle. This depicts the functions of the respiratory centres, respiratory muscles and the mechanics of the lung and chest wall<ref name=":0">Hough, A. Physiotherapy in Respiratory Care; An evidence-based approach to respiratory and cardiac management. 3<sup>rd</sup> eds. United Kingdom: Nelson Thomes Ltd, 2001 p.69</ref>. | ||
The normal adult value is 10% of VC, approximately 300-500ml (6‐8 ml/kg)<ref name=":0" />; but can increase up to 50% of VC on exercise<ref>Luce JM, Pierson DJ, Tyler MT. Intensive Respiratory Care, W. B. Saunders, Philadelphia, PA.p.21</ref> | |||
* '''Inspiratory Reserve Volume(IRV)''' | * '''Inspiratory Reserve Volume(IRV)''' | ||
It is the | It is the amount of air that can be forcibly inhaled after a normal tidal volume.IRV is usually kept in reserve, but is used | ||
during deep breathing. The normal adult value is 1900-3300ml. | |||
* '''Expiratory Reserve Volume(ERV)''' | * '''Expiratory Reserve Volume(ERV)''' | ||
It is the | It is the volume of air that can be exhaled forcibly after exhalation of normal tidal volume. The normal adult value is 700-1200ml. ERV is reduced with obesity, ascites or after upper abdominal surgery<ref name=":0" /> | ||
* '''Residual Volume(RV)''' | * '''Residual Volume(RV)''' | ||
It is the | It is the volume of air remaining in the lungs after maximal exhalation. Normal adult value is averaged at 1200ml(20‐25 ml/kg) .It is indirectly measured from summation of FRC and ERV and cannot be measured by spirometry. | ||
In patients with obstructive lung diseases where there is incomplete emptying of the lungs and air trapping, RV may be significantly increased. Patients with high RV who require surgery and [[Ventilation and weaning|mechanical ventilation]] require high peri-operative inflation pressures. This increases the risk of barotrauma, [[pneumothorax]], infection and reduced venous return due to high intra thoracic pressures. The RV can also be expressed as a percentage of total lung capacity and values in excess of 140% significantly increase the risks of these former complications<ref>Wilde M, Nair S, Madden B. Pulmonary function tests-a review. Care of the Critical ill. 2007; Dec 23(6):173-7.</ref>. | |||
== Lung capacities == | == Lung capacities == | ||
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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> Measurement can be done using Spirometry, Body plethysmography, Nitrogen washout and Helium dilution. | 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> Measurement can be done using Spirometry [[Pulmonary function test|see...]], Body plethysmography, Nitrogen washout and Helium dilution. | ||
# '''Body plethysmography''': primarily measures FRC using Boyle's law. Body plethysmography is particularly appropriate for patients who have air spaces within the lung that do not communicate with the bronchial tree. | # '''Body plethysmography''': primarily measures FRC using Boyle's law. Body plethysmography is particularly appropriate for patients who have air spaces within the lung that do not communicate with the bronchial tree. | ||
# '''Nitrogen washout''': This technique is based on washing out the N2 from the lungs, while the patient breathes 100% O2 using dilution properties of gases. | # '''Nitrogen washout''': This technique is based on washing out the N2 from the lungs, while the patient breathes 100% O2 using dilution properties of gases. | ||
Revision as of 16:43, 14 May 2018
Original Editor - Simisola Ajeyalemi Top Contributors - Simisola Ajeyalemi, Uchechukwu Chukwuemeka, Kim Jackson, Joao Costa and Adam Vallely Farrell
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 one respiratory cycle. This depicts the functions of the respiratory centres, respiratory muscles and the mechanics of the lung and chest wall[1].
The normal adult value is 10% of VC, approximately 300-500ml (6‐8 ml/kg)[1]; but can increase up to 50% of VC on exercise[2]
- Inspiratory Reserve Volume(IRV)
It is the amount of air that can be forcibly inhaled after a normal tidal volume.IRV is usually kept in reserve, but is used
during deep breathing. The normal adult value is 1900-3300ml.
- Expiratory Reserve Volume(ERV)
It is the volume of air that can be exhaled forcibly after exhalation of normal tidal volume. The normal adult value is 700-1200ml. ERV is reduced with obesity, ascites or after upper abdominal surgery[1]
- Residual Volume(RV)
It is the volume of air remaining in the lungs after maximal exhalation. Normal adult value is averaged at 1200ml(20‐25 ml/kg) .It is indirectly measured from summation of FRC and ERV and cannot be measured by spirometry.
In patients with obstructive lung diseases where there is incomplete emptying of the lungs and air trapping, RV may be significantly increased. Patients with high RV who require surgery and mechanical ventilation require high peri-operative inflation pressures. This increases the risk of barotrauma, pneumothorax, infection and reduced venous return due to high intra thoracic pressures. The RV can also be expressed as a percentage of total lung capacity and values in excess of 140% significantly increase the risks of these former complications[3].
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.[4] Measurement can be done using Spirometry see..., Body plethysmography, Nitrogen washout and Helium dilution.
- Body plethysmography: primarily measures FRC using Boyle's law. Body plethysmography is particularly appropriate for patients who have air spaces within the lung that do not communicate with the bronchial tree.
- Nitrogen washout: This technique is based on washing out the N2 from the lungs, while the patient breathes 100% O2 using dilution properties of gases.
- Helium dilution: The method for measuring lung volumes is based on the equilibration of gas in the lung with a known volume of gas containing helium.
Resources[edit | edit source]
European Respiratory Journal http://erj.ersjournals.com/content/26/3/511
References[edit | edit source]
- ↑ 1.0 1.1 1.2 Hough, A. Physiotherapy in Respiratory Care; An evidence-based approach to respiratory and cardiac management. 3rd eds. United Kingdom: Nelson Thomes Ltd, 2001 p.69
- ↑ Luce JM, Pierson DJ, Tyler MT. Intensive Respiratory Care, W. B. Saunders, Philadelphia, PA.p.21
- ↑ Wilde M, Nair S, Madden B. Pulmonary function tests-a review. Care of the Critical ill. 2007; Dec 23(6):173-7.
- ↑ Pellegrino R, Viegi G, Enright P, et al. Interpretative strategies for lung function testing. Eur Respir J 2005; (In press).
The method for measuring lung volumes is based on the equilibration of gas in the lung with a known volume of gas containing helium
