Lung volumes and capacities Flashcards
Tidal Volume (TV)
Tidal volume is the amount of air that moves in or out of the lungs with each respiratory cycle.
It measures around 500 mL in an average healthy adult male and approximately 400 mL in a healthy female.
It is a vital clinical parameter that allows for proper ventilation to take place.
Inspiratory Reserve Volume (IRV)
The extra volume of air that can be inspired with maximal effort after reaching the end of a normal, quiet inspiration.
Common abbreviation is IRV.
The normal adult value is 1900-3300ml.
Expiratory Reserve Volume (ERV)
The extra volume of air that can be expired with maximum effort beyond the level reached at the end of a normal, quiet expiration.
Common abbreviation is ERV.
The average ERV volume is about 1100 mL in males and 800 mL in females.
Residual Volume (RV)
Residual volume (RV) is the volume of air remaining in the lungs after maximum forceful expiration. In other words, it is the volume of air that cannot be expelled, thus causing the alveoli to remain open at all times.
Normal adult value is averaged at 1200ml(20‐25 ml/kg) .
Inspiratory Capacity (I.C)
The maximum volume of air that can be inspired after reaching the end of a normal, quiet expiration.
It is the sum of the TIDAL VOLUME and the INSPIRATORY RESERVE VOLUME. Common abbreviation is IC.
IC = TV + IRV
Expiratory Capacity (E.C)
Your expiratory reserve volume is the amount of extra air — above anormal breath — exhaled during a forceful breath out. The average ERV volume is about 1100 mL in males and 800 mL in females.
It is calculated by summing tidal volume and expiratory reserve volume.
EC = TV + ERV
Functional Residual Capacity (FRC)
Functional residual capacity (FRC), is the volume remaining in the lungs after a normal, passive exhalation.
FRC = ERV + RV
In a normal individual, this is about 3L.
The FRC also represents the point of the breathing cycle where the lung tissue elastic recoil and chest wall outward expansion are balanced and equal.
Vital Capacity (VC)
The vital capacity (VC) is defined as the total volume of air that can be displaced from the lungs by maximal expiratory effort.
The total volume of air that can be forcefully taken in and forcefully breathed out.
VC = TV+IRV+ERV
Total Lung Capacity (TLC)
Lung capacity or total lung capacity (TLC) is the volume of air in the lungs upon the maximum effort of inspiration.
Among healthy adults, the average lung capacity is about 6 liters.
Age, gender, body composition, and ethnicity are factors affecting the different ranges of lung capacity among individuals.
TLC = TV + IRV + ERV + RV
What is forced spirometry?
Spirometry is a simple test used to help diagnose and monitor certain lung conditions by measuring how much air you can breathe out in one forced breath. It’s carried out using a device called a spirometer, which is a small machine attached by a cable to a mouthpiece.
Forced Expiratory Volume in 1 sec (FEV 1)
Forced expiratory volume (FEV) measures how much air a person can exhale during a forced breath.
The amount of air exhaled may be measured during the first (FEV1), second (FEV2), and/or third seconds (FEV3) of the forced breath.
Forced vital capacity (FVC) is the total amount of air exhaled during the FEV test.
Forced Vital Capacity (FVC)
Forced vital capacity (FVC) is the total amount of air exhaled during the FEV test.
Spirometry tests / pulmonary function tests can be used to measure a patient’s forced vital capacity or FVC, which is the amount of air that an individual is able to forcibly exhale from his / her lungs after taking the deepest breath they can.
FEV1/FVC ratio
The FEV1/FVC ratio is the ratio of the forced expiratory volume in the first one second to the forced vital capacity of the lungs.
The FEV1/FVC ratio is the amount of air exhaled in the first second divided by all of the air exhaled during a maximal exhalation.
The normal value for this ratio is above 0.75-85, though this is age-dependent.
This figure is multiplied by 100 to get a % value.
What are obstructive pulmonary diseases?
Obstructive lung disease is a category of respiratory disease characterized by airway obstruction. Many obstructive diseases of the lung result from narrowing (obstruction) of the smaller bronchi and larger bronchioles, often because of excessive contraction of the smooth muscle itself.
Examples:
- Chronic obstructive pulmonary disease (COPD), which includes emphysema and chronic bronchitis.
- Asthma.
- Bronchiectasis.
- Cystic fibrosis.
What are restrictive pulmonary diseases?
Restrictive lung disease, a decrease in the total volume of air that the lungs are able to hold, is often due to a decrease in the elasticity of the lungs themselves or caused by a problem related to the expansion of the chest wall during inhalation.
People with restrictive lung disease cannot fully fill their lungs with air. Their lungs are restricted from fully expanding.
Examples:
- interstitial lung disease, such as idiopathic pulmonary fibrosis.
- Sarcoidosis, is an autoimmune disease.
- Obesity, including obesity hypoventilation syndrome.
- Scoliosis.
- Neuromuscular diseases, such as muscular dystrophy or amyotrophic lateral sclerosis (ALS)
