Lung Volumes and Lung Function Flashcards
What is tidal volume?
Volume of air inspired during normal quiet breathing
What is inspiratory reserve volume (IRV) ?
Extra air that can be inspired after normal tidal inspiration
What is expiratory reserve volume (ERV)?
Extra air that can be expelled ‘actively’ after ‘passive’ expiration
What is residual volume (RV) ?
Amount of air left in lungs which cannot be expelled
What is functional residual capacity (FRC)?
Lung volume at end of normal quiet expiration (ERV+RV)
What is inspiratory capacity (IC)?
From end of normal quiet expiration to maximal inspiration (TV+IRV)
What is vital capacity (VC)?
From maximal inspiration to maximal expiration (IRV+TV+ERV)
What is total lung capacity (TLC)?
From maximal inspiration to residual volume (IRV+VT+ERV+RV)
What is the gas dilution method used for in lung volume and capacity measurement?
The gas dilution method is used for measuring RV (Residual Volume) or FRC (Functional Residual Capacity)
Why can’t RV or FRC be measured by simple spirometry?
Because they are the volumes of gas remaining in the lungs after a full exhalation, which cannot be measured by simply exhaling into a spirometer.
What gas is usually used in the gas dilution method for measuring RV or FRC?
Helium
What is calculated once you have RV or FRC?
TLC
Q: What is another method used for measuring lung volumes and capacities?
Body plethysmography
Q: What is another method used for measuring lung volumes and capacities?
Body plethysmography
What are dynamic volumes/capacities in respiratory measurements?
Dynamic volumes/capacities are time-based measurements in respiratory measurements
- FEV1 and FVC
What is FEV1 in respiratory measurements?
FEV1 is the forced expiratory volume in 1 second in respiratory measurements.
What is FVC in respiratory measurements?
forced vital capacity
What is the diagnostic value of FEV1/FVC ratio in respiratory measurements?
- FEV1/FVC > 80% (normal)
- FEV1/FVC > 90% (‘Restrictive’ disease)
- FEV1/FVC = 40% (‘Obstructive’ disease)
What is the significance of measuring flow-volume loops in respiratory function testing?
Flow-volume loops provide information about the volume of air that can be expelled during different stages of breathing.
- help diagnose obstructive and restrictive lung diseases based on the shape of the curve and the FEV1/FVC ratio.
What is the characteristic flow-volume loop pattern of obstructive lung disease?
- a reduced peak expiratory flow rate (PEFR)
- concave curve on the flow-volume loop
- FEV1/FVC ratio < 70%
What is the characteristic flow-volume loop pattern of severe obstructive lung disease?
- “steeple” pattern on the flow-volume loop, indicates a marked reduction in expiratory flow rates
- FEV1/FVC ratio is very low
What is the characteristic flow-volume loop pattern of restrictive lung disease?
- normal-shaped flow-volume loop with reduced lung volumes
- FEV1/FVC ratio is typically normal or high
What is Peak Expiratory Flow Rate (PEFR)?
A measure of how fast air can be expelled from the lungs during a forced exhalation
How is PEFR measured?
Using a peak flow meter, which is a handheld device that measures the maximum speed of air that can be exhaled forcefully after taking a deep breath.
What is the significance of measuring PEFR?
Often used as a screening tool for asthma and other respiratory disorders. It can also be used to monitor the severity of respiratory symptoms and the effectiveness of treatment.
What factors affect lung volume?
Body size
Age
Gender
Muscle training
Disease
