Lung volumes and capacities Flashcards
What are the purposes of lung function tests?
Assessing health of the respiratory system
Measuring the efficacy of breathing mechanisms
Assisting diagnosis of respiratory diseases
Monitoring the progress of pulmonary diseases
Measuring the effectiveness of treatment
What is a spirometer?
Records lung volumes and capacities
What are the static lung function tests?
Tests measuring the functioning of the lungs which are not related to time
* Tidal volume (TV)
* Inspiratory reserve volume (IRV)
* Expiratory reserve volume (ERV)
* Residual volume (RV)
* Inspiratory capacity (IC)
* Vital capacity (VC)
* Functional residual capacity (FRC)
* Total lung capacity (TLC)
What are the dynamic lung function tests?
Related to time
* Forced Vital Capacity (FVC)
* Peak Expiratory Flow Rate (PEFR)
* Respiratory Minute Volume (MV)
* Maximum Voluntary Ventilation (MVV)
What is tidal volume?
Volume of air inspired/expired during normal respiration
TV = 500ml
What is inspiratory reserve volume?
Volume of air maximally inspired by forced inspiration after a normal inspiration
IRV = 3000ml
What is expiratory reserve volume?
Volume of air maximally expired from the end of normal expiration
ERV = 1100ml
What is residual volume?
Volume of air remaining in the lungs after maximal expiration
RV = 1200ml
How is residual volume measured?
Helium dilution method
What factors increase the residual volume?
Old age and emphysema
What are lung capacities?
Two or more volumes
What is inspiratory capacity?
Maximum volume of air that can be inspired by forced inspiration after a normal expiration
IC = TV + IRV = 3500ml
What is vital capacity?
Maximum volume of air maximally expired from the lungs following a maximum inspiration
VC = TV + IRV + ERV = 4600ml
What is functional residual capacity?
Volume of air remaining in the lungs at the end of normal expiration
FRC = RV + ERV = 2300ml
Significance of FRC?
Helps continuous exchange of gases across the lungs and blood between breaths
When is FRC increased?
Obstructive lung disease