Exam #6: Lung Volumes Flashcards
How are lung volumes measured?
Spirometry
What is tidal volume?
Volume normally breathed in & out
What is inspiratory reserve volume?
Volume inspired with maximal inspiration - tidal volume
What is expiratory reserve volume?
Volume of expired air past tidal volume
What is the inspiratory capacity?
“Everything that can be breathed in”
Tidal volume + inspiratory reserve
What is the vital capacity?
“Everything that can be breathed in & out”
What is the residual volume?
Volume of air left in the lungs after maximal expiration
What is the importance of residual volume?
Prevention of alveolar collapse
What is the total lung capacity?
Total volume of air in lung
Can residual volume or functional residual capacity be measured with spirometry?
NO
What is a restrictive lung pathology? How does this pathology change lung volumes? Provide examples of this pathology.
Condition that restricts expansion of lung
–>Volumes are smaller compared to normal population
E.g.
- Pleural effusion
- Increased elasticity
- Inflammation
What is an obstructive lung pathology? How does this pathology change lung volumes? Provide examples of this pathology.
More air in than out & dramatic increase in residual volume
–> “air trapping”
E.g.
- COPD
- Asthma
What is FVC?
Forced vital capacity= total amount of air that can be forcibly expired after maximal inspiration
What is FEV1?
The volume of air that can be forcibly expired in the first second
*Speed
Why is the FEV1/FVC ratio important?
It is a reflection of RESISTANCE to airflow
- Big ratio= small resistance
- Small ratio= big resistance (obstructive)
.75- 0.8= normal
Draw the flow volume curve. Label the large & small airways.
X= Volume (L) Y= Flow (L/s)
What is PIF?
Peak inspiratory flow
What is PEF?
Peak expiratory flow
What is FEF?
Forced expiratory flow
What is FEF 25, 50, & 75?
Forced expiratory flow rate at varying volumes of air out
Draw the change seen with obstructive lung disease on volume & flow curve. How can this be used clinically?
Measure the efficacy of bronchodilators
Draw the flow-volume curve in upper airway FB obstruction.
N/A
Draw the flow-volume curve in restrictive lung disease.
N/A
How does the FEV1/FVC ratio change in obstructive lung disease? Why?
Less than 0.7
- FCV & FEV1 decreased, but FEV1 is decreased more than FVC
How does the FEV1/FVC ratio change in restrictive lung disease? Why?
Greater than 0.8
FVC & FEV1 are decreased, but FEV1 is decreased less than FVC
What is physiologic dead space?
Volume of the lung that does NOT participate in gas exchange–the volume of the conducting airways
Note that this is decreased with intubation
How is physiologic dead space clinically related to mechanical ventilation?
Must be substracted
What is the functional dead space?
Alveoli that do NOT participate in gas exchange i.e. ventilated but not perfused
*This is 0 normally
What is minute ventilation?
Total rate of air movement into and out of the lungs in one minute
Tidal volume x RR
What is the alveolar ventilation?
Rate at which new air reaches the gas-exchange areas of the lungs (minute ventilation minus dead space)
RR x VT- VD
Write the alveolar ventilation equation. What is the essential premise of this equation?
Alveolar ventilation must match metabolism
Work through examples on slide #38.
N/A
What cannot be measured with a spirometer?
RV
FRC
TLC
