Lung Volumes Flashcards
What is the test for lung volumes?
Spirometer
What is the tidal volume?
The amount you normally breathe in and out per minute
What is inspiratory reserve volume? During which phase of breathing does the measurement for this start?
the volume of gas that is inhaled into the lungs during a maximal forced inspiration
starting at the end of a normal tidal inspiration.
What is the expiratory reserve volume (ERV)? During which phase of breathing does the measurement for this start?
ERV is the volume of gas that is expelled from the lungs during a maximal forced expiration that
starts at the end of a normal tidal expiration.
What is the vital capacity?
The sum of the inspiratory and expiratory reserve
What is the difference between capacity and volume?
Capacity has the ability to change
What is at the zero line on an inspirometer?
Equal forces for inspiration and expioration
Can we measure residual volume with a spirometer?
No
What is the residual volume? Why is this important?
The volume of air in your lungs after you maximally expire
Without this the alveoli would collapse
What is the total lung capacity?
Vital capacity + residual volume
How many breaths does it take to replace the residual volume?
16-20 breaths
What are the two main categories of lung diseases?
Restrictive
Obstructive
What is a restricted lung disease?
Anything the restricts the expansion of the lung
What is an obstructive lung disease?
Anything that maintains air in the lung
Increasing the collagen or elastic tissue in the lungs will result in what type of disease?
Restrictive
What happens to the volumes measured by spirometry in a restrictive disease?
every point lowered
What happens to volumes in an obstructive disease?
You can breathe in more easily than breathe out, thus air is trapped
Increasing in elastic fibers will do what to disease?
Make it more restricted
What happens to the volumes measured by spirometry in a obstructive disease? What volume expands the most?
Increases all volumes measured, but mostly residual volume
What are the conditions that cause obstructive lung disease?
Asthma
COPD
What is FEV1?
Forced expiratory volume in the first second of exhalation
What is the forced vital capacity (FVC)? When in the respiratory cycle is it measured?
The total volume of air that can be forcibly expired after a maximal inspiration (as fast as you can)
In the first second
What does the FEV1/FVC ratio measure?
The resistance to airflow (% of air able to be expelled after 1 second. Thus the smaller, the more resistance)
What is the peak inspiratory flow?
The maximal rate of air intake
What is the peak expiratory flow?
The max rate of air expiration
What is FEF25, FEF50, an FEF75?
Forced expiratory rate at each percent of vital capacity
Which part of the airways are utilized in the upslope of the inspiration graph?
Large airways
What part of the airways are utilized in the downslope of the inspiration graph? What causes this?
Small airways
Resistance
What happens to the upslope and downslope of the flow-volume curve in obstructive diseases?
Resistance is met at lower volumes, but overall volume remains largely the same (thus the upslope remains the same, but the downslope increases markedly)
What causes resistance in obstructive lung diseases, the large or small airways?
Small airways
What happens to the flow-volume curve in an upper airway obstruction?
Lowers maximal flow, volume stay the same largely
What happens to the flow-volume curve in a restrictive lung disease?
Everything becomes smaller (lower flow, lower volume)
What is the FEV1/FVC ratio in normal ppl?
0.8
What is the FEV1/FVC ratio in obstructive lung disease?
<0.7
What is the FEV1/FVC ratio in restrictive lung disease?
> 0.8
What is the anatomic dead space?
Volume of the conducting airways that does not participate in gas exhange
What is the functional dead space?
Alveoli that do not participate in gas exchange (seen in diseases)
What is the total physiological dead space?
Anatomic dead space + functional dead space
What is the functional dead space in a normal individual?
0
What is the anatomic dead space in a normal individual?
Some amount >0 (usually ~150 ml)
What is the minute ventilation? Equation?
Total rate of air movement into and out of the lungs within one minute
(Vt * RR)
What is the alveolar ventilation rate? Equation?
the rate at which new air reaches the gas-exchange areas of the lungs
VA = RR*(Vt-Vd)
What is the alveolar ventilation equation?
VA = (Vco2)*K / PAco2
The alveolar ventilation rate has to match what?
The metabolic rate
The alveolar ventilation equation demonstrates what relationship?
The inverse relationship between alveolar ventilation and alveolar Pco2
What happens to the ventilation rate in hypothyroidism? Why?
Goes down d/t lower metabolic rate
What is the tidal volume controlled by?
The activity of the respiratory control centers in the brain as
How is the residual volume determined?
by the force generated by the muscles of expiration and the inward elastic
recoil of the lungs as they oppose the outward elastic recoil of the chest wall
What happens to the RV in COPD?
Increases
How do you determine the ERV?
the difference between the functional residual capacity (FRC)
and the RV.
How do you measure the inspiratory reserve volume?
by the strength of contraction of the inspiratory muscles, the inward elastic
recoil of the lung and the chest wall, and the starting point, which is the FRC plus the VT.
What is the functional residual capacity?
The volume of gas remaining in the lungs at the end of a normal tidal expiration
What is considered to represent the balance point between the inward elastic recoil of the lungs and the outward elastic recoil of the chest wall?
The functional residual capacity
What is the inspiratory capacity? During which phase of breathing does the measurement for this start?
the volume of air that is inhaled into the lungs during a maximal inspiratory effort that
begins at the end of a normal tidal expiration (the FRC).
What is the vital capacity (VC)? During which phase of the breathing cycle is it measured?
the volume of air expelled from the lungs during a maximal forced expiration starting after
a maximal forced inspiration
IRV + Vt = ?
IC
IRV + VT + ERV = ?
VC
TLC – RV = ?
VC
ERV + RV = ?
FRC
RV + VT + ERV + RV
TLC
Which parameters cannot be measured by an inspirometer?
Residual volume
Functional residual capacity
Total lung capacity
What are FEV1, FEV2, FEV3?
The forced expiratory volume in the first, second, and third second
What does the FEV1/FVC ratio measure? What is the usual value for this? What does this reflect?
the fraction of total FVC that can be
expelled in the first second.
Normal value is 0.8.
This reflects resistance to air movement
What is the FEF? How is this represented on the flow-volume curve?
Forced expiratory flow in the middle of expiration
Represented by the downslope of the PEF to the FVC
What happens to the FVC and the FEV1 in obstructive diseases like asthma? What is the FVC1/FVC ratio?
Decreased, but FEV1 is decreased more than FVC
Thus the ratio is decreased
What happens to the FVC and the FEV1 in restrictive diseases like alveolar fibrosis? What is the FVC1/FVC ratio?
both FVC and FEV1 are decreased, but FEV1 is
decreased less than FVC is. So the FEV1/FVC ratio can actually be increased compared to normal individuals
What is the relationship between the alveolar ventilation and alveolar pCO2?
Inversely related
Increases in alveolar ventilation cause what in PACO2
A decrease
