Ch. 16: Pulmonary Function Testing Flashcards
What is the minimum percent increase in expiratory flow following a before-and-after bronchodilator study that indicates significant improvement?
12%
Which of the following pulmonary function tests would best determine the patient’s ability to cough?
MIP
The volume of air (usually in milliliters) that is inhaled or exhaled during a normal breath
Tidal Volume - VT
The maximum volume of air that can be inspired after a normal inspiration.
Inspiratory Reserve Volume - IRV
IRV normally is not measured during simple spirometry, but if it is, it should be measured from a _____.
Slow vital capacity
IRV normal value
3000 mL
Normal VT value
400-700 mL
The volume of air exhaled after a normal expiration.
ERV
Normal ERV value
1000 mL
The volume of air left in the lungs after a maximal expiration.
Residual Volume - RV
Normal RV value
1500 mL
The amount of air left in the lungs after a normal expiration
FRC
When is a closed circuit He dilution test said to be completed?
Once equilibrium is reached
Nitrogen washout test
The nitrogen concentration in the lungs is
approximately 79% at the beginning of the test, which is gradually washed out as the patient breathes ________% O2.
100
Complete nitrogen washout occurs in about ________.
7 minutes
Normal FRC value
2500 mL
The maximum amount of air that can be inspired after a normal expiration
Inspiratory Capacity
Inspiratory Capacity normal value
3500 mL
The technique of plethysmography is based on ____________ law.
Boyle’s
What is the most accurate for measuring FRC in COPD patients?
Body box
Why may FRC measurements be higher with the body box than those measured by the helium dilution or nitrogen washout method?
Because body plethysmography actually measures the total amount of gas in the thorax
Normal FRC value
2500 mL
The maximum amount of air that can be exhaled after a maximum inspiration
Vital Capacity
What measurement is trying to be obtained?
At the bedside, use a mouthpiece connected to a respirometer. Instruct the patient to inhale as deeply as possible and then slowly and completely exhale through the mouthpiece.
VC
Vital Capacity normal value
4500 mL
The maximum amount of air that can be exhaled as quickly and forcefully as possible after a maximum inspiration
Forced Vital Capacity
The amount of air remaining in the lungs at the end of a maximal inspiration
Total Lung Capacity
TLC normal value
6000 mL
This is the percentage of the TLC that remains in the lungs after a maximal expiration
RV/TLC ratio
Normal RV/TLC value
20-35%
The volume of air that is exhaled over a specific time interval during the FVC maneuver.
FEV
Because the FEV1 is most commonly measured, look for an FEV1/FVC of less than ____% to
indicate an obstructive disease.
70
The average flow rate during the
middle portion of the FEV.
FEF25%–75%
FEF25–75% Normal
4-5 L/sec
The maximum flow rate achieved during an FVC.
Peak flow
Peak flow normal range
400 to 600 L/min (6.5 to 10 L/s).
The maximum volume of air moved into and out of the lungs voluntarily in 10 to 15 seconds.
MVV
What measurement tests for overall lung function, ventilatory reserve capacity, and air-trapping?
MVV
Normal MVV value
170 L/min
may be calculated by using the following formula: 40 x FEV1)
________ is displayed on a graph and represents the flow generated during an FVC maneuver followed by a forced inspiratory volume maneuver; both are plotted against volume change.
Flow-Volume Loop
What represents the gas exchange capabilities of the lungs?
Diffusion capacity of the lungs (DL)
The most common method for measuring DL is the _________.
single-breath method
Normal diffusion capacity is approximately ____ mL/min/mm Hg.
25 to 30
DLCO is decreased as a result of:
(1) O2 toxicity
(2) Emphysema
(3) Sarcoidosis
(4) Edema
(5) Asbestosis
V/Q SCANNING
For the determination of gas distribution, the patient inhales ________ and holds the breath for 10 to 20 seconds. Radiographs (photoscintigrams) are obtained to observe how the xenon was distributed in the lungs.
radioactive isotope xenon
What measurements are decreased in obstructive diseases?
- FEV1
- FEV/FVC
- FEF 25-75%
- FEF 200-1200
What measurements are increased in obstructive diseases?
- FRC
- TLC
- RV
What measurements are decreased in restrictive diseases?
- FRC
- FVC
- IC
- IRV
and normal FEV/FVC value
Severity of obstruction (by interpretation of FEV1)
Mild
70-74%
Severity of obstruction (by interpretation of FEV1)
Moderate
60-69%
Severity of obstruction (by interpretation of FEV1)
Moderately severe
50-59%
Severity of obstruction (by interpretation of FEV1)
Severe
35-49%
Severity of obstruction (by interpretation of FEV1)
Very severe
<35%
Predicted values are determined from what?
- Age
- Gender
- Height
- IBW
- Race
