Pulmonary Function Testing Flashcards
Spiral spirometry
Tests for lung volumes/capacities
Compare actual (observed) results to predicted values based on gender, height, weight, age, and ethnicity
Used to classify obstructive, restrictive, or combined pulmonary dysfunction
Spirometry process
Someone inhales maximally and then they exhale rapidly to their fullest extent; tube measures
Can be performed in a fast/hard measure for FVC
Can be performed in a more relaxed measure - Slow Vital Capacity
If the test comes back abnormal, they will get a bronchodilator, then perform again
FEV1
Reflects airflow in LARGE and MEDIUM sized airways
75% of FVC should be exhaled in the first second
Will be decreased in obstructive diseases
FEV1 values
> 2.0 L No obstruction
1-2 L Mild to moderate obstruction
FEV1/FVC
Decreased = obstructive disease
Near normal or elevated = restrictive disease
FEF 200-1200
Looks at larger airways
The flow of 1st L of gas immediately following the first 200 mL
> 5 L/sec normal
FEF 25-75
Looks at smaller airways
Forced mid-expiratory flow
Amt of air exhaled during the middle half of the FVC divided by the time taken to exhale it
4 L/sec normal
Peak Expiratory Flow Rate (PEFR)
Max flow that occurs during any point during the FVC
Normally 9-10 L/sec
Max Voluntary Ventilation (MVV)
Max amt gas a pt can move in 1 minute
Identified nonspecific mechanical lung dysfunction, strength, and endurance of ventilatory mm
Resting minute ventilation 6-10 L
Avg male MVV 160-180 L/min
Flow Volume Loop
Graphic way of representing what happens during forced exhalation followed by forced inspiration
Reversibility
PFT measured again 5-20 min after bronchodilator
Normal or PURELY restrictive disease should show no difference
People with obstructive disease should show reversibility if there is > 15% increase in at least two of the following…
FVC
FEV1
FEF 25-75
Diffusing Capacity of the Lung
DL or DLCO
Amt of gas entering pulmonary blood flow per unit time
Relative to the difference btwn partial pressure of the gas in the alveoli and in the pulmonary blood
mL/min/mmHg
CO use
Used for DLCO testing
If Hb is normal, all alveolar CO should bind to Hb and the partial pressure of CO in the plasma should be zero
Can be reduced in three cases…
Decreased hemoglobin
Increased thickness of alveolar-capillary membrane
Decreased surface area for diffusion (primary factor)
Interpreting PFT
Is it normal? Watch for poor pt effort
Obstructive v restrictive?
Obstructive - reversible?
Restrictive - combined obstructive or restrictive abnormality?
What is the disease progression?
Is there isolated gas exchange abnormality?
PFT
Can be used for diagnosing and monitoring respiratory symptoms and disease
Looks at…
Lung volumes/capacities
Gas flow rates
Flow volume loops
Gas diffusion
