PFT Testing Flashcards
How many lung volumes are there?
4
What are 3 measurement types?
- lung volumes/capacities
- flow rates
- gas diffusion
How many lung capacities are there?
4
What does one lung capacity equal?
2 or more lung volumes
What are the directly measured lung volumes?
- IC
- IRV
- ERV
- VC
- VT
What are the indirectly measured lung volumes?
- RV
- FRC
- TLC
How do we measure indirect volumes?
Perform a SVC maneuver
How would you instruct a patient to perform a SVC?
Take a maximal inspiration followed by a maximal expiration without force
What kind of disease will the SVC provide important volumes for?
Restrictive diseases
What is the definition of IRV?
Maximum volume of air inspired following normal inspiration. Not clinically significant
What is the definition of the ERV?
Normal inhale followed by maximal exhalation (20-25% of VC)
What is the definition of IC?
Normal exhalation followed by maximal inhalation
What is the definition of VC?
- inspiration: maximal exhalation followed by inhaling deeply as possible
- expiration: maximal inhalation followed by exhaling maximally
- 80% of TLC
- obtained from VC maneuver
What is pulmonary mechanics?
- Evaluates lungs ability to move large volumes quickly
- measures FLOWS
What disease will FVC provide important flow rates for?
Obstructive
How would you instruct a patient to perform a FVC maneuver?
Take a maximal inspiration followed by a maximal expiration as forcefully and rapidly as possible
What are some important facts about FVC?
- effort dependent
- must begin exhalation quickly
- exhalation must be > or = to 6 seconds
- should equal SVC
- indicates obstruction if not completed in 3 seconds
What is FEF25-75?
Small airways
What is FEF200-1200?
Large airways
What are some important facts about PEFR?
- effort dependent
- typical value 10 L/sec (600 L/min)
- sometimes used to evaluate asthmatic patients, pre/post bronchodilation
- ID in flow-volume graph as highest point
What is FEV/FVC ratio?
FEV for a given interval expressed as a % of a FVC
What is FEV1.0?
- volume of gas expired over a given 1 second
- best indicator of obstructive disease
What does it mean if your FEV1/FVC ratio <70%?
Obstructive
What does it mean if your FEV1/FVC ratio is >70%
Indicates no obstruction so normal or restrictive
What is a flow volume loop?
Measures the volumes and flow rates of the FVC
What are the directions of a flow volume loop?
- patient performs a FEV from TLC
- followed by a FIV from RV
What is measured on the FVC vertical axis?
- flow rates measured directly on the vertical axis
- expiratory flows above base line
- inspiratory flows below base line
What is measured on the FVC horizontal axis?
-volume measured directly on the horizontal axis
What would the shape be of a restrictive flow-volume loop?
tall and skinny
What would the shape be of an obstructive flow-volume loop?
scooped out
What does fixed airway obstruction cause?
equal decreases in both expiratory and inspiratory flow rates
How would you know if you had an intrathoracic airway obstruction?
- flattened on expiration
- flow limitation
How would you know if you had an extrathoracic large airway obstruction?
flow limitation on inspiration
What is the purpose of the pre and post bronchodilator PFT testing?
used to measure the reversibility of an obstructive pattern
A bronchodilator post study is considered to be significant with an increase in how much?
15% or more
When should all bronchodilator therapy be held?
8 hours prior to testing
What is bronchial provocation?
looks for airway reactivity
What are some ways bronchial provocation is done?
- methacholine challenge
- histamine challenge
- cold air challenge
- exercise challenge
How is it determined that a patient has reactive airways after bronchial provocation?
a 20% or more decrease in FEV1 occurs
