Spirometry Mod 2 Flashcards
What is Spirometry?
- What values are observed?
Measures how an individual inhales and exhales volumes of air
- Measures Flow and Volume to Time (secondary)
- Spirometry is done fast (FVC)
- Slow flow is indicative of IC and VC
What does Spirometry measure?
- The function of the muscles of breathing
- Gas flow in and out of the lungs
What is being assessed in terms of muscle function from spirometry testing ?
- Diaprhagm, thoracic muscles
- Capability to expand and contract the thorax
What is being assessed in terms of Gas flow of the lungs from spirometry testing?
- Airway patency
- OBstructions to flow
What are 3 phases of Forced Vital Capacity (FVC)?
- Maximal inspiration
- Blast of exhalation
- Continued exhalation until end of test
What are the procedures for FVC?
- ATS guidlines…
- Prepare the subject
- Wash hands
- Instruct and demonstrate the test
- Perform Maneuverer (closed circuit method)
What is the maximum accepted leak value before beginning the test?
BEV <5% of FVC or 0.100 L; whichever is greater
What is the Acceptability and Usability criteria for Spirometry testing?
- 10 categories
- Add the specific ones outside of the table (slide 16)
How many attempts do you have at acquiring a usable test result
7-8 before test may be biased to pt fatigue
- aim for usable results rather than perfect acceptability
What does the between manoeuvre criteria (test) measure/performed/need to be met?
- (slide 24)
Ensures repeatable; of the 3 tests;
- the 2 largest values of FVC and FEV1 must be within 0.150 L of each other.
- The further the amount in litres, the lower the grade
How much of the FVC is blown out in the 1st second of the FEV1 (2 and 3 as well)
80% of air should be blown out within the 1st sec
What FVC results are reported to the doctor?
Largest FVC and FEV1
- Need at least 3 FVC to meet acceptability criteria
What is the Grading system for FEV1 and FVC
- i.e A-F
What is FEV1% also referred to as?
FEV1/FVC
On a flow volume loop; what points would the pt display effort dependant portion vs effort independant portion ?
- Slide 37
How does VC and IC test procedure differ from FVC tests?
Less forceful and effort needed
- usually performed before FVC because FVC could fatigue the pt before this test
- Still uses 3 tests
- Slow inhale and exhale flow rate
- tests TLC and RV? -> helps identify air trapping
Between manoeuvre evaluation for VC and IC?
Difference between largest and second largest manoeuvres should be no more than 150ml
- rest period of > 1 min between tests
- Needs 3 manoeuvres
What does Maximum Voluntary Ventilation (MVV) assess?
Used for exercise tolerance testing
- The max volume of air a subject can move in and out in the lungs in a specific period of time (within 12 sec)
- A alt if Spirometry testing is not viable (cannot test FEV1)
slide 70
We want their Vt to me half of VC?
What is differentiates upper and lower airway obstruction?
If the issue is derived above or below the carina
- If there’s time; break this table into other cards
What is Forced vital capacity (FVC)?
Max effort, rapid exhalation of VC
- validity = 3 maneuver variation <5%
How do airway obstructions affect FVC?
Airway obstructions = Increased airway resistance
- FVC exhalation requires more time due to decreased flow rate
- FVC test will have a 1 sec lag before flow starts regulating
How do Restrictive diseases affect FVC
Restrictive diseases typically infer low lung compliance and therefore limited lung expansion
- Small FVC exhaled quickly
What is the difference between FVC and FEVx?
Both are measures associated with volume-time measurements
- FVC = total forced exhalation of vital capacity
- FEV = Forced expiratory volume per time (x)
What is FEF (25-75*)
Forced expiratory flow
during middle half of FVC
- Dependent on the FVC
- Flow is from the medium to small airways
What information can you gather from FVC tests?
Helps reveal obstructive and restrictive conditions.
- Assess volumes + ability of Pt to forcefully exhale
What is the optimal test to assess restrictive conditions?
Slow vital capacity (SVC)
What information can Maximum Minute
Ventilation (MVV) testing provide and why do we use it?
Amount of air able subject can move in and out of the lungs over a specified period of
time.
- Used for obstructive disorders, can be a substitute for FEV1. (But FEV1 is
preferred). - Used when FEV1 is unattainable (FVC procedure too difficult to coordinate)
Main pulmonary characteristics of Obstructive Disease
Decreased Expiratory flow caused.
- High airway resistance will increased WOB
Main pulmonary characteristic of restrictive disease
Decreased volumes and capacities.
Decreased chest wall compliance (or lower lung compliance) will lead to increased WOB
Add this table later
What is EOFE?
End of Forced Exhalation
what is considered a
good Spirometry test?
Back Extrapolated Volume (BEV)
- Determines true start of test time
- Ensures accurate time zero for other measurements such as FEV1
- BEV must be <5% of FVC or 100 mL; whichever is greater
What is the max cut off time for 1 test/attempt?
15 seconds
Aside from accurate volumes; what other between maneuver criteria should be met before termination of testing
A total of 8 tests have been performed (max)
- fatigue can affect results
- Pt may tire and may not be safe to perform more testing
What information if measured and used when assessing FEV?
FEV1, FEV2, and FEV3 (forced exhalation within 1-3 seconds) is measured.
- FEV1 is the most important -> 80% of volume should be blown out here
What is PEF
Peak expiratory flow
- on a flow volume loop; it’d be the peak
When determining the largest FVC and largest FEV1; which manoeuvres should be selected?
The largest sum of FVC+FEV1 to determine other indices
How do you identify a obstructive condition via FVC interpretation?
If the FEV1 <80 is classified as having obstructive disease
- FVC less than predicted would also support this
- Lung volumes may be indicated
- Bronchodilators?
- FEF 25-75% is less than 60% predicted
How can you identify a restrictive condition via FVC interpretation?
FEV/FVC is less than 0.80
- FVC and FEV1 are proportionally reduced
- lung volumes and/or muscle pressures may be indicated.
what advantage can Flow Volume Loops (FVL) have over FVC testing?
Detecting upper airway obstructions
- you need to see the maximal inspiration flows to determine upper airway involvement
Test procedures for FVL?
Pt performs full inspiratory and expiratory maneuver in the same test
- slow full inspiration to TLC
- Forced complete expiration w/max force until no more gas can be expelled
- Quick max inspiration, end of tes
Complete slide 28
–>Grading system
Left off @ slide 34 (within manuever critera for FVL)
What could be a factor as to why FEV1% is less than predicted?
Obstruction could be present
- FEV1% < 80% is classified as having obstructive disease
What could be implied if FVC and FEV1 are both reduced proprtionally?
- what do you do about it?
A restriction may be present
- lung volumes/muscle pressure may be indicated
What is implied if FEV1 and FVC are less than predicted but are not proritonally reduced?
Obstruction may be present
What is a normal FVC/FEV1?
FVC/FEV1 normal > 0.80
What could be implied if FEF 25-75% is less than 65% of normal, assuming FEV1 is borderline normal?
Airway obstruction may be present
- Remember FEF is dependent on FVC since it is a measure of the middle of a FEV
What measure is reported from FEF 25-75%?
The highest sum of FVC and FEV1 measured from test
What measure is reported for FEV1/FVC?
Calculated from the largest FEV1 and FVC that was reported
What advantage do Flow Volume Loops (FVL) have over Maximal expiratory flow volume loops and FVC?
Not much, but FVL is better at detecting upper airway obstructions
- you need to see max inspiratory flows to determine upper airway involvement
Flow Volume Loop (FVL) test procedure?
Test subject performs a full inspiratory and expiratory maneuver in the same test
- Slow full inspiration to TLC
- Forced complete expiration with max force until no more gas can be expelled
- quick max inspiration
- End test
FVL within maneuver criteria
Same as FVC; add slide 34
What does it mean when a breath is effort independent?
No further increase in Pt. effort will increase flow.
- Flow in this area is influenced by dynamic compression of the airway aka equal pressure point
- Think of when you continue to exhale past your breathe
- Changes in the lower portion of the loop can be either due to elastic recoil or resistance in the small airways
Break this card up: Variations in FVL w/pathologies
What can be suspected if the FVL does not have a sharp rise to PEF?
Large airway obstruction or patient effort
What can be suspected from a concave (inward) curve from PEF?
Airway obsturction
When could you suspect hyperactive airways from a FVL?
If PEF and PIF values arent consistent?
- But if PEF or other expiratory flows fall with repeated effort
What can be suspected if the inspiratory curve isn’t reproducible?
Variable effort or fatigue
What can a sawtooth breath pattern be caused by?
Abnormality of the muscular control of th e posterior pharynx and larynx (usually w/sleep apnea)
- There would be sudden changes in reproducibility for this
What is the difference between VC/IC maneuvers and FVC?
VC/IC are both done slowly to obtain the maximal air movement between inspiration and exhalation
- unforced except when at RV or TLC where some effort is needed
When should VC and IC tests be conducted?
Prior to a FVC, possible fatigue or air trapping less likely to occur
Why are VC and IC tests at risk of producing misleading values?
After max inspiratory efforts, pts with obstructive disease can return a falsely high FRC or RV due to air trapping
How maneuvers is optimal for a good upper limit test for VC and IC procedures?
4 maneuvers
VC and IC test procedure
Flow should be constant throughout
- Have the pt. breath normally for 3-4 breaths, establishing a good baseline
- Pt exhales completely to RV
- Inhales to maximal TLC (slowly)
- Slowly exhale to RV again
Why do VC and IC tests need constant and slow breaths?
- aka what is it testing for?
Needed to grab a accurate IC and ERV
Reported results for VC and IC procedures?
- Largest values from at least 3 acceptable maneuvers for VC
- The average of at least 3 acceptable maneuvers for IC
What is Peak Expiratory Flow (PEF)?
Highest flow achieved from a max forced expiratory maneuver started from a position of max lung inflation
Why variables could affect the accuracy of Peak Expiratory Flow (PEF)?
PEF are effort and lung volume dependant
- posture and neck position could scew results
- Hesitation in blow (>2) can decrease PEF by as much of 10%
How many maneuvers should be performed on a PEF?
3 efforts of 1-3 seconds expiratory breaths
Acceptability criteria for PEF?
Slide 58
How often should PEF be monitored?
BID Morning and evening
- over 2-3 weeks
- PR best seen in the evening after max therapy (daily measures compared to against the PR)
PEF of 80-100% of PB suggest
Routine treatment can continue
- consider reducing meds
PEF of 50-80% of PB suggests
Acute exacerbation may be present. temporary increase in med may be indicated
- maintain therapy may need to be increased
PEF of < 50% of PB suggests
Bronchodilators should be taken immediately
- clinician should be notified if PEF fails to return to yellow or green
Peak flow device recommendations for Adults
ATS recommends 100-850 L/min
- +/- 10 or 20 L/min
Peak flow device recommendations for Pediatrics
ATS recommends a 60 – 400 L/min range
- 10% or 20L/min
What is Maximum Voluntary Ventilation (MVV)?
Max volume of air a subject can move in and out of the lungs in a specific period of time, usually 12 sec
- FEV1 is considered the more valuable value
What could be suspected if there is a disproportionate decrease in MVV compared to FEV1?
Possible neuromuscular disorder
What secondary purpose could MVV have?
Estimate ventilatory reserve during cardiopulmonary exercise testing
Test procedure for MVV
- Subject should be sitting (can make the subject very dizzy)
- Subject should be wearing nose clips
- Subject breaths normally at rest for at least three tidal breaths
- Then breathing as rapidly and deeply as possible
How long should test intervals be for MVV?
normally 12 secs
Ideal respiratory rate for MVV?
90-110 breaths/min
What variables could scew the results of a MVV?
Changes in RR or Vt during maneuver
within maneuver evaluation for MVV?
Between Maneuver evaluation for MVV?
Test results selection for MVV
Highest MVV and MVV rate should be reported
- MVV/(40*FEV1) should be > 0.80
- lower suggests poor effort or disease
How long should a MVV test be run for?
At least 12 secs
