Final Flashcards
What are indications for PFT (4)
- Diagnosis
- Screening
- Monitoring
- Effects of medications and therapy
What do PFTs measure? (standard PFT)
- Spirometry
- Lung volumes
- DLCO
What is the GOLD standard test for diagnosing obstructive lung diseases?
Spirometry
Lung volumes are used for diagnosing
restrictive lung diseases
DLCO is used to measure
gas exchange
PFT help classify lung diseases into 4 categories, what are they?
- Obstructive (CBABE)
- Restrictive
- Mixed or combined lung diseases
- Pulmonary vascular diseases
What are some specialized PFT
- ABGS
- 6-minute walk
- peak flow
- exercise oximetry
What is the maximal # of test on a basic PFT?
8
How should you prepare for a PFT?
- No caffeine
- No smoking
- No large meals
- No perfumes
Predicated values come from a national data base and are based on 4 demographics
HGAR
Height should be measured
W/o shoes
Weight is not an actually predicated value but should be included as it can be a variable info for Dr, in determining cause
something to know
PFT are __________ dependent
effort
Test must be ______________ and _____________
acceptable and replicateable
To get valid result that pt must be
coached
What are reasons for an invalid test (5)
- not understanding
- lack of coordination
- poor effort
- pain
- coughing
What to do if you get invalid results? (5)
- Try again
- Reinstruct the pt
- redemonstrate the manuver
- Ask another RT
- Make comments in pt report
If test is not replicable or within
Within 5% FVC, then it is not valid
Vital capacity can be
slow of forced
Slow vital capcity
measures the TOTAL VOLUME of air exhaled out of the lungs after a maximum inhalation (RELAXED)
Forced vital capacity
measures the TOTAL VOLUME of air out the lungs after a maximum inhalation (BLAST IT OUT)
_____ should NEVER be smaller than ____
SVC ;
FVC
What does it mean if SVC is smaller than FVC?
poor pt effort
What circumstance would you see the SVC larger?
obstruction
SVC is larger than FVC only during an obstruction (air trapping) such as (2)
emphysema or asthma
SVC the pt has
plenty of time to get the air out
FVC the pt has
limited time to get the air out
FEV1 is
forced expiratory volume over 1 second
When is FEV1 measured?
during FVC
FEV/FVC ratio defines
obstruction
FEV1 defines the
degree or severity of the obstruction
FEV/FVC ratio less than ___% predicated indicates an
75%
obstructive disease (CBABE)
FVC is normal/high (80%) you have an
obstruction only
FVC is low (<80%) you may have a
restrictive component (mixed)
FEV1 < 80% is used to determine the severity such as (5)
- mild
- moderate
- moderately severe
- severe
- very severe
Mild
70-79%
Moderate
60-69%
Moderately severe
50-59%
Severe
35-49%
Very Severe
<35%
FEF 25%-75% reflects
abnormalities in the small airways
FEF 50% is the most accurate measure used to determine
pt effort
What is peak flow?
a maximal inspiration, followed by a maximal forced exhalation
Predicted values for peak flow are based on
HAG
Peak flow are used for
asthmatics
What is the ultimate goal for lung volumes?
To get the TLC
What is TLC
the volume of gas remaining in the lungs at the end of a maximal inspiration
What does an increased RV/ TLC ratio indicates
severe air trapping??
How do we measure Residual volume?
RV cannot be measured directly
What are the 3 methods to indirectly measure RV
- Helium dilution
- Nitrogen washout
- Body plethysmography
Multibreath Helium dilution needs a (4)
- closed circuit
- source of o2
- helium analyzer
- co2 and h2o absorbers
The helium is diluted until
equilibrium is reached
HE dilution is used to measure RV but it may……
especially in
underestimate lung volumes;
sick pts
What can cause lung volumes to be overestimated?
leaks
Multibreath nitrogen washout uses (4)
- open circuit
- pneumatchometer
- nitrogen analyzer
- 100% o2
What is a pneumatchometer?
measures the flow of gases during breathing
If there is a sudden spike or increase in the fall of N2, then you have
a leak
If you have a leak you must
retest
What are the 2 types of Body box
- constant volume
- flow based
body box is based on who’s law?
Boyle’s
Which one is the most accurate ?
Body box
Changes in alveolar pressure is measured at the
mouth when the shutter is closed
How many phases of exhalation are there?
4
Phase 3 is the
plateau
An increase in the slope of phase 3 means
uneven distribution
When airway closure begins in phase 4 ___________ ___________ are measured
closing volumes
We measure closing volumes to determine
closing capacity and is expressed as a % of TLC
TLC=
- IRV
- VT
- ERV
- RV
FRC=
- ERV
- RV
IC=
- IRV
- VT
VC=
- IRV
- VT
- ERV
Contraindications for PFT (4)
- MI
- Active bronchospasms
- pneumothorax
- cataract surgery
If the FEV1/ FVC ratio is not available what do you look at next?
FVC
High TLC and RV means
hyperinflantion
High TLC and normal RV
Airtrapping
How long to wait in between retesting N2 washout
15 mins
How long to wait for He dilution
5 mins
What gas does DLCO use? And why?
carbon monoxide because it binds to hb 210x more than 02
What disease can cause DLCO to decrease
emphysema
What disorder can cause DLCO to increase
polycythemia
For DLCO how many test can you take
5 ( average 2 best test)
If pt has a restrictive disease process we would look at the DLCO to determine if the restriction is
interstitial or extrastitial
If DLCO is decreased in the presence of a restriction it usually means its cuased
interstitially
If DLCO is normal in the presence of a restriction it means the pt has
normal lung function and the restriction is related to something outside the lungs
Minute ventilation
VE= Vt x RR
VE must be correlated w/
blood gases
As body temp increases CO2 increases. What is the body’s natural response
take in larger volumes
Hypoventilation
PCO2 and pH
PCO2 >45
pH <7.35
Hyperventilation
PCO2 and pH
PCO2 <35
pH >7.45
p100 is the pressure generated at the mouth
during the 1st 100 milliseconds of an inspiratory effort against an occluded airway
Normal p100
1.5- 5 cm H20
What is the bronchoprovocation challenge aka bronchial challenge?
Used to identify and characterize hyperresponsiveness in the airways
The less gas it takes to evoke a negative response..
the more hyperreactive the airway is
Methacholine challenge is inhaled by the pt in increasing doses
0.016 to 16 mg/mL and prepared in 2 to 4 fold dilutions
The lower the dose needed to illicit a bronchospams
the more hyper responsive the airway is
What is the timing for the Jones method
measures breath hold from 0.3 of the inspiratory time to the midpoint of the alveolar sample
What does the maximum voluntary measure? (3)
- Resistance
- lung compliance
- respiratory muscle strength
What are examples of bronchoprovocation (3)
- methacholine challenge
- histamine challenge
- exercise challenge
Does the methacholine challenge evoke a bronchospasms indirectly or directly
directly
(exercise challenge evokes a bronchospasm indirectly)
What is PC20
The point in which there is 20% decrease in FEV1
What is the formula for Vt?
VT= MV/RR
What is the Severghaus electrode used for?
PaCO2
What does the Clark electrode used for?
PaO2
What is the. Sanz electrode used for?
pH
What are the 5 types of flow sensors?
- Turbine
- Pressure-differential
- Heated wire
- Pitot flow flow sensors
- Ultrasonic flow sensors
What is the most popular flow sensor
- turbine (the Wright’s Respirometer)
How many turbines does the turbine flow sensor have
5
Which electrode is polarographic and needs a polarized voltage
Clark electrode
The Clark electrode is good for _________ testing
exercise
Define steady state
When HR remains constant for 1 minute
How to determine max HR?
220- age
What is VO2 max?
the minimum rate of oxygen consumption during incremental exercise (maximum aerobic capacity)
Will VO2 max be higher on the treadmill or on the cycle ergometer? Why?
Treadmill b/c you are exerting more energy and the body is consuming more O2 that it needs
What is the Borg scle
Perceived exertion (the pt perception) on how hard they feel they are working
How often is workload increased using the borg scale?
every 3 minutes
How do you increase workload on the treadmil
change the speed and slope of walking
How do you increase workload on the cycle ergometer
Adjust the resistance of the pedals and frequency (rpms)
Where should you instruct the pt to keep their hands during the treadmill test
The pt should relax w/ their hands resting on the side rails slightly above their body in front of them
What are 3 ancillary groups for rehab
- Better breathers (COPD)
- Harmonic (COPD)
- Quest for breath (for idiopathic CF)
How does a pt get into pulmonary rehab
- must have a referral to rehab program from dr
- PFTs/ABG/SpO2 (must be done)
- smoking history
- H&P
- current meds
- commitment to the program
- Transportation/ financial resources
- negative pulmonary stress
If spirometry values (FEV1, FVC, FEV1/FVC ratio) what would be the first value to look to determine obstruction or restrriction
FEV1/ FVC ratio
If FEV1/ FVC ratio is not availble, what should you look at next?
FVC
If you only have lung volumes (RV, TLC, FRC, RV/TLC ratio, etc.) where should you start to rule out obstruction or restriction
RV/TLC ratio
