Quiz 4 Flashcards
Specialized test are often standard test performed under special conditions to evauate
response to a condition or medication
Specialized test can be used in pts who have:
- Normal PFTs but have respiratory symptoms
- uncertain results of bronchodilator testing
- used to identify and characterized hyperresponsiveness in airway
- Assess changes of hyperactivity or assess severity of symptoms
- For those at risk of environmental or occupational exposure to antigens
What is the Bronchoprovaction challenge aka Bronchial challenge used for?
To identify and characterize hyperresponsive in the airways
The less gas it takes to evoke a negative response,
the more hyperreactive the airway is
With this test we provoke bronchospasm in the airways
Bronchial challenge
Direct stimulus include:(4)
- Methacholine
- Histamine
- Prostagladins
- Leukotrienes
Indirect Stimulus includes (5)
- Mannitol
- Adenosine
- Exercise
- Eucapnic voluntary hyperventilation beta blockers
- Hypertonic saline
Direct stimulus work directly on the
parasympathetic muscle to cause bronchospam
Indirectly stimulus causes ___________________ via intermediary cells
bronchoconstriction
____________________ and ______________ are chemicals that increase parasympathetic response in bronchial smooth muscle
Methocholine and Histamine
What uses cold air or room temp gases and causes heat and water loss from the airway?
Eucapnic Voluntary Hyperventilation
Methacholine is inhaled by the pt, along with increasing doses from
0.016 mg/ml to 16 mg/ml, prepaired in two to four fold dilutions
Methacholine is used in pts who cannot
tolerate repeated spirometry testing
When is it considered a positive result in Metha Challenge?
When FEV1 is reduced by 20%
(PC20 or proactive concentration)
Metha challenge test is considered negative if the
dose reaches 16 mg/ml w/o 20% reduction in FEV1
_____ pts will experience a change in airway w/ increasing concentrations?
ALL
A healthy subject will not
display a decrease of 20% or more in FEV1
What disease process usually drops 20% w/ dose as low as 8 mg/ml or less during metha challenge and why?
Asthma b/c they have very sensitive airways
What other disease process may usually drop during Metha challenge (3)
- COPD
- CF
- Bronchitis
What is the test criteria for Methacholine challenge?
Pts must be ASYMPTOMATIC
- no coughing or wheezing
- no recent upper or lower respiratory infections
- baseline FEV1 should be normal or at least > 60% predicted
What are some contraindications of the Metha challenge?
- Myocardial infarction in last 3 months
- Stroke
- Aortic aneurism
- Uncontrolled HTN
- FEV1 < 50% predicted or <1.0L b/c risk that the challenge may leave the individual w/ compromised lung function
How long should SABAs be withheld?
8hrs
How long should LABA’s be withheld
48hrs
Beta agonist (range)
12-24hr
Anticholinergics
24hrs
Theophyline (range)
12- 24 hrs
Extended Theophyline
48 hrs
Antihistimines
72 hrs
What are the 2 methods of delivery for Metha challenge?
- 5-breath dosimeter (most common)
- 2 min Tidal breathing method
For a 5 breath dosimeter method the delivered dose of the methacholine is standardized by using a fixed
number of 5 breaths for each
For the 2 minute method, the delivered dose is standardized by using a
fixed length of time
What are the 2 dosing methods?
- Quadrupling method (4x)
- Doubling method (2x)
The highest dose for either test is
16 mg/ml
Methacholine is administered sequentially in increasing concentration ranging from
0.016 to 16 mg/ml
Methacholine is given via
neb starting with the lowest (most diluted) concentration
Doismeter (most common) is delivered in
5 breaths
Methacholine is prepared in
5 concentration each dose is 4x larger than the previous
Can doismeter be prepared and advance?
Yes, must be stored in fridge. Must be room temperture at the time of use
Why is doismeter preferred?
B/c it delivers a consistent volume of drug w/ a fixed volume of aerosol on each breath
The pt takes 5 breaths of first concentration through
mouth w/ nose clips on (closed circuit)
How should the breaths be during this test?
deep and slow
(RV to IRV) w/ slight breath hold at TLC
When should spirometry be repeated? (Range)
30 to 90 seconds after each breath
After the test is completed what should be done?
Bronchodilator to reverse bronchospasm
If at anytime during testing FEV1 decreases by >20% then the
test is complete
What device is used for the 2 minute tidal breathing method?
Small volume neb
A _________ should be used on the _____________ limb
filter;
expiratory
Output needs to be
0.13 ml/min
Pt rebreathes ______________ methacholine solution w/ normal relaxed breaths thru mouth w/ nose clips for 2mins
nebulized
The 2 min tidal breathing method dosage starts at
0.031 mg/ml and increases 2x each step until the max is reached of 16.0 mg/ml
This test method can also be prepared ahead of time and must be at room temp when used
something to know
Why is a filter used on the expiratory side?
To prevent methacholine release in the room
If FEV1 decreases 20% or greater it is considered a
positive response (pt airway is hypersensitive)
How do you report a decrease of 20% in FEV1 after the first dose?
PC20 at < first dose
How do you report no decrease after the last dose
PC20 >16 mg/ml
If there is a decrease in FEV1 of 20% (PC20) at low doses of methacholine, there is a
high probability of asthma
If FEV1 decrease of less than 20% at 16.0 mg/ml negative results
asthma is unlikely
Pts requiring higher doses 8-16 mg/ml often do not
have asthma
____________________ challange stimulates bronchoconstriction directly
Histamine
Aerosolized histamine extract is similar to
methacholine challenge
How is the test performed?
- spirometry is performed
- A concentration of Histamine is administered and the spirometry to get FEV1
As long as the pt does not have a decrease in FEV1 of 20% during the Histamine challenge w/ the diluent then……
the test continues
Pts breathes in ___ breaths of the 1st concentartion
5
For histamine, dosing begins at
0.03mg/ml and doubled until reaching the max dose 10mg/ml
What are some of the most common side effects of Histamine?
- flushing
- headache
- sleepy
Pt should not have these for 48 hrs b.c it can cause bronchospasms
Antihistamines
What is the peak action of histamine
30 sec to 2 min, same as methcholine
Exercise challenge is commonly used in pts w/ suspected
Exercise Induced Asthma (EIA)
Bronchospasm usually occurs….
during or immediately after vigorous exercise
What is bronchospasm usually related to during exercise?
Heat and water loss in the airway due to increased ventilation
Candidates for Exercise Testing
- Normal PFTs have SOB on exertion
- Other challenge test such as methacholine or histamine were normal but pt is symptomatic
- Evaluating therapy in a known EIA pt
- Screening pts who may have associated risk if they are asthmatic
Would you perform an exercise challenge on an Asymptomatic pt?
No b/c they have no symptoms
How long should we wait to perform another exercise challenge? and why?
4hrs; Due to catecholamine release (neurotransmitters such as epinephrine and dopamine) will cause bronchoconstriction to lessen w/ additional testing
What is needed before an exercise challenge test?
- History and physical
- EKG
- No bronchodilators prior to test
- FEV1 should be no less than 65%of predicated
- No vigorous exercise for 4hrs prior
- No respiratory infections 3-6 weeks prior
Workload should be at
80-90% of max HR for 4 to 6 mins
During the exercise test what should be monitored? (4)
- EKG
- HR
- BP
- sats
When should you monitored vitals?
1 to 2 mins post exercise
When is the exercise challenge test positive?
Decrease of 10 to 15% of FEV1
In a healthy pt exercise will
increase the FEV1.
(if it increases then pt most likely does not have EIA)
Eucapnic Voluntary Hyperventilation Testing is similar to
exercise testing, b/c it provokes a bronchospasm due to heat and water loss from the airways
EVH usually uses (2)
- cold, dry gas
- CO2 is added to prevent hyperventilation (creating a co2 narcosis)
To perform the EVH a mixture of air is passed over a….
heat exchanger or cooling coil to chill air to -10 to -20 degrees Celsius
No ___________________ prior to test b/c we are trying to
bronchodilators;
invoke a bronchospasm
What is the most common test used for EVH
Cold air method
During the EVH test, pt’s must rebreathe in gas w/ ______________ respirations.
elevated
Pts must ventilate at 60- 85% of their
MVV for 4-6 minutes during the EVH test
What is added to prevent hyperventilation during the EVH test?
CO2
A decreased FEV1 of ___ % in the EVH test indicates a reactive airway (positive)
10%
In a healthy person EVH will usually cause _______________ not a bronchospasm
bronchodilation
Some asthmatics will experience an significant decrease FEV1 of
20-60%
Exhaled Nitric Oxide (ENO) is a method used for assessing
airway inflammation
ENO measures
inflammation in the lungs
ENO specifically measures
Eosinophilic inflammation
Increased eosinophilic is common in what disease process (2)
- Asthma
- COPD
What causes a decrease in ENO?
smoking
Before an ENO test pt’s should not (3)
- smoke
- eat
- drink
(for 1 hr prior)
When should the ENO test be performed?
before ALL the other test
What should be recorded before the test?
current meds and health status
What can decrease inflammation?
Corticosteriods
How can ENO be measured? (2)
- Online
- Offline
Sample exhaled gas continuously at the mouth is most common. Which ENO measuring method is this?
Online
This measures collected gas in an sampling device
Offline
For online pt inhales thru
Nitric oxide scrubber.
They exhale to RV, and inspire over 2 to 3 seconds to TLC (slow, even deep breath)
To prevent nasal no contamination….
nose clips is needed
Exhaled gas with the online method, measuring should be (#)
0.05L/sec
We must have at least ___ acceptable test withing ___% of each other then average them
2;
20%
How long should you wait in between measurements for online?
30 seconds
For offline measuring the pt inhales to
TLC through no scrubber or from a reservoir of no-free gas
Where is the sample collected in the offline measurement?
In a ballon
How long does analysis take for offline?
12 hr
For nasal nitric oxide air is aspirated into
one side of the nose and out the other
What is the normal FENO in adults and children
adults 10-35 ppb
children 5-25
If levels are elevated above the norms, what does this mean?
Suspected eosinophilic inflammation of the airways or alveolitis
Why do changes in Nitric oxide happen quicker than changes in PFTs?
It demonstrates immediate changes in airway inflammation markers
