pulmonary function tests and asthma Flashcards
What are the three basic pulmonary function tests
- airflow spirometry
- lung volumes
- diffusion capacity of the lungs for carbon monoxide (DLCO)
describe how you would coach a patient through a spirometry test
- relax and breathe normally
- take a deep breath in
- forcefully exhale all of your air
- visualization may be provided (candles, balloons)
- take another deep breath in
- repeat testing at least 3X
What is forced vital capacity
- deep breath in (full inspiration)
- blow out air as fast as possible (forced expiration)
What is FEV-1
- volume of air forcibly expelled in the first second of exhalation
An FEV-1/FVC ratio of is consistent with an obstructive airway disease
< 0.7
Why is bronchodilator testing done
- reversibility testing
- if positive: FEV1 is increased by 12% and 200 ml
- aides in diagnosis
- provides treatment options
- improves compliance
how is bronchodilator testing done
- nebulizer or inhaler
- monitor technique: hold inhaled medication in lungs 5-10 sec
- testing completed 15 min after medication provided
What is the Methacholine challenge test? What is a positive test?
- dilute solution of methacholine given via nebulizer
- spirometry conducted at 30-90 seconds
- concetration increases
- Positive test: FEV1 decreases by 20%
this spirometry reading indicates which type of airway disease
obstructive disease
restrictive airway disease has what characteristic shape
peaked appearance
vital capacity
volume of air we breathe out following maximal inhalation
draw out lung volumes
diffusion capacity (DLCO) can be misleading in what condition
- anemic
- will give false reduction and must be adjusted for hemoglobin level
function of diffusion capacity (DLCO)
- measures the ability of the lungs to transfer gas and saturate the hemoglobin (alveolar-capillary membrane)
- CO is used as a surrogate for oxygen transfer
describe diffusion capacity (DLCO) technique
- patient inhales a single breath of gas consisting of helium/CO, then expires, and measurement of exhalation is taken
- when lungs are healthy; little CO is collected during exhalation
- when lungs are diseased; less CO diffuses into lungs, thus higher levels are measured in exhaled gas
describe obstructive airway disease
- aiwary narrowing
- have high lung volumes and airflow is limited in expiration
- inspiration is likely normal
Are the following lung volumes likely to be increased or decreased in obstructive airways disease?
- TLC
- FVC
- RV
- FEV1
- FEV1/FVC
- TLC: increased
- FVC: normal
- RV: increased
- FEV1: decreased
- FEV1/FVC: decreased
Are the following lung volumes likely to be increased or decreased in restrictive airways disease?
TLC
FVC
RV
FEV1
FEV1/FVC
- TLC: decreased
- FVC: decreased
- RV: decreased
- FEV1: decreased
- FEV1/FVC: normal or increased
name some conditions that are classified under obstructive airway disease
- asthma
- bronchitis
- COPD
- cystic fibrosis
- emphysema
- upper airway obstruction
name some conditions that are classified under restrictive airway disease
- pulmonary fibrosis
- infectious lung disease
- pleural effusion
- tumors
- obesity
name the 5 step approach to PFT interpretation
- examine flow-volume curve for shape
- examine FEV-1 value
- examine FEV-1/FVC ratio
- examine the response to bronchodilator
- examine DLCO
which Forced expiratory value is more sensitive for detecting early airway obstruction
FEF 25-75%
- forced expiratory flow
if FEV-1 is < 80% of predicted value, patient likely has?
an obstructive airway disease
if the FEV-1/FVC ratio is decreased to 70% or less, what does the patient likely have?
obstructive process
if the if the FEV-1/FVC ratio is at 70% to less than normal, what does the patient likely have?
- mild obstruction cannot be excluded
- refer to FEV-1 and FEF 25-75% for asthma consideration
if the FEV-1/FVC ratio is normal or increased, what does the patient likely have?
possibly a restrictive disorder
If a patients FEV-1 increases by 12% and 200 ml after bronchodilator, this is suggestive of what
- hyperactive, reversible airways
If a patients FEV-1 remains below 0.7 after bronchodilator, this is suggestive of what
COPD
a normal or increased DLCO is indicative of
asthma
a decreased DLCO is indicative of
COPD
define asthma
- chronic airway inflammation
- intermittent and reversible airway obstruction
- bronchial hyper-responsiveness
what are the hallmark symptoms of asthma
- wheezing**
- coughing
- nocturnal
80% of patients with asthma develop symptoms by what age
5 yo
risk factors of asthma
- atopy
- med intolerance (ASA/NSAID)
- food allergies
- GERD
- RSV
- +FMH
- maternal smoking
- obestiy
what history questions should you ask a patient with a known h/o asthma
- medications?
- last use of inhaler
- how often is inhaler needed
- number of ED visits in last month-year
- any hospitalization needed (intubation?)
patients with asthma typically wheeze during what phase
prolonged expiratory phase
- may also be heard during inspiration
what are signs of severe asthmatic obstruction
- tachypnea
- tachycardia
- tripod posturing
- accessory muscle use
- pulsus paradoxus
What is the ASA Triad/Samter’s Triad
- nasal polyps, ASA intolerance, severe asthma
- life threatening reaction to ASA
- may be associated with chronic rhinosinusitis
What is the atopic triad
- allergic rhinitis
- atopic dermatitis
- asthma
Spirometry helps confirm diagnosis of asthma, but at what age is it recommended to start using this test
> 5 yo
What is needed to diagnose asthma
- FEV1 < 80%
- FEV1/FVC: normal or decreased relative to predicted values
- reversibility > 12% (>8% in young children) and 200mL in FEV1 with bronchodilator
What parameters are needed to diagnose a patient with intermittent asthma
- # symptoms
- nightime awakenings
- PFT
- FEV1
- FEV1/FVC
- activity level
- how often SABA is used
- Sx < or = 2 days/week
- nighttime awakenings
- ages < 4yo: none
- ages > 5yo: < or = 2 nights/month
- normal PFTs in between exacerbation
- FEV1>80%
- FEV1/FVC normal (>85% ages 5-19)
- normal activity
- < or = 2 days/week SABA use to control sx
What parameters are needed to diagnose a patient with mild persistent asthma
- # symptoms
- nightime awakenings
- FEV1
- FEV1/FVC
- activity level
- how often SABA is used to control sx
- # symptoms: > 2 days/week but not daily
- nightime awakenings
- ages < 4 yo: 1-2 nights/month
- ages > 5 yo: 3-4 nights/month
- FEV1 >80%
- FEV1/FVC normal (>80% ages 5-19%)
- activity level: minor limitation
- how often SABA is used to control sx: > 2 days/week (not daily)
What parameters are needed to diagnose a patient with moderate persistent asthma
- # symptoms
- nightime awakenings
- FEV1
- FEV1/FVC
- activity level
- how often SABA is used to control sx
- # symptoms: daily
- nightime awakenings
- ages < 4 yo: 3-4x/month
- ages > 5 yo: >1x/week (not nightly)
- FEV1: 60-80%
- FEV1/FVC reduced by 5%
- activity level: some limitations
- how often SABA is used to control sx: daily
What parameters are needed to diagnose a patient with severe persistent asthma
- # symptoms
- nightime awakenings
- FEV1
- FEV1/FVC
- activity level
- how often SABA is used to control sx
- # symptoms: throughout the day
- nightime awakenings
- ages < 4 yo > 1x/week
- ages > 5 yo: nightly
- FEV1 < 60%
- FEV1/FVC reduced by 5%
- activity level: extremely limited physical activity
- how often SABA is used to control sx: several times a day
SABA
inhaled short acting beta 2 agonist
LABA
long acting beta 2 agonist
ICS
inhaled corticosteroid
LTRA
leukotriene receptor antagonist
treatment of Intermittent asthma
SABA prn
treatment of mild persistent asthma
- SABA prn
- low dose ICS daily
- OR: LTRA or Cromolyn
treatment of moderate persistent asthma
- refer to specialist
- SABA prn
- medium dose ICS (all ages)
- OR low dose ICS + LTRA or LABA (ages > 5)
treatment of severe persistent asthma
- SABA prn
- medium dose ICS and LABA OR LTRA in ages < 4yo
What are other treatment options to try if patient with severe persistent asthma is not controlled
- high dose ICS and LABA or LTRA in ages < 11 yo
- high dose ICS and LABA and oral steroids
- use LTRA instead of LABA in patients < 4 yo
What are other treatment option can you add if patient is over 12 yo with severe persistent asthma and allergies
Omalizumab (Xolair)
what is the appropriate follow up time with asthma patients
- initially 1-3 months then every 3-12 months depending on severity
what is the rules of two
- do you have asthma symptoms more than 2x/week
- do you awaken with asthma symptoms more than 2x/month
- do you refill your quick relief inhaler canister more than 2x/year
- does your peak flow meter measure < 20% from baseline
- if yes, then asthma is not under control
PEFR
peak expiratory flow rate
what do the colors signify in the peak flow meter
- green: > 80%: good control
- yellow: 50-80%: caution- SABA and med change
- red: < 50%: medical alert -ED
what is the treatment for asthma exacerbation
- O2
- SABA/SVN (nebulizer): albuterol or xopenex +/- Ipratropium bromide
- systemic corticosteroids: prednisone 1 mg/kg/day
- f/u within 1 week
