PFT and Asthma Flashcards
Basic PFTs
- Airflow spirometry
- Lung Volumes
- Diffusion Capacity of the lungs for Carbon Monoxide (DLCO)
How many times should you do spirometry
repeat at least 3X
FVC
total volume of air expelled with maximal effort (full inspiration + blow air out as fast as possible)
Most useful value for obstruction
FEV1
FEV1/FVC ratio
determines obstructive vs. restrictive
<0.7 = OBSTRUCTIVE (<5th percentile LLN)
FEF 25-75%
forced expiratory flow;
airflow measurement during middle 1/2 of forced expiration
nonspecific for small airway obstruction but may be an early indicator of disease
Bronchodilator testing
2-4 puffs; hold med in lungs for 5-10 sec; spirometry completed 15 min after med provided
3-8 rouds of testing and possible repeated during flare
(+) bronchodilator test
FEV1 increases by 12% AND 200 mL
Bronchoprovocation (methacholine challenge)
- diluted methacholine given via nebulizer
- spirometry @ 30 and 90 seconds
- concentration increases
(+) bronchoprovocation test
FEV1 decreases by 20% (may have false positive)
***** closely monitor!
Quality of curves
volume-time curve plateaus
expiration > 6 sec
2 best efforts w/i 0.2L
flow volume loop free of artifact
obstructive curve
peaks the drops (expiration)
Restrictive curve
normal, but less volume (smaller)
TLC
volume of air in lungs after max inhalation
Vital capacity
volume of air we breathe out following max inhalation
Residual volume
volume of air remaining in lungs following max exhalation
TLC equation
TLC = RV + VC
DLCO test
used to measure ability of lungs to transfer gas and saturate Hgb (alveolar-capillary membrane)
False DLCO test
anemia (must be adjusted for Hgb level)
Results of DLCO
inhale helium/CO and expire:
- health lungs: little CO collected during exhalation
- diseased lungs, less CO diffuses into lungs, higher levels measures in exhaled gas
What is obstructive
airway narrowing
limits airflow w/ expiration
reduced airflow w/ high lung volumes
inspiration likely normal
Values for obstructive
TLC: increased FVC: Normal RV: increased FEV1: decreased FEV1/FVC: decreased
What is restrictive
reduction in LUNG VOLUME
reduced lung expansion
inspiration & expiration look normal but flow & volume are reduced
Values for restrictive
TLC: decreased FVC: decreased RV: decreased FEV1: Decreased FEV1/FVC: normal or increased
Obstructive disorders
asthma asthmatic bronchitis bronchitis COPD CF emphysema Upper airway obstruction
Restrictive disorders
pulmonary fibrosis infectious lung disease thoracic deformity PE tumor NM disease Obesity
increased slope
restrictivww
scooped out
obstructive
FEV1 examination
normal: r/o obstruction/restriction
dec. >15-20%: obstruction (FEV1 <80%)
- correlate w/ TLC: if this increases by 15-20% = favors obstructive
FEV1/FVC ratio determination
<70%: obstructive
70%-LLN: mild obstruction cannot be excluded (asthma?)
Normal or increased: restrictive
DLCO in asthma
increased
Frequency of lung function measurements
at diagnosis
after 3-6 mo of tx (FEV1)
periodically every 1-2 yrs
Definition of asthma
- chronic airway inflammation
- intermittent and reversible airway obstruction
- bronchial hyperresponsiveness
Sx of asthma
usually before 5 YO:
- coughing: NOCTURNAL, >3 weeks
- Wheezing*** (inspiration and expiration)
- CP, presure, dyspnea, SOB
Meds that trigger asthma sx
BB, ASA, NSAIDS
risk factors for asthma
atopy med intolerance (ASA/NSAID) food allergy GERD RSV \+FMH maternal smoking obesity
PE for asthma
increased AP diameter
wheezing w/ prolonged expiratory phase (most often expiratory)
associated signs of rhinitis, sinusitis, conjunctivitis, URI, atopic derm
Signs of severe asthma obstruction
tachy
tripod positioning
accessory mm. use
pulsus paradoxs
Aspirin-exacerbated respiratory disease (ASA Triad/Samter’s Triad)
nasal polyps
ASA sensitivity
severe asthma
Upper and lower respiratory rxns to ASA
avoid NSAIDs
75% have respiratory response to alcohol
Atopic Triad
allergic rhinitus
atopic dermatitis
asthma
Atopic March
allergic rhinitis
atopic dermatitis
asthma
food allergy
Dx of asthma
spirometry >5 YO (may need repeated):
- FEV1 <80%
- FEV1/FVC ratio: normal or decreased (70-85%)
- Reversibility: >12% and 200 mL w/ bronchodilator (>8% in young children)
Intermittent asthma (step 1)
sx <2 days/week
Nighttime awakening: age 0-4 - none; >5: <2 nights/month
normal PFTs in between exacerbation FEV1 >80% FEV1/FVC: normal (>85% ages 5-19) Normal activity <2 days/week SABA
Mild-persistent asthma (step 2)
sx >2 days/week
Nighttime: age 0-4: 1-2 nights/month; >5 yo: 3-4 nights/month
FEV1 >80%
FEV1/FVC: normal (>80%)
minor limitation in activity
> 2 days/week SABA (not daily)
Mod-persistent asthma (step 3)
daily symptoms
nighttime: age 0-4: 3-4x/month; >5: 1x/week (not nightly)
FEV1: 60-80%
FEV1/FVC reduced by 5%
some activity limitations
daily use of SABA
Severe persistent asthma (step 4)
Sx throughout the day
nighttime: 0-4: 1x/week; >5 yo: nightly
FEV1: <60%
FEV1/FVC reduced >5%
Extremely limitied activity
SABA several times a day
LTRA
leukotriene receptor antagonist (Montelukast)
Montelukast use
ages 0-4
Monoclonal antibodies
omalizumab (anti-IgG)
benralizumab (anti-IL5 receptor a)
Methlxanthine
theophyline
Tx for step 1
SABA PRN* (+/- ICS)
Tx for step 2
low dose ICS daily* OR
LTRA or cromolyn
(+ SABA)
Tx for step 3
refer to specialist
medium dose ICS* OR low dose ICS + LABA
Tx for step 4
medium dose ICS & LABA (or LTRA in 0-4 yo)
Tx for step 5
high dose ICS & LABA (or LTRA ages 0-11)
Tx for step 6
high dose ICS & LABA (or LTRA) & oral steorid
Consideration for steps 5 & 6
consider omalizumab (Xolair) for ages >!2 w/ allergies
Rule of 2’s to know if asthma is under control
sx >2x/week
awaken more than 2x/month
refill inhaler >2x/yr
does your peak flow meter measure < 2x10 (20%) from baseline?
F/u for asthma
initially 1-3 mo, then every 3-12 months depending on severity
Well controlled asthma
sx <2 days/week
awaken <1x/month (0-11 yo), or <2x/month (>12)
FEV1: >80%
FEV1/FVC: >80%
Dx for acute exacerbatiton
PEFR (peak expiratory flow rate)
Values for PEFR
> 80%: GREEN: good control
50-80%: YELLOW: caution - SABA & Med
<50%: RED: emergency dep.
ABG for acute exacerbation
respiratory alkalosis initially (hyperventilation) - if PaCO2 normal, considering patient getting tired/breathless
CXR for acute exacerbation
only if r/o infection or obstruction
may show hyperinflation
Tx for exacerbation
- O2
- SABA/SVN: albuterol or xopenex +/- itraptroium (repeat PEF) - SVN may be repeated or given continuous
- Systemic corticosteroid (prednisolone 1 mg/kg/day); abx PRN; respiratory monitoring; severe may warrant C-PAP, BiPAP, or intubation
- f/u in 1 week
