3 Pulmonary Function Tests And Asthma Flashcards
What are the three basic PFTs?
Airflow spirometry
Lung volumes
Diffusion Capacity of the Lungs for Carbon Monoxide (DLCO)
Preferred patient position during spirometry
Sitting (because less likelihood of syncope)
How do you perform spirometry?
Patient sits
Tight seal over mouthpiece must be maintained
Visualization may be provided for motivation (ie candles)
Coaching is encouragaed (pt ed is key - useless if they don’t do it right)
Repeat testing at least 3X
How do you determine Forced Vital Capacity (FVC)
Deep breath in (full inspiration)
Blow out air as fast as possible (forced expiration)
FVC = total volume of air with maximal effort
Why do we use Forced Expiratory Volume in first second (FEV1)
Most useful information for obstruction
The FEV1/FVC ratio defines severity of obstruction - assists in differentiating obstruction and restrictive disease
<0.7 = obstructive pattern (<5th percentile LLN)
What does FEF 25-75% mean?
Airflow measurement during middle half of forced expiration
No specific for small airway obstruction but may be an early indicator of disease
Why do we do bronchodilator testing with spirometry?
Reversibility testing - if FEV1 increases by 12% and 200 ml after bronchodilator
If positive - aids in diagnosis, provides Tx options, improves compliance
How is reversibility testing performed?
Nebulizer or inhaler
Technique needs to be monitored - 2-4 puffs (preferably with chamber), and hold inhaled meds in lungs for 5-10 sec
Spirometry completed 15 min after meds provided
3-8 rounds of testing and possibly repeated during flare
What is bronchoprovocation and how is it performed?
Methacholine Challenge Test
- Dilute solution of methacholine given via nebulizer
- Spirometry conducted at 30 and 90 seconds
- Concentration increases
Positive test: FEV1 decreases by 20% (may have false positive)
RISK - must be closely monitored
Volume of air within the lung after maximal inhalation
Total Lung Capacity (TLC)
TLC = VC + RV
Volume of air we breathe out following maximal inhalation
Vital Capacity (VC)
TLC = VC + RV
Volume of air remaining in the lungs following maximal exhalation
Residual Volume (RV)
TLC = VC + RV
Measurement of the ability of the lungs to transfer gas and saturate the hemoglobin (alveolar-capillary membrane)
Diffusion Capacity (DLCO)
Can be misleading if a person is anemic (false reduction) and must be adjusted for hemoglobin level
CO is used as a surrogate for oxygen transfer
Technique for measuring DLCO
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, higher levels are measured in exhaled gas
Obstructive disease is characterized by …
Airway narrowing —> limits airflow with EXPIRATION
Reduced airflow with HIGH lung volumes (air trapping)
Inspiration likely normal
PFT results with obstructive disease
TLC: \_\_\_\_\_\_\_ FVC: \_\_\_\_\_\_\_ RV: \_\_\_\_\_\_\_\_\_ FEV1: \_\_\_\_\_\_\_ FEV1/FVC: \_\_\_\_\_\_\_\_
TLC: Increased FVC: Normal RV: Increased FEV1: Decreased FEV1/FVC: Decreased
Restrictive disease is characterized by…
Reduction in lung volume and reduced lung expansion
INSPIRATION & EXPIRATION will overall look normal but flow and volume are significantly reduced
PFT results for restrictive disease
TLC: \_\_\_\_\_\_\_ FVC: \_\_\_\_\_\_\_ RV: \_\_\_\_\_\_\_\_\_ FEV1: \_\_\_\_\_\_\_ FEV1/FVC: \_\_\_\_\_\_\_\_
Everything decreased except the ratio
TLC: Decreased
FVC: Decreased
RV: Decreased
FEV1: Decreased
FEV1/FVC: Normal or increased
Examples of obstructive lung disease
Asthma Asthmatic bronchitis Bronchitis COPD CF Emphysema Upper Airway Obstruction
Examples of Restrictive lung disease
Pulmonary fibrosis Infectious Lung Disease Thoracic deformities Pleural effusion Tumors Neuromuscular diseases Obesity
5 steps to approaching PFT interpretation
- Examine the flow-volume curve
- Examine the FEV1 value
- Examine the FEV1/FVC ratio
- Examine the response to bronchodilator
- Examine the DLCO
What are we looking for when we examine the flow-volume curve?
Is it normal appearing?
Is the curve scooped out, indicating an obstructive pattern?
Is the slope increased/peaked, indicating a restrictive process?
FEV1<80% suggests…
Suggestive of obstructive disease but NOT diagnostic
Could also examine FEF 25-75% as it is more sensitive for detecting early airway obstruction
If TLC available, correlate with this measurement. If it is also increased by 15-20% predicted, this favors obstructive disease
FEV1/FVC ratio of ________ indicates obstructive disease
≤ 70% LLN
If the ratio is normal or increased, possibly a restrictive disorder
If FEV1 increases by 12% and 200 ml in response to a bronchodilator, it suggests…
Suggestive of hyper reactive, reversible airways
What is DLCO for?
Measures the ability of O2 to get to the blood and be transported
How often do we perform PFTs?
Assessment at diagnosis
After 3-6 months of controller treatment (is FEV1 improved?)
Periodic assessments at least every 1-2 years (may need to be more often if higher risk patients and in children)
How is Asthma defined?
Chronic airway inflammation
Intermittent and Reversible Airway Obstruction (may test normally if not acute)
Bronchial hyperresponsiveness
80% of asthma patients develop symptoms before….
Age 5
But often misdiagnosed
Symptoms of asthma
Coughing - NOCTURNAL, seasonal, response to specific exposures, duration longer than 3 weeks
Wheezing - hallmark symptom (may be heard with inspiration AND expiration)
Other Sx: CP, chest pressure, dyspnea, SOB
Important DDx for asthma
GERD - especially if patient experiences nighttime cough right after laying down
Asthma Sx are episodic and often associated with characteristic triggers, such as…
URI Exercise Weather Stress Irritant exposure (tobacco, pets, etc) Meds (BB, ASA, NSAIDs)
Risk factors for Asthma
Atopy Med intolerance (ASA/NSAID) Food allergies GERD (also a DDx) RSV (+) FMH Maternal smoking (prenatal and second hand exposure) Obesity
Physical exam findings in asthma
Increased AP diameter
Wheezing with PROLONGED EXPIRATORY PHASE - wheezing most commonly heard during forced expiratory phase but may also be heard during inspiration
Associated signs of rhinitis, sinusitis, conjuctivitis, URI, atopic dermatitis
Signs of severe obstruction: tachypnea, tachycardia, tripod positioning, accessory muscle use, pulses paradoxus
Aspirin-exacerbated respiratory disease is characterized by what triad?
Samter’s Triad
Sinus disease with nasal polyps
ASA sensitivity
Severe asthma
What should patients with ASA-exacerbated respiratory disease avoid?
NSAIDS
Alcohol (b/c 75% also have respiratory response to alcohol)
What is the atopic triad?
Atopic Dermatitis
Allergic Rhinitis
Asthma
Asthma DDx in infants and children
GERD**** Allergic rhinosinusitis URI CF Pertussis FB or mass RAD (reactive airway disease) CHD Laryngotracheomalacia Eosinophilic bronchitis
Asthma DDx in adolescents and adults
GERD COPD CHF PE Vocal Cord Dysfunction Obstructive sleep apnea Chronic upper airway syndrom (post nasal drip) Cough secondary to ACE inhibitor
Initial presentation of asthma
Hx, PE, and variable expiratory airflow limitation
Spirometry helps confirm Dx of asthma if >5 years of age
May need to be repeated on several occasions or during symptoms to confirm Dx
FEV1<80%
FEV1/FVC: Normal or decreased relative to predicted values (70-85%) (Note, it’s <70% for COPD)
Reversibility >12% (>8% in young children) in FEV1 with bronchodilator
Name the Asthma Step:
Sx ≤ 2 days/week
Nighttime awakenings:
Ages 0-4 - None
Ages ≥ 5 - ≤ 2 nights/month
Intermittent Asthma (Step 1)
Normal PFTs in between exacerbations
FEV1 >80%
FEV1/FVC normal (>85% ages 5-19)
Normal activity
≤ 2 days/week SABA use
Name the asthma step
Sx >2 days/week (not daily)
Nighttime awakening:
Ages 0-4: 1-2 nights/month
Ages ≥5: 3-4 nights/month
Mild Persistent Asthma (Step 2)
FEV1 > 80%
FEV1/FVC normal (>80% ages 5-19)
Minor limitation in activity
> 2 days/week of SABA use to control Sx (not daily)
Name the asthma step:
Daily Sx
Nighttime awakenings:
Ages 0-4: 3-4x/month
Ages ≥5: >1x/week (not nightly)
Moderate Persistent Asthma (Step 3)
FEV1 60-80%
FEV1/FVC reduced by 5%
Some activity limitations
Daily use of SABA
Name the asthma step:
Sx throughout the day
Nighttime awakenings:
Ages 0-4: >1x/week
Ages ≥5: Nightly
Severe Persistent Asthma
FEV1 <60%
FEV1/FVC reduced by >5%
Extremely limited physical activity
SABA used to control Sx several times daily
Different meds used to manage asthma
SABA: inhaled short acting ß2 agonist LABA: long activity ß2 agonist ICS: Inhaled corticosteroid LTRA: Leukotriene receptor antagonist - Montelukast (used in ages 0-4) Monoclonal Antibodies (Omalizumab or Benralizumab) Methylxanthines (Theophyline) Mast Cell Stabilizers Anticholinergics
Step 1 asthma treatment
SABA prn
Step 2 asthma treatment
Low dose ICS daily
(Or LTRA/Cromolyn in younger patients)
SABA prn
Step 3 Asthma treatment
Medium dose ICS OR
Low dose ICS + LABA (or LTRA if ≥ 5 years)
SABA prn
Refer to specialist
Step 4 asthma treatment
Medium dose ICS + LABA (or LTRA in 0-4 YO)
SABA PRN
Step 5 asthma treatment
High dose ICS + LABA
SABA PRN
Consider adding Omalizumab (Xolair) for ages ≥ 12
Step 6 asthma treatment
High dose ICS + LABA + oral steroids
SABA PRN
Consider adding Omalizumab (Xolair) for ages ≥ 12
Rule of Twos for determining if asthma is under control
Asthma Sx > 2x/week
Night Sx > 2x/month
Refill SABA > 2x/year
Peak flow meter measures less than 2 x 10 (20%) from baseline
How often do we follow up with asthma patients?
Initially 1-3 monthns then every 3-12 months depending on severity
Stats for well controlled asthma
Sx ≤ 2 days/week
Nighttime awakenings ≤ 1x/month for ages 0-11, ≤ 2x/month for ages ≥ 12
FEV1 >80%
FEV1/FVC >. 80%
Stats for not well controlled asthma
Sx ≥ 2 days/week
Nighttime awakenings >1x/month for ages 0-4, ≥ 2x/month for ages 5-11, 1-3x/week for ages ≥12
FEV1 60-80%
FEV1/FVC 75-80%
Stats for very poorly controlled asthma
Sx daily
Nighttime awakenings >1x/week for ages 0-4, ≥2x/week for ages 5-11, ≥4x/week for ages ≥ 12
FEV1: < 60%
FEV1/FVC < 75%
Signs of severe obstruction in asthma patients
Tachypnea Tachycardia Tripod positioning Accessory muscle use Pulses paradoxus
What are the different “zones” when using Peak Expiratory Flow Rate?
> 80% = Green (good control)
50-80% = Yellow (Caution - SABA and Med increase)
<50% = Red (Med alert - go to ED)
When should you go to the ER based on Peak Flow Meter?
If less than 50% (the red zone)
Other diagnostics considered in asthma
ABG - Respiratory alkalosis initially due to hyperventilation (if PaCO2 normal, consider patient getting tired/breathless)
CXR - only if ruling out infection or obstruction (may show hyperinflation)
Treatment for Asthma Exacerbation
O2
SABA/SVN (Albuterol or Xopenex +/- Ipratropium Bromide)
Systemic corticosteroids (Prenisolone 1mg/kg/day with max dosing based on weight)
Other possibilities:
• Abx PRN
• Respiratory monitoring if in ED or inpatient
• Severe may warrant C-PAP, BiPAP, or intubation
The main goal of asthma treatment?
Prevent persistent symptoms and asthma progression with appropriate medication management
Key patient ed points for asthma patients
Smoke free home
Regular bedding washing
No pets
Remove triggers if possible
Allergy testing and immunotherapy may be beneficial
Write out care plan with specific meds and routine follow up
Demonstrate appropriate technique for inhaled meds
