Asthma Facts Flashcards
How many Canadians have asthma?
8.4% (3.8 Million) Higher chance in children & females
How many asthmatics have their symptoms under control?
1/3
Asthma is:
A chronic condition
Recurring respiratory symptoms
Associated with chronic inflammation
Airway hyperresponsiveness that is normally reversable
What are the risk factors for hospitalization due to asthma?
- Hospital admission in the last 2 years
- > 8puffs of rescue medication in past 24hrs
- Lower socioeconomic status
What are some factors that affect QoL for asthmatic children?
- Sleeping difficulties
- Severity of attacks
- School absenteeism
What is the natural history of asthma?
Genetic disposition & Environmental exposure leads to TH2 cell response leading to Chronic inflammation & Airway remodeling that leads to Symptom Complex
What are the two main factors of transient wheeze in children less than 2?
RSV & Maternal smoking
How many URTI per year do children 5 and under get?
6-8
Asthmatic Airways
airway remodeling due to activation of the EMTU (epithelial-mesenchymal trophic unit) reduces responsiveness, increase in immune cells (mast cells, eosinophils, T-helper 2 cells)
Atopy
is the tendency to produce an exaggerated IgE immune response. (Allergic response)
Factors favouring TH1 phenotype
- Rural Environment
- Older Siblings
- Daycare
- TB, Measles, or Hep A infection
Factors favouring TH2 phenotype
- Antibiotic use
- Western lifestyle & diet
- Sensitization to house dust mites, cockroaches
- Urban environment
What is the hygiene hypothesis?
When we are born our immune system is skewed towards TH2 cytokine generation. With exposure to environmental stimuli such as infections, will activate TH1 to bring the relationship between them back to a balance. If children are not exposed to stimuli then it is thought that it promotes IgE antibodies (made from TH2 cells) to key allergens thus increasing the risk of asthma.
Prevalence of Asthma
As children males > females, as adults Females>Males
What happens with airway remodeling?
thickening of walls, increase smooth muscle mass, mucus hypersecretion leading to mucus plugs, increase # & size of blood vessels which can compress adjacent airways
- decreased response to treatment over time, occurs early in asthmatic airways, is the main reason why airway function may not be reversible over time.
Asthma & Eosinophils
Increased eosinophils in sputum, blood, bronchoalveolar lavage tissue and airway tissue
Asthma & Mast Cells
Increase mast cells = increased hyperresponsiveness
(mast cells release histamine, lukotrienes, prostaglandin D2) Roles in exercise induced asthma
Asthmas & Lymphocytes
Increase in T lymphocytes which releases cytokines which increases eosinophilic inflammation which increases IgE (produced by B lympocytes) which causes airway hyperresponsiveness
Inflammatory Mediators involved in athma
- Chemokines
- Cytokines
- Cysteinyl leukotrienes
- Histamine
- Nitric oxide
- Prostaglandin D2
What mediator, if inhibited will improve lung function and asthma symptoms?
Cysteinyl leukotrienes
What % of children who wheeze experience wheezing in adolescence?
60%
Aeroallergens that cause asthma are:
- Perennial Aeroallergens: Dander, urine, feces, saliva from animals, dust mites, cockroach, molds
- Seasonal Aeroallergens: <10um in size trees, grasses, weeds
- Smoke (Cig & Cannabis)
- Viruses (Rhinovirus, coronavirus, influenza, parainfluenza, RSV, Adenovirus & metapneumovirus
- Bacteria (S. pneumoniae, S. aures, M. catarrhalis,
H. influenzae/parainfluenzae
What is an aeroallergen?
Airborne substance that results in IgE mediated allergic response
What is an IgE mediated allergic response?
TH2 recruitment, Mast cell activation, eosinophil influx
What is an AQHI (Air Quality Health Index) of 1-3 mean?
Low-Good
What is an AQHI of 4-6 mean?
Moderate-Consider rescheduling
What is an AQHI of 7-10 mean?
High-Reschedule
What is an AQHI of 10+ mean?
Very High- Avoid
What are non allergic inhaled irritants?
smoke, strong odours (perfumes), particulates (chalk dust, talcum powder), fumes (cleaning products, paints etc), exhaust, ozone
What are the medications that can trigger asthma symptoms?
- ASA
- NSAIDS
- Beta Blockers
What % of adult asthmatics will have an acute worsening of asthma symptoms after ingesting NSAIDs?
5-10%
Occupational asthma…
Occurs primarily in adults
Causes 10-15% of asthma
Common in farming, painting, cleaning & plastic manufacturing
What is Rhinitis?
Inflammation of the mucous membrane inside the nose
What is rhinosinusitis?
Inflammation of the sinuses & nasal cavity
How does GERD affect asthma?
Airway responsiveness or aspiration-induced inflammation
How does asthma affect GERD?
Beta agonists & methylxanthines (theophylline) can impair function of the lower esophageal sphincter
What % of children with atopic dermatitis will develop allergic rhinitis and/or asthma?
40-60%
What is Exercise Induced Bronchoconstriction?
Narrowing of airways following vigorous exercise
What is the mechanism behind EIB?
increased RR leads to increase water loss leads to increased airway osmolarity that leads to mast cell degranulation that leads to release of inflammatory mediators (histamine etc) which results in bronchoconstriction
What % of the general population have EIB?
10%
What % of asthmatics have EIB?
90%
Diagnosis of EIB
FEV1 reduced by 10% or more from pre-exercise
What % of asthmatic women have worsening symptoms during menstration?
20-40%
Why does asthma have an effect on pregnancy?
Diaphragm rises 4 cm
Diameter of thoracic cage increases by 2 cm
Thoracic circumference increase by 6 cm
Reduced ERV & RV (Term 17-25% reduction in FRC)
20% increase in Oxygen consumption &15% increase is metabolic rate therefore 40-50% increase in MV
What is the occurrence of worsening asthma symptoms during pregnancy?
1/3 of pregnancies have worsening symptoms, 1/3 stay under control, 1/3 have less symptoms
What is work exacerbated asthma?
Asthma made worse by triggers at work
What is occupational asthma?
New asthma diagnosis induced at work
What is RADS?
Reactive airway dysfunction syndrome- acute onset of asthma after single high irritant exposure
Examples of work place asthma irritants
Platinum, isocyanates, chromium, cobalt
Asthma Symptoms
- Cough
- Wheeze
- SOB
- Reduced activity
- Past family hx
- Therapeutic trials with low does ICS
Asthma Physical Exam
Expiratory wheeze on auscultation, hyper-expansion of thorax, increase nasal secretions, nasal polyps, atopic dermatitis
Asthma Spirometry
Reversibility of obstruction shown by an improvement of FEV1 with bronchodilator by 12% and 200 mls
What is diurnal variation in PEF in Well Controlled Asthma?
<10-15%
What is diurnal variation in PEF in uncontrolled asthma?
8-10%
What is the green zone?
PEF 80-100% Reliever no more than 3 times per week Symptoms no more than 3 times per week Can do normal physical activity/sports Night asthma symptoms less than 1 night/week No missed work/school
What is the yellow zone?
PEF 60-80% Reliever more than 3 times per week Symptoms more than 3 times per week Physical activity is limited Night asthma symptoms more than 1 night/week
What is the red zone?
PEF <60% Reliever lasts 2-3 hours or less Continuous asthma symptoms Wheezing all the time Severe SOB "ASTHMA ATTACK"
What medication is used to treat allergic asthma?
ICS first then Omalizumab (Xolair) lowers IgE levels
What is indirect challenge testing?
Exercise or Cold air challenge
>10-15% decrease is FEV1 post exercise
What is a positive methacholine challenge test?
PC20 <4mg/mL
Dose of methacholine <4mg/mL induces a 20% reduction in FEV1
PC20 4-16 is borderline
PC20> 16mg/mL is negative
What is considered a positive skin prick test?
Wheal diameters > or = 3 mm
What does an Asthma Control Test result of > or = to 20 mean?
Well controlled asthma
ACT result of 16-15?
Not well controlled asthma
ACT result of < or equal to 15
Poorly controlled asthma
What does a ACQ-5 Questionnaire score below 0.75 mean?
Well controlled asthma
ACQ-5 score above 1.50
Inadequately controlled asthma
ACQ-5 score between 0.76-1.49
Indeterminate
What is a normal sputum eosinophil count?
Less than 2-3%
What is the Pediatric Respiratory Assessment Measure? (PRAM)
Assessment of acute severity
0-3 Mild 4-7 Moderate 8-12 severe
(uses o2 saturation, suprasternal retractions, air entry & wheezing)
What is the Pediatric Respiratory Assessment Measure? (PRAM)
Assessment of acute severity
0-3 Mild 4-7 Moderate 8-12 severe
(looks at o2 saturation, suprasternal retractions, air entry & wheezing)
What was the GOAL study?
Gaining Optimal Asthma Control study
What were the outcomes of the GOAL study ?
The study demonstrated ICS/LABA therapy is superior to ICS monotherapy for achieving control
Asthma Exacerbation Treatment
Oxygen, SABA, SAMA, Systemic steroids, ICS
Epinephrine & Theophiline, Magnesium sulfate IV (not routine)
Prednisone dosage for Asthma Exacerbation
Adult: 50 mg/day for 7 days
Child: 1 mg/kg for 3-5 days
What are the long term side effects of high does ICS?
Bruising, adrenal suppression, decreased bone density, increase risk of TB
What are side effects of OCS-prednisone?
Osteoporosis, arterial HTN, diabetes, bruising, muscle weakness, weight gain