Asthma Flashcards
What is the airway pathology associated with asthma?
- Chronic inflammation **** the cornerstone
- Eventual airway remodeling and fibrosis d/t chronic inflammation
- Airway wall edema
- Mucus gland hypertrophy
- Mucus hypersecretion/plugging
- Smooth muscle hypertrophy
- Bronchoconstriction
- Airway hyperresponsiveness
What are the symptoms of asthma?
yspnea, wheezing, chest tightness, cough
Adult starts wheezing, what is your ddx?
COPD, asthma, vocal cord dysfunction
VCD is inspiratory. They can be discracted from it but it’s true pathology
Criteria for Dx of Asthma
- Presence of episodic sx of airflow obstruction / airway hyperresponsiveness
- Objective assessment - one of the following
- at least partially reversible w/SABA
- increase in FEV1, of > 12% from baseline
- increase in predicted FEV1, of > 10% points from baseline
- increase PEF of > 20% (or 60 l/min) from baseline
- Diurnal variation in PEF (measured 2x daily) of >10%
- at least partially reversible w/SABA
What is FEV1?
Forced Expiratory Volume in 1 second
What is FVC?
Forced Vital Capacity (total volume of full exhalation after full inhalation)
FEV1/FVC normal values for 20-39yo
80%
FEV1/FVC normal value for 40-59yo
75%
FEV1/FVC normal value for 60-80yo
70%
Mild (intermittent or persistent) asthma: what is their FEV1/FVC?
may be normal
Pts w/moderate persisten asthma: what is their FEV1/FVC?
5% less than normal
Severe persistent asthma: what is their FEV1/FVC?
>5% less than normal
Goals of chronic asthma mgmt
Reduction of impairment
Reduction of risk
How can impairment d/t chronic asthma be reduced?
- Minimizing intensity and frequency of symptoms
- _<_2 days/week SABA use
- _<_2 nights/month with symptoms
- Maintenance of normal activity
- Optimization of lung function
- Improved patient satisfaction
How can risk d/t chronic asthma be reduced?
- Prevention of exacerbations
- Preservation of lung function
- Tolerance of medications with minimal adverse effects
Characteristics of mild intermittent asthma
- Sx ≤ 2d/ wk
- Noct sx ≤ 2d/mo
- FEV1>80%, 0-1 exac/yr
Characteristics of mild persistent asthma
- Sx 3-6d/wk
- Noct sx 3-4d/mo
- FEV1>80%, _>_1 exac/yr
Characteristics of moderate persistent asthma
- Daily sx
- Noct sx >1d/wk
- FEV1>60%, _>_1 exac/yr
Characteristics of severe persistent asthma
- Constant sx
- Noct sx often nightly
- FEV1 ≤60%
- Frequent exacerbations
Initial Tx: mild intermittent
no daily meds
SABA prn
Initial tx: mild persistent asthma
Preferred: low-dose ICS
Alternative: Cromolyn, LTRA, Nedocromil, Theophyline
Initial Tx: Moderate persistent asthma
Preferred: Low-dose ICS + LABA OR Medium Dose ICS
Alternative: Low-dose ICS + either LTRA, Theophyline, or Zileuton
Initial Tx: Severe persistent asthma (step 4)
Preferred: Medium-dose ICS + LABA
Alternative: Medium-dose ICS + either LTRA, Theopyline, or Zileuton
Initial Tx: Severe persistent asthma (step 5)
Preferred: High-dose ICS + LABA
AND
Consider Omalizumab for pts who have allergies
What is Step 6 for asthma?
Preferred: High dose ICS + LABA + PO corticosteroid
AND
Consider Omalizumab for pts who have allergies
If a patient with asthma has coexisting allergic rhinitis, what is the recommended maintenance drug?
LTRA instead of ICS
How should exercise indduced bronchoconstriction / asthma be treated?
- Pretreat w/ SABA or MCS
- Beware of masking symptoms. Consider controller
- Warm up period in cold weather. Scarves, warm clothes.
How should asthma be managed during pregnancy?
- Albuterol = preferred bronchodilator
- ICS = preferred controller. Budesonide (Pulmacort) is preferred.
- No Singulaire
- Risk of poor control outweighs risk of med adverse effects
Metered Dose Inhalers (MDI): how to use
- Shake the inhaler well before use; remove cap
- Exhale away from inhaler
- Bring the inhaler to your mouth.
- Place it in your mouth between your teeth and close you mouth around it.
- Start to breathe in slowly.
- Press the top of you inhaler once and keep breathing in slowly until you have taken a full breath.
- Remove the inhaler from your mouth, and hold your breath for about 10 seconds, then breathe out.
Diskus (Dry powder inhaler): how to use
- Hold Diskus in palm of hand (sandwich)
- Push thumb grip until it clicks into place
- Slide lever away from you
- Place it in your mouth between your teeth and close you mouth around it.
- Start to breathe in deeply and rapidly.
- Remove the inhaler from your mouth, and hold your breath for about 10 seconds, then breathe out.
- Always check the number in the dose counter window to see how many doses are left
Twisthaler (Dry powder inhaler): how to use
- Twist white cap counter clockwise
- Exhale away from Twisthaler
- Hold horizontally
- Place it in your mouth between your teeth and close you mouth around it.
- Start to breathe in deeply and rapidly.
- Remove the inhaler from your mouth, and hold your breath for about 10 seconds, then breathe out.
- Replace cap and twist clockwise.
- Make sure it clicks to completely close it.
- Rinse mouth and gargle
Spacers: benefit
- Enhanced drug delivery, highly recommended with ICS for pediatrics
- Canister holds drug in place. Can inhale at own pace – good for pedi who may not have high lung capacity
What controller medications are available for asthma tx?
- Inhaled Corticosteroids
- Leukotriene receptor antagonists (montelukast)
- Long acting bronchodilators (b2-agonists)
- Mast cell stabilizers (cromolyn and nedocromil) more in pedi
- Methylxanthines (theophylline)
- Biologics (omalizumab, trial therapies) new frontier
What rescue meds are available for asthma tx?
- short acting bronchodilators (b2-agonists, antichol) preferentially SABA, sometimes antichols, sometimes combo
- corticosteroids: oral, IV
Benefits of ICS
- The cornerstone of “controller” therapy:
- Decrease inflammation
- Decrease AHR
- Reduce risk of exacerbations
- Reduce symptoms
- More effective than LTRA for most stages
When would you use an oral steroid with asthma?
acute exacerbation and severe dz
Side effects of ICS
- Inhaled: Thrush, dysphonia - thrush can be severe and refractory even to good technique
- Oral (or high ICS with frequent OCS): cataracts, adrenal suppression, hyperglycemia, osteoporosis, skin fragility
If refractory to other methods, but reserved d/t side effects
When are mast cell stabilizers used?
- Frequently used in children, less in adults:
- Seasonal, cold-induced sx
- Exercise induced asthma
- Mild to moderate anti-inflammatory effect
Not really used w/adults at all
Mast cell stabilizer MOA
- Prevents degranulation of mast cells
- ↓ release of pro-inflammatory cytokines
Side effects of mast cell stabilizers
- Mild throat irritation, cough
- Metallic taste
Mast cell stabilizers: agents
- Cromolyn sodium
- Nedocromil sodium
How do endogenous leukotrienes contribute to asthma?
- Product of the arachadonic acid metabolic pathway
- Potent proinflammatory effects: LTB4
- Potent bronchoconstrictor effects: LTC4, LTD4
- Increase mucus production while impeding mucociliary clearance
- Promote vascular permeability
- Receptors on respiratory mucosa, including nasal mucosa
How do leukotriene inhibitors work?
- Zileuton inhibits leukotriene production, while LTRAs (Montelukast, zafirlukast) inhibit receptors → mild bronchodilator/anti-inflammatory effects
Side effects of leukotriene inhibitors
-
mostly well tolerated
- Mildly elevated LFTs
- +/- Mild sedation (give in evening)
Main limiting factor of leukotrien inhibitors?
main limiting factor is not SEs, but whether accomplishes goal
How do beta 2 agonists work?
- Stimulate β2-adrenergic receptor –> smooth muscle bronchodilation
- Decreased sensitivity of β2 receptor with age
When do you use LABAs?
Only in combo with ICS!
many given combo first now - but you should start w/ICS to avoid risks, per speaker
Onset and duration of SABAs
rapid onset (minutes), 4-6h duration
Onset and duration of LABAs
variable onset (2-5min formoterol, >20min salmeterol), 12h duration
Side effects of beta agonists
- Common: Tachycardia, tremor, nervousness (β1 effect)
- Hypokalemia – if given very frequently, e.g., in acute setting
- Vasodilation: stimulation of β2-receptor on vascular smooth muscle
- mild hypoxia (pulmonary vasodilatation –> shunt)
- Hypotension
- Reflex tachycardia
- increased cardiac output
Methylxanthines (Theophylline): how does it work & why is it not often used?
-
good drug, works for many, but many issues w/it
- Multiple mechanisms (BD, anti-inflammatory, etc)
- Narrow therapeutic window – monitoring essential
- Multiple drug interactions
- High occurrence of side effects/toxicity
Anti-IgEs: what are the agents?
omalizumab (Xolair)
How do Anti-IgEs work?
- Monoclonal Ab blocking binding of IgE to receptors on mast cells and basophils – e.g., allergic to dust mites
- Injections every 2-4 wks, small risk of anaphylaxis
Who is at high risk for acute exacerbations of asthma?
- Prior ICU/intubation
- > 2 hospitalizations or >3 ED visits in past year
- High SABA use
- Poor symptom perception – don’t recognize until crisis point. PFMs at home can be helpful in training.
- Low SE status, urban residence
- Comorbid drug use, psychiatric disease, heart/lung disease
Characteristics of mild / moderate asthma exacerbation
- SOB with activity that may limit some normal activities
- Usually treated at home; may require UV or ED
- PEF>40% personal best
- Symptoms relieved temporarily with SABA use
Tx for mild / moderate exacerbation
- Frequent SABA
- Oral systemic steroids
- 40-60mg “bursts”
- 5-10 days
- <1wk course no need to taper – commonly taper but not necessary
- Should expect improvement in 24-48hrs
Characteristics of severe/life threatening exacerbation
- SOB at rest, unable to converse
- Requires hospitalization, possibly ICU
- PEF<40% personal best
- Incomplete improvement with SABA
Tx of severe/life threatening exacerbation
- Oral/IV steroids
- ~40-80mg/d equivalent
- Oral = IV if absorbed
- No data for higher doses – unless absorption problem
- Frequent SABA/SAMA, possibly continuous SABA
- IV Magnesium
- Heliox –inhaled helium & oxygen. Improves laminar flow through tight airway
- Careful ventilator management
Important co-morbidities in asthma (may lead to exacerbation)
- Rhinosinusitis (and consider evaluation for ABPA/AF disease)
- GERD - often missed
- Sleep disordered breathing
- Depression
- Anxiety
- Obesity
- Cardiac disease
Two important factors to monitor in deciding asthma therapy
severity
control
What must asthma Tx include
First line pharm therapy + constant education, prevention, trigger control, and co-morbid management to optimize care
