Asthma Flashcards
Etiopathogenesis of Bronchial asthma
Heterogenous disease
Characterized by:
- Chronic airflow inflammation that varies markedly both spontaneously and with treatment
Associated with airway hyperresponsiveness and airflow inflammation.
Cells:
- Mast cells
- Eosinophils
- T-cells
- Neutrophils
Measures how much air an individual can exhale during a forced breath during the first second
Forced Expiratory Volume in 1 second (FEV1)
Total amount of air exhaled during the FEV test
Forced vital capacity (FVC)
FEV1/FVC Ratio
(FEV1%)
- Normal: 75-80%
- Reduced: Obstructive diseases
- Asthma
- COPD
- May be normal or increased in Restrictive diseases
- Fibrosis
Individual’s maximum speed of expiration, measured by a peak flow meter
Peak Expiratory flow
Clinical Manifestations of Asthma
Typical symptoms: (worse at night or early morning and vary over time and intensity)
- dyspnea
- wheeze
- cough
- chest tightness
Symptoms usually demonstrates REVERSIBILITY AND VARIABILITY
Most frequent PE abnormality in Bronchial Asthma
Expiratory weheezing or rhonchi on ausculation
Asthma Phenotypes
- Allergic Asthma
- Non-Allergic Asthma
- Late-onset Asthma
- Asthma with fxed airflow limitation
- Asthma with obesity
Allergic asthma
- Most frequent
- Atopy
- Sputum examination
- eosinophilic airway inflammation
- Responds well to inhaled corticosteroids
Non-allergic asthma
- Sputum examination
- neutrophilic or paucigranulocytic airway inflammation
- Less responsive to ICS
Late-onset Asthma
- Common in women
- Adulthood
- Requires higher doses of ICS or are relatively refractory to ICS
Asthma with fixed airflow limitation
- Seen in patients with long standing asthma who develop fixed airflow limitation due to airway wall remodeling
Asthma with obesity
- Obesisty
- little eosinophilic inflamamtion
- prominent respiratory symptoms
Diagnostic Criteria for asthma
1. History of variable Respiratory symptoms
- Cough, dyspnea, Wheezing, chest tightness
- More than one respiratory symptom
- Occurs variably
- Worse at night or early morning
- Triggered by exercise, allergies, viral infections, laughter
2. Confirmed Variable Expiratory Airflow Limitation
- Documented excessive variability in lung function AND
- Documented Airflow limitation
- FEV1 low, FEV1/FVC reduced (0.75-0.80)
- The greater the variation, the more likely the Dx of asthma
Tests to Document Variable Expiratory Limitation
-
Positive bronchodilator Reversibility test
- Increase in FEV1 >12% and >200ml from baseline
- 10-15 mins after albuterol 200-400 mcg or equivalent
- Bronchodilator meds witheld
- >4 hours for SABA
- >12 hours for LABA
-
Excessive VAriability in PEF
- Average diurnal variability : >10%
- calculated from twice daily readings, average for over 2 weeks
- Day’s Highest - Day’s lowest / (mean of day’shighest and lowest PEF)
-
Increase in lung function after 4 weeks of anti-inflammatory treatment
- FEV1 >12% and >200ml from baseline after 4 weeks of treatment
-
Others
-
Positive Exercise test
- fall in FEV1 <10% and >200 ml from baseline
- (+) bronchial challenge test
- fall in FEV1 >20% with methacholine or histamine or >15% with hyperventilation, saline, mannitol
- Excessive variation in lung function between visits
-
Positive Exercise test
Assesing Asthma Symptom Control
Risk Factors for Poor Asthma Outcomes
Measure FEV1 start of treatment, after 306 months of controller treatment, then periodically
Presence of 1 or more increases the risk of exacerbations
-
Potentially Modifieble independent risk factors for exacerbations
- Uncontrolled asthma sx
- High SABA use
- Inadequate ICS
- Low FEV1 (<60%)
- Major psychological or socioeconomic problems
- Exposure: smokinh, allergen
- Comorbidities
- Sputum or blood eosinophilia
- elevated FENO
-
Others
- History of intubation or ICU admission for asthma
- >1 severe exacerbation per year
Goals of Asthma Therapy
- Minimal (ideally no) chronic symptoms, including nocturna sx
- Minimal exacerbations
- No emergency visits
- Minimally use of as required B2-agonist
- No limitations on activities
- PEF circadian variation <20%
- Normal PEF
- Minimal or no adverse effects from medications
Reliever Medications
- SABA
- SAMA
- Methylxanthines
SABA
Stimulate adenyly cyclase increasing cAMP levels -> bronchodilation
Rapid onset of bronchodilation and best use for symptom relief
- Salbutamol
- Procaterol
- terbutaline
- Albuterol
No effect on chronic inflammation
May cause tremors, palpitations, and mild hypokalemia
SAMA
Muscarinic receptor antagonists
Inhibits only the cholinergic reflex components and therby less effective than SABA
- Ipatropium
provide (+) benefits if with SABA
AE: dry mouth, urinary retention, glaucoma
Methylxanthines
Inhibit phosphodiesterase activity causing increase in cAMP levels and bronchodilation
- Theophylline
- Aminophylline
- Doxofylline
Nausea, vmiting, Headache(most common)
Controller Medications
Used for regular maintenance treatment
- ICS
- Systemic Steroids
- LABA
- LAMA
- Leukotriene modifying drugs
- Cromones
- Anti-IgE
Inhaled Steroids (ICS)
Most effective anti-inflmmatory agents for asthma control
Best route
- Beclomethasone
- Budesonide
- Fluticasone
AE: hoarseness/dysphonia and oral candidiasis. pneumonia
Systemic Steroids for BA
useful for treatment of acute exacerbations
- Prednisone
- Methylprednisone
- Hydrocortisone
AE: truncal obesity, bruisability, osteoporosis, DM, HPN, ulcers, proximal myopathy, depression, cataracts
LABA for Bronchial Asthma
Improve asthma control and reduce inflmmation when added to ICS, allowing lower doses of ICS to be given
Should not be given in the absence of LABA
- Formoterol
- rapid onset
- Salmeterol
- Bambuterol
- Vilanterol
- Indacaterol
- Olodaterol
LAMA for bronchial asthma
blocks acetylcholine’s effect on muscarinic receptors
- Tiotropium
For STEP 4
Leukotriene modifying drugs
Block leukotriene receptors or inhibit lipoxygenase
- Montelukast
- Zafirlukast
- Zileuton
Less effective than ICS
Add on therapy in those not controlled with low dose ICS
Indicated for aspirin or exercised induced asthma
Cromones
Inibit mast cell and sensory nerve activation
- Cromolyn sodium
- nedocromil sodium
very short duration of action needing frequent dosing
favorable safety profile
Daily Doses of ICS for Adults
Anti-IgE
inhibits IgE-mediated Reactions
- Omalizumab
Very expensive
Limited to patients with elevated serum IgE levels
Initial Controller?
- Symptoms or need for SABA <2x/month
- No waking due to asthma in the last month; and
- no risk factors for exacerbation; and
- No exacerbations in the last year
NO controller
Initial Controller?
- Infrequent symproms, but with >1 risk factors for exacerbation
- Sx or need for SABA 2x/month to 2x/week or wakes due to asthma >1x/month
- Sx or need for SABA >2x/week
LOW DOSE ICS
(Start with step 2)
Initial Controller?
- Troublesome symptoms most days; or
- Waking due to sx >1x/week
- Especially f with any risk factors for exacerbations
Moderate-High dose ICS or Low dose ICS/LABA
(step 3)
Initial Controller?
- Initial presentation is with severely uncontrolled asthma or
- Initial presenation with an acute exacerbation
Short-course oral corticosteroids and regular controller (high dose ICS or moderat dose ICS/LABA)
Stepwise management for Asthma
How many months after initial controller treatment befor reviewing response?
2-3 months or according ro urgency
Consider Stepping down
symptoms controlled for 3 months, low risk for exacerbations
Diagnostics of Asthma Exacerbations
Assessment for Severity of exaccerbations
Management of Acute Exacerbations Depending on setting
Assessing Asthma Severity
- Mild
- Well controlled with step 1 or step 2
- Moderate
- Controlled with step 3
- Severe ASthma
- requires Step 4 or Step 5
Disposition or Discharge Planning for Patients in asthma Exacerbations
- Clinical status and oxygenation should be reassessed fequently (titrate treatment as needed)
- Msaure lung function in all patients one hour after initial treatment
Sample Doses
- Salbutamol
- metered dose inhaler 100 mcg/ actuation
- Adult: 2 puffs then after 2 hours can add another 2 puffs
- Pedia: 2 puff (inhaler with spacer)
- Budesonide
- 200 mcg MDI
- Adult: 2 puffs OD
- Pedia: 1 puff OD
- Salmeterol
- 50 mcg MDI
- Adult: 1-2 times
- Pedia: 1
- Salmeterol + fluticasone
- 25mg/125mg
- Adult 2 puffs
Etiopathogenesis in exacerbations in asthma
- Represent an acute/subacute worsening o of symptoms and lung function from the usual status that may require a change in treatment (or “step-up”)
- May be the initial presentation of asthma
Examples of Systemic Steroids
- Prednisolone 50 mg OD PO
- Hydrocortisone 200 mg in divided doses (5-7 days)
Asthama-COPD Overlap (ACO)
- Describes aptients who have features of both asthma and COPD
- Referral to specialists for confirmation of diagnosis and mangement is recommended
- Outcomes for ACO are often worse than for asthma or COPD alone
