Overview
Lecture covers asthma definition, triggers, presentation, diagnosis, classification, stepwise treatment, monitoring, and medication side effects.
Definition and Pathophysiology
- Asthma: chronic inflammatory respiratory disease with reversible airflow obstruction.
- Key features: episodic obstruction, bronchial hyperresponsiveness, and bronchial inflammation.
- Bronchioles in asthma: constricted, reddened, inflamed; episodes are reversible.
Triggers and Types
- Extrinsic (allergic): allergens like pollens, dust mites, pets, floor dust; atopy and family history; good prognosis.
- Intrinsic (non-allergic): viral infections (especially children), cold air exposure.
- Medication triggers: beta blockers (block beta-2), NSAIDs (increase leukotrienes).
- GERD association: asthma patients thrice more likely; reflux irritates airways.
- Second-hand smoke: childhood exposure raises asthma risk.
Clinical Presentation
- Symptoms with exposure: persistent dry cough, dyspnea, chest tightness, expiratory wheeze.
- Obstructive pattern: difficulty expelling air, air trapping, hyperresonant lungs.
- Episodic nature: normal baseline between exacerbations.
Diagnosis
- Age ≥5 years: typical symptoms plus reversible bronchoconstriction evidence.
- Spirometry (PFTs): decreased FEV1 and decreased FEV1/FVC ratio during attack.
- Normal between attacks: consider bronchial provocation if suspicion remains.
Bronchial Provocation Tests
- Agents: methacholine challenge; detect ≥20% FEV1 decrease as diagnostic.
- Risks: potential to trigger severe bronchoconstriction/status asthmaticus; less used clinically.
- Alternative: exercise in cold air to reveal reversible obstruction on spirometry.
Distinguishing Asthma vs COPD
- COPD: persistent baseline obstruction with exacerbations.
- Asthma: normal baseline with episodic symptoms.
- Bronchodilator reversibility: albuterol 200–400 mcg improves FEV1 by >12% in asthma; little change in COPD.
Classification and Severity Criteria
- Categories: intermittent; persistent (mild, moderate, severe).
- Based on symptom frequency, nighttime awakenings, activity limitation, spirometry.
Asthma Severity Summary
| Category | Symptoms Frequency | Night Awakenings | Activity Limitation | FEV1 (% predicted) |
|---|
| Intermittent | <2 days/week | ≤2/month | None | ≥80% |
| Mild Persistent | >2 days/week | 3–4/month | Minor | ≥80% |
| Moderate Persistent | Daily | >1/week | Some | 60–80% |
| Severe Persistent | Throughout the day | Nightly | Extreme | <60% |
Treatment: Stepwise Approach
- Two components targeted: bronchoconstriction (beta-agonists) and inflammation (steroids).
Intermittent Asthma
- Rescue only: SABA inhaler (e.g., albuterol 90 mcg/puff), 2–4 puffs as needed.
- Inhaler technique: shake, full exhale, seal lips, inhale while actuating, hold 10 seconds.
- Daily therapy: generally not required; 2020 GINA suggests considering low-dose ICS.
Mild Persistent Asthma
- Daily: low-dose inhaled corticosteroid (e.g., budesonide, fluticasone).
- Alternatives: leukotriene receptor antagonists (montelukast, zafirlukast).
- Rescue: SABA for exacerbations.
Moderate Persistent Asthma
- Daily: low-dose ICS plus formoterol (LABA) in single inhaler preferred.
- Use same ICS-formoterol for maintenance and as-needed rescue (SMART approach).
- Alternatives: ICS + other LABA; ICS + LAMA; ICS + LTRA; add SABA if not using ICS-formoterol rescue.
- Note: LABAs are never used alone; always combined with ICS.
Severe Persistent Asthma
- Daily: ICS + LABA + LAMA (e.g., ICS with formoterol and tiotropium-like agent).
- Rescue: SABA for attacks if not using ICS-formoterol as reliever.
- If uncontrolled: add oral corticosteroids due to severe inflammation and disability.
General Management Measures
- Medication review: avoid beta blockers and NSAIDs in asthma patients.
- Allergen avoidance: use impermeable pillow covers and bedsheets; avoid known triggers.
- Treat comorbidities: GERD with proton pump inhibitors when present.
- Smoking cessation: essential; strongest first-line counseling.
- Peak flow monitoring: teach use to track airflow and response to inhalers.
- Inhaler technique: assess and teach; use spacer if technique is inadequate.
Follow-Up and Adjustment
- Reassess 2–4 weeks after initiating therapy.
- Monitor: symptom frequency, exacerbation rate, PFTs for improvement.
- Step-down: consider after a stable period with good control.
- Poor response: verify adherence and inhaler technique before stepping up therapy.
Key Terms & Definitions
- FEV1: forced expiratory volume in first second; reduced in obstruction.
- FVC: forced vital capacity; used to compute FEV1/FVC ratio.
- SABA: short-acting beta-agonist; rapid bronchodilator rescue.
- LABA: long-acting beta-agonist; maintenance; never monotherapy in asthma.
- ICS: inhaled corticosteroid; reduces airway inflammation.
- LAMA: long-acting muscarinic antagonist; blocks parasympathetic bronchoconstriction.
- LTRA: leukotriene receptor antagonist; counters leukotriene-mediated constriction.
- Bronchodilator reversibility: >12% FEV1 increase post-albuterol suggests asthma.
- Methacholine challenge: provocation test; ≥20% FEV1 fall indicates hyperresponsiveness.
Medication Side Effects
- Inhaled corticosteroids: oral candidiasis; advise mouth rinsing after use.
- SABAs: tremor; typically mild.
- Oral corticosteroids: diabetes, cataracts, osteoporosis, adrenal suppression; reserve for severe cases.
Action Items / Next Steps
- Educate patients on trigger avoidance, inhaler technique, and peak flow use.
- Review medications for contraindicated agents and adjust as needed.
- Schedule follow-up in 2–4 weeks to reassess control and adjust therapy.
- Verify adherence and technique prior to any step-up in therapy.