In-depth Study Notes on Asthma

ASTHMA DESCRIPTION

  • Definition: Chronic, episodic, obstructive, reactive, inflammatory respiratory disorder characterized by difficulty in expelling air.
    • Reversible condition.
  • Key Features:
    1. Bronchial airway hyperreactivity: Caused by triggers leading to bronchospasm and inflammation.
    2. Bronchospasm: Results in reversible airway obstruction.
    3. Bronchial inflammation: Causes swelling, edema, and increased mucus production.

TRIGGERS/ALLERGENS

  1. Environmental Factors:
    • Pet dander, dust.
  2. Physiological Factors:
    • GERD, hormonal changes, stress, exercise.
  3. Medications:
    • Acetylsalicylic acid, beta blockers, NSAIDs.
  4. Occupational Exposure:
    • Chemicals, aerosols, perfumes, cleaners.
  5. Food Additives:
    • MSG, food coloring.
  6. Comorbidities:
    • Obesity, viral infections.

PATHOPHYSIOLOGY

  • Mechanism of Asthma:
    • Trachea and bronchi react aggressively to allergens (as detected by irritant receptors), leading to inflammation.
    • Consequences include:
    • Hypersecretion of mucus: Narrows airways.
    • Bronchospasm: Smooth muscle spasms and swelling narrow airways significantly.
    • Airway narrowing: Occurs due to mucus production, edema, and bronchial swelling.
    • During an asthma attack: Expiratory airflow decreases, resulting in gas trapping within the airways.

RISK FACTORS

  1. Genetics: Strongest risk factor; genetic predisposition to an IgE-mediated response to allergens.
  2. Family History: A family's history of asthma increases risk.
  3. Allergies: Existing allergies can predispose individuals.
  4. Antenatal Exposure: Exposure to tobacco smoke and pollution before birth is a risk factor.

SIGNS/SYMPTOMS

  • Variation in Symptoms: Symptoms may differ among individuals and can manifest spontaneously or triggered by various factors.
  • Nocturnal Symptoms: Conditions may worsen at night, known as nocturnal asthma.

Subjective Signs

  • Dyspnea (shortness of breath).
  • Chest tightness.
  • Dry cough (possibly sweaty).

Objective Signs

  • Vital Signs:
    • Tachycardia, tachypnea, high blood pressure, decreased pulse oximetry.
  • Inspection Findings:
    • Visible signs of dyspnea, use of accessory muscles for respiration, increased anteroposterior thoracic diameter (barrel-shaped chest), restlessness, confusion (altered mental status), cyanosis (late sign).
  • Auscultation Findings:
    • Expiratory wheezes, diminished breath sounds, prolonged exhalation.

CLOSED THROAT Mnemonic

  • C: Chest tightness
  • L: Long exhalation
  • O: Obstructed airway by mucus, edema, and bronchial swelling
  • S: Sounds wheezy
  • E: Expiratory wheezes
  • D: Diminished breath sounds
  • T: Tachycardia
  • H: Heavy sweating
  • O: Cyanosis noted
  • A: Altered mental status
  • T: Tachypnea

DIAGNOSIS

  1. Chest X-ray: May reveal hyperinflation and diaphragm flattening due to hyperinflation.
  2. Pulmonary Function Tests: Typically show decreased peak flow rates and forced expiratory volume in the first second (FEV1).
  3. Peak Flow Monitoring: Values <80% of personal best indicate need for action; <50% suggests severe exacerbation.
  4. Pulse Oximetry: May indicate decreased oxygen saturation.

TREATMENT/INTERVENTIONS

  1. Asthma Classification: Based on the frequency and severity of symptoms.
  2. Maintain Airway: Supplemental oxygen to keep spO2 > 92%.
  3. Vital Monitoring: Monitoring of pulse oximetry and vital signs.
  4. Nonpharmacologic Management:
    • Techniques such as relaxation and controlled breathing can reduce anxiety and improve breathing.
  5. Avoid Triggers: Identification and avoidance of known triggers is crucial.
  6. Allergy Shots: Recommended for those with persistent asthma who react to specific allergens.
  7. Medications: Following the stepwise approach based on classification of asthma:
    • Beta-2 Agonists: Albuterol nebulizer/inhaler; bronchodilates, may increase heart rate.
    • Anticholinergics: Ipratropium bromide (Atrovent) nebulizer; does not increase heart rate.
    • Corticosteroids: Can be inhaled, nebulized, or used orally to reduce inflammation.
    • Long-acting Anticholinergic: Tiotropium bromide (Spiriva) inhaler; helps relax smooth muscles.
    • Leukotriene Antagonists: Montelukast sodium (Singular) oral; reduces hyperreactivity of airways.