Lung Diseases and Airflow Mechanics

Airflow in Healthy Lungs

• Inhaled air travels through the pharynx, trachea, bronchi, bronchioles, and ultimately reaches the alveoli.
• Alveoli are the primary sites for gas exchange.

Obstructive Lung Disease

• Characterized by reduced gas exchange due to impaired airflow in and out of the alveoli.
• Conditions causing obstruction include:
  • Asthma
  • Bronchiectasis
  • Chronic Bronchitis
  • Emphysema
  • Foreign Body Obstruction

Restrictive Lung Disease

• Results in limited airflow as the lungs cannot expand fully.
• Common causes include:
  • Pulmonary stiffness or muscle rigidity
  • Pneumonia
  • Pleurisy
  • Pleural Effusion
  • Pneumothorax
  • Respiratory depression from CNS issues
  • Acute Respiratory Distress Syndrome (ARDS)
  • Sudden Infant Death Syndrome (SIDS)

Asthma

• Involves chronic airway inflammation leading to hyperresponsiveness, mucosal edema, and increased mucus production.
• Initially reversible, can progress to irreversible with worsening pathology.
• Predisposing factors include atopy and female gender.
• Causal factors involve exposure to allergens and occupational sensitizers.

Contributing Factors of Asthma

• Respiratory infections
• Air pollution
• Active and passive smoking
• Other factors: diet, small birth size

Risk Factors for Asthma Exacerbations

• Allergens
• Respiratory infections
• Exercise and hyperventilation
• Weather changes
• Sulfur dioxide exposure
• Food or medication sensitivities

Symptoms of Asthma

• Wheezing
• Coughing, with or without mucus
• Dyspnea (difficulty breathing)
• Chest tightness

Inflammatory Response in Asthma

• Mast cells release mediators like histamine and leukotrienes, perpetuating inflammation.
• Results in increased blood flow, vasoconstriction, fluid leakage, increased mucous secretion, and bronchoconstriction.

Clinical Manifestations of Asthma

• Symptoms may worsen progressively or occur abruptly.
• Notable symptoms include:
  • Cough
  • Dyspnea from constricted airways
  • Wheezing during expiration, potentially progressing to inspiration
  • Tachycardia
  • Diaphoresis
  • Cyanosis indicates hypoxemia (late sign).
  • Status Asthmaticus represents a life-threatening condition.

Diagnostics for Asthma

• Medical history and physical examination focusing on familial and environmental factors.
• Laboratory tests may reveal:
  • Eosinophilia during acute episodes
  • Elevated serum IgE with allergic triggers
  • Arterial blood gas analysis indicating hypocapnia from rapid breathing, leading to respiratory alkalosis.
  • Pulse oximetry may show decreased oxygen saturation.

Medical Management of Asthma

• Administering oxygen for hypoxia.
• Monitoring blood gases during severe attacks to prevent acidosis.
• Pulse oximetry for acutely ill patients.
• Treating underlying allergic reactions.
• Using smooth muscle relaxants and steroids (inhaled/systemic).
• Spirometry for assessing treatment efficacy.

Pharmacologic Management of Asthma

• Short-acting beta2-adrenergic agonists (SABA): e.g., albuterol; they relax smooth muscles.
  • Dosage:
    • Nebulized: 2.5 – 5 mg every 20 minutes for 3 doses.
    • MDI: 4 – 6 puffs every 20 minutes for 3 doses.
• Anticholinergics: Inhibit muscarinic receptors to reduce vagal tone in the airways; e.g., Ipratropium.

This quiz covers the anatomy of healthy lungs and the pathophysiology of obstructive and restrictive lung diseases. It focuses on conditions such as asthma, chronic bronchitis, and pulmonary restrictions that affect airflow and gas exchange. Test your knowledge on these critical respiratory topics!