Respiratory Illnesses Flashcards
What is Asthma?
Inflammatory disease of the airways causing recurrent and variable airflow limitations which makes breathing difficult
- Trigger coughing and wheezing when breathing out and shortness of breath
- Bronchospasm can occur secondary to inflammation
What are the risk factors of asthma?
Can be a genetic component with >20 genes identified as linked to asthma, however, there typically needs to be a trigger to cause symptoms: allergens (pollen, dust mites, food, pets), drugs (beta-blockers and NSAIDs, aspirin and indomethacin), respiratory infections, exercise, emotional factors, and hormonal changes
What is the pathophysiology of Asthma?
The triad of effects associated with asthma include inflammation, bronchoconstriction and excess mucus secretion. Exposure to a trigger can lead to inflammation and a hyperactive airway
• Inflammation increases inflammatory cells (eosinophils, mast cells, neutrophils, T lymphocytes) in the bronchi = release inflammatory mediators (histamine, leukotrienes, enzymes) = further exacerbates the problem and may cause bronchoconstriction (typically short-lived and reversible in acute cases, however, can fatal) • The inflammatory process triggers hypersecretion of mucus = block the airways = cause swelling of mucosa due to inflammation associated with vascular leakage and oedema = increased WOB, decreased ventilation and impaired gas exchange *In chronic severe asthma, there is remodelling of the airways to increase bronchial smooth muscle content = irreversibly narrow airway = limits the effectiveness of treatment
What are the types of triggers for asthma?
• Intrinsic: trigger for asthma may be intrinsic/ non-atopic (no external cause can be identified) = non-immune mechanisms and typically appear in adulthood and may not improve - Triggered by emotional factors, hormonal changes, exercise, respiratory infections, drugs (aspirin, indomethacin), occupational exposure (20% of working population) including isocyanates (present in industrial and polyurethane coatings) and fumes (welding or soldering) • Extrinsic: trigger for asthma may be extrinsic/ atopic (identified though IgE mediated reaction of mast cells) Primary mediator (histamine) or secondary mediators (leukotrienes, prostaglandin D2(PGD2)) are released in response to an outside trigger - exposure to dust mites, pollen or pet dander = increase in vascular permeability and thus increased mucous secretions & bronchoconstriction
What are the morphological changes associated with bronchoconstriction? (4)
hyperinflation of the lungs, air trapping and mucus plugs= histological changes:
• Thickening of the basement membrane of the bronchial epithelium
• Inflammatory infiltration of the bronchial wall (oedema)
• Increased mucosal glands
• Hypertrophy of the bronchial smooth muscle (in the case of chronic asthma)
How do you diagnose Asthma?
based on patient history, physical examination, laboratory findings, pulmonary function tests (spirometry) and radiology
• Spirometry: measures ventilation of air exchanged in breathing - most likely reflect a decreased expiratory flow rate and forced expiratory volume
• ABG: moderate or severe cases of asthma = hypoxaemia
Chest X-rays: utilised to rule out other causes (e.g. pneumonia)
What is the pharmacological treatment for acute Asthma?
What are the pharmacological treatments for asthma aimed at and based on?
treated with drugs that reverse bronchoconstriction (inhaled bronchodilators) and relieve inflammation. May also require oxygen or oral corticosteroids
aimed at eliminating the causative agent and based on the severity of the asthma
What is the pharmacological treatment for chronic Asthma?
best treatment is prevention and to avoid known allergens/ triggers. Inhaled anti-inflammatory agents like corticosteroids:
• Long acting β2-agonists and ipratropium used to control persistent bronchospasm
• leukotriene receptor antagonists (montelukast and zafirlukast)
*Leukotrienes inflammatory mediators (LTC4, LTD4, LTE3) are associated with causing mucus secretion, airway wall oedema and bronchospasm
Define mild, moderate and severe asthma
Worsening of asthma control - just outside normal range for the individual:
More symptoms than usual, needing a reliever more than usual, waking up with asthma, asthma is interfering with usual activities
Tx:
• β2-agonist (salbutamol) is used as a reusable inhalant.
• Short course of inhaled corticosteroids may be appropriate
Events that are troublesome or distressing to the patient - require a change in tx;
not life-threatening;
do not require hospitalisation
More symptoms than usual, increasing difficulty breathing, waking often at night with asthma symptoms
Tx: • Oxygen therapy may be required
• Salbutamol (5-10 mg; 8 puffs every 15 min for 3 doses)
Used initially with corticosteroids (50 mg oral prednisolone, 250 mg hydrocortisone) and then reviewed one hour after last dose
Require urgent action by the patient (or carers) and health professionals to prevent a serious outcome (hospitalisation or death)
Needing reliever again within 3 hours, difficulty with normal
Tx:
• Oxygen is required to maintain SpO2at >92%
• Continuous β2-agonists administered IV and corticosteroids/ipratropium
• Asthmaticus (asthma attacks follow one another without pause)intubation required
What is COPD?
COPD is an umbrella term for two pathological lung conditions that cause chronic and recurrent airflow obstruction: chronic bronchitis and emphysema
What is chronic bronchitis?
lining of the airways is constantly inflamed = lining to swell and produce more mucus making it hard to breathe
*clinical diagnosis that requires the presence of a chronic cough with sputum production for three months per year for at least two consecutive years
What is emphysema?
Pathological, permanent dilation of the respiratory bronchioles, alveolar ducts, and alveolar sacs - due to the destruction of the walls of the airways without fibrotic changes = disrupting gas exchange
*Clinical diagnosis characterised by the abnormal, permanent enlargement of the airspaces with alveolar wall destruction
What is the most common cause of COPD and other risk factors?
smoking; Expiratory airflow normally decreases with age, however, cigarette smoking accelerates this decline. Other risk factors and causes include genetic/hereditary (deficiency in α1-antitrypsin), occupational/environmental exposure (organic/inorganic dusts, gases, pollution), passive smoking and infections
What is the pathophysiology of chronic bronchitis?
• Inspired irritants/triggers (smoking/recurrent infections) increase mucus production and increase the size and number of mucous glands and goblet cells = sticky mucus makes it easy for bacteria to adhere and rapidly multiply in the airway secretion • Ciliary function is impaired = pulmonary infection and injury = inflammation Persistent inflammation and oedema = bronchospasm, permanent narrowing of the airways, gas trapping = V/Q mismatch, hypoventilation, increased in PaCO2and hypoxemia
What are the clinical manifestations of chronic bronchitis?
• “blue bloater” - cyanosis: bluish colour of the lips and skin seen in patients who are ≥50 years - decrease in the amount of O2reaching the blood
• Ankles and legs may be swollen, distention of the neck veins, and the patient exhibits wheezing, dyspnoea, productive cough (smoker’s cough) and frequent pulmonary infections
Airway obstruction and decreased forced expiratory volume (FEV) accompanies a decrease in alveolar (minute) ventilation and a rise in PaCO2which may lead to hypoxemia, polycythaemia and cor pulmonale
