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What is asthma?
Asthma is an inflammatory disorder of the airways characterized by symptoms such as airflow obstruction, dyspnea, chest tightness, wheezing, sputum production, and cough associated with variable degrees of airway hyperresponsiveness to endogenous or exogenous stimuli.
Pathology of Asthma
Asthma involves inflammation of the airways and can be induced by allergens, chemical sensitizers, air pollution, viruses, and occupational exposures. It is characterized by airway hyperresponsiveness, airflow limitation, and symptoms such as cough, wheeze, chest tightness, and dyspnea.
Mechanisms of Asthma Inflammation
Asthma inflammation can be categorized into atopic asthma (IgE-mediated hypersensitivity), non-atopic asthma (no allergen sensitization), drug-induced asthma (sensitivity to certain drugs), occupational asthma (stimulants such as fumes, organic and chemical dusts), and exercise-induced asthma (worsening after exercise, especially in cold and dry climate).
Asthma Clinic Presentation
Clinically, bronchial asthma presents as mild intermittent asthma (responsive to bronchodilators and precipitating factors), chronic persistent asthma (due to inflammation with persistent dyspnea), severe acute asthma (does not respond to routine treatment), and exercise-induced asthma (precipitated by exercise and worsened in cold, dry climate).
Symptoms of Asthma
Symptoms of asthma include frequent episodes of breathlessness, chest tightness, wheezing, or cough, which may worsen at night, early morning, after exercise, or exposure to allergens or irritants. They improve with bronchodilators or corticosteroids.
Risk Factors for Asthma
Risk factors associated with the development of asthma include predisposing factors such as atopy, genetics, and gender, causal factors such as indoor and outdoor allergens, contributing factors such as air pollution, diet, low birth weight, respiratory infections, and smoking.
Diagnosis of Asthma
Asthma diagnosis is based on reversible airway obstruction after bronchodilator, variable airflow limitation over time, and airway hyperresponsiveness. Assessing allergic status involves breathing tests such as spirometry to test lung volumes and airflow.
Allergens
Substances that cause allergic reactions.
Occupational Sensitizers
Substances in the workplace that trigger allergies or asthma symptoms.
Outdoor Allergens
Allergens found outside, such as pollen and mold spores.
Contributing Factors
Factors that can worsen asthma, such as air pollution, diet, low birth weight, respiratory infections, and smoking.
How to Diagnose Asthma
Diagnosis based on reversible airway obstruction after bronchodilator, variable airflow limitation over time, and airway hyperresponsiveness.
Assessing Allergic Status
Involves breathing tests, spirometry testing lung volumes, peak flow monitoring, and assessing exposure to allergens like house dust mites, tobacco smoke, cockroaches, pets, mold, air pollution, trees, grass, and weed pollen.
How to Avoid Asthma Triggers
1. Reduce exposure to house dust mites 2. Reduce exposure to environmental tobacco smoke 3. Reduce exposure to cockroaches 4. Reduce exposure to pets 5. Reduce exposure to mold 6. Avoid air pollution 7. Minimize exposure to trees, grass, and weed pollen.
Asthma Management
Includes the use of drugs like short-acting β2 agonists, long-acting β2 agonists, systemic glucocorticosteroids, methylxanthines, anticholinergics, mast cell stabilizers, and leukotriene receptor antagonists.
Salbutamol Indications
Used for bronchospasm in bronchial asthma and chronic bronchitis. Also used for prophylaxis in bronchial asthma and reversible airways obstruction, often combined with bromhexine for mucus plugging.
Salbutamol Contraindications
Should not be used for labor induction, threatened abortion during the first or second trimester of pregnancy, and in cases of hypersensitivity.
Salbutamol Pharmacokinetics
Onset of action: 30 minutes orally, 5 minutes by inhalation. Duration of action: 4-8 hours orally, 3-8 hours by inhalation.
Salbutamol Dosage
Tablets: Adults - 4 mg, 3-4 times daily (max single dose 8 mg). Syrup: Adults - 5-20ml three or four times daily. Children under 2 years: not recommended. Aerosol inhalation: 100-200 micrograms, 1-2 puffs as necessary. Prophylaxis in exercise-induced bronchospasm: 200 micrograms, 2 puffs.
Salbutamol Nebules
For severe acute asthma: 25 mg-5 mg if necessary. Prophylaxis in exercise-induced bronchospasm: 200 micrograms, 2 puffs.
Salbutamol Cautions
Serious hypokalemia, concomitant treatment with theophylline and its derivatives, corticosteroids, diuretics, and hypoxia, potentiate hypokalemia.
Salbutamol Precautions
Hyperthyroidism, myocardial insufficiency, arrhythmias, susceptibility to QT prolongation, especially in IV administration, diabetics, and ketoacidosis.
Salbutamol Side Effects
Fine tremors (usually hands), nervous tension, headache, peripheral vasodilation, palpitations, tachycardia, rarely muscle cramps and hypokalemia, hypersensitivity reactions (urticaria, angioedema), slight pain on intramuscular injection.
Inhalation
The act of breathing in or drawing air into the lungs.
Rarely Muscle Cramps
Infrequent occurrence of involuntary muscle contractions or spasms.
Hypokalemia After High Doses
Low potassium levels in the blood resulting from excessive intake of potassium-depleting drugs or substances.
Hypersensitivity Urticaria and Angioedema
Extreme sensitivity leading to hives and swelling of the deeper layers of skin, often caused by allergic reactions.
Slight Pain on Intramuscular Injection
Mild discomfort or ache experienced at the site of intramuscular injection.
Formoterol Indications
Long term maintenance treatment of asthma and prevention of bronchospasm in adults and children 5 yrs. Long term maintenance treatment of bronchoconstriction patients with COPD.
Formoterol Contraindications
Not indicated for patients whose asthma is significantly worsening or acutely deteriorating asthma.
