Respiratory Disorders — Revision Notes

⚡ 30-Second Revision

Asthma: — Reversible airway obstruction, inflammation, bronchoconstriction. Triggers: allergens, exercise. Symptoms: Wheezing, dyspnea. Management: Bronchodilators, corticosteroids.
Emphysema: — Irreversible alveolar destruction, loss of elastic recoil. Cause: Smoking. Symptoms: Progressive dyspnea, 'pink puffer'. Spirometry: Irreversible reduced FEV1/FVC.
Chronic Bronchitis: — Chronic productive cough ($\ge 3$ months in $\ge 2$ years). Cause: Smoking. Symptoms: Productive cough, 'blue bloater'.
COPD: — Emphysema + Chronic Bronchitis.
Silicosis: — Silica dust exposure. Pathology: Pulmonary fibrosis, nodular opacities.
Asbestosis: — Asbestos fiber exposure. Pathology: Diffuse interstitial fibrosis, increased cancer risk.
Pneumonia: — Acute lung infection (bacteria, viruses). Pathology: Alveolar consolidation. Symptoms: Fever, cough, dyspnea.
Tuberculosis (TB): — *Mycobacterium tuberculosis*. Pathology: Granulomas (tubercles). Symptoms: Chronic cough, fever, night sweats, weight loss. Treatment: DOTS, multi-drug therapy.
ARDS: — Acute severe lung injury, diffuse bilateral infiltrates, refractory hypoxemia, non-cardiogenic pulmonary edema.

2-Minute Revision

Respiratory disorders impair breathing and gas exchange. Key obstructive diseases include Asthma, Emphysema, and Chronic Bronchitis (the latter two forming COPD). Asthma involves reversible airway inflammation and bronchoconstriction, often triggered by allergens, causing wheezing and dyspnea.

Emphysema, primarily from smoking, is characterized by irreversible destruction of alveolar walls, leading to reduced gas exchange and progressive shortness of breath. Chronic Bronchitis, also linked to smoking, is defined by a chronic productive cough due to excessive mucus production and impaired ciliary function.

Occupational lung diseases like Silicosis (silica dust) and Asbestosis (asbestos fibers) cause progressive pulmonary fibrosis due to workplace exposures. Pneumonia is an acute infection of the lung parenchyma, leading to alveolar consolidation.

Tuberculosis, caused by *Mycobacterium tuberculosis*, is a chronic infection forming granulomas, presenting with chronic cough, fever, and night sweats. Acute Respiratory Distress Syndrome (ARDS) is a severe, acute lung injury causing widespread inflammation and fluid in alveoli, leading to profound, refractory hypoxemia.

Diagnosis often relies on clinical history, physical exam, and spirometry (FEV1/FVC ratio is key for obstruction). Management focuses on cause-specific treatment and symptom control.

5-Minute Revision

Respiratory disorders are conditions affecting the respiratory system, hindering efficient gas exchange. They are broadly categorized into obstructive (difficulty exhaling) and restrictive (difficulty inhaling/reduced lung volume) types.

Obstructive Disorders:

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Asthma: — A chronic inflammatory disease of the airways, characterized by recurrent episodes of reversible bronchoconstriction, airway hyperresponsiveness, and mucus production. Triggers include allergens, exercise, cold air. Symptoms are wheezing, dyspnea, chest tightness, cough. Diagnosis involves spirometry showing reversible obstruction. Management includes bronchodilators for quick relief and inhaled corticosteroids for long-term control.
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Chronic Obstructive Pulmonary Disease (COPD): — A progressive, irreversible airflow limitation, primarily caused by smoking. It encompasses:

* Emphysema: Irreversible destruction and enlargement of the alveoli, leading to reduced surface area for gas exchange and loss of elastic recoil. Patients often present with progressive dyspnea and are termed 'pink puffers'.

Spirometry shows irreversible reduced FEV1/FVC ratio. * Chronic Bronchitis: Clinically defined as a chronic productive cough for at least three months in two consecutive years. Involves inflammation, mucus gland hypertrophy, and impaired mucociliary clearance.

Patients may be 'blue bloaters' due to hypoxemia.

Occupational Lung Diseases: Caused by workplace exposure to harmful substances.

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Silicosis: — From inhaling silica dust (e.g., mining). Causes progressive pulmonary fibrosis and nodular opacities.
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Asbestosis: — From inhaling asbestos fibers. Causes diffuse interstitial fibrosis and increases cancer risk (lung cancer, mesothelioma).

Infectious Disorders:

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Pneumonia: — Acute inflammation of lung parenchyma, usually bacterial (*Streptococcus pneumoniae*) or viral. Leads to alveolar consolidation, fever, cough, dyspnea. Diagnosed by chest X-ray showing infiltrates.
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Tuberculosis (TB): — Caused by *Mycobacterium tuberculosis*. Characterized by granuloma formation (tubercles) in the lungs. Symptoms include chronic cough, low-grade fever, night sweats, weight loss. Diagnosed by sputum tests (AFB smear, culture, molecular tests) and chest X-ray. Treated with long-term multi-drug therapy (DOTS).

Acute Severe Lung Injury:

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Acute Respiratory Distress Syndrome (ARDS): — A severe, life-threatening lung injury characterized by acute onset, severe hypoxemia refractory to oxygen, and diffuse bilateral pulmonary infiltrates on chest imaging, without evidence of cardiac failure. Often a complication of sepsis or severe trauma. Requires intensive supportive care.

Key Diagnostic Tool: Spirometry, especially the FEV1/FVC ratio, is crucial. A reduced ratio indicates obstruction; its reversibility helps differentiate asthma from COPD. Prevention, particularly smoking cessation and occupational safety, is paramount for many chronic disorders.

Prelims Revision Notes

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Asthma: — Chronic inflammatory airway disease. Key features: Reversible airflow obstruction, airway hyperresponsiveness, bronchoconstriction, mucus production. Triggers: allergens (pollen, dust mites), exercise, cold air, smoke. Symptoms: Wheezing, dyspnea, chest tightness, cough (often nocturnal). Diagnosis: Spirometry showing significant reversibility of FEV1 after bronchodilator. Management: Inhaled corticosteroids (controller), short-acting beta-agonists (reliever).
2
Chronic Obstructive Pulmonary Disease (COPD): — Irreversible, progressive airflow limitation. Primarily caused by smoking. Comprises Emphysema and Chronic Bronchitis.

* Emphysema: Irreversible destruction of alveolar walls and enlargement of airspaces. Loss of elastic recoil. Reduced surface area for gas exchange. Symptoms: Progressive dyspnea (often minimal cough), 'pink puffer' appearance.

Spirometry: Irreversibly reduced FEV1/FVC ratio, increased total lung capacity (TLC). * Chronic Bronchitis: Clinical definition: Chronic productive cough for $\ge 3$ months in $\ge 2$ consecutive years.

Pathology: Chronic inflammation, mucus gland hypertrophy, increased mucus, impaired ciliary function. Symptoms: Persistent productive cough, frequent infections, 'blue bloater' appearance (cyanosis, edema).

1
Occupational Respiratory Disorders: — Caused by workplace exposure.

* Silicosis: Inhalation of silica dust (mining, quarrying). Pathology: Progressive pulmonary fibrosis, nodular opacities. Increased risk of TB. * Asbestosis: Inhalation of asbestos fibers (construction, shipbuilding). Pathology: Diffuse interstitial fibrosis. Increased risk of lung cancer and mesothelioma.

1
Pneumonia: — Acute infection of lung parenchyma (alveoli and bronchioles). Causative agents: Bacteria (*Streptococcus pneumoniae*), viruses (Influenza, RSV). Pathology: Alveolar consolidation (fluid/pus filling alveoli). Symptoms: Fever, chills, cough (productive), dyspnea, pleuritic chest pain. Diagnosis: Chest X-ray (infiltrates).
2
Tuberculosis (TB): — Chronic infectious disease by _Mycobacterium tuberculosis_. Transmission: Airborne droplets. Pathology: Granuloma formation (tubercles). Symptoms: Chronic cough (often productive, sometimes hemoptysis), low-grade fever (evening), night sweats, weight loss, fatigue. Diagnosis: Sputum smear (AFB), culture, molecular tests (GeneXpert), Chest X-ray (cavities, infiltrates). Treatment: Long-term multi-drug therapy (DOTS).
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Acute Respiratory Distress Syndrome (ARDS): — Severe, acute lung injury. Characterized by: Acute onset, severe hypoxemia refractory to oxygen, diffuse bilateral pulmonary infiltrates on chest X-ray, and absence of cardiac failure as primary cause. Etiology: Sepsis, severe pneumonia, trauma. Pathology: Damage to alveolar-capillary membrane, non-cardiogenic pulmonary edema. Management: Supportive, mechanical ventilation.

Vyyuha Quick Recall

For common respiratory disorders and their key features, remember 'A C E P T S':

Asthma: Allergic, Airway inflammation, Airflow Reversible.
COPD (includes Chronic Bronchitis & Emphysema): Cigarettes, Chronic cough (bronchitis), Collapsed alveoli (emphysema), Chronic obstruction Irreversible.
Emphysema: Elasticity loss, Enlarged air sacs, Exhalation difficulty.
Pneumonia: Pus in alveoli, Pathogen infection, Pleuritic pain.
Tuberculosis: Tubercles (granulomas), Transmissible, Treatment long-term (DOTS).
Silicosis/Asbestosis: Scarring (fibrosis), Stone/Asbestos dust, Slow onset.