RESPIRATORY DISORDERS.
Acute Respiratory Distress Syndrome (ARDS)
Definition:
Acute Respiratory Distress Syndrome (ARDS) is a life-threatening lung condition characterized by severe inflammation and fluid accumulation in the alveoli, leading to hypoxia and respiratory failure.
Causes:
- Infections (Sepsis, Pneumonia, COVID-19, Influenza, RSV)
- Aspiration (Meconium aspiration syndrome, near-drowning)
- Trauma (Chest injury, burns, shock)
- Toxic inhalation (Smoke, chemicals, drug overdose)
Signs & Symptoms:
- Severe dyspnea and tachypnea
- Hypoxemia unresponsive to oxygen therapy
- Cyanosis
- Intercostal and subcostal retractions
- Crackles (on auscultation)
Complications:
- Respiratory failure requiring mechanical ventilation
- Multi-organ failure due to hypoxia
- Pulmonary fibrosis (long-term)
Diagnosis:
- Arterial Blood Gas (ABG): Hypoxia with respiratory alkalosis
- Chest X-ray: Bilateral lung infiltrates (“white lung”)
- PaO₂/FiO₂ ratio: ≤300 confirms ARDS
Management:
- Oxygen therapy (High-flow nasal cannula, CPAP, Ventilation)
- Sedation and Paralysis (if ventilated)
- Surfactant therapy (for neonates)
- Fluid management (diuretics if pulmonary edema)
Bronchiolitis
Definition:
Bronchiolitis is a viral lower respiratory tract infection, causing inflammation and obstruction of small airways (bronchioles), primarily in infants <2 years.
Causes:
- Respiratory Syncytial Virus (RSV) (most common cause)
- Parainfluenza, Adenovirus, Rhinovirus, Influenza
Signs & Symptoms:
- Cough, wheezing, nasal congestion
- Tachypnea (>50-60 breaths/min)
- Chest retractions, nasal flaring
- Low-grade fever
- Crackles and wheezing on auscultation
Complications:
- Respiratory failure
- Apnea (in premature infants)
- Secondary bacterial pneumonia
Diagnosis:
- Clinical examination
- Nasopharyngeal swab (RSV antigen test, PCR)
- Chest X-ray: Hyperinflation, peribronchial thickening
Management:
- Supportive therapy (Oxygen, fluids, nasal suctioning)
- Nebulized hypertonic saline
- Ribavirin (for severe cases in immunocompromised children)
- Palivizumab (RSV prophylaxis for high-risk infants)
Croup (Laryngotracheobronchitis)
Definition:
Croup is a viral infection of the upper airway, causing subglottic swelling, leading to barking cough and stridor.
Causes:
- Parainfluenza virus (most common)
- Influenza A/B, RSV, Adenovirus
Signs & Symptoms:
- Barking cough (“seal-like”)
- Inspiratory stridor
- Hoarseness of voice
- Low-grade fever
- Worse symptoms at night
Complications:
- Severe airway obstruction
- Respiratory failure
Diagnosis:
- Clinical assessment (Cough, stridor, hoarseness)
- X-ray (“Steeple sign”) – Subglottic narrowing
Management:
- Mild cases: Humidified air, hydration
- Moderate-severe cases:
- Dexamethasone (IM/PO, 0.6 mg/kg single dose)
- Nebulized epinephrine (if severe stridor or respiratory distress)
Pneumonia
Definition:
Pneumonia is an infection of the lung parenchyma, leading to alveolar inflammation and consolidation.
Causes:
- Viral (RSV, Influenza, Parainfluenza, Adenovirus) (most common in infants)
- Bacterial (Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae)
- Atypical (Mycoplasma pneumoniae, Chlamydia pneumoniae)
Signs & Symptoms:
- Fever, chills
- Tachypnea, dyspnea
- Productive cough (with sputum in bacterial pneumonia)
- Grunting, nasal flaring
- Diminished breath sounds, crackles, bronchial breath sounds
Complications:
- Pleural effusion, empyema
- Sepsis
- Respiratory failure
Diagnosis:
- Chest X-ray: Consolidation, infiltrates
- CBC: Leukocytosis in bacterial pneumonia
- Sputum culture, Blood culture
Management:
- Oxygen therapy for hypoxia
- Antibiotics:
- Amoxicillin (for community-acquired pneumonia)
- Ceftriaxone + Vancomycin (for severe bacterial pneumonia)
- IV fluids, antipyretics
Asthma
Definition:
Asthma is a chronic inflammatory disease of the airways characterized by bronchial hyperreactivity, airflow obstruction, and reversible bronchoconstriction.
Triggers:
- Allergens (dust, pollen, pet dander)
- Cold air, exercise
- Respiratory infections
Signs & Symptoms:
- Wheezing, cough (especially at night)
- Dyspnea, chest tightness
- Prolonged expiration
- Use of accessory muscles
Complications:
- Status asthmaticus (severe persistent attack)
- Respiratory failure
Diagnosis:
- Spirometry (FEV1/FVC <70%)
- Peak Expiratory Flow Rate (PEFR)
Management:
- Acute attack:
- Nebulized Salbutamol + Ipratropium
- Systemic steroids (Prednisolone, Dexamethasone)
- Oxygen therapy
- Long-term control:
- Inhaled corticosteroids (Budesonide, Fluticasone)
- LABA (Salmeterol, Formoterol)
Key Points for Competitive Exams
✔️ Most common cause of pneumonia in infants? – RSV
✔️ Most common bacterial pneumonia in children? – Streptococcus pneumoniae
✔️ “Steeple sign” on X-ray is seen in? – Croup
✔️ Wheezing is most common in? – Asthma, Bronchiolitis
✔️ Most common cause of bronchiolitis? – RSV
✔️ Most specific test for asthma? – Spirometry (FEV1/FVC <70%)
✔️ Drug for severe croup? – Dexamethasone + Nebulized Epinephrine
Peritonsillar Abscess (Quinsy)
Definition:
A peritonsillar abscess (PTA) is a pus collection between the tonsillar capsule and the pharyngeal muscles, often as a complication of untreated tonsillitis.
Causes:
- Bacterial infections – Streptococcus pyogenes (Group A Strep), Staphylococcus aureus, Fusobacterium
- Tonsillitis progression
- Poor oral hygiene
- Immunocompromised status
Signs & Symptoms:
- Severe unilateral throat pain
- Fever, chills
- “Hot potato” (muffled) voice
- Trismus (difficulty opening mouth)
- Uvular deviation to the opposite side
- Swelling and redness of tonsils
Complications:
- Airway obstruction
- Sepsis
- Lemierre’s syndrome (Jugular vein thrombosis)
Diagnosis:
- Clinical examination
- Needle aspiration of pus
- CT scan (if deep abscess is suspected)
Management:
- IV antibiotics (Ampicillin-Sulbactam or Clindamycin)
- Needle aspiration or incision & drainage
- Tonsillectomy (for recurrent cases)
Bronchiectasis
Definition:
Bronchiectasis is a chronic irreversible dilation of the bronchi, leading to mucus accumulation, recurrent infections, and progressive lung damage.
Causes:
- Post-infectious (most common) – Severe pneumonia, pertussis, tuberculosis
- Cystic Fibrosis (CF)
- Primary Ciliary Dyskinesia (PCD)
- Immunodeficiency (e.g., IgA deficiency, HIV)
- Foreign body aspiration
Signs & Symptoms:
- Chronic cough with purulent sputum
- Recurrent respiratory infections
- Clubbing of fingers
- Wheezing, coarse crackles on auscultation
- Hemoptysis (coughing up blood in severe cases)
Complications:
- Lung abscess
- Respiratory failure
- Cor pulmonale (right heart failure due to lung disease)
Diagnosis:
- High-resolution CT scan (HRCT) – “Tram-track” appearance
- Sputum culture (to detect bacterial infections, e.g., Pseudomonas)
- Pulmonary function tests (PFTs) – Obstructive pattern
Management:
- Airway clearance (Chest physiotherapy, postural drainage)
- Antibiotics (Azithromycin, Ciprofloxacin for Pseudomonas)
- Bronchodilators (Salbutamol, Ipratropium)
- Surgical resection (in severe cases)
Pulmonary Tuberculosis (TB)
Definition:
Pulmonary tuberculosis (TB) is a chronic infectious disease caused by Mycobacterium tuberculosis, leading to granuloma formation in the lungs.
Risk Factors:
- Malnutrition
- Close contact with TB patient
- HIV/AIDS
- Low socioeconomic status
Signs & Symptoms:
- Persistent cough (>2 weeks)
- Fever, night sweats
- Weight loss, failure to thrive
- Hemoptysis (in advanced cases)
- Lymphadenopathy
Complications:
- Miliary TB (disseminated TB in blood)
- Tuberculous meningitis
- Pleural effusion
- Pulmonary fibrosis
Diagnosis:
- Tuberculin Skin Test (Mantoux test) (>10 mm induration in children is positive)
- Chest X-ray (Cavitary lesions, Ghon complex in primary TB)
- Sputum AFB (Acid-Fast Bacillus) stain & culture
- GeneXpert (Rapid TB detection test)
Management:
- First-Line Anti-TB Therapy (2HRZE/4HR):
- 2 months: Isoniazid (H), Rifampicin (R), Pyrazinamide (Z), Ethambutol (E)
- 4 months: Isoniazid, Rifampicin
- BCG vaccination for prevention
Pleural Effusion
Definition:
Pleural effusion is the accumulation of excess fluid in the pleural space, causing lung compression and breathlessness.
Types:
- Transudative (low protein content) – CHF, nephrotic syndrome
- Exudative (high protein content) – TB, pneumonia, malignancy
Signs & Symptoms:
- Progressive dyspnea
- Dullness on percussion
- Diminished breath sounds
- Decreased tactile fremitus
- Chest pain (pleuritic, sharp pain on inspiration)
Complications:
- Empyema (infected pleural fluid)
- Lung collapse (atelectasis)
- Fibrosis of pleura
Diagnosis:
- Chest X-ray (Blunting of costophrenic angle)
- Ultrasound (to assess fluid amount)
- Thoracentesis (fluid analysis for protein, WBC, AFB, culture)
Management:
- Treat underlying cause
- Therapeutic thoracentesis (for symptom relief)
- Antibiotics if bacterial infection is present
Cystic Fibrosis (CF)
Definition:
Cystic fibrosis is a genetic disorder affecting CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) protein, leading to thick mucus accumulation in lungs, pancreas, and other organs.
Causes:
- Autosomal recessive mutation in CFTR gene (Chromosome 7)
Signs & Symptoms:
- Chronic cough with thick mucus
- Recurrent lung infections (Pseudomonas, Staph aureus)
- Nasal polyps, sinusitis
- Meconium ileus (in newborns)
- Pancreatic insufficiency (Steatorrhea, fat malabsorption)
- Clubbing of fingers
Complications:
- Bronchiectasis
- Diabetes (CF-related diabetes, CFRD)
- Infertility (absence of vas deferens in males)
Diagnosis:
- Sweat chloride test (>60 mEq/L = positive for CF)
- Genetic testing (CFTR gene mutation analysis)
- Chest X-ray (Hyperinflation, bronchiectasis)
Management:
- Airway clearance (Chest physiotherapy, mucolytics – Dornase alfa)
- Antibiotics for infections (Azithromycin, Tobramycin inhalation)
- Pancreatic enzyme supplements (Creon)
- High-calorie, high-fat diet
- CFTR modulators (Ivacaftor, Lumacaftor for specific mutations)
Key Points for Competitive Exams
✔️ Most common cause of pediatric pleural effusion? – Tuberculosis, Pneumonia
✔️ Gold standard test for CF? – Sweat chloride test
✔️ “Tram-track” appearance on HRCT? – Bronchiectasis
✔️ Most common bacteria in CF lung infections? – Pseudomonas aeruginosa
✔️ Uvula deviated in? – Peritonsillar abscess