Definition, Phenotypes & Severity Assessment

Question	Answer
1. Define Severe Acute Asthma (Status Asthmaticus).	Severe Acute Asthma (or Status Asthmaticus) is an acute, severe exacerbation of bronchial asthma characterized by rapidly progressive bronchospasm, airway mucosal edema, and mucous plugging that produces marked respiratory distress, hypoxemia, and airflow limitation that is refractory to initial standard therapy with short-acting beta-2 agonists (SABA).
2. What is the Pediatric Respiratory Assessment Measure (PRAM Score) and how is it scored?	PRAM is a validated 12-point clinical scoring system used in the emergency department to grade asthma severity in children aged 2–17 years: 1) Suprasternal Retractions: 0 = None, 2 = Present; 2) Scalene Muscle Contraction: 0 = None, 2 = Present; 3) Air Entry: 0 = Normal, 1 = Decreased at bases, 2 = Decreased widespread, 3 = Minimal/Absent; 4) Wheezing: 0 = None, 1 = Expiratory only, 2 = Both inspiratory & expiratory, 3 = Silent chest / inaudible; 5) $SpO_2$ on Room Air: 0 = $\ge 95\%$, 1 = $92–94\%$, 2 = $<92\%$. Severity Grading: Mild (1–3), Moderate (4–7), Severe (8–12).
3. What is the physiological mechanism of Pulsus Paradoxus in severe asthma?	Pulsus paradoxus is an exaggeration of the normal inspiratory drop in systolic blood pressure ($>10-15\text{ mmHg}$). In severe asthma, severe air-trapping generates enormously negative intrathoracic pressures during inspiration to overcome airway resistance (down to $-30\text{ to } -40\text{ cm H}_2\text{O}$). This markedly increases right ventricular venous return, causing the interventricular septum to bulge leftward into the left ventricular cavity (ventricular interdependence). Concurrently, left ventricular afterload rises, acutely reducing LV stroke volume and systolic pressure.
4. What are the clinical signs of "Impending Respiratory Arrest" in an asthmatic child?	1) Silent Chest: Total absence of wheezing and breath sounds despite maximal respiratory effort (critical airflow velocity $<25\%$); 2) Paradoxical Thoracoabdominal Breathing: Chest wall collapses inward while the abdomen protrudes outward during inspiration (diaphragmatic fatigue); 3) Altered Sensorium: Agitation progressing to confusion, lethargy, or coma (severe cerebral hypoxia and $CO_2$ narcosis); 4) Central Cyanosis in room air; 5) Bradycardia and hypotension (terminal signs).
5. VIVA TRAP: What is the significance of a "Normal" PaCO2 (40 mmHg) in a child presenting with severe asthma?	Examiner: "The ABG of a child in status asthmaticus shows pH 7.35, PaCO2 40 mmHg, PaO2 60 mmHg. Are you reassured by this PaCO2?" Response: "No, sir/ma'am! I would be extremely alarmed! In an acutely tachypneic child in status asthmaticus, alveolar hyperventilation should drive the $PaCO_2$ down into the hypocapnic range ($<30-35\text{ mmHg}$). A 'normal' $PaCO_2$ ($40\text{ mmHg}$) in the presence of severe tachypnea and retractions signifies respiratory muscle exhaustion, severe dead-space ventilation, and impending hypercapnic respiratory failure. This child requires immediate PICU transfer and preparation for advanced airway management!"

Pharmacotherapy & Emergency Room Protocol

Question	Answer
1. What is the first-line emergency department bronchodilator protocol for severe asthma (Hour 1)?	1) Oxygen: Maintain $SpO_2$ 94–98%; 2) Inhaled Salbutamol: Nebulization with $2.5-5.0\text{ mg}$ (or 6–10 puffs via MDI with spacer) administered every 20 minutes for 3 doses in the first hour; 3) Inhaled Ipratropium Bromide: Add $250\text{ mcg}$ (for $<20\text{ kg}$) or $500\text{ mcg}$ (for $>20\text{ kg}$) to the first 3 doses of Salbutamol nebulization. (Dual therapy achieves synergistic bronchodilation and reduces hospital admission rates); 4) Systemic Corticosteroids: Administer immediately within the first hour: Oral Prednisolone $1-2\text{ mg/kg}$ (max 40–50 mg) or IV Hydrocortisone $4\text{ mg/kg}$ Q6H / IV Methylprednisolone $1-2\text{ mg/kg}$ Q12H.
2. What is the evidence and mechanism of Intravenous Magnesium Sulfate (MgSO4) in acute asthma?	IV Magnesium Sulfate is a second-line rescue agent indicated for children with severe acute asthma (PRAM $\ge 8$) who show poor response to initial inhaled bronchodilators in the first hour. Dose: $40-50\text{ mg/kg}$ (max 2 g) IV infusion in $100\text{ mL}$ normal saline over 20 to 30 minutes. Mechanism: Acts as a physiological calcium antagonist; blocks voltage-gated calcium channels in bronchial smooth muscle cells, directly promoting bronchodilation, inhibits acetylcholine release at motor nerve terminals, and stabilizes mast cells.
3. Why does transient oxygen desaturation occur immediately following initial high-dose Salbutamol nebulization?	Beta-2 agonists are potent vasodilators. In acute asthma, hypoxic pulmonary vasoconstriction (HPV) normally diverts blood flow away from poorly ventilated alveoli to preserve $V/Q$ matching. Inhaled Salbutamol relaxes pulmonary vascular smooth muscle in non-ventilated lung units before it can overcome bronchospasm and mucous plugging in the bronchioles. This acutely increases perfusion to non-ventilated alveoli, transiently worsening ventilation-perfusion mismatch ($V/Q$ mismatch) and lowering $SpO_2$ by $2-4\%$. Hence, high-dose SABA should always be administered with supplemental oxygen.
4. What are the Indications and Dosing for Intravenous Terbutaline or Aminophylline in refractory asthma?	Indicated in PICU for status asthmaticus refractory to continuous inhaled beta-agonists and IV magnesium sulfate: 1) IV Terbutaline: Loading dose $2-10\text{ mcg/kg}$ IV over 10 minutes, followed by continuous infusion at $0.2-0.4\text{ mcg/kg/min}$ (titrate up to $2-3\text{ mcg/kg/min}$). Requires cardiac monitoring for arrhythmia and hypokalemia; 2) IV Aminophylline: Loading dose $5-6\text{ mg/kg}$ IV over 20-30 min (omit if child on oral theophylline), followed by maintenance infusion at $0.9-1.0\text{ mg/kg/hr}$. Therapeutic level: $10-20\text{ mcg/mL}$.
5. VIVA TRAP: Should antibiotics be routinely prescribed during an acute asthma exacerbation?	Examiner: "The child has fever, tachypnea, and leukocytosis during an asthma exacerbation. Will you start IV Ceftriaxone?" Response: "No, sir/ma'am! Routine antibiotic prescription in asthma exacerbations is strictly contraindicated. Over $80-90\%$ of pediatric asthma exacerbations are triggered by viral respiratory infections (Rhinovirus, RSV, Metapneumovirus). Fever, leukocytosis, and patchy atelectasis on CXR are common features of viral infection and mucous plugging, NOT secondary bacterial pneumonia. Antibiotics are indicated only if there is objective evidence of bacterial pneumonia (lobar consolidation on CXR with high procalcitonin), purulent otitis media, or persistent high fever with septic appearance."

Long-Term Maintenance & GINA 2024 Guidelines

Question	Answer
1. What is the fundamental difference between GINA Track 1 and Track 2 for asthma management?	GINA Track 1 (Preferred for adolescents $\ge 12$ years): Uses low-dose ICS-Formoterol as both the single maintenance and reliever therapy (MART) across all steps. When symptoms flare, taking the reliever automatically delivers a dose of anti-inflammatory steroid, reducing severe exacerbations by $>30\%$. GINA Track 2 (Alternative): Uses a short-acting beta-2 agonist (SABA) as the reliever, paired with regular daily maintenance Inhaled Corticosteroids (ICS). For children aged 6–11 years, Track 2 remains common (Step 1: low-dose ICS taken whenever SABA is used; Step 2: daily low-dose ICS; Step 3: low-dose ICS-LABA or medium-dose ICS).
2. How do you assess inhaler technique in a 6-year-old child using an MDI and spacer?	Seven-step check: 1) Remove inhaler cap and shake canister vigorously 5-6 times; 2) Insert into spacer upright; 3) Instruct child to sit upright and breathe out gently away from the spacer; 4) Place mouthpiece in mouth between teeth with a tight lips seal (or tight-fitting mask); 5) Press the canister once to actuate a single puff; 6) Instruct child to take 5 slow, deep tidal breaths (or one deep breath held for 10 seconds); 7) Wait 30-60 seconds before administering a second puff; rinse mouth with water post-inhalation to prevent oral thrush.
3. What is the Modified Asthma Predictive Index (mAPI)?	Used in young children ($<3\text{ years}$) with recurrent wheezing ($\ge 4$ episodes in past year) to predict asthma persistence at 6–13 years. Requires 1 Major Criterion (Physician-diagnosed parental asthma; Physician-diagnosed atopic dermatitis; Allergic sensitization to $\ge 1$ aeroallergen) OR 2 Minor Criteria (Allergic sensitization to milk/egg/peanut; Wheezing unrelated to colds; Peripheral blood eosinophilia $\ge 4\%$). A positive mAPI gives a $>75\%$ likelihood of asthma at school age.
4. What are the key components of an individualized Written Asthma Action Plan (WAAP)?	A 3-zone color-coded plan: 1) Green Zone (Well / Controlled): $PEF > 80\%$, no cough/wheeze; take regular daily controller medications; 2) Yellow Zone (Caution / Worsening): $PEF 50-80\%$, cough, night waking, mild wheeze; step up reliever (Salbutamol 2-4 puffs Q4H) and double controller dose; 3) Red Zone (Medical Alert / Danger): $PEF < 50\%$, severe breathlessness, speaking in single words, retractions; immediately take 6-10 puffs of Salbutamol and seek emergency medical care.