Paediatric Emergencies: Respiratory Distress vs Failure, Sepsis, Anaphylaxis

Paediatric Emergencies: Respiratory Distress vs Failure, Sepsis, Anaphylaxis

A high-density, practical guide for clinicians and learners

What Is This?

This guide distinguishes respiratory distress (compensated breathing difficulty) from respiratory failure (impending collapse), and covers sepsis and anaphylaxis in children—three life-threatening emergencies requiring rapid recognition and intervention. Use it to act fast, avoid misdiagnosis, and save lives in acute care settings.

Why It Matters

• Respiratory emergencies are the #1 cause of paediatric cardiac arrest.
• Sepsis kills 1 in 5 children globally; early antibiotics reduce mortality by 50%.
• Anaphylaxis can kill within minutes; delayed epinephrine increases fatality risk.
• Misdiagnosis (e.g., mistaking sepsis for viral illness) delays critical treatment.

Core Concepts

1. Respiratory Distress vs. Failure: The Spectrum

Rule of thumb: - Distress = compensating (body is fighting). - Failure = decompensating (body is losing).

2. Sepsis: The "Silent Killer"

• Definition: Life-threatening organ dysfunction caused by dysregulated host response to infection.
• Paediatric sepsis criteria (Phoenix Sepsis Score ?2):
• Temperature >38.5°C or <36°C
• Tachycardia (age-specific thresholds)
• Tachypnoea (age-specific thresholds)
• Altered mental status (lethargy, irritability)
• Poor perfusion (cap refill >3s, mottling, weak pulses)
• Red flags:
• Petechiae/purpura (meningococcal sepsis until proven otherwise).
• Hypotension (late sign—act before this).

3. Anaphylaxis: The "Allergic Tsunami"

• Definition: Severe, systemic allergic reaction with airway obstruction and/or circulatory collapse.
• Triggers: Food (peanuts, milk), drugs (antibiotics), insect stings.
• Diagnostic criteria (any 1 of 3):
• Acute onset + skin/mucosal involvement (hives, swelling) + respiratory compromise (wheeze, stridor) OR hypotension.
• ?2 systems involved after exposure to likely allergen:
  • Skin (urticaria, angioedema)
  • Respiratory (dyspnoea, wheeze)
  • GI (vomiting, diarrhoea)
  • CVS (hypotension, syncope)
• Hypotension alone after exposure to known allergen.

How It Works: Pathophysiology in 60 Seconds

Respiratory Distress-Failure

1. Obstruction (e.g., croup, asthma)-? work of breathing-fatigue.
2. Hypoxia-pulmonary vasoconstriction-right heart strain.
3. Hypercarbia-respiratory acidosis-CNS depression.
4. Exhaustion-bradypnoea/apnoea-cardiac arrest.

Sepsis Cascade

1. Infection-cytokine storm-vasodilation + capillary leak.
2. Hypovolaemia-poor perfusion-organ dysfunction.
3. Coagulopathy-DIC (disseminated intravascular coagulation).
4. Septic shock-refractory hypotension-death.

Anaphylaxis Mechanism

1. IgE-mediated-mast cell degranulation-histamine release.
2. Vasodilation-hypotension.
3. Bronchospasm-wheeze/stridor.
4. Mucosal oedema-airway obstruction.

Hands-On: Immediate Actions

Prerequisites

• Equipment: Stethoscope, pulse oximeter, BP cuff, IV access, oxygen, epinephrine auto-injector (e.g., EpiPen), BVM (bag-valve-mask).
• Knowledge: Paediatric vital sign ranges, basic airway manoeuvres, drug doses (e.g., epinephrine 1:1000 0.01 mg/kg IM).

Step-by-Step: Respiratory Distress vs. Failure

1. Assess in <30 Seconds

• Appearance: Agitated (distress) vs. lethargic (failure).
• Work of breathing: Retractions (distress) vs. weak effort (failure).
• Circulation: Tachycardia (distress) vs. bradycardia (failure).

2. Intervene Based on Severity

3. Escalate if:

• SpO? <90% on 100% oxygen-intubate.
• Bradycardia-start CPR (HR <60 in infants, <40 in children).

Step-by-Step: Sepsis

1. Recognise (Use the "Sepsis 6" for Kids)

1. Oxygen (100% via non-rebreather mask).
2. IV/IO access-blood cultures + lactate.
3. IV antibiotics (e.g., ceftriaxone 50 mg/kg + vancomycin if meningitis suspected).
4. IV fluids (20 mL/kg bolus over 5–10 mins; repeat if no improvement).
5. Inotropes (if hypotensive despite fluids: adrenaline 0.1–1 mcg/kg/min).
6. Monitor (urine output, lactate, BP).

2. Red Flags Requiring ICU

• Lactate >4 mmol/L (tissue hypoxia).
• Purpura (meningococcal sepsis).
• Refractory hypotension (after 60 mL/kg fluids).

Step-by-Step: Anaphylaxis

1. Act in <60 Seconds

1. Epinephrine 1:1000 0.01 mg/kg IM (max 0.5 mg) in anterolateral thigh.
2. Repeat every 5–15 mins if no improvement.
3. Oxygen (100% via non-rebreather).
4. IV fluids (20 mL/kg bolus if hypotensive).
5. Adjuncts:
6. Antihistamines (e.g., diphenhydramine 1 mg/kg IV).
7. Steroids (e.g., hydrocortisone 4 mg/kg IV).
8. Salbutamol (if wheeze persists).

2. Watch for Biphasic Reaction

• 20% of cases have a second wave 4–12 hours later.
• Observe for 4–6 hours post-epinephrine.

Common Pitfalls & Mistakes

1. Respiratory Emergencies

• Mistake: Waiting for cyanosis to act. Fix: SpO? <90% = emergency—don’t wait for blue lips.
• Mistake: Underestimating grunting (sign of impending failure). Fix: Grunting = alveolar collapse—give oxygen + consider CPAP.
• Mistake: Over-relying on pulse oximetry in shock (poor perfusion-inaccurate readings). Fix: Check cap refill + mental status—not just SpO?.

2. Sepsis

• Mistake: Delaying antibiotics for "viral illness." Fix: If sepsis is suspected, give antibiotics within 1 hour—don’t wait for cultures.
• Mistake: Giving too much fluid too fast (risk of pulmonary oedema). Fix: Reassess after each 20 mL/kg bolus—stop if crackles develop.
• Mistake: Ignoring tachycardia (early sign of shock). Fix: Tachycardia + poor perfusion = sepsis until proven otherwise.

3. Anaphylaxis

• Mistake: Using antihistamines/steroids instead of epinephrine. Fix: Epinephrine is the only life-saving drug—give it first.
• Mistake: Discharging too soon (risk of biphasic reaction). Fix: Observe for 4–6 hours post-epinephrine.
• Mistake: Giving epinephrine IV (risk of arrhythmias). Fix: Always give IM (unless in cardiac arrest).

Best Practices

Respiratory Emergencies

• Positioning: Sit child up (unless hypotensive) to improve lung expansion.
• Oxygen delivery:
• Mild distress: Nasal cannula (1–2 L/min).
• Moderate-severe: Non-rebreather mask (10–15 L/min).
• Avoid: Over-sedating (can suppress respiratory drive).

Sepsis

• Antibiotics: Broad-spectrum first (e.g., ceftriaxone + vancomycin if meningitis suspected).
• Fluids: Use normal saline (avoid dextrose—can worsen acidosis).
• Monitor: Lactate clearance (improving lactate = good response).

Anaphylaxis

• Epinephrine auto-injectors:
• EpiPen Jr (0.15 mg) for 7.5–25 kg.
• EpiPen (0.3 mg) for >25 kg.
• Avoid: Oral medications (absorption is unreliable in shock).
• Document: Trigger + time of epinephrine (critical for follow-up).

Tools & Frameworks

Real-World Use Cases

1. 2-Year-Old with Croup (Respiratory Distress)

• Scenario: Barking cough, stridor, retractions, SpO? 92%.
• Actions:
• Nebulised adrenaline (5 mL 1:1000).
• Dexamethasone 0.6 mg/kg PO/IV.
• Oxygen via face mask.
• Avoid: Intubation unless stridor + lethargy (risk of laryngospasm).

2. 5-Year-Old with Meningococcal Sepsis

• Scenario: Fever, petechial rash, cap refill 4s, tachycardia.
• Actions:
• IV ceftriaxone 50 mg/kg (within 1 hour).
• 20 mL/kg NS bolus (repeat if no improvement).
• Adrenaline infusion if hypotensive.
• ICU transfer for inotropes.

3. 8-Year-Old with Peanut Anaphylaxis

• Scenario: Hives, wheeze, vomiting, BP 70/40.
• Actions:
• Epinephrine 0.3 mg IM (EpiPen).
• Oxygen 15 L/min via non-rebreather.
• 20 mL/kg NS bolus.
• Observe for 6 hours (risk of biphasic reaction).

Check Your Understanding (MCQs)

Question 1

A 3-year-old presents with wheeze, retractions, and SpO? 91% on room air. They are agitated but alert. What is the most appropriate next step? A. Intubate immediately. B. Give nebulised salbutamol + oxygen. C. Administer IV steroids only. D. Start CPR.

Correct Answer: B (Nebulised salbutamol + oxygen). Explanation: The child has respiratory distress (not failure)—they are compensating. Salbutamol + oxygen will improve bronchospasm and hypoxia. Why the Distractors Are Tempting: - A: Intubation is for respiratory failure (lethargy, bradypnoea). - C: Steroids take hours to work—bronchodilators first. - D: CPR is for cardiac arrest (not indicated here).

Question 2

A 6-month-old has fever, tachycardia, and cap refill 4s. Lactate is 5 mmol/L. What is the most critical intervention? A. Oral paracetamol. B. IV ceftriaxone within 1 hour. C. 10 mL/kg normal saline bolus. D. Wait for blood culture results.

Correct Answer: B (IV ceftriaxone within 1 hour). Explanation: This is sepsis (tachycardia + poor perfusion + high lactate). Antibiotics within 1 hour reduce mortality. Why the Distractors Are Tempting: - A: Paracetamol treats fever but doesn’t address sepsis. - C: Fluids are important but antibiotics are time-critical. - D: Waiting for cultures delays life-saving treatment.

Question 3

A 4-year-old develops hives, wheeze, and hypotension 10 minutes after eating peanuts. What is the first drug you administer? A. Diphenhydramine IV. B. Hydrocortisone IV. C. Epinephrine 0.01 mg/kg IM. D. Salbutamol nebulised.

Correct Answer: C (Epinephrine 0.01 mg/kg IM). Explanation: Epinephrine is the only life-saving drug in anaphylaxis—it reverses bronchospasm and hypotension. Why the Distractors Are Tempting: - A/B: Antihistamines/steroids are adjuncts—not first-line. - D: Salbutamol helps wheeze but doesn’t treat hypotension.

Learning Path

Beginner (0–6 Months)

1. Memorise paediatric vital sign ranges (e.g., HR, RR by age).
2. Practice Broselow tape for weight-based dosing.
3. Simulate