Chapter 36: Emergency Care – Cardiovascular System: Shock, Heart Failure, CHD, Ventilation

Recognition of shock (compensated / hypotensive) · Heart failure · Congenital heart disease (duct‑dependent lesions) · Treatment of shock · Therapeutic effects of ventilation in circulatory failure
❤️ Core principles: Shock = tissue hypoperfusion. Compensated shock: tachycardia, cool extremities, delayed cap refill, normal BP. Hypotensive shock: decreased BP, altered mental status. Duct‑dependent CHD → PGE1. Ventilation improves circulation: reduces work of breathing, enhances coronary perfusion, decreases ventricular afterload in HF.

❤️ Summary: shock recognition, heart failure, CHD, treatment, ventilation effects

⚠️ Recognition of shock
Compensated: tachycardia, cool extremities, delayed capillary refill (>2 sec), normal BP. Hypotensive: decreased BP, weak pulses, altered sensorium, oliguria.
💔 Heart failure (HF)
Signs: tachypnea, gallop rhythm, hepatomegaly, pulmonary crackles, poor feeding, failure to thrive. Cardiogenic shock → fluid restriction, inotropes, afterload reduction.
🫀 Congenital heart disease (CHD)
Duct‑dependent lesions (e.g., hypoplastic left heart, pulmonary atresia, TGA) → PGE1 infusion. Hyperoxia test: cyanotic newborn not improving on 100% O2 suggests CHD.
💊 Treatment of shock
ABC, high‑flow O2, IV/IO access. Fluid bolus 20 mL/kg isotonic crystalloid (repeat up to 60 mL/kg). Vasoactive support (epinephrine, dopamine) for fluid‑refractory shock.
🫁 Therapeutic effects of ventilation in circulatory failure
Reduces work of breathing → decreases O2 consumption. Improves coronary perfusion (↑ PaO2, ↓ PaCO2). Decreases ventricular afterload in HF. Enhances organ perfusion.
📊 Key distinctions: Septic shock → distributive (warm shock). Cardiogenic shock → hepatomegaly, gallop, cool extremities. Early inotropes in cardiogenic shock (avoid excessive fluids).

🔍 Approach to the child with suspected cardiovascular emergency

1
Primary survey – perfusion assessment – Heart rate, pulses (central vs peripheral), capillary refill, blood pressure, mental status, urine output.
2
Differentiate shock types – Hypovolemic (trauma, dehydration), distributive (sepsis, anaphylaxis), cardiogenic (CHF, myocarditis), obstructive (tamponade, tension pneumothorax, duct‑dependent CHD).
3
Identify congenital heart disease (neonate) – Cyanosis not improving with 100% oxygen (hyperoxia test), absent femoral pulses (coarctation), murmur, shock with differential cyanosis.
4
Heart failure recognition – Tachypnea, grunting, hepatomegaly, gallop rhythm, poor feeding, sweating with feeds. Cardiomegaly on CXR.
5
Ventilation in circulatory failure – Intubation/mechanical ventilation reduces O2 demand, improves cardiac output, and can salvage failing circulation (especially cardiogenic shock).

📋 Stepwise management – cardiovascular emergencies

1
Immediate stabilization (ABC) – High‑flow O2, establish IV/IO access. Monitor ECG, SpO2, NIBP.
2
Fluid resuscitation (hypovolemic/distributive shock) – 20 mL/kg crystalloid bolus, reassess; repeat up to 60 mL/kg. If cardiogenic shock suspected, give smaller boluses (5-10 mL/kg) with caution.
3
Vasoactive support – For fluid‑refractory shock: epinephrine (0.05-0.3 mcg/kg/min) or dopamine (5-15 mcg/kg/min). Norepinephrine for distributive shock.
4
Duct‑dependent CHD (neonate with shock/cyanosis) – Start PGE1 (alprostadil) 0.05-0.1 mcg/kg/min IV. Monitor for apnea, fever, hypotension.
5
Mechanical ventilation in circulatory failure – Indications: severe cardiogenic shock, impending arrest, or increased work of breathing. Positive pressure reduces preload and afterload, improving cardiac efficiency.
⚡ Key reminder: In cardiogenic shock, excessive fluids worsen outcome – use inotropes early. In duct‑dependent lesions, PGE1 is life‑saving but may cause apnea; prepare for intubation.

🧠 Reflex prompts – shock, CHD, heart failure, ventilation effects

📉 First sign of compensated shock?
Tachycardia, decreased peripheral pulses, delayed cap refill (normal BP).
💊 First vasoactive drug in fluid‑refractory septic shock?
Epinephrine (or dopamine). Norepinephrine for vasodilatory shock.
🫀 Duct‑dependent CHD – emergency drug?
Prostaglandin E1 (alprostadil) 0.05-0.1 mcg/kg/min.
🩺 Hyperoxia test in cyanotic newborn – interpretation?
No improvement in SpO2 on 100% O2 suggests cyanotic CHD (vs pulmonary disease).
🫁 How does positive pressure ventilation help in heart failure?
Reduces preload, decreases afterload, lowers O2 consumption → improves cardiac output.
❤️ Sign of cardiogenic shock?
Hepatomegaly, gallop rhythm, cool extremities, narrow pulse pressure.