3.1 Cardiogenic Shock

Cardiogenic Shock in the Pediatric ICU

Cardiogenic shock is inadequate tissue perfusion caused by primary failure of the heart as a pump. In children the common drivers differ from adult coronary disease: myocarditis, cardiomyopathy, arrhythmia-induced cardiomyopathy, post–cardiac surgery stunning, acute graft dysfunction after transplant, and decompensated congenital heart disease (left-heart obstructive lesions, failing single-ventricle physiology, or sudden loss of shunt or conduit flow). Whatever the cause, stroke volume collapses, cardiac output falls, and compensatory systemic vascular resistance (SVR) rises. Blood that cannot be ejected backs into the pulmonary and systemic venous beds, producing the classic "cold and wet" picture — cool mottled extremities, delayed capillary refill, pulmonary edema or hepatomegaly, and oliguria — rather than the flat-neck-vein dryness of pure hypovolemia.

Hemodynamically, expect low cardiac index, elevated atrial/ventricular filling pressures (high CVP; high left-atrial or pulmonary-artery wedge pressure when measured), high SVR, and low SvO2/ScvO2 with rising lactate. Distinguishing this profile from hypovolemic shock is a high-yield CCRN-Pediatric skill: both can show tachycardia and cool skin, but cardiogenic shock has high — not low — filling pressures and usually crackles, a gallop, or radiographic pulmonary venous congestion.

Age-Specific Vital Signs and Early Recognition

Children compensate with tachycardia long before they drop blood pressure. Waiting for adult-threshold hypotension misses the window. Interpret every number against age norms and the child's own baseline (especially single-ventricle or chronic heart-failure patients who "live" at atypical saturations or blood pressures).

*Systolic thresholds approximate PALS/age-based minima used for shock recognition; treat the trend and perfusion exam, not a single number.

Clinical recognition cluster: progressive tachycardia; narrow pulse pressure; prolonged capillary refill (>2–3 seconds centrally); cool/mottled skin; weak central pulses relative to work of breathing; crackles or frothy secretions; hepatomegaly; oliguria (<1 mL/kg/hr); altered mentation or inconsolability; rising lactate; falling ScvO2. In infants, poor feeding, diaphoresis with feeds, and grunting are perfusion red flags. Post-op cardiac surgical patients add sudden changes in atrial pressure, chest-tube output, or regional saturation (NIRS) as early pump-failure signals.

Inotropes, Vasopressors, and Supportive Pharmacology

Therapy goals are to restore oxygen delivery without drowning the lungs: optimize preload carefully, improve contractility, and adjust afterload so the failing ventricle can eject. Large undifferentiated fluid boluses are not first-line in clear cardiogenic shock; give small aliquots only when filling pressures or ultrasound suggest underfilling, and reassess after each.

Milrinone is especially useful when the ventricle is stiff or after cardiopulmonary bypass because it improves diastolic relaxation and lowers pulmonary vascular resistance — valuable in right-ventricular failure and many congenital lesions. Epinephrine remains a workhorse for profound low-output states. Match the agent to the physiology: a congested child with high SVR may need inotropy and afterload reduction (milrinone ± vasodilator strategy), whereas a profoundly hypotensive child may need a pressor to protect coronary perfusion while an inotrope is titrated. Correct hypocalcemia, acidosis, and arrhythmias — each steals stroke volume. Intubation and positive-pressure ventilation can unload the left ventricle but may impede venous return; prepare vasoactives before induction in tenuous patients.

Mechanical Circulatory Support Concepts

When medical therapy cannot restore perfusion, mechanical support bridges recovery, transplant, or decision-making.

• VA-ECMO provides cardiac and pulmonary support via venous drainage and arterial return. Indications include refractory cardiogenic shock, failure to wean from bypass, and fulminant myocarditis. Nursing priorities: cannula security and limb perfusion (especially femoral arterial cannulation), circuit integrity, ACT/anti-Xa anticoagulation targets, bleeding versus clotting surveillance, and neurologic checks.
• Pediatric VADs (for example Berlin Heart EXCOR in smaller children; durable intracorporeal devices in larger adolescents) support weeks to months as a bridge to transplant or recovery. Focus on driveline/cannula site care, anticoagulation, infection prevention, and stroke surveillance.
• Temporary percutaneous devices (selected Impella or similar platforms) appear in larger children/adolescents at specialized centers; IABP is uncommon in small children because of size and heart-rate constraints.

Mechanical support does not replace nursing assessment — it changes the failure mode. Watch for harlequin syndrome on VA-ECMO with residual native cardiac output and lung failure, differential hypoxia, and rising lactate that signals inadequate support or cannula malposition.

Priority Nursing Actions

1. Recognize early using age norms, lactate trend, ScvO2/NIRS, urine output, and the cold-wet exam — escalate before frank hypotension.
2. Support airway and oxygen delivery: supplemental O2, consider noninvasive or invasive ventilation for pulmonary edema and work of breathing; minimize oxygen demand (treat fever, control pain/agitation carefully).
3. Vascular access and monitoring: reliable arterial pressure, central venous access for vasoactives and ScvO2 sampling when used, continuous ECG for arrhythmia triggers.
4. Titrate vasoactives on dedicated lines; never bolus flush a vasoactive lumen into the patient; use smart pumps and independent double-checks.
5. Fluid discipline: small, goal-directed aliquots only; prefer blood products for anemia that limits oxygen content.
6. Afterload and congestion care: head-of-bed elevation as tolerated, careful diuresis once perfusion allows, avoid abrupt SVR spikes from cold stress or uncontrolled pain.
7. Family communication: explain shock, medication purpose, and possible ECMO/VAD escalation in plain language; involve child life when developmentally appropriate.

Cardiogenic shock questions on the CCRN-Pediatric exam reward matching the high-filling-pressure, low-output profile to inotropy without indiscriminate volume, age-correct vital-sign interpretation, and knowing when the next step is mechanical support, not another fluid bolus.