# Pediatric Shock: Recognition and Resuscitation

## Introduction

Shock in children is a clinical state of inadequate tissue perfusion and oxygen delivery relative to metabolic demand. Unlike adults, children maintain blood pressure until late in the decompensation process due to robust sympathetic compensatory mechanisms. This makes early recognition of compensated shock critical, as progression to decompensated shock carries significantly higher morbidity and mortality. The pediatric clinician must be adept at identifying subtle signs of poor perfusion before hemodynamic collapse occurs.

## Classification of Pediatric Shock

| Type | Preload | SVR | Cardiac Output | Common Causes | First-Line Treatment |
|------|---------|-----|---------------|---------------|---------------------|
| Hypovolemic | Decreased | Increased | Decreased | Hemorrhage, dehydration, burns | Isotonic crystalloid 20 mL/kg boluses |
| Distributive (septic) | Decreased (relative) | Decreased (warm) or Increased (cold) | Variable | Sepsis, anaphylaxis, neurogenic | Fluids + vasopressors (epi or norepi) |
| Cardiogenic | Increased | Increased | Decreased | Myocarditis, CHD, arrhythmia | Cautious fluids (5-10 mL/kg), inotropes |
| Obstructive | Variable | Increased | Decreased | Tension pneumo, tamponade, PE, ductal lesions | Treat underlying cause (PGE1 for ductal) |

### Hypovolemic Shock

Hypovolemic shock is the most common type in the pediatric population worldwide. Causes include hemorrhage, dehydration from gastroenteritis, burns, and third-spacing. It is characterized by decreased preload, increased systemic vascular resistance (SVR), and decreased cardiac output. Clinical signs include tachycardia, poor skin turgor, dry mucous membranes, delayed capillary refill, and a sunken fontanelle in infants.

### Distributive Shock

Distributive shock results from inappropriate vasodilation leading to relative hypovolemia. It includes septic shock (the most common form in the PICU), anaphylactic shock, and neurogenic shock. Septic shock may present as warm shock (early, vasodilated, with bounding pulses) or cold shock (late, vasoconstricted, with thready pulses). Notably, cold shock is more common than warm shock in pediatric sepsis, differing from the adult pattern.

### Cardiogenic Shock

Cardiogenic shock is caused by myocardial dysfunction leading to decreased cardiac output. Etiologies include myocarditis, cardiomyopathy, congenital heart disease, arrhythmias, and post-cardiac surgery states. Signs include hepatomegaly, jugular venous distension, gallop rhythm, and pulmonary edema. Fluid resuscitation must be cautious, with 5-10 mL/kg boluses and frequent reassessment.

### Obstructive Shock

Obstructive shock involves mechanical obstruction to cardiac output from tension pneumothorax, cardiac tamponade, massive pulmonary embolism, or ductal-dependent congenital heart lesions. It requires identification and treatment of the underlying cause. Prostaglandin E1 infusion is life-saving for ductal-dependent lesions in neonates.

<image>Diagram illustrating the four types of pediatric shock (hypovolemic, distributive, cardiogenic, obstructive) with corresponding hemodynamic profiles showing preload, afterload, and cardiac output changes for each type</image>

## Recognition: Compensated vs. Decompensated Shock

### Compensated Shock

In compensated shock, blood pressure is maintained through increased heart rate and SVR. Tachycardia is often the earliest sign. Subtle findings include prolonged capillary refill (greater than 2 seconds), cool extremities, mottled skin, altered mental status (irritability or lethargy), and decreased urine output (less than 1 mL/kg/hr in infants). The window of opportunity for intervention is during this phase.

### Decompensated Shock

Hypotension is a late and ominous sign in children. Hypotension thresholds are systolic BP less than 60 mmHg in neonates, less than 70 mmHg in infants aged 1-12 months, less than 70 plus (2 times age in years) mmHg in children aged 1-10 years, and less than 90 mmHg in children over 10 years. Decompensated shock represents failure of compensatory mechanisms and progresses rapidly to cardiopulmonary arrest if not immediately addressed.

<image>Clinical photograph comparison showing a well-perfused child versus a child in compensated shock with mottled skin, demonstrating the subtle signs of poor peripheral perfusion including skin color changes and capillary refill assessment technique</image>

## Resuscitation Approach

### Initial Assessment and Stabilization

The Pediatric Assessment Triangle (PAT) evaluates appearance, work of breathing, and circulation to skin and is performed in the first 30 seconds. Airway, breathing, and circulation are assessed simultaneously with vascular access (two large-bore peripheral IVs or intraosseous access if IV is not obtained within 90 seconds). Supplemental oxygen is provided to all patients in shock.

### Fluid Resuscitation

Isotonic crystalloid (normal saline or lactated Ringer's) is administered as a 20 mL/kg bolus over 5-20 minutes. After each bolus, the patient is reassessed using heart rate, blood pressure, capillary refill, mental status, and urine output. Up to 60 mL/kg may be given in the first hour for septic and hypovolemic shock. The FEAST trial demonstrated that in resource-limited settings with febrile illness, aggressive fluid boluses may increase mortality, underscoring that context matters in resuscitation decisions.

### Vasoactive Support

| Agent | Dose Range | Indication | Mechanism |
|-------|-----------|------------|-----------|
| Epinephrine | 0.05-0.3 mcg/kg/min | Cold shock (first-line) | Inotropy + vasoconstriction |
| Norepinephrine | 0.05-1 mcg/kg/min | Warm shock (first-line) | Vasoconstriction + inotropy |
| Dopamine | 5-20 mcg/kg/min | Second-line (falling out of favor) | Dose-dependent receptor activity |
| Milrinone | 0.25-0.75 mcg/kg/min | Cardiogenic shock, post-cardiac surgery | Inodilator (PDE3 inhibitor) |

Vasoactive agents are initiated if shock is fluid-refractory (persistent signs after 40-60 mL/kg). Epinephrine at 0.05-0.3 mcg/kg/min is first-line for cold shock (low cardiac output, high SVR). Norepinephrine at 0.05-1 mcg/kg/min is first-line for warm shock (vasodilatory). Dopamine has fallen out of favor as a first-line agent due to inconsistent pharmacodynamics in children. Milrinone should be considered for cardiogenic shock or post-cardiac surgery as an inodilator.

### Monitoring and Endpoints of Resuscitation

Targets include heart rate normalization, capillary refill less than 2 seconds, warm extremities, and normal mental status. Urine output goals are greater than 1 mL/kg/hr in infants and greater than 0.5 mL/kg/hr in older children. Lactate clearance greater than 10% per hour serves as a marker of improving tissue perfusion. Central venous oxygen saturation (ScvO2) greater than 70% is targeted in septic shock. Point-of-care ultrasound (POCUS) assists with cardiac function assessment and IVC collapsibility evaluation.

<image>Flowchart depicting the stepwise resuscitation algorithm for pediatric shock, starting from initial recognition through fluid boluses, reassessment checkpoints, escalation to vasoactive agents, and decision points for intubation and central access</image>

## Special Considerations

### Septic Shock

The Surviving Sepsis Campaign pediatric guidelines emphasize early antibiotics within 1 hour and blood cultures before antibiotics when feasible. Hydrocortisone (stress-dose steroids) is indicated for catecholamine-resistant shock or suspected adrenal insufficiency. The risk of adrenal crisis should be considered in children on chronic corticosteroids.

### Neonatal Shock

Neonatal shock has unique etiologies including ductal-dependent cardiac lesions, inborn errors of metabolism, and neonatal sepsis (Group B Streptococcus, E. coli). A hyperoxia test helps differentiate cyanotic heart disease from pulmonary disease. There should be a lower threshold for prostaglandin E1 initiation.

## Clinical Pearls

Tachycardia is the earliest and most sensitive sign of shock in children, and unexplained tachycardia should never be dismissed. Hypotension is a late finding, and clinicians should not wait for it to diagnose shock. Cold shock (vasoconstricted) is more common than warm shock in pediatric sepsis, differing from the adult pattern. Intraosseous access is a rapid, reliable alternative when peripheral IV access fails, and resuscitation should not be delayed. Cardiogenic shock should always be considered before aggressive fluid loading, and bedside echocardiography can guide management. The Pediatric Assessment Triangle provides a rapid, hands-off first impression that can identify shock within seconds.

## References

1. Davis AL, Carcillo JA, Aneja RK, et al. American College of Critical Care Medicine Clinical Practice Parameters for Hemodynamic Support of Pediatric and Neonatal Septic Shock. *Critical Care Medicine*. 2017;45(6):1061-1093.
2. Weiss SL, Peters MJ, Alhazzani W, et al. Surviving Sepsis Campaign International Guidelines for the Management of Septic Shock and Sepsis-Associated Organ Dysfunction in Children. *Pediatric Critical Care Medicine*. 2020;21(2):e52-e106.
3. Maitland K, Kiguli S, Opoka RO, et al. Mortality after fluid bolus in African children with severe infection (FEAST trial). *New England Journal of Medicine*. 2011;364(26):2483-2495.
4. American Heart Association. Pediatric Advanced Life Support (PALS) Provider Manual. 2020 Edition.