Conceptual Overview

Shock is inadequate oxygen delivery to meet metabolic demand. In pediatrics, the challenge is that children are exceptional compensators. A child in shock can maintain normal blood pressure through tachycardia and increased systemic vascular resistance long after an adult with the same degree of volume loss would be hypotensive.

This is both the gift and the curse of pediatric physiology. It gives you a window of time to intervene - but it also means the vital signs can look deceptively normal until sudden cardiovascular collapse occurs. Your job is to recognize compensated shock (normal BP with signs of poor perfusion) before it becomes decompensated shock (hypotension = cardiovascular failure).

Hypotension in a child = late finding: By the time a child is hypotensive, they may have lost 25-30% of their circulating blood volume and their compensatory mechanisms have failed. Treat compensated shock aggressively. Don't wait for blood pressure to drop - look for the earlier signs: tachycardia at rest, prolonged capillary refill, cool/mottled extremities, weak distal pulses, and altered mental status (irritability, then lethargy).

Compensated vs. Decompensated Shock

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Feature	Compensated Shock	Decompensated Shock
Blood pressure	Normal for age	Hypotension (SBP < 5th percentile)
Heart rate	Tachycardia (compensatory)	Tachycardia or bradycardia (ominous)
Mental status	Irritable, anxious, restless	Lethargic, obtunded, unresponsive
Capillary refill	Prolonged (3-5 seconds)	Markedly prolonged (>5 seconds) or absent
Skin	Cool extremities, mottled, pale	Gray, cyanotic, cold throughout
Pulses	Central strong, peripheral weak	Central weak, peripheral absent
Urine output	Decreased	Minimal/absent
Intervention window	Time to intervene - act NOW	Impending arrest - emergent intervention

Check capillary refill on the sternum, not the finger: Peripheral capillary refill (tested on a finger or toe) is affected by ambient temperature - a cold ED bay can produce falsely prolonged cap refill. Central capillary refill tested on the sternum or forehead is a more reliable indicator of true perfusion status. Normal is <2 seconds. >3 seconds in a warm environment is concerning.

Hypovolemic Shock

Most common type of pediatric shock worldwide. Caused by decreased circulating blood volume from hemorrhage, dehydration (vomiting/diarrhea), or third-spacing (burns, sepsis).

Common Causes

Diarrhea/vomiting: #1 cause globally; can produce severe dehydration rapidly in infants due to high body surface area:volume ratio
Hemorrhage: Trauma, GI bleeding, surgical
Burns: Massive fluid shifts in the first 24 hours
DKA: Osmotic diuresis leading to profound dehydration

Management

Volume resuscitation: 20 mL/kg isotonic crystalloid (NS or LR) bolus over 5-20 minutes
Reassess after each bolus: Heart rate, capillary refill, mental status, urine output
Repeat boluses: Up to 60 mL/kg in the first hour if needed (3 boluses of 20 mL/kg)
Hemorrhagic: If no improvement after 40-60 mL/kg crystalloid, transition to blood products (10-20 mL/kg pRBCs)
Control the source: Stop external bleeding, surgical consultation for internal hemorrhage

Push the bolus: "20 mL/kg over 5-20 minutes" means push it. A 10 kg infant needs 200 mL of NS given rapidly - this won't happen by gravity drip. Use a 60 mL syringe and push-pull technique through a stopcock, or use a pressure bag on the fluid. In shock, slow drips don't resuscitate - they just keep the IV running.

Dehydration assessment: Mild (3-5%): slightly dry mucous membranes, normal vitals. Moderate (6-9%): tachycardia, decreased tears, sunken fontanelle (infants), delayed cap refill. Severe (≥10%): hypotension, altered mental status, absent tears, significantly sunken eyes/fontanelle, mottled skin. Severe dehydration = hypovolemic shock.

Distributive Shock (Septic)

Distributive shock is caused by inappropriate vasodilation leading to relative hypovolemia. In pediatrics, septic shock is by far the most common type of distributive shock. Anaphylaxis and neurogenic shock also cause distributive shock but are less common.

Warm vs. Cold Septic Shock

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Feature	Warm Shock (Vasodilated)	Cold Shock (Vasoconstricted)
Extremities	Warm, flushed, pink	Cool, pale, mottled
Capillary refill	Flash (<1 second)	Prolonged (>3 seconds)
Pulses	Bounding	Weak, thready
Pulse pressure	Wide	Narrow
Primary problem	Low SVR (vasodilation)	Low CO + high SVR
First-line vasopressor	Norepinephrine (vasoconstriction)	Epinephrine (inotropy + vasopressor)
More common in	Adults, older children	Infants, younger children

Septic Shock Management (First Hour)

0-5 minutes: Recognize shock → obtain IV/IO access → draw labs (blood culture, lactate, glucose, CBC, BMP)
5-15 minutes: 20 mL/kg NS bolus × 3 PRN (up to 60 mL/kg in first hour). Give antibiotics within 1 hour of recognition
15-60 minutes: If fluid-refractory (still in shock after 40-60 mL/kg), start vasopressors:
- Cold shock → epinephrine 0.1-1 mcg/kg/min
- Warm shock → norepinephrine 0.1-2 mcg/kg/min
Consider: Stress-dose hydrocortisone (2 mg/kg, max 100 mg) for catecholamine-resistant shock or known adrenal insufficiency

Antibiotics within 1 hour - no exceptions: Every hour of delay in antibiotic administration in septic shock increases mortality by approximately 7-8%. Draw blood cultures, but do NOT delay antibiotics waiting for culture results. Broad-spectrum coverage (e.g., ceftriaxone + vancomycin for most pediatric patients) should be given as soon as septic shock is recognized. The clock starts at recognition, not at culture results.

Cardiogenic & Obstructive Shock

Cardiogenic Shock

Caused by pump failure - the heart cannot generate adequate cardiac output. Less common in pediatrics than in adults, but important causes include:

Myocarditis: Viral (often Coxsackievirus B) - presents with vague symptoms (fatigue, poor feeding) then sudden decompensation
Congenital heart disease: Ductal-dependent lesions presenting in the first 1-2 weeks of life as the ductus arteriosus closes
Arrhythmias: SVT is the most common arrhythmia causing shock in infants
Post-cardiac surgery: Low cardiac output syndrome

Do NOT fluid-overload cardiogenic shock: Unlike hypovolemic and septic shock, large-volume fluid boluses in cardiogenic shock can worsen pulmonary edema and further impair cardiac function. Give cautious 5-10 mL/kg fluid boluses with careful reassessment. If there's any clinical suspicion of cardiogenic shock (hepatomegaly, pulmonary crackles, elevated JVP), start inotropic support (milrinone, dobutamine) early rather than pushing fluids.

The neonate with "sepsis" who isn't getting better: A neonate (1-3 weeks old) presenting with poor feeding, tachypnea, gray color, and shock is often treated as sepsis. If they don't respond to fluids and antibiotics, think ductal-dependent congenital heart disease. Start a prostaglandin E1 (PGE1) infusion at 0.05-0.1 mcg/kg/min to reopen the ductus arteriosus. This can be lifesaving. Side effects to monitor: apnea (have BVM ready), hypotension, fever.

Obstructive Shock

Mechanical obstruction to blood flow - the heart wants to pump but can't fill or eject effectively.

Tension pneumothorax: Needle decompression followed by chest tube. Listen for absent breath sounds. Don't wait for confirmatory X-ray in an unstable patient
Cardiac tamponade: Pericardiocentesis. Beck's triad (hypotension, muffled heart sounds, JVD). May be post-traumatic or from malignancy
Massive pulmonary embolism: Rare in children but increasing with central line use. Consider tPA
Ductal-dependent cardiac lesions: Overlaps with cardiogenic; PGE1 is the treatment

Key Labs & Monitoring

Lactate: The single best lab marker for tissue perfusion. Normal <2 mmol/L. >4 mmol/L = severe tissue hypoperfusion. Trending lactate clearance (target >10% decrease per hour) is more useful than a single value
Blood glucose: Check immediately in ALL sick children. Hypoglycemia is common and easily treatable. Treat <60 mg/dL with D10W 5 mL/kg IV
VBG/ABG: pH and base deficit quantify acidosis severity. Base deficit >-6 suggests significant shock
Blood cultures: Draw before antibiotics but don't delay antibiotics to draw cultures
CBC, BMP, coags: Baseline for trending and identifying coagulopathy (DIC in septic shock)
Urine output: Target ≥1 mL/kg/hr (infants), ≥0.5 mL/kg/hr (older children). Foley catheter for accurate measurement in critically ill patients

Lactate clearance > single value: A single lactate of 4 mmol/L tells you the child is in shock. A lactate that dropped from 8 to 4 over 2 hours tells you they're responding to treatment. A lactate that rose from 4 to 6 tells you they're getting worse despite your interventions. Trend it. Repeat it every 1-2 hours during active resuscitation.

Quick Reference

Fluid Resuscitation

Bolus: 20 mL/kg NS or LR over 5-20 min
Reassess after each bolus
Up to 60 mL/kg in first hour for hypovolemic/septic shock
Cardiogenic shock: Cautious 5-10 mL/kg boluses only
Hemorrhagic: Switch to pRBCs after 40-60 mL/kg crystalloid

Vasopressors

Cold shock: Epinephrine 0.1-1 mcg/kg/min
Warm shock: Norepinephrine 0.1-2 mcg/kg/min
Cardiogenic: Milrinone 0.375-0.75 mcg/kg/min or Dobutamine 5-20 mcg/kg/min
Catecholamine-resistant: Consider stress-dose hydrocortisone 2 mg/kg (max 100 mg)

Hypotension Thresholds

Term neonate: SBP <60
Infant (1-12 mo): SBP <70
Child (1-10 yr): SBP <70 + (2 × age)
Adolescent (>10 yr): SBP <90

Clinical Pearls

"Treat the patient, not the number": A child with a blood pressure of 85/50 who is interactive, has brisk capillary refill, and strong pulses is perfusing adequately. A child with a blood pressure of 95/60 who is listless with mottled skin and weak pulses is in compensated shock despite a "normal" BP. Perfusion parameters (cap refill, pulse quality, mental status, urine output) matter more than any single number.

The "toilet sign": One of the most underappreciated assessments of pediatric hydration status is asking the parent: "When was the last wet diaper?" or "How many times has your child urinated today?" Decreased urine output is an early, sensitive marker of dehydration and reduced renal perfusion. Fewer than 3-4 wet diapers in 24 hours (for an infant) is always concerning.

Warm up your fluids: Large-volume crystalloid resuscitation with room-temperature or cold fluids in a small child can rapidly induce iatrogenic hypothermia. Hypothermia worsens coagulopathy, impairs cardiac function, and increases oxygen demand (shivering). Use a fluid warmer when giving >40 mL/kg, and monitor core temperature during aggressive resuscitation.

Point-of-care ultrasound (POCUS) is your friend: Bedside cardiac ultrasound can differentiate hypovolemic shock (hyperdynamic, small LV, collapsing IVC) from cardiogenic shock (poorly contractile, dilated LV, distended IVC) in minutes. This distinction fundamentally changes your management. If you have the skill and the probe, use it early.

References

Ralston M, Hazinski MF, et al. Pediatric Advanced Life Support (PALS) Provider Manual. American Heart Association; 2020.
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. Pediatr Crit Care Med. 2020;21(2):e52-e106.
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. Crit Care Med. 2017;45(6):1061-1093.
Advanced Pediatric Life Support (APLS): The Pediatric Emergency Medicine Resource. 6th ed. Jones & Bartlett Learning; 2020.
Topjian AA, Raymond TT, Atkins D, et al. Part 4: Pediatric Basic and Advanced Life Support: 2020 AHA Guidelines. Circulation. 2020;142(16_suppl_2):S469-S523.

Pediatric Shock