11.2 Pediatric Shock, Dehydration & Weight-Based Dosing
Key Takeaways
- Compensated shock in pediatric patients manifests with tachycardia and poor peripheral perfusion, while blood pressure remains normal; hypotension is a late, catastrophic sign of decompensated shock.
- The minimum acceptable systolic blood pressure for children aged 1 to 10 years is calculated using the formula: 70 + (2 x Age in years).
- First-line fluid resuscitation involves a 20 mL/kg bolus of isotonic crystalloid (0.9% NS or LR) over 5-20 minutes, administered using a rapid push-pull syringe technique.
- For fluid-refractory septic shock, epinephrine (0.05-0.3 mcg/kg/min) is the primary agent for cold shock, whereas norepinephrine is preferred for warm shock.
- Pediatric cardiac arrest defibrillation starts at 2 J/kg, escalating to 4 J/kg, with IV/IO epinephrine administered at 0.01 mg/kg (0.1 mL/kg of 0.1 mg/mL concentration).
Pediatric Shock, Dehydration & Weight-Based Dosing
Shock in pediatric critical care is defined as a state of acute circulatory failure resulting in inadequate systemic tissue perfusion and oxygen delivery to meet metabolic demands. Pediatric patients possess robust compensatory mechanisms—specifically intense peripheral vasoconstriction and marked tachycardia—that maintain normal blood pressure despite significant intravascular volume depletion. Consequently, transport paramedics must recognize early physiological markers of shock before cardiovascular collapse occurs.
Pediatric Shock Classification & Pathophysiology
Pediatric shock progresses through distinct stages: Compensated, Decompensated, and Irreversible.
Compensated vs. Decompensated Shock
[ Compensated Shock ] [ Decompensated Shock ]
• Tachycardia (earliest sign) • Hypotension (LATE CATASTROPHIC SIGN!)
• Delayed Cap Refill (>2 sec) • Weak/Absent Central Pulses
• Cool, Pale, Mottled Extremities • Marked Lethargy / Stupor
• Diminished Peripheral Pulses • Anuria / Oliguria
• Normal Systolic Blood Pressure • Immittent Cardiac Arrest
CRITICAL PARAMEDIC PRINCIPLE: Hypotension is a LATE sign of shock in pediatric patients! A child can lose up to 25–35% of circulating blood volume before blood pressure drops. Once hypotension occurs, cardiovascular collapse and cardiac arrest can occur within minutes.
Minimum Acceptable Systolic Blood Pressure Formulas
To rapidly evaluate for decompensated shock, paramedics must calculate age-specific minimum acceptable systolic blood pressure (5th percentile SBP):
| Age Group | Minimum Acceptable Systolic Blood Pressure (mmHg) |
|---|---|
| Term Neonates (0–28 days) | $<60\text{ mmHg}$ |
| Infants (1–12 months) | $<70\text{ mmHg}$ |
| Children (1–10 years) | $< 70 + (2 \times \text{Age in years})\text{ mmHg}$ |
| Children ($>10$ years) | $<90\text{ mmHg}$ |
Calculation Example: For a 6-year-old child, the minimum acceptable SBP is $70 + (2 \times 6) = 82\text{ mmHg}$. A SBP below $82\text{ mmHg}$ indicates decompensated shock requiring immediate, aggressive fluid and vasopressor intervention.
Fluid Resuscitation & Delivery Techniques
Initial resuscitation for hypovolemic and septic shock focuses on restoring intravascular volume.
Isotonic Fluid Dosing Guidelines
- Fluid Choice: Isotonic crystalloid solutions (0.9% Normal Saline or Lactated Ringer's). Avoid hypotonic fluids (e.g., D5W or 0.45% NS) for fluid resuscitation due to the risk of rapid cerebral edema.
- Bolus Volume: 20 mL/kg administered rapidly over 5 to 20 minutes.
- Reassessment: After each bolus, re-evaluate heart rate, capillary refill, mental status, lung sounds, and liver size.
- Maximum Volume: Boluses may be repeated up to 60 mL/kg total within the first hour. If shock persists after $40–60\text{ mL/kg}$, initiate vasoactive drug support immediately.
Special Consideration: In cardiogenic shock or suspected diabetic ketoacidosis (DKA), fluid boluses are reduced to 5 to 10 mL/kg over 30–60 minutes to prevent acute pulmonary edema or cerebral edema.
The Push-Pull Technique for Rapid Fluid Administration
Standard gravity IV drip lines or volumetric infusion pumps cannot deliver fluid fast enough during pediatric resuscitation. The push-pull technique ensures rapid, precise volume delivery:
- Connect a 3-way stopcock between the IV catheter extension set and the isotonic crystalloid bag.
- Attach a 20 mL to 60 mL syringe to the side port of the stopcock.
- Turn the stopcock off to the patient and draw fluid from the bag into the syringe.
- Turn the stopcock off to the bag and manually push the fluid into the patient.
- Repeat until the target $20\text{ mL/kg}$ volume is delivered.
Vasoactive Inotropic & Vasopressor Support in Pediatric Septic Shock
When septic shock remains refractory to $40-60\text{ mL/kg}$ of fluid resuscitation, vasoactive continuous infusions are indicated. Pediatric septic shock presents as either Cold Shock (low cardiac output, high SVR) or Warm Shock (high cardiac output, low SVR).
Pediatric Vasopressor & Inotrope Dosing Table
| Clinical Phenotype | First-Line Vasoactive Agent | Dosage & Administration | Mechanism & Action |
|---|---|---|---|
| Cold Shock (Cold extremities, delayed cap refill, poor pulses, low cardiac output) | Epinephrine Infusion | $0.05 - 0.3\text{ mcg/kg/min}$ continuous IV/IO infusion | $\beta_1$ and $\alpha_1$ agonist; increases cardiac contractility, rate, and systemic vascular resistance. |
| Warm Shock (Warm flushed skin, flash cap refill, bounding pulses, low SVR) | Norepinephrine Infusion | $0.05 - 0.3\text{ mcg/kg/min}$ continuous IV/IO infusion | Potent $\alpha_1$ agonist with modest $\beta_1$ activity; increases SVR and restores mean arterial pressure (MAP). |
| Refractory Adrenal Insufficiency | Hydrocortisone | $2\text{ mg/kg}$ IV/IO bolus (max 100 mg) | Indicated for fluid-refractory, catecholamine-resistant shock with suspected adrenal collapse. |
Pediatric Cardiac Arrest & PALS Protocols
Pediatric cardiac arrest most commonly stems from progressive hypoxia and respiratory failure (asphyxial arrest) rather than primary cardiac arrhythmias.
CPR Quality & Defibrillation Dosing
- Compression Depth: At least 1/3 the anteroposterior (AP) diameter of the chest (approx. 1.5 inches / 4 cm in infants; 2 inches / 5 cm in children).
- Compression-to-Ventilation Ratio: 15:2 for two-rescuer healthcare provider CPR.
- Defibrillation Energy Dosing (Shockable Rhythms - VF / Pulseless VT):
- First Shock: 2 J/kg
- Second Shock: 4 J/kg
- Subsequent Shocks: $\ge 4\text{ J/kg}$ up to a maximum of 10 J/kg or standard adult dose.
- Epinephrine Administration (Non-shockable & Shockable):
- Dose: 0.01 mg/kg ($0.1\text{ mL/kg}$ of the $0.1\text{ mg/mL}$ / 1:10,000 solution) IV/IO every 3 to 5 minutes. (Max single dose: 1 mg).
- Antiarrhythmics for Refractory VF/pVT:
- Amiodarone: 5 mg/kg IV/IO bolus (may repeat up to 3 times for refractory VF/pVT).
- Lidocaine: 1 mg/kg IV/IO loading dose.
Intraosseous (IO) Access Sites & Administration
When peripheral intravenous (IV) access cannot be rapidly obtained in a critically ill pediatric patient (within 90 seconds or 2 attempts), intraosseous access must be established immediately.
[ Proximal Tibia Site ]
• 1-2 cm Medial and 1 cm Distal to the Tibial Tuberosity
• Avoids Epiphyseal Growth Plate
• Flat surface of anteromedial tibia
Recommended Pediatric IO Sites
- Proximal Tibia (Primary Site): Anteromedial surface of the tibia, approximately 1–2 cm medial and 1 cm distal to the tibial tuberosity. Direct needle angled slightly caudally (away from the joint space and growth plate).
- Distal Tibia: Flat inner aspect of the tibia, 1–2 cm proximal to the prominent aspect of the medial malleolus.
- Distal Femur: Midline anterior femur, 1–2 cm above the superior border of the patella.
- Proximal Humerus: Greater tubercle of the humerus (reserved for older children with identifiable bony landmarks).
A 6-year-old pediatric patient involved in trauma displays tachycardia, cool clammy skin, delayed capillary refill of 4 seconds, and weak peripheral pulses. What is the minimum acceptable systolic blood pressure threshold for this child?
A 15 kg child with severe gastroenteritis and dehydration presents in compensated hypovolemic shock. What is the initial recommended fluid bolus volume and preferred rapid administration technique?
During resuscitation of an 8-year-old child in cardiac arrest, the monitor reveals Ventricular Fibrillation. What is the correct sequence of energy doses for the first two defibrillation attempts?