9.4 Pediatric Trauma and Resuscitation

Pediatric Trauma and Resuscitation

Pediatric Trauma Dynamics and Anatomy

Trauma remains the leading cause of mortality and morbidity in pediatric patients over the age of one. Resuscitating a pediatric trauma patient in the transport environment requires a detailed understanding of the anatomical differences that dictate injury patterns:

• Compliant Thoracic Cage: The pediatric rib cage is highly compliant, composed largely of cartilage. As a result, blunt force trauma (e.g., motor vehicle collisions, pedestrian strikes) is transmitted directly to the underlying thoracic organs without fracturing the ribs. A flight paramedic can encounter severe pulmonary contusions, hemothoraces, or tension pneumothoraces in a child with absolutely no external signs of trauma or rib fractures.
• Multi-System Trauma: Because children have a smaller body mass, kinetic energy from trauma is distributed over a smaller body surface area. This results in a much higher incidence of multi-system injury (e.g., concurrent head trauma, thoracic injury, and intra-abdominal hemorrhage) compared to adults.
• Intra-abdominal Vulnerability: The pediatric liver and spleen are relatively larger, sit lower below the costal margin, and are less protected by the thin abdominal wall musculature and compliant ribs. This makes them highly vulnerable to blunt abdominal trauma. The majority of solid-organ injuries (spleen and liver) in hemodynamically stable children are managed non-operatively, but they require close monitoring for delayed hemorrhage during flight.
• SCIWORA (Spinal Cord Injury Without Radiologic Abnormality): The pediatric spinal column is highly elastic and can stretch up to 2 inches (5 cm) without disruption. However, the spinal cord itself is relatively inelastic and cannot stretch. This anatomical disparity allows the vertebral column to slide or stretch and then recoil without sustaining fractures or ligamentous disruption visible on plain radiographs or CT scans, while the underlying spinal cord suffers transient or permanent ischemic or shearing injury. SCIWORA is unique to pediatric patients and requires strict spinal immobilization when a neurologic deficit is present.
• Head Trauma: Children have a large head-to-body ratio, which acts as a fulcrum during deceleration, predisposing them to high-cervical spine injuries and traumatic brain injury (TBI). The thin skull provides less protection to the brain. In infants with open fontanelles, intracranial bleeding can accumulate in large volumes before signs of increased intracranial pressure (ICP) manifest, leading to occult hemorrhagic shock originating solely from the head.

Fluid Resuscitation and the 4-2-1 Maintenance Rule

Fluid resuscitation in pediatric trauma must be precise to avoid the complications of over-resuscitation (ARDS, abdominal compartment syndrome) and under-resuscitation (hypoperfusion, organ failure).

Crystalloid Resuscitation

• Initial Bolus: If signs of hypoperfusion or hemorrhagic shock are present, administer 20 mL/kg of a warm isotonic crystalloid (Lactated Ringer's is preferred to reduce the risk of hyperchloremic metabolic acidosis associated with Normal Saline).
• Titration: Reassess the patient's heart rate, capillary refill, mental status, and blood pressure. A second or third 20 mL/kg bolus (up to a total of 40-60 mL/kg) may be administered if perfusion remains inadequate.

Blood Product Resuscitation

• PRBCs/Whole Blood: If the patient remains hemodynamically unstable after 40-60 mL/kg of crystalloids, or has obvious massive hemorrhage, immediately transition to blood products. Administer 10 mL/kg of packed red blood cells (PRBCs) or 10-20 mL/kg of reconstituted whole blood.
• Massive Transfusion Protocol (MTP): For severe, ongoing hemorrhage, initiate MTP with a 1:1:1 ratio of PRBCs, Fresh Frozen Plasma (FFP), and Platelets. Administer in cycles of 10-20 mL/kg of the combined products to prevent dilutional coagulopathy and hypocalcemia (secondary to citrate toxicity; monitor ionized calcium levels and administer calcium chloride or gluconate as indicated).

Maintenance Fluids: The 4-2-1 Rule

For pediatric patients requiring maintenance IV fluids during transport, calculate the hourly rate using the 4-2-1 Rule:

• 4 mL/kg/hr for the first 10 kg of body weight.
• 2 mL/kg/hr for the next 10 kg of body weight (weights 11-20 kg).
• 1 mL/kg/hr for each kilogram of body weight above 20 kg.
• Example: For a 26 kg child:
  • First 10 kg: $10 \times 4 = 40\text{ mL/hr}$
  • Next 10 kg: $10 \times 2 = 20\text{ mL/hr}$
  • Remaining 6 kg: $6 \times 1 = 6\text{ mL/hr}$
  • Total Maintenance Rate: $40 + 20 + 6 = 66\text{ mL/hr}$.

The Pediatric Lethal Triad

Pediatric patients are highly vulnerable to the Lethal Triad of Trauma:

1. Hypothermia: Due to a high surface area-to-mass ratio, lack of shivering capability, and thin skin. Hypothermia causes severe vasoconstriction, shifts the oxyhemoglobin dissociation curve to the left (reducing tissue oxygen delivery), and directly impairs the enzymatic activity of the coagulation cascade.
2. Coagulopathy: Worsened by blood loss, hypothermia, hemodilution from crystalloid administration, and consumption of clotting factors.
3. Acidosis: Caused by tissue hypoperfusion and anaerobic metabolism, which generates lactic acid. Acidosis impairs myocardial contractility and decreases the efficiency of coagulation factors.

Hypothermia Mitigation in Flight

Preventing hypothermia is a primary responsibility of the flight paramedic:

• Warm the aircraft cabin to at least 24-26°C (75-78°F) prior to loading the patient.
• Wrap the patient in dry, warm blankets and a thermal barrier. Cover the head (which accounts for a large portion of heat loss in infants and young children).
• Infuse all IV/IO fluids and blood products through a commercial inline fluid warming device.

Specific Injury Management

Traumatic Brain Injury (TBI)

Hypoxia and hypotension are the primary causes of secondary brain injury in pediatric TBI.

• Oxygenation: Maintain $SpO_2 \ge 94%$. Avoid hypoxemia.
• Blood Pressure: Maintain SBP above the 5th percentile for the child's age ($70 + 2 \times \text{age}$).
• Ventilation: Target normocapnia ($PaCO_2$ of 35-40 mmHg). Hyperventilation causes cerebral vasoconstriction, which can induce severe cerebral ischemia. Only hyperventilate the patient (targeting a $PaCO_2$ of 30-35 mmHg) if there are active signs of cerebral herniation (e.g., asymmetric pupils, decerebrate posturing, Cushing's triad).

Burn Resuscitation

• TBSA Estimation: Use the Lund-Browder Chart rather than the adult Rule of Nines, as children have a disproportionately larger head and smaller lower extremities.
• Parkland Formula: Administer 3-4 mL of Lactated Ringer's $\times$ weight (kg) $\times$ %TBSA burned. Give the first half of the calculated volume over the first 8 hours (from the time of the burn injury) and the remaining half over the next 16 hours.
• Maintenance: For children weighing less than 30 kg, the flight paramedic must add hourly maintenance fluids (calculated via the 4-2-1 rule) to the Parkland resuscitation volume.
• Urine Output Targets: Monitor resuscitation adequacy via urine output. Target 1-2 mL/kg/hr in infants and young children, and 0.5-1 mL/kg/hr in children older than 12 years.