Traumatic Brain Injury

Severe traumatic brain injury (TBI) is the most common cause of death in injured children. An acceleration or deceleration injury can result in a cerebral contusion, which may be located on the same side as the impact, on the opposite side of the impact (contra-coup injury), or both. Blunt or penetrating trauma may cause an intracranial hemorrhage. A tear of the middle meningeal artery produces an epidural hematoma, and trauma that causes rupture of bridging veins results in a subdural hematoma. Any of these aforementioned injuries may produce a condition known as diffuse axonal injury (DAI), which is associated with permanent disability. Children are more susceptible to TBI because of less central nervous system (CNS) myelination, thinner and more compliant cranial bones, and a larger head-to-body ratio than adults.

Contusions and intracranial bleeds are diagnosed by computed tomography (CT). Patients with DAI and abnormal neurologic exams may initially have a normal CT scan. Cerebral edema may be evident on a subsequent scan.

TBI should be suspected in children with head trauma despite an absence of neurologic abnormalities. Indicators of occult TBI include loss of consciousness any time after the event, and multiple episodes of emesis. Sedated children with multiple injuries should be considered to have TBI because of their inability to perform a reliable neurologic exam.

Child Abuse

TBI resulting from child abuse is the leading cause of death in children under 1 year of age. This diagnosis should be considered when the child’s injuries are out of proportion to the history or the child’s developmental level. Common presenting signs include irritability, emesis, decreased level of consciousness, seizures, and coma. There may be multiple injuries at different stages of healing. Injuries may be severe and include subdural hematoma, subarachnoid hemorrhage, skull fracture or DAI with or without cerebral edema. Although state law varies, all physicians must report suspected child abuse to the proper authorities (i.e., social services, child protective services, police, etc.). Careful documentation of the history, physical examination and intraoperative findings is helpful if legal testimony is required at a later date.

Suffocation

While this category includes chocking, Sudden Infant Death Syndrome (SIDS) is the leading cause of death in children from 1 month to 1 year of age. According to the Centers for Disease Control and Prevention (CDC), 26% of SIDS deaths are caused by accidental suffocation or strangulation in bed (ASSB). In 1994 a national “Safe to Sleep Campaign” was launched to combat this epidemic. Since the initiation of “Safe to Sleep,” SIDS deaths have decreased by 50% in the United States. Over half of all infants that present with SIDS will require escalation of care and most will proceed to have significant neurologic injury from hypoxia.

Cervical Spine Injury

The incidence of spinal cord injury (SCI) in pediatric trauma is estimated to be 1%, which is lower than the adult population because of greater flexibility of the pediatric cervical spine. Any child with an unknown mechanism of injury, multisystem trauma, brain injury, or a known injury above the clavicle should be suspected to also have SCI. Approximately 50% of children with SCI have concomitant TBI. Conversely, the presence of TBI substantially increases the risk for SCI.

SCI in children is diagnosed and managed in a similar manner to adults. Radiographs of the cervical spine should include anteroposterior and lateral views that include the cervicothoracic junction (“swimmer’s view”), and views of the odontoid process of C2. However, the cervical spine cannot be “cleared” by radiographic examination without a normal neurologic exam. Therefore children with normal cervical spine radiographs should be kept immobilized until thoroughly examined because spinal cord instability and neurologic deficits may occur without a fracture. A neurologic deficit without a fracture is called SCIWORA (spinal cord injury without radiologic abnormalities). The term was coined in the pre-MRI era. We now know that most of these children will have demonstrable abnormalities on magnetic resonance imaging (MRI). SCIWORA can occur in the cervical or thoracic spinal cord, mainly in children less than 8 years of age. In about one-quarter of children with SCIWORA, the onset of the neurologic deficit is delayed. These children will initially have minor sensory or motor deficits that progress over time. The majority of SCIWORA injuries are caused by severe flexion or extension injuries of the neck that cause ligamentous stretching or disruption without bony injury. Continued immobilization and cervical spine precautions are necessary because of the possibility of evolving injury.

Other Common Injuries

The majority of thoracic trauma in children consists of blunt injuries caused by motor vehicle accidents. Adults struck by cars typically experience pelvic or lower extremity fractures because of the level of the bumper of a car. For most school age and younger children, the level of the bumper corresponds to the thorax or head. Therefore children are more likely to suffer thoracic injuries and TBI when struck by a car. Thoracic injuries are the second leading cause of death despite accounting for less than 5% of pediatric trauma. Pulmonary contusion is the most common type of thoracic injury; rib fractures are less common than in adults. Because of the relatively high compliance of the chest wall of young children (noncalcified rib cage) severe intrathoracic injuries can occur without obvious external injuries or rib fractures. As in adults, pneumothorax, hemothorax, and lung laceration are important sequelae of penetrating thoracic trauma.

Blunt abdominal trauma is primarily associated with injuries to the spleen and liver, but renal, pancreatic, and hollow viscous injuries can also occur. When a child restrained by a lap belt presents with abdominal or flank ecchymosis (lap belt sign), there is likely an abdominal injury or a horizontal fracture of a lumbar vertebral body (Chance fracture). Management of solid organ injury is largely expectant unless the child demonstrates hypotension unresponsive to resuscitative measures. Penetrating abdominal injuries usually result in intestinal injury and require surgical intervention. Extremity injuries with or without underlying vascular tears are common in children, as are complex lacerations and growth plate injuries. Simple scalp lacerations may be the cause of a significant amount of blood loss.

Attention to the quantity and quality of the urine output is important. Head trauma is associated with development of diabetes insipidus or SIADH. Direct muscle injury may result in rhabdomyolysis, which may cause myoglobinuria and lead to renal damage.

Assessment and Resuscitation

Cardiovascular Management

Primary cardiac arrest is unusual in pediatric trauma unless the child has suffered direct cardiothoracic trauma. Commotio cordis is the term given to the development of ventricular fibrillation after a sudden, intense, nonpenetrating impact on the chest wall over the anatomic location of the left ventricle. Animal studies demonstrate that the timing of this impact in relation to the cardiac cycle (between the QRS complex and the T wave) is crucial for development of this fatal complication.

Pediatric trauma commonly causes shock, which is usually classified as hypovolemic, cardiogenic, neurogenic, or septic. The traumatized, hypovolemic child presents unique physiologic patterns, in that children tend to compensate for blood loss and may retain normal vital signs until 30% to 40% of their blood volume has been lost. In other words, blood pressure may remain normal during clinically significant anemia and hypovolemia. The systolic and diastolic blood pressures may be maintained by vasoconstriction and the pulse pressure may be narrow, rather than wide, as observed during general anesthesia and neurogenic shock (owing to loss of arterial and venous peripheral tone). Hypotension and decreased urine output are more ominous signs of hypovolemic shock; however, they may not occur in children until more than 30% blood volume has been lost. Bradycardia in this setting is life-threatening, as heart rate is a major component of cardiac output in small children.

TBI can be associated with hypotension. The hypertensive component of Cushing’s triad may not be present and cerebral perfusion pressure (CPP; mean arterial pressure minus ICP or CVP, whichever is higher) may not be maintained. The minimum CPP necessary to meet metabolic demands in infants and children has not been established and is largely extrapolated from adults. In children under 6 years of age, cerebral blood flow averages 106 mL per 100 g of brain tissue, and cerebral metabolic rate averages 5.2 mL/min per 100 g of brain tissue. This is in contrast to 58 mL and 3.3 mL per 100 g of brain, respectively, in the adult, and indicates greater cerebral blood flow and metabolic requirements in children. As cerebral autoregulation can also be impaired in children with TBI, systemic blood pressure should be maintained above normal in the absence of ICP monitoring. In injured children, an increased ICP (>20 mm Hg) and decreased CPP (<50 mm Hg) are associated with a poor outcome. Additional risk factors in brain-injured children include Pa o ₂ <60 mm Hg, Pa co ₂ <25 mmHg or >45 mm Hg, and a systolic blood pressure <90 mm Hg.

Vascular access is an important and often challenging component of pediatric trauma management. A 22-gauge or larger peripheral IV catheter will suffice for induction of general anesthesia but may not be adequate for resuscitation of the child with major trauma. In the latter scenario, at least two large-bore IV catheters are recommended. Saphenous veins are larger than the peripheral veins of distal extremities and thus are commonly used to secure vascular access, either percutaneously or by surgical exposure. In an emergent situation, if peripheral access is unobtainable after three rapid attempts or duration greater than 90 seconds in young children, intraosseous (IO) access should be inserted using any large-bore needle, EZ IO or bone marrow needle. Any nontraumatized long bone may be used. The preferred site is the anteromedial surface of the proximal tibia, 2 cm below and 1 to 2 cm medial to the tibial tuberosity on the flat part of the bone. Other possible sites of insertion include the distal femur 3 cm above the lateral condyle in the midline, and the medial surface of the distal tibia 1 to 2 cm above the medial malleolus. The insertion technique entails the advancement of a large-bore needle until the periosteum of the bone is contacted. With a twisting, boring motion the needle is advanced until it is felt to penetrate into the marrow cavity by a loss of resistance. Negative aspiration of marrow does not preclude use of the intraosseous line provided that infused fluids do not extravasate into the subcutaneous tissues. If marrow is obtained, it may be sent for routine lab investigation and type-and-crossmatch. Any type of crystalloid or colloid solution may be infused into the marrow, and higher than normal infusion pressures may be required. This route of access is temporary until more definitive access can be secured.

It is important to recognize the risk for hyperkalemia in significant blood transfusion in pediatric trauma patients. Because of smaller caliber intravenous catheters, the risk for hemolysis from shearing forces is greater. This can lead to increase in the release of intracellular potassium as the cell membrane is compromised. The age of the O negative blood used must also be considered as both length of storage and irradiation can cause leaking of the intracellular potassium in to the supernatant. In infants and toddlers this potassium load from rapid infusion can quickly cause cardiac compromise and even asystole.

Central venous catheters are acceptable routes of venous access in children. The femoral vein is preferred in children with head or neck injuries; however, it is contraindicated in abdominal trauma with suspected inferior vena cava injury.

In the immediate post injury phase, aggressive fluid resuscitation is critical, as hypoperfusion and hypoxia can induce anaerobic cellular metabolism resulting in the formation of inflammatory mediators that can have significant systemic effects. There are no evidence-based data to unequivocally support either crystalloid or colloid as preferred resuscitative fluid in pediatric trauma. Initial fluid resuscitation in children consists of warmed isotonic crystalloids solution (e.g., Lactated Ringer’s) as a bolus of 20 mL/kg. If there is no physiologic response or there is evidence of persistent volume loss, a second bolus should be administered. The goal of initial crystalloid resuscitation is to rapidly achieve normal age-appropriate hemodynamic values and to restore adequate tissue perfusion. Children with evidence of hemorrhagic shock who fail to respond to initial crystalloid resuscitation efforts should receive a red blood cell transfusion (at least 10 mL/kg) and undergo immediate surgical evaluation for possible operative interventions. Hypotonic dextrose-containing crystalloid solutions should be avoided and hydroxyethyl starch administration is discouraged because it may exacerbate a coexisting coagulopathy when administered in amounts greater than 20 mL/kg. Hypertonic saline lowers intracranial pressure and improves cerebral blood flow in patients with TBI, but further study is ongoing to determine its role in pediatric trauma resuscitation.

Neurologic Assessment

In infants, the Glasgow Coma Scale (GCS) has a modified verbal component to allow a developmentally appropriate evaluation. The trend in GCS is more important than the absolute number. Pupillary examination is also an important component of the neurologic assessment. For example, pinpoint pupils indicate pontine herniation and dilated pupils suggest uncal herniation.

In the final phase of the primary survey, the entire body must be examined while avoiding hypothermia. Normothermia is maintained by increasing the room temperature, and using overhead warming lights and forced warm-air blankets.

Secondary Survey

Once the child is in stable condition, a secondary survey should be considered. The secondary survey includes a complete history and detailed full body examination to rapidly identify and begin to treat all nonlife-threatening injuries. The mnemonic AMPLE can be helpful in quickly obtaining a relatively comprehensive history of the injury mechanism, as well as preexisting medical conditions:

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  A llergies (medications, including anesthetics)

  
  
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  M edications currently used (including steroid use)

  
  
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  P ast illnesses and medical history (including recent viral illnesses)

  
  
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  L ast meal or oral intake (assume full stomach unless otherwise confirmed)

  
  
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  E vents/Environment related to the injury scene

Because of age-related communication limitations with children, such history must often be obtained from family members, others present at the injury scene, or prehospital personnel with knowledge of the injury scene and medical care provided during transport. Priorities for treatment and further diagnostic investigations (e.g., imaging and laboratory studies) can then be determined, including appropriate subspecialist consultation and decisions for operating room intervention. If the child becomes unstable at any point during the secondary survey, return to the primary survey and resuscitation.

Patient examination during the secondary survey involves exposing the child by fully undressing to assess for any hidden injuries, but with special care to avoid hypothermia. Key portions of the physical examination in injured children include the following:

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  Palpation of the skull and face for pain or deformities.

  
  
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  Careful assessment of the cervical spine for tenderness while maintaining cervical immobilization until the spine is “cleared” by a combination of physical exam and radiographic assessment; because of their more cartilaginous spine structure, young children have a higher incidence than adults of SCIWORA, and may require CT or MRI imaging rather than plain film imaging, in cases of high concern.

  
  
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  Assessment for flail chest segments, chest wall tenderness, and crepitance, as well as auscultation for poorly transmitted or asymmetric breath sounds, and for heart murmurs.

  
  
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  Abdominal examination for external signs of internal injury (e.g., “seatbelt sign”), distention, tenderness, open wounds, and presence of bowel sounds; crying children often “swallow” significant amounts of air that can lead to abdominal distention that can limit the utility of the abdominal palpation exam, and increases the risk for vomiting and aspiration.

  
  
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  Rectal examination for anal sphincter tone (e.g., absence of tone in complete spinal cord injury), prostate position, and presence of blood in the stool.

  
  
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  Perineal examination for hematoma or blood in the urethral meatus (e.g., urethral injury).

  
  
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  Careful examination of all extremities for deformity, open wounds, distal pulses, and motor/sensory function.

After the history and physical examination, blood samples are collected for hemoglobin and electrolyte assessments, and should also include coagulation studies, type and cross-match, and an arterial blood gas in the case of more severe injuries or intubated children. In older children, possible use of drugs or alcohol should be assessed by blood or urine toxicology, particularly if urgent surgical intervention and general anesthesia are planned. Hemoglobin levels sampled early in hypovolemic shock patients are not always a sensitive indicator of blood loss because hemodilution from crystalloid resuscitation may not yet have occurred.

As in adult trauma management, the recommended radiologic examination during initial assessment and stabilization of major blunt trauma include plain films of the chest, pelvis and cervical spine. In stable patients with intraabdominal injuries, the diagnostic test of choice is a rapid abdominal CT scan. Diagnostic peritoneal lavage (DPL) and “focused abdominal sonography for trauma” (FAST) can also be used to assess intraabdominal injuries, but requires operators with special expertise and training to perform and interpret these exams properly in children. Other radiologic examinations (e.g., extremity plain films) are performed based on the physical examination findings. Children with suspected child abuse injuries less than 2 years of age generally require a more complete skeletal survey including radiographs of the skull, chest, abdomen and long bones.

Preoperative Considerations

After initial resuscitation in the emergency room, children may require emergent surgical interventions to control ongoing bleeding or craniotomy for TBI. In addition, some children with acute injuries who are otherwise stable may require procedural sedation in the emergency room for diagnostic or therapeutic procedures, or for radiologic examination. Still other children may require more elective (nonemergent) surgical interventions for management of their traumatic injuries.

Because of the critical nature of certain injuries, a focused preanesthetic evaluation with a brief history should elicit information regarding allergies, medications, time of the last meal, and events (AMPLE mnemonic, see above) surrounding the injury. Except in emergent surgical cases, a thorough anesthesia-oriented physical examination should be performed with the main focus on airway, breathing, and circulation, and the extent of associated injuries and their possible impact on the conduct of the anesthetic. A general principle is that the true fasting interval is the time between the most recent meal and the traumatic event. Patients who have fasted for at least 8 hours from the time of the injury are still considered to be at risk for pulmonary aspiration of gastric contents during induction of general anesthesia because gastric emptying may be delayed by a variety of factors that include catecholamine release, opioid administration, and abdominal trauma.

Hemodynamically stable children should receive sedation and analgesia in the emergency department. Unstable children who receive only muscle relaxants to facilitate tracheal intubation may have recall of the event and should receive amnestic agents as tolerated.

Anesthetic Techniques

Before transport, the operating room should be adequately staffed and contain all age-appropriate equipment and medications, including those to facilitate the adequate management of hypovolemic shock, such as IV and intraosseous access supplies, fluid and blood warmers, a rapid transfusion system, and an age-appropriate infusion pump. The operating room should also be equipped with a defibrillator with appropriately sized paddles for both internal and external defibrillation. The ambient operating room temperature should be warmed, preferably to 26 ° C for infants and young children.

Premedication is avoided in children who are hemodynamically unstable or if increased ICP is suspected. However, in stable children, a small dose of IV midazolam can be given to facilitate separation from parents and placement of monitors before induction.

In pediatric trauma, general principles of airway management are followed, with the focus on the possibility of a difficult ventilation or intubation. Preoxygenation may be difficult to achieve in the frightened or agitated child. One has to weigh the risks and benefits of forcing preoxygenation in this setting. As in adult trauma, an IV induction technique is preferred. The choice of induction agent will depend on the child’s clinical condition and provider familiarity. Etomidate 0.2 to 0.3 mg/kg will provide a rapid onset, hemodynamic stability, and decrease the cerebral metabolic rate of oxygen consumption, which ultimately decreases cerebral blood flow and ICP. Etomidate is known to cause transient suppression of adrenocortical function; however, many providers believe its short-term benefits outweigh its potential long-term risks. Ketamine 1 to 2 mg/kg is an alternative induction agent that does not usually cause hemodynamic depression; however, it is avoided in children with possibly increased ICP. Succinylcholine should be used to rapidly obtain endotracheal intubation. Although succinylcholine has been shown to transiently increase ICP, this effect has not been shown to adversely affect the outcome in children with associated TBI. Alternatively, rocuronium 1.2 to 1.6 mg/kg may be used but will entail a greater duration of action.

A balanced anesthetic technique is most often selected for maintenance. Nitrous oxide is avoided because of its diffusion into closed spaces and exacerbation of pneumocephalus, pneumothorax, and bowel distention, and the possibility that it may increase intracranial pressure. Isoflurane and sevoflurane have similar effects on cerebral autoregulatory capacity. IV fentanyl 2 to 20 μg/kg, or morphine 0.1 to 0.2 mg/kg, may be administered as a bolus during induction of general anesthesia, or in divided doses or continuous infusion (fentanyl 1–4 μg/kg/h; morphine 10–40 μg/kg/h) during maintenance. Remifentanil is more easily titratable during periods of hemodynamic instability. Neuromuscular blockade can be achieved with any nondepolarizing neuromuscular blocker. It is important to consider possible awareness as the child’s depth of anesthesia is balanced with his or her hemodynamic status.

Monitoring

In the severely traumatized child, direct arterial access is recommended for continuous monitoring of blood pressure and facilitation of blood sampling. Central venous pressure monitoring can be used to follow trends in intravascular volume status. Urine volume and content should be continuously monitored. Intracranial pressure monitoring can be useful for detecting and monitoring increased ICP, but outcome studies of its use in children have not been performed. A study in adults did not demonstrate a benefit in overall survival. Continuous temperature monitoring is essential because of the high likelihood of hypothermia in trauma patients. Intentional hypothermia as a brain protection strategy is not currently advocated in children. Coagulopathy occurs early in severe trauma and should be treated expectantly.

Glucose

When cerebral ischemia occurs in the presence of hyperglycemia, anaerobic metabolism produces accumulation of excess lactic acid, which can worsen neurologic injury. In a retrospective study of the relationship between serum glucose on admission and outcome after TBI in children, hyperglycemia (glucose >250 mg/100 mL) was associated with worse outcomes. There are no prospective controlled trials that have determined the relationship between serum glucose and outcome in pediatric trauma patients. However, sustained hyperglycemia should be treated aggressively.

Because of the increased metabolic demand of the pediatric patient, nutrition should be started as soon as possible in the postoperative period. Enteral feeding has demonstrated superior metabolic matching compared with parenteral feeding, but is not always feasible with bowel or thoracic injuries. If possible, placement of feeding tubes (nasogastric) as soon as safely possible to minimize lean muscle mass loss is critical.

Classification

Burns are classified according to percentage body surface area (BSA) involved and depth ( Fig. 37.1 ). The total percentage BSA derives from the “Rule of Nines,” which is different in children than in adults because the pediatric head accounts for a larger percentage of BSA. The depth of the burn is classified as first-, second-, or third-degree ( Table 37.2 ).

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