Clinical and Health Affairs
Pediatric Trauma—Unique Considerations in Evaluating and Treating Children
By Jeffrey S. Schiff, M.D., Brian Moore, M.D., and Jeff Louie, M.D.
Abstract
In Minnesota, accidental traumatic injury remains the leading cause of death and disability among people ages 1 through middle age. Trauma care providers who treat children must be aware of fundamental differences between pediatric patients and adults. The intent of this article is to provide readers with a primer on some of the clinical issues surrounding the anatomy and physiology of children, the key aspects of pediatric triage, and current perspectives on early treatment of children with traumatic injuries.
Trauma has long been recognized as the leading public health problem in our country.1-3 Although great strides to prevent and mitigate the effects of trauma have been made through the use of child and adult passenger vehicle restraints, improvements in roadway engineering (banked curves, guard rails, and divided highways), and fire safety requirements (such as installing smoke detectors and egress windows in all bedrooms), the potential for sustaining a traumatic injury remains too great. Workable strategies to avoid injury (primary prevention) or mitigate against more severe injury (secondary prevention) are yet to be developed.
In Minnesota, as in the rest of the nation, accidental traumatic injury remains the leading cause of death and disability among people ages 1 through 45. Motor vehicle crashes are the primary mechanism for fatal injury, followed by crashes involving vehicles and pedestrians, falls, and drownings. The second and third leading causes of death among adolescents are suicide and homicide.
Beyond the tragedy associated with fatal injuries is the toll of nonfatal trauma. It is estimated that 1 in 3 children seeks medical care for an injury each year.1 Of those, some require emergency room visits or hospitalization. In Minnesota in 2002, 101,412 children (birth to age 19) were seen in emergency departments for treatment of an injury, 5,016 were hospitalized, and 295 died from the results of an injury. 4
In addition to the cost of medical care, the burden of injury includes the psychosocial impact, the economic costs, and the adjustments families must make to care for their children day to day—realities that are often not considered when discussing the cost of injury. Lifelong disability and decreased productivity magnify the impact of childhood injury on our society. These terribly high costs make effective care of pediatric trauma victims a critical issue.
The subject of pediatric trauma care is beyond the scope of a single paper. Thus, the intent of this article is to orient the reader to some of the unique clinical issues surrounding the anatomy and physiology of children, the key aspects of pediatric triage, and current perspectives on early treatment of children with traumatic injuries.
Anatomy and Physiology
Children are different from adults. They have unique anatomy and physiology that cannot be merely attributed to their proportionately smaller size. For one thing, a child’s anatomic proportions compared with those of an adult must be considered. This includes body proportion (head-to-body ratio); skin surface area (surface-to-mass ratio); and the size of their airway, chest, and abdomen. In addition, children’s heart rates, respiratory rates, blood pressure, respiratory mechanics, and circulatory responses differ from those of adults.
Children have a large venous capacitance with a strong ability to compensate initially for blood loss. It is estimated that children can compensate quickly for a 25% loss in circulating blood volume through vasoconstriction with only subtle changes in vital signs and mental status.5 In the case of more extensive volume loss, these compensatory mechanisms fail quickly and lead to rapid deterioration in physiologic status. Paying meticulous attention to vital signs, perfusion, and mental status will identify children who are slipping from compensated to uncompensated shock. Clinicians and emergency medical services providers also need to be aware that the normal ranges of vital signs vary with age. Information detailing these ranges should be readily available to all providers (see Table).
Temperature, although not different from adult normal ranges, requires much closer monitoring in the young child. Because children have a larger skin surface-to-weight ratio than adults, they lose core body heat through their skin more easily. After injury, children have a diminished ability to compensate for this heat loss because of immobility or changes in physiologic status (shock). Consequently, significant hypothermia can occur.6 Hypothermia can add metabolic demands to an already compromised child. If untreated or if the child is unable to compensate, hypothermia can potentiate metabolic acidosis from circulatory shock. External warming is warranted to prevent the development of hypothermia or to treat existing hypothermia.
The force of impact from any injury is distributed throughout the body. For children, this force is distributed over a smaller mass, often resulting in a disproportionately greater number of injured organs. In children, brain injuries are more common than in adults because children’s heads are proportionately larger than the rest of their bodies and because of their relative lack of neck strength. Brain injury is the leading traumatic cause of death and disability among children.7
Cervical spinal cord injuries, while uncommon (found in less than 2% of injured children), are not always associated with spinal fractures in children. In some studies, only half of children with neurologic injuries show radiologic abnormalities.8 A large head on a relatively weak neck combined with greater flexibility of the cervical ligamentous structures puts children at greater risk for transmission of force to the cervical spinal cord. For that reason, spinal cord injury without radiologic abnormality (SCIWORA)—a unique class of injury—disproportionately affects children. Direct injury to the respiratory tract, direct injury to the central nervous system, and physiologic compensation for metabolic acidosis all affect breathing. Although trauma is most often thought of in terms of shock, hypoventilation is the most common cause of arrest in the pediatric trauma patient.9
Several factors make children more susceptible to respiratory failure than adults. The pediatric airway is smaller, and the tongue is relatively larger. The trachea is shorter, more flexible, and narrower. Small decreases in airway caliber because of swelling, uncleared secretions, or the presence of blood have significant effects on air-flow resistance. Children have a metabolism that is much faster than can be explained just on the basis of their relatively smaller size. Therefore, their need for more oxygen results in a disproportionately greater minute ventilation. Further, children’s lungs hold a smaller residual volume, the reserve capacity of oxygen held in the lungs. Also, children’s chests are softer and more compliant. Thus, direct trauma to the chest transfers greater impact to the heart, lungs, and abdominal organs. All of these differences result in less respiratory reserve capacity in children than in adults.
In children, the solid intra- abdominal organs—the liver and spleen—are only partially protected within the lower rib cage, resulting in greater exposure to direct force. Similarly, the bladder is more exposed and less protected by the pelvis.
These anatomical differences combined with developmental immaturity result in several injury patterns that are unique to children:
• First, because of the disproportionate size of the head, intercerebral injuries are more common.
• Second, the premature use of adult lap and shoulder belts results in children “submarining” (where the upper torso and waist are held in a relatively fixed position and the legs and pelvis are thrust forward during rapid deceleration) during a crash, which transmits force to the liver, spleen, and hollow abdominal organs.
• Third, injuries from crashes involving pedestrians and motor vehicles can result in Waddell’s triad—a combination of head, spleen, and femur injures.
• Fourth, battered child syndrome results in multiple injuries inflicted on different occasions, injuries not consistent with the described mechanism, injuries not consistent with the child’s level of development, and occult injuries, including subdural hematomas and retinal hemorrhages that can be associated with shaken baby syndrome.
Triage
Appropriate triage of the pediatric trauma patient is an important component of effective trauma care. Triage must address the unique needs of children in terms of identifying whether they are at risk for more severe injuries, appropriate transport mechanisms, and appropriately prepared receiving facilities.
Optimal primary (ambulance-to-hospital) and interfacility (hospital-to-hospital) triage of injured children continues to be a challenge. Although well-established triage protocols exist for adults, validated pediatric protocols are yet to be developed. Extrapolation of adult criteria to a pediatric population has not been effective because of the differences between the anatomy and physiology of adults and children. Further, most studies have small sample sizes, lack validation, and retrospectively apply the many scoring systems for trauma (pediatric trauma score, revised trauma score, trauma score, etc.) to a database rather than test them prospectively in the field.10
Triage systems have two goals. First, the system must be easily applied to a broad group of patients by a wide variety of providers. Second, the system must not under-triage or fail to appropriately triage significantly injured children, and must not over-triage or unnecessarily send too many patients with minor injuries to more comprehensive trauma centers.11 Some have suggested that this would translate to a triage sensitivity of >95% (correctly identifying >95% of all severely injured patients) with a specificity of 25% to 50% (sending no more than 25% to 50% of the patients unnecessarily to a Level I or II trauma center).
When triaging a pediatric patient, 3 sets of criteria should be considered: physiologic criteria (vital signs and neurologic status), type of injury by anatomic location, and mechanism of injury, including some measures of severity (ejection from the vehicle, height of fall, etc.). Of those criteria, only a few key components are common to all trauma triage protocols. They include neurologic status (usually as measured by Glasgow Coma Score or AVPU—alert, responds to verbal stimuli, responds to pain, or unresponsive to all stimuli), respiratory status, and blood pressure. Other physiologic, anatomic, and mechanism of injury criteria vary greatly.
The judgment of prehospital providers in appropriately triaging pediatric patients has been evaluated with mixed results. Paramedic judgment alone has resulted in increased activation of trauma teams, sometimes without the need for significant intervention. Using physiologic, anatomic, and mechanism of injury criteria greatly improves the predictive value of these prehospital evaluations.12,13 Pediatric trauma centers have developed a tiered response to pediatric trauma team activation. A 2-tiered trauma activation system mobilizes personnel based on the predicted severity of the injury. By using a 2-tiered system, select patients may be managed by a smaller trauma team, thus better utilizing staff and possibly reducing costs while ensuring favorable outcomes. The trauma activation can be upgraded or downgraded upon arrival of the patient based on additional information and clinical status. Pediatric trauma triage protocols have begun to predict which patients will be more likely to have serious injuries. Published protocols have been analyzed and demonstrate that they can be used effectively and are neither too conservative nor too liberal.14,15
The Minnesota Comprehensive Statewide Trauma System Plan, which is being proposed through the Department of Health, includes the development of pediatric triage criteria. Over time, those criteria can be refined as the medical literature and our own experience better define which children need specialized trauma care. As a start, the pediatric protocols developed by the Minnesota Emergency Services for Children Resource Center, a collaboration among Children’s Hospitals and Clinics, the University of Minnesota, and the Emergency Medical Services Regulatory Board, include a worksheet that regional ambulance agencies can use to assess the capabilities of local facilities to care for injured and ill children (see p. 49). Working through such a process in advance will optimize regional triage decisions in regard to injured children.
Pediatric Triage Worksheet
Selected Issues in Initial Care
Nonoperative Management of Blunt Abdominal Trauma
Among the major advances in the care of injured children in the past 2 decades is the decrease in operative management of children with blunt abdominal trauma (BAT) to the liver, spleen, and kidney.16,17 This observational approach has decreased the laparotomy rate to as little as 0.3% at pediatric trauma centers and prompted a discussion about the role of the surgeon in the immediate resuscitation of the injured child.18 With this approach, the decision to perform a laparotomy is made based on clinical instability, not on the grade of the injury as judged by CT scan. Patients with BAT requiring initial fluid resuscitation of more than 40ml/kg, possible intestinal injury, or who are experiencing clinical deterioration because of shock are all candidates for immediate laparotomy.19 All others can be observed.
Concerns about excessive transfusion of these patients have not been borne out. Lower hemoglobin levels (to 7g/dL in clinically stable children) are tolerated. This has resulted in a decreased need for transfusion and, hence, less risk of transmission of blood-borne diseases.
FAST Ultrasonography
In U.S. emergency departments, ultrasound has become an increasingly popular imaging modality. Trauma surgeons and emergency physicians have been using ultrasound to evaluate BAT victims for more than 10 years with good success. The dedicated BAT ultrasound exam is now known as the focused assessment with sonography for trauma (FAST), a term coined by Rozycki in 1996.20 The original FAST exam consisted of 4 views: perihepatic, perisplenic, pelvic, and pericardial.21
The FAST exam has now evolved and typically includes more views, including: 1) subxiphoid or parasternal to view for pericardial fluid, 2) right upper quadrant (Morison’s pouch) and right hemithorax, 3) right paracolic gutter, 4) left upper quadrant and left hemithorax, 5) the left paracolic gutter, and 6) longitudinal and transverse pelvic. Ideally, the FAST exam should take no longer than 5 minutes. The purpose of the abdominal views is to identify free fluid, an indication of the potential need for emergency laparotomy. The pericardial view was originally studied on victims with penetrating cardiac injuries. It was found to improve survival rates by significantly decreasing the time to diagnosis.21 The role of the pericardial view remains less defined, although some researchers are now using it to look for myocardial contusion, valve injury, pericardial fluid, and asystole following blunt trauma.22 Short- comings of the FAST exam are an inability to consistently detect injuries to solid organs and to the intestines.
Outcomes data from adult victims of BAT have shown promising results with the FAST exam, although the role of bedside modality remains controversial given today’s spiral computed tomography (CT), especially in hemodynamically stable trauma victims.
Controversy over application of the FAST exam for pediatric trauma victims focuses on two issues: 1) that children may lack free peritoneal fluid after BAT, and 2) that the use of CT is superior in children. More than 80% to 90% of all pediatric BAT victims are managed nonoperatively. Thus, researchers have argued that a FAST exam is of no added benefit in stable patients even if free peritoneal fluid is found.23 In addition, if free peritoneal fluid were found, those patients would certainly undergo an abdominal CT scan. Conversely, recent studies are now showing that pediatric trauma victims may have significant intra- abdominal injuries without any free peritoneal fluid.24 These studies suggest the superiority of the CT scan in pediatric trauma victims.25 The best role to date for the pediatric FAST exam seems to be with hypotensive or unstable patients suffering BAT. Although more clinical research still needs to be done, Holmes et al. have shown with promising results that a FAST exam in this selected population is warranted.23,26
Cervical Spine Injury
A pediatric spinal cord injury (SCI) can be devastating. Of the estimated 15,000 SCIs each year, approximately 1,500 involve children younger than 15 years of age.27 The management of SCI in a child is comparable to that for an adult, albeit, pediatric cases require the use of smaller but appropriate cervical spine hard collars. In the emergency department, a common problem when children arrive with a prehospital c-spine collar in place is the misinterpretation of radiographs. This happens for 3 reasons: 1) SCIWORA, 2) pseudosubluxation of C2 over C3, and 3) other normal variants unique to pediatrics.
Patients with SCIWORA have true spinal cord injuries with neurological deficits that don’t show any radiographic abnormalties. Before the development of magnetic resonance imaging (MRI), the SCIWORA rate was as high as 50%.8 The rate has dropped to less than 6% since the advent of MRI.28,29 Patients with SCIWORA will show a spectrum of clinical presentations from acute SCIs following blunt trauma to transient neurological defects following what appears to be trivial neck or back injuries. These patients also may present days after injury with waxing and waning signs or symptoms of a SCI, depending on the location of the injury, and may present with isolated muscle weakness, decreased sensation, or paresthesias.30 If left unnoticed or untreated, these children may progress to complete neurological devastation.
As mentioned, cases of true SCIWORA are becoming rare as MRI technology improves. MRI can now be used, albeit carefully, as a potential predictor of which patients will experience some degree of recovery. A study by Dare et al. determined that if a child had a neurological deficit with an abnormality found on MRI, the chance of recovery was dismal. On the other hand, children who did not have any MRI findings tended to make partial or full recoveries.31 This study and others also found that children with SCIWORA who had complete neurological injuries tended to be less than 8 years of age and that those children who had only partial injuries tended to make a full recovery.31,32
Interpretation of radiographic cervical spinal films can be difficult. A common reason for referral to a pediatric trauma center is for apparent cervical spine subluxation of C2 over C3 following neck trauma. Fortunately, most of these children will have a common radiographic finding called pseudosubluxation.33 Pseudosubluxation is theorized to be the result of ligamentous laxity. It occurs in about 40% of normal children younger than 7 years of age and in 24% of those younger than 16 years of age.34 Swischuk’s line defines this “normal variant,” in which there is anterior displacement of C2 on C3 of up to 2 mm on lateral cervical spine radiographs of children. Swischuk’s line connects the anterior cortices of the spinous processes of C1 and C3.35 It should intersect or lie within 1 mm of the anterior cortex of the spinous process of C2 and is useful in distinguishing pseudosubluxation from pathological subluxation.
Other radiographic findings that can pose diagnostic challenges are prevertebral swelling or thickening and predental space. Cervical spine prevertebral swelling can be useful for finding a c-spine injury—especially in adults.36 Unfortunately, in children, this can often be a pseudoabnormality, especially if the child’s neck is slightly flexed.36 In addition, children may have no prevertebral finding and still have significant cervical spinal injury.37 Another pseudoabnormality is predental space. Normal adult predental space, which is the distance between C1 and the dens, is typically less than 2.5 mm. In children younger than 8 years of age, this space can be as wide as 4 mm.38 In addition, the space can vary as much as 2 mm with flexion and extension films. Regardless of any variant the practitioner may come across, good common sense, clinical skills, and an acute index of suspicion is required to diagnose any pediatric spine injury.
Conclusion
Children are different than adults. Because of their unique anatomy and physiology, they require specialized evaluation and care. This includes paying meticulous attention to the changes in the physiology of an injured child as well as creating systems to ensure that emergency department staff have and maintain the skills needed to care for these patients. A statewide trauma system would serve as the foundation for this care. MM
Jeffrey Schiff and Jeff Louie are pediatric emergency physicians at Children’s Hospitals and Clinics. Brian Moore is a pediatric emergency physician with Mayo Clinic Emergency Services. Jeffrey Schiff is also the medical director of Emergency Medical Services for Children’s Resource Center of Minnesota.
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