Chapter 115 Abdominal Trauma in Pediatric Critical Care

Christopher P. Coppola, James C. Gilbert

• In the initial resuscitation of trauma victims, the first priority remains the ABCs of airway, breathing, and circulation.

• When in doubt about the reliability of the airway, perform endotracheal intubation.

• The standard of care in treating hemodynamically stable children with hepatic or splenic injury is nonoperative observation.

• Patients who are hemodynamically stable may undergo further radiographic workup, whereas patients with evidence of an abdominal injury who remain clinically unstable after resuscitation with 40 mL/kg of fluid should be taken to the operating room for exploration.

• Splenic preservation is more important in younger children and is usually possible with nonoperative management or embolization.

• Vigilance and reexamination are necessary to detect a small bowel injury, which results in increases morbidity if missed for greater than 24 hours after trauma.

Trauma is the leading cause of morbidity and mortality in the pediatric age group. An estimated 1.5 million pediatric injuries occur each year, resulting in 500,000 hospitalizations and 20,000 deaths.¹ Thus trauma exceeds all other causes of death combined. Abdominal injuries are a marker of severe trauma, and evaluation of the child with an abdominal injury must include a thorough examination of the entire child. Failure to accurately assess the abdomen is the single most common error in the early treatment of the injured patient. Management of pediatric trauma requires a multidisciplinary approach with emergency department physicians, critical care specialists, anesthesiologists, and surgeons working as a multidisciplinary team to provide prompt stabilization, assessment, and treatment. Performing the primary and secondary survey, instituting fluid resuscitation, and arriving at a decision as to the most appropriate management plan are the principal goals of the trauma team leader.

The vast majority of abdominal injuries in children are preventable. Health care providers must work with the broader community to identify and alleviate causes of pediatric trauma. Education, public safety measures, and legislation will serve to prevent many cases of pediatric injury. Intentional abdominal trauma to children must be considered and, if suspected, must be reported to the appropriate agency. New developments in pediatric abdominal trauma include use of imaging modalities such as Focused Abdominal Sonography for Trauma (FAST) and embolization of solid organ injuries, which allows for increased utilization of nonoperative management. Laparoscopy can be applied in select scenarios. As part of disaster preparedness, clinicians providing trauma care for children should have an awareness of wartime and mass casualty injury management.

Mechanisms and Patterns of Injury

The severity and pattern of abdominal injury correlate with the mechanism of injury. Blunt injury accounts for 90% of abdominal trauma in children. The most common mechanisms are motor vehicle accidents, motor pedestrian accidents, falls from heights, bicycle accidents, and nonaccidental trauma. In pediatric blunt abdominal trauma, solid viscus organs such as the liver, spleen, and kidney are more frequently injured than hollow viscus organs. Children suffering lap belt injury, handlebar injury, or kicks may suffer small bowel perforation. Pedestrians struck by motor vehicles can have a pattern of head injury, splenic fracture, and left femur fracture (Waddell triad). In addition, urban violence and the high prevalence of firearms result in penetrating abdominal injuries in children. Although the mechanism of injury may correlate with the extent of injury, ongoing clinical assessment is a more sensitive indicator of the extent of blood loss and hemodynamic instability, and determines the resuscitation and management of the child with an abdominal injury.

Penetrating Abdominal Trauma

A national decrease in violent crime has reduced the incidence of penetrating trauma since the 1980s. Penetrating abdominal injuries are most commonly caused by firearm use or stabbings. In children, abdominal gunshot wounds result in more severe injuries than stab wounds because of the increased energy delivered by firearms, particularly shotguns and military rifles.² Significant intraperitoneal injuries are present in most children who sustain gunshot wounds, suggesting the need for abdominal exploration in all gunshot victims. There is a controversial trend toward selective exploration of penetrating injuries in adults. For example, computed tomography has been successfully used to determine the use of selective laparotomy in penetrating torso trauma.³ However, most trauma centers continue to perform mandatory laparotomy on all patients with gunshot wounds to the abdomen, although some nontherapeutic explorations will occur. Abdominal stab wounds that are found to penetrate the transversalis fascia on local wound exploration should undergo laparotomy or laparoscopy. Expectant observation of stab wounds in children should rarely be applied because the true extent of injury is not always appreciated on local exploration.

Recreational and Sports Injury

Specific recreational activities commonly practiced by children, such as bicycling, all-terrain vehicle (ATV) use, skiing, snowboarding, and horseback riding result in predictable injury patterns that guide evaluation. Snowboard injuries are increasing and include abdominal injuries in 25% of cases.⁴ ATV crashes produce a particularly damaging pattern of injury as the ATV has the weight of a car and the lack of protection of a motorcycle. This results in a combination of an ejection and rollover mechanism of injury with the worst of both. The majority of deaths involve head and spine injuries. Lack of helmet use is associated with a higher mortality. ATV abdominal injuries include crush injuries to liver, spleen, and kidney. Child drivers are more susceptible to crash and it is alarming that child-sized ATVs are in production. Even where laws restrict ATV use by children, they are frequently injured and have a high rate of missed injuries.⁵ Blunt impalement on a bicycle handlebar can result in a predictable pattern of injury to bowel, mesentery, or pancreas.

Wartime Trauma

It is unfortunate to note that children can also be victims of wartime trauma causing abdominal and other injuries. In contrast to wars of the past, modern warfare is often conducted in urban areas with a civilian population present and the frequent involvement of children. Additionally, medical infrastructure is disrupted in a war zone and many residents suffer malnutrition and infections which makes them more debilitated in the face of a new injury. Military high-energy rifles cause penetrating wounds in which the pressure wave of the projectile results in a cone of tissue destruction. In abdominal injuries, this necessitates wide debridement of soft tissues, and often a second-look laparotomy is required to detect evolving intestinal necrosis. It is common for children to suffer blast and fragmentation injuries from land mines, bombs, indirect fire weapons (rockets and mortars), improvised explosive devices, and suicide bombings.⁶ Land mines and air-delivered cluster bomblets are particularly insidious because their interesting colors and shapes attract children’s curiosity. Wounds include pressure wave blunt injury, shrapnel penetration, and burns. These injuries in children often require a damage-control laparotomy, wide debridement of soft tissues, temporary abdominal closure, and multiple operations. Vacuum-assisted wound dressings are particularly useful.⁷ Wide-bore feeding tubes allow improvised feeds such as eggs, milk, honey, and grains. Long hospital stays are needed to ensure that the child can survive at home with little medical attention.

Evaluation and Resuscitation

Evaluation and resuscitation occur simultaneously when a child presents with an abdominal injury. The Advanced Trauma Life Support (ATLS) protocols developed by the American College of Surgeons should be used. The initial assessment, or primary survey, includes stabilization of the cervical spine while evaluating for airway patency, function of breathing, and adequacy of circulation (the ABCs). Prompt endotracheal intubation should occur in any patient in whom the stability of these functions is in doubt. Intravenous access in the small child can be particularly challenging, and skilled personnel should be employed. Pediatric Advanced Life Support (PALS) guidelines suggest utilizing an intraosseous line after three failed attempts to establish intravenous access or 90 seconds have expired and access has not been obtained. Basic neurologic function is assessed. The patient must be completely exposed for examination and then covered with blankets to maintain body temperature. Children are more susceptible to heat loss and dehydration because of their greater surface area/mass ratio.

Physical Examination

Abdominal examination includes observation of external signs, then palpation for tenderness, distension, or firmness. Children swallow a large amount of air when they cry and gastric distension may require nasogastric tube decompression. Upper quadrant ecchymosis, tenderness, and associated rib fractures suggest the presence of liver or spleen injury. Midabdominal ecchymosis from a seat belt suggests the possibility of a small bowel injury. Stability of the pelvis is assessed with lateral and axial manual compression of the pelvic ring. Extraperitoneal bladder ruptures may cause localized suprapubic tenderness, whereas an intraperitoneal bladder rupture may present as generalized abdominal distension.

Laboratory Tests

Laboratory examinations, including complete blood counts, serum chemistries, and urinalysis, should be obtained on all trauma patients. Additional studies, such as liver function tests and pancreatic enzymes, are indicated in certain injuries. Elevated transaminase levels suggest nonspecific parenchymal liver injury whereas elevated amylase and lipase levels suggest a pancreatic injury. A base deficit of greater than 6 meq/L is a strong indicator of intraabdominal injury in blunt trauma. Hematuria is associated with intra-abdominal injury and renal injury. Urinalysis demonstrating more than five red blood cells per high-power field combined with clinical assessment accurately predicts intra-abdominal injury. Hemoglobin concentrations as low as 7 g/dL are well tolerated in children after blunt abdominal injury, provided intravascular volume is repleted.

Radiographic Assessment

Prompt plain radiographs of the chest, lateral cervical spine, and pelvis should be obtained during the initial assessment. Patients who are hemodynamically stable may undergo further radiographic workup, while patients with evidence of an abdominal injury who remain clinically unstable after resuscitation with 40 mL/kg of fluid should be taken to the operating room for exploration.

Computed Tomography

Computed tomography is the procedure of choice for definitive radiographic assessment after blunt abdominal trauma in children. Clinical impression remains the most sensitive indicator of the need for computed tomography. Computed tomography can be used to identify hepatic, splenic, intestinal, pancreatic, renal, and bladder injuries in children and can even detect intestinal and mesenteric injury with sensitivities of 94% and 96%, respectively.⁸ Serial clinical assessments must be made before computed tomography. If the patient deteriorates, stabilization in the PICU or immediate operative intervention must be considered. Findings on computed tomography suggestive of intestinal injury are unexplained free fluid without solid visceral organ disruption, abnormal distribution of bowel loops, contrast extravasation, and contrast enhancement of intestinal wall.⁹ The Organ Injury Scaling Committee of the American Association for the Surgery of Trauma has developed a grading system to estimate the extent of abdominal injury.^10,¹¹ Short of operative exploration, computed tomography is the most accurate method used to grade the extent of injury.

Sonography

FAST is a rapid, noninvasive, and portable method to evaluate the abdomen. Various reports note that sonography for abdominal trauma has a sensitivity of 55% to 86% and a specificity of 95% to 98%.¹²^–¹⁴ Sonography accurately identifies intraperitoneal free fluid, but it does not accurately identify the source of that fluid. Sonography is comparable to diagnostic peritoneal lavage (DPL) as a method for detecting free peritoneal fluid, but is less invasive. However, it does not supplant computed tomography in its ability to define the specific nature and extent of abdominal injury.