Number
Percent
Male
838
73.6
Penetrating mechanism
478
42.8
Upper extremity
406
35.7
Abdomen
275
24.2
Lower extremity
212
18.6
Chest
150
13.2
Neck
113
9.9
26.3 Clinical Evaluation and Diagnostic Imaging
Successful assessment and management of pediatric vascular injury assumes expeditious provision of adequate airway, breathing, and circulation. The mechanism of injury is often useful when assessing for immediately life-threatening injuries. In particular, obvious blunt or penetrating torso injuries presenting with hypotension are associated with increased morbidity and mortality in children. Given the physiological reserve of children, it is important not to underestimate the severity of injury on the basis of adequate blood pressure alone. Tachycardia, tachypnea, cool extremities, and lethargy despite a relatively normal or measurable blood pressure are worrisome signs for impending cardiovascular collapse from hypovolemic shock in a child.
Initial assessment for possible truncal or peripheral vascular injury in a child relies on exquisite physical examination. Evidence for arterial injury is generally divided into hard and soft signs of injury, and this remains a useful clinical algorithm for determining further intervention in children. Hard signs of vascular injury include pulsatile bleeding from the wound(s), a rapidly expanding or pulsatile hematoma, evidence of an arteriovenous fistula, or signs of distal ischemia (pallor, pulselessness, poikilothermia, paresthesias, and pain). Importantly, many pediatric vascular injuries are associated with open extremity fractures and/or soft tissue injury, and therefore, the ability to rapidly assemble a multidisciplinary team with expertise in pediatric resuscitation, trauma, orthopedics, vascular surgery, plastic surgery/microvascular reconstruction, and radiology is imperative.
The presence of hard signs necessitates prompt intervention to control hemorrhage and attempts at restoration of vascular continuity. Soft signs of injury include persistent shock despite ongoing resuscitation, wound hematoma, diminished peripheral pulses, proximity of wound trajectory to major vessels, or evidence of injury to a nerve adjacent to a vessel. In hemodynamically normal children with suspected extremity vascular injury, the most appropriate next step is to determine the ankle brachial index (ABI). An ABI of less than 0.9 in a young adult or child greater than 1 year of age should prompt further diagnostic evaluation for vascular injury. A potential exception is in newborn infants discussed below.
Following resuscitation and clinical examination, diagnostic evaluation of hemodynamically normal children with clinical signs of vascular injury is indicated. Traditionally, biplanar angiography has been considered the gold standard imaging modality. However, similar to the adult experience, imaging techniques that are less invasive than conventional angiography are gaining wider acceptance. CT angiography is now emerging as one of the more valuable, adjunctive diagnostic tools for vascular injury in children given the nearly universal presence and immediate access to CT scan imaging at pediatric hospitals.
Prospective, systematic evaluation of imaging alternatives for pediatric vascular injuries has been challenging, in part, due to the infrequent nature of these injuries. The difficulty in determining the most appropriate diagnostic modality is underscored in a retrospective review of blunt carotid artery injury in the National Pediatric Trauma Registry, a multicenter national registry with 78 participating institutions [10]. This study demonstrated a blunt carotid injury rate of 0.03 % (15 of 57,659 pediatric blunt trauma patients). Recorded diagnostic imaging procedures included angiography, duplex ultrasonography, and magnetic resonance angiography. Unfortunately, definitive conclusions regarding the best imaging modality for these injuries could not be made because of the low incidence of pediatric vascular injuries and the variability in pediatric hospital-based imaging resources.
The utility of contrast-enhanced CT scan imaging was evaluated in a retrospective review of adults presenting with thoracic, abdominal, and/or pelvic trauma over a 30-month period. CT imaging was compared to conventional angiography for those patients undergoing angiography within 24 h of contrast-enhanced CT scan imaging [11]. A total of 63 traumatic torso injuries were evaluated in 48 patients (46 blunt with trauma, 2 with penetrating trauma). Contrast-enhanced CT scan imaging findings strongly correlated with angiographic findings; CT scan imaging was found to have 94.1 % sensitivity and 97.6 % negative predictive value for detection of ongoing hemorrhage within the torso and 92.6 % sensitivity for predicting need for surgical or endovascular intervention. Despite this retrospective study’s limited sample size and lack of CT angiographic imaging technique, these findings demonstrate significant diagnostic utility using contrast-enhanced CT scan imaging for identification of torso vascular injuries requiring further intervention.
While there are no randomized comparisons of CT versus MR angiography in the diagnosis of pediatric traumatic vascular injuries, MR angiography is valuable in identification of intracerebral and cervical vascular injuries associated with traumatic brain injury. However, when MR angiography is compared to CT angiography, there are distinct advantages for CT angiography in children. These include more rapid imaging acquisition and decreased need for significant sedation and/or anesthesia. The results from several studies evaluating the use of CT angiography in adult vascular trauma have also provided the rationale for its use in children with possible cervical, torso, or extremity vascular injury [12, 13]. A retrospective series from a Level 1 Trauma Center at the University of Miami reviewed the use of CT angiography in 78 pediatric patients with suspected cervical or extremity vascular injuries caused by either blunt or penetrating trauma [14]. CT angiography was diagnostic for major vascular injury in 11 patients with penetrating trauma, giving rise to 100 % sensitivity, 93 % specificity, a positive predictive value of 85 %, and a negative predictive value of 100 %. For 8 patients with vascular injury from blunt trauma, CT angiography was 88 % sensitive and 100 % specific with a 100 % positive predictive value and 97 % negative predictive value. The accuracy of CT angiography to identify major vascular injury for either penetrating or blunt trauma in children less than 19 years of age exceeded 95 % in this report.
Similar to the adult experience, CT angiography appears to have comparable sensitivity and specificity to conventional contrast angiography in pediatric trauma. Additionally, greater resolution of injuries to adjacent structures is achieved with CT in comparison to angiography. The relative ease of access, shorter time to achieve diagnostic images, greater ability to simultaneously assess adjacent structures, and less invasive nature of CT angiography are compelling factors to consider when imaging is deemed necessary. Both conventional angiography and CT angiography share the risk of radiation exposure and contrast-induced nephropathy. However, controlling the scan pass frequency, x-ray tube current, peak voltage, pitch factor, and gantry rotation allows for reduction of radiation exposure [15]. Complications of conventional angiography in pediatric patients include issues related to sedation and difficulty with vascular access. Arterial access complications include hematoma, pseudoaneurysm and arteriovenous fistula formation, acute arterial thrombosis, and lower extremity limb-length discrepancy resulting from chronic femoral artery occlusion.
Finally, for pediatric extremity vascular injuries, duplex ultrasonography may be useful in initial evaluation and long-term follow-up. However, the use of duplex ultrasonography in the acute assessment of pediatric vascular injury has not been well studied, and its use is generally reflective of institutional availability and experience.
26.4 Specific Vascular Injuries in Children
The diagnosis and management of most vascular injuries in children follows all established guidelines for adults. A few unique clinical management issues in children and adolescents with vascular injury are more thoroughly discussed below.
26.4.1 Aortic Injuries
The incidence rate of aortic injuries in adults is well established and remains one of the most commonly reported causes of death at the scene of motor vehicle crashes. The incidence rate of traumatic aortic rupture in children is lower but continues to carry significant morbidity and mortality. The incidence of pediatric thoracic aortic injury ranges from 0.1 to 2.1 % with blunt mechanisms most common [1, 16]. A retrospective review from Seattle reported the most common cause of thoracic aorta injury in children was blunt trauma from car versus pedestrian (46 %) followed by motor vehicle crashes (38 %); none of the children with thoracic aortic injury from motor vehicle crashes were wearing seat belts [17]. Aortic disruption due to blunt trauma can be caused by either direct chest wall compression or sudden torsional and/or deceleration causing shear stress [18]. While the aortic arch is relatively fixed, the descending aorta is more mobile, causing the aortic isthmus to be the most common site of blunt aortic injury in both children and adults.
Signs associated with blunt injury to the thoracic aorta are similar in both adults and children. Suspicious findings on chest x-ray include widening of the mediastinum, loss of the aortic knob, presence of a left pleural cap, deviation of the trachea to the right, fracture of the first or second ribs, scapula fracture, depression of the left mainstem bronchus, obliteration of the aortopulmonary window, and deviation of the esophagus to the left. Given the relative compliance of the chest wall in younger patients, children may have blunt aortic injury without demonstrable rib, clavicular, or scapular fractures. Presence of these signs upon initial examination mandates further evaluation of the aorta. CT angiography has largely replaced conventional angiography as the primary modality used to diagnose pediatric aortic injury.
Management of pediatric traumatic aortic rupture requires modification of some perioperative and operative strategies. Due to the significant forces required to injure the aorta, these children are at high risk for other organ injuries, particularly the brain, solid organs, spine, and spinal cord. In the absence of significant traumatic brain injury, early use of beta-blockade and control of blood pressure is warranted. Operative repair with or without mechanical circulatory support remains the standard treatment for comparison [19]. In the presence of traumatic brain injury, the use of medications to reduce heart rate and blood pressure must be judiciously weighed against the need for maintaining adequate cerebral perfusion pressure. Most children with traumatic aortic rupture are adolescents that approximate adult size; in younger children, the aorta is significantly smaller in caliber and is generally more fragile. Establishment of intraoperative cardiopulmonary bypass procedures in children may be technically challenging and requires size- and weight-specific cannulas, instrumentation, and surgeon experience. The use of femoral arterial and/or venous access for bypass may be limited by the diminutive caliber of these vessels in smaller children.
Access and use of size-specific aortic grafts in children must also consider future growth, and both short- and long-term follow up is essential. Children undergoing thoracic aortic repair for trauma should be followed by an experienced pediatric cardiologist to determine flow characteristics across the graft; if hemodynamically significant “pseudocoarctation” occurs across the graft during adolescence or adulthood, graft replacement is warranted. Finally, in the presence of traumatic brain injury or other associated injuries at risk for hemorrhage, strategies aimed at minimizing systemic anticoagulation during repair include using heparin-coated cardiopulmonary bypass circuits, utilization of aortic bypass techniques with intracorporeal shunts that do not require systemic heparin, and selective deployment of endovascular stent grafts.
The rationale for using endovascular stent grafts to treat pediatric aortic rupture reflects the successful use of stents in adult trauma victims and, in part, the experience with stent grafts to treat congenital aortic coarctation. A multicenter observational study conducted by the Congenital Cardiovascular Interventional Study Consortium (CCISC) evaluated 350 adult and pediatric patients undergoing stent placement, operative repair, or balloon angioplasty to treat aortic coarctation [20]. There was a significantly lower acute complication rate with stent placement compared with patients undergoing operative repair or balloon angioplasty. In this nonrandomized study, stents were placed in patients that were significantly older (mean age 16.6 years) and larger (mean bodyweight 55 kg) compared to patients undergoing operative repair or balloon angioplasty. Subgroup analysis of patients 6–12 years of age demonstrated that stenting had a lower overall acute complication rate (1.8 %) compared to surgery or balloon angioplasty (13 % each). The CCISC reviewed 398 patients ages 4–19 years old undergoing aortic stenting for native or recurrent aortic coarctation and reported an overall complication rate of 12.6 % for this specific age group [21]. The authors concluded that aortic stenting was an effective treatment for coarctation, but it remained technically challenging with a high complication rate. Technical complications decreased over the course of the study and were attributed, in part, to improved catheter and stent technology.
There are several small series and case reports of successful endovascular stent repair of pediatric traumatic aortic injuries [19, 22–24]. These patients are typically older children or adolescents with significant extracardiac injuries or physiological compromise felt to create prohibitive risk for open repair (e.g., bilateral pulmonary contusion, traumatic brain injury with intracranial hemorrhage, abdominal or pelvic injuries at risk for hemorrhage). These studies note size-specific issues related to available grafts for use in children and vascular access for stent graft deployment; if the femoral vessels are too small to accommodate the sheath or stent, operative approaches to the iliac artery or infrarenal aorta may be required.
Perioperative use of unfractionated heparin in children undergoing endovascular stent placement is recommended; therefore, the risk of bleeding from associated injuries with systemic antithrombotic therapy must be weighed against the potential for thromboembolism. Complications of aortic stenting for pediatric aortic injury should mirror the adult experience, including technical complications related to stent deployment or migration, injury to the aorta, and both neurological and peripheral vascular complications from ischemia and thromboembolism. In selected children with significant extrathoracic injuries, endovascular stent repair may temporize an immediately life-threatening injury and defer direct operative aortic reconstruction until other injuries have resolved. It remains important to note that endovascular stent repair has not been widely used in children with aortic injury, and the immediate and long-term efficacy of this approach remains unclear.
In summary, pediatric traumatic aortic rupture is an uncommon but significant, immediately life-threatening injury typically diagnosed using CT angiography. Initial management should be directed at control of heart rate and blood pressure if practical while simultaneously identifying all other associated injuries. Management options require individualization based upon the child’s size, associated injuries, and institutional experience. The degree and location of injury, as well as the caliber of the aorta and access vessels, require careful assessment when deciding the method of aortic repair. As experience increases with pediatric endovascular stent grafts, this approach may offer an effective treatment in selected children with aortic injury. The immediate and long-term efficacy of endovascular stenting for pediatric aortic injury remains to be determined.
26.4.2 Extremity Injuries
The upper and lower extremities are the first and third most common sites of pediatric vascular injury, respectively [2, 6]. Penetrating injuries from gunshot wounds, glass, lawn mower blades, or boat propeller blades are common causes of extremity vascular injury in children. Blunt vascular injuries are typically from motor vehicle crashes, falls, or pedestrians struck by vehicles, and these are often associated with fractures. Historically, more than half of pediatric extremity vascular injuries were from glass; in more recent series, gunshot wounds are accounting for an equivalent proportion [6, 25]. Blunt upper extremity injury associated with open or closed supracondylar fracture accounts for a consistent 35–40 % of all reported pediatric vascular injuries. Management of extremity vascular injury in children offers both diagnostic and treatment challenges due to the small caliber of the vessels, the greater effect of arterial spasm, and considerations for further limb growth. Arterial vasospasm may be pronounced and prolonged in children and adolescents in response to both blunt and proximal penetrating injuries. Early consultation and prompt transfer to a regional trauma center with expertise in pediatric vascular and microvascular reconstruction is highly desirable if there is a threatened extremity from vascular injury that exceeds local capacity for treatment or intervention. In the absence of a mangled extremity, limb amputation for traumatic extremity arterial insufficiency is extremely infrequent in the neonatal and pediatric population.
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