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Pediatric Endovascular Hemorrhage Control: An Idea Whose Time Has Come
Endovascular hemorrhage control is a technique that has been used for over a decade in the highest acuity American adult trauma centers. However, the application of this technique in pediatric patient populations has not been adopted as robustly. Several reasons why this technique is not used as commonly in children may include a general lack of appreciation for the capabilities of endovascular hemorrhage control, physician inexperience in endovascular techniques for the pediatric population, and an assessment that the materials required for such an undertaking are not available for the pediatric population. I will attempt to outline several scenarios where endovascular hemorrhage control may be expressly advantageous for children and will identify methods for the implementation of an endovascular hemorrhage control program for children in each case.
Solid Organ Embolization
Endovascular hemorrhage control of solid organ injuries is already frequently utilized in the care of pediatric trauma. These techniques are typically employed by interventional radiologists or vascular surgeons working in coordination with pediatric trauma surgeons. Common sites for embolization include liver, spleen, and kidney injuries. The indications for arterial embolization have changed over the years, but when they are performed for the appropriate indications, solid organ embolization may mitigate or purposely delay the need for an exploratory laparotomy. Further such embolization can be used to retain organ function that is advantageous for a child’s future long-term development.
For example, splenic embolization allows pediatric trauma patients to retain their splenic function and minimizes the risk of asplenia sequela. Adaptation of the arterial access techniques already used for solid organ embolization at children’s hospitals across the country can serve as a foundation for the implementation of the advanced endovascular hemorrhage control techniques used in the trauma setting.
REBOA
Retrograde endovascular balloon occlusion of the aorta (REBOA) is a technique that can accomplish the same goal as a resuscitative thoracotomy i.e., prioritizing circulatory volume of the heart and brain during uncontrolled hemorrhage. This method involves placing an occlusive balloon into the aorta either above the diaphragm or above the aortic bifurcation (zone 1 and zone 3 respectively) to maintain an adequately perfusing blood pressure to the coronary and cerebral circulatory systems until adequate hemostasis is obtained. This technique has shown a survival benefit when compared to resuscitative thoracotomy for patients not requiring CPR before its use. (Brenner JACS 2018) A gap analysis performed by Stephenson et al. (Journal of Pediatric Surgery 2020) suggests that 20% of pediatric trauma patients may benefit from the use of the REBOA technique. Despite this favorable initial evaluation, several factors limit the rapid adaptation of REBOA to pediatric cases. First, the REBOA device is a well-engineered balloon system adapted from adult endovascular techniques and designed specifically for the average adult aorta. REBOA delivery equipment accessing the common femoral artery is designed for adult-sized vessels. This equipment would have to be adapted in size to the Broselow pediatric distribution of device sizes for trauma. Secondly, currently few pediatric trauma training centers offer endovascular training. Pediatric trauma care providers would have to undergo formal training in this technique since the inappropriate deployment of this equipment can result in significant morbidity and mortality. Despite these few limitations, the adaptation of the REBOA technique for the pediatric trauma patient population should be aggressively pursued as pediatric patients withstand hemorrhagic shock better than adults. A greater survival benefit may be conferred by REBOA for children.
Direct Site Endovascular Repair or Control
REBOA is a technique that is used to maintain adequate blood pressure during unidentified and uncontrolled hemorrhage circumstances. Direct site endovascular (DSE) techniques are used once the injury to the vascular system has been identified.
Three specific instances where DES repair or control is advantageous in adults and could be applied to the pediatric population are outlined below:
TEVAR
Thoracic endovascular aortic repair (TEVAR) for blunt aortic injury is frequently used in adult trauma centers as an alternative to open thoracic repair of the aorta. This technique is an adaptation of endovascular aortic repairs used in elective vascular surgery and confers significant advantages when compared to open repair. The first benefit of this approach is the elimination of the thoracotomy altogether and its subsequent comorbidities. The open repair is also associated with significant blood loss which is essentially mitigated using an endovascular technique. In addition, overall operative time in experienced hands for a TEVAR for blunt aortic injury can be less than 45 minutes, whereas an open repair often takes several hours. (Demetriades 2008)
Subclavian Arterial Injuries
One of the most challenging vascular injuries to address openly is a penetrating injury to the subclavian/axillary artery. The exposure required for proximal and distal control can be associated with significant blood loss and can result in significant morbidity. In adult patients, these injuries can be repaired using an endovascular approach via stent-graft placement across the zone of arterial injury. When stent-graft placement is not anatomically possible, proximal (via groin access) and distal (via brachial access) arterial balloon control can allow hemostasis to be achieved. Both techniques are well described in adult patients, however, this application has not been adapted for the same injuries and children
Pelvic Hemorrhage Control
Currently, pelvic hemorrhage control in pediatric trauma patients is primarily focused on embolization of distal arterial injuries.
Larger vessel injuries in the pelvis may be amenable to stent graft or balloon occlusion control techniques, however, these injuries occur with far less frequency in children. In most cases, pelvic hemorrhage embolization is already a frequently used and effective technique at pediatric trauma centers. Adaptation of more advanced endovascular hemorrhage control techniques for this injury group may not be warranted given the effectiveness of embolization at this time.
Two considerations warrant special consideration when evaluating direct endovascular site repair techniques for children: 1) the true longevity of uncomplicated stent-graft placement and 2) patient growth following the deployment of the stent-graft. The expected lifespan for most stent-grafts are not clearly defined. However, when placing a stent graft in an adult, the service life of the graft is typically assumed to be long enough, compared to the patient’s expected lifetime, that the benefits of an endovascular approach far outweigh the risks of inadequate graft service lifetime. Further, following the placement of a stent-graft in a 50-year-old, no future growth is expected. However, in a 16-year-old patient of comparable size, subsequent post-repair growth is possible, and management of a size mismatch may be necessary. The solution to both of these concerns is the development of an absorbable stent graft that will adequately seal and support the vascular injury during the healing process yet dissolve without embolization or injury to the intimal lining of the artery. A product of this type will also need to be available in a range of sizes adequate for the variation in size of pediatric blood vessels. The development of such products is already underway for use with adults and, when they are successfully approved, will only require scaling for application with children.
Direct endovascular site control is the technique that has the most immediate applicability for use in pediatric trauma patients. This technique involves controlling hemorrhage using both proximal and distal balloon occlusion of the injured artery and is generally well-described in the adult trauma literature. In most cases, such techniques could utilize existing arterial access equipment for pediatric cases. The adaptation for pediatric use would involve selecting existing balloon devices designed for distal adult vascular applications and applying them to injuries to great vessels of children to occlude flow. An example might include, using an adult coronary artery angioplasty balloon to occlude the retrograde flow to a subclavian or axillary artery injury.
Endovascular hemorrhage control is associated with equivalent or superior control of bleeding when compared to open techniques. It can mitigate the need for large incisions and subsequent surgical site infections. Endovascular hemorrhage control can also be performed in a hybrid suite allowing for control of hemorrhage before required exploratory laparotomy for other indications. Most Level One pediatric trauma centers already have high-capacity angiography suites. Pediatric endovascular interventionalists or surgeons working in collaboration with pediatric trauma surgeons could implement an endovascular hemorrhage control program with limited investment. Based on the successes reported in the care of adult trauma, endovascular hemorrhage control programs should be investigated by pediatric trauma surgeons to advance the complicated care of these patients.