There is a saying, "Complexity in the face of adversity breeds chaos." I'm not sure where this maxim originated, but it is definitely true in resuscitation settings. That's the crux of this post: Is the abdominal tourniquet simplicity in the face of adversity compared with the resuscitative endovascular balloon occlusion of the aorta (REBOA)?
We all know how futile it feels to do CPR on a traumatic cardiac arrest patient with suspected massive blood loss. Just what are we pumping, and if there is any remaining intravascular blood, where are we pumping it?
I will never forget the pain of trying to resuscitate an 11-year-old boy who was run over by a neighbor turning into her driveway. She never saw him as he rolled down the street lying flat on his skate board. He received everything we had, including an open thoracotomy and aortic cross-clamping. He ultimately died from severe liver lacerations and venous injuries.
This patient and thousands like him demonstrate that we need more tools in the fight against this type of traumatic cardiac arrest. Before someone else points it out, we need to be clear that traumatic arrests are not simply the proverbial internal injuries. The Centers for Disease Control and Prevention estimated that 30 percent of all injury-related deaths are due to brain injuries in the United States. (MMWR Surveill Summ 2017;66:1.) Many of those patients will also have noncompressible torso hemorrhage.
Open thoracotomy can occasionally be life-saving, and cross-clamping the aorta may be helpful in stopping exsanguinating noncompressible torso hemorrhage. This procedure, however, is not very practical in rural and resource-limited settings. It can be performed by a trained operator, but it creates the "now what?" scenario. The rural emergency physician has to manage an unstable patient who has an open chest and cross-clamped aorta and who needs to be transferred emergently for ongoing resuscitation and critical care. Open thoracotomy can be dangerous to the operator. Lacerations from errant scalpels and jagged edges of broken ribs commonly occur. Exposure to body fluids and blood is almost unavoidable despite the best personal protective equipment.
Open thoracotomy, nevertheless, makes sense for treating penetrating wounds of the heart and life-threatening pericardial effusions, as does cross-clamping the aorta for noncompressible torso hemorrhage. But what if we could compress torso hemorrhage at the same time we cross-clamp the aorta? That leads us to a discussion of the abdominal aortic and junctional tourniquet (AAJT) and REBOA.
REBOA is touted by many, and some evidence suggests that it is effective. One meta-analysis of studies comparing REBOA to cross-clamping of the aorta showed that the odds of mortality did not differ between the compared groups. (World J Emerg Surg 2017;12:30.) But REBOA simply stops blood flow in the aorta. It does not actually compress sites of torso hemorrhage. Even if REBOA stops blood flow in the aorta, venous bleeding will continue until the injured veins are empty. It is also not an entirely practical solution because training, experience, and availability of REBOA remain primarily limited to trauma centers. It is even less available in the prehospital arena where it would be most effective.
On the other hand, the AAJT can cross-clamp the aorta and provide compression to torso hemorrhage, and it is available in prehospital and austere environments. For the record, feedback from field use suggests that training in the correct application of the AAJT is important, and the tourniquet will cause a degree of pain and discomfort in the awake patient.
Several interesting abstracts on the AAJT and REBOA were presented at the Military Health System Research Symposium (MHSRS) 2017. The animal studies were far from conclusive, but they are an excellent start to answering some important questions. One abstract compared the AAJT and REBOA in a model of noncompressible pelvic hemorrhage using 20 Yorkshire swine. Those authors reported that the AAJT and zone 3 REBOA achieved hemostasis and that blood pressure was elevated with AAJT use proximal and distal to aortic occlusion. The AAJT application increased pulmonary pressure and inspiratory pressure but not the PaO2/FiO2 ratio or SpO2, and lactate and hemoglobin levels were elevated in AAJT-compared with the REBOA-treated animals. No differences were observed in inflammatory markers or microscopic examination of tissues between the two modalities. (See table.)
Also helpful was a paper recently published in Military Medicine by Rall, et al. (Mil Med 2017;182:e2001.) The paper admittedly suffered from the limitations inherent in animal models of trauma and hemorrhage, but it demonstrated that the application of the AAJT improved ROSC in a hemorrhagic cardiac arrest swine model. Twelve male Yorkshire swine weighing between 70 and 90 kg were used in the procedures. The animals underwent controlled hemorrhage until cardiac arrest defined as carotid systolic pressure below 10 mm Hg for 10 seconds occurred.
After three minutes, all animals underwent CPR, transfusion of five units of blood, and were randomized to treatment with or without an AAJT. The primary outcomes for the study were survival and time. Survival time was significantly different between the two groups, and five of the six animals in the CPR with AAJT group survived, while only one animal in the CPR alone (control) group survived to the end. We now have some evidence that applying the AAJT while aggressively transfusing blood might save lives.
Locally, I have been asking why we don't apply the AAJT to all traumatic arrests. Recognizing that time is a factor, ultrasound can fairly effectively rule out hemothorax, pneumothorax, and a life-threatening pericardial effusion. The presence of these findings may indicate that an open thoracotomy is needed. Additional questions exist that need to be answered before the AAJT is applied routinely to all traumatic arrests. If there is concern for a thoracic aorta injury, is application of the AAJT a contraindication? Or if there is a head or c-spine injury in a traumatic cardiac arrest patient, is the AAJT appropriate for these patients? In the end, these are probably judgment calls. But in the words of a colleague on this subject: "Most of these patients are going to die whether or not you apply the AAJT, so you have nothing to lose." I tend to share this opinion.
The AAJT appears to be a simpler and less complex solution to the problem of noncompressible torso hemorrhage, and evidence is finally starting to trickle in that supports the use of the AAJT in traumatic cardiac arrest patients.
Watch a video of Dr. Mellick explaining how to use the AAJT to save lives in the ED.
Watch a demonstration by Richard Schwartz, MD, who along with John Croushorn, MD, invented an abdominal tourniquet.