Approach to traumatic cardiac arrest in the emergency department: a narrative literature review for emergency providers

Abstract

BACKGROUND:

Traumatic cardiac arrest (TCA) is a major contributor to mortality and morbidity in all age groups and poses a significant burden on the healthcare system. Although there have been advances in treatment modalities, survival rates for TCA patients remain low. This narrative literature review critically examines the indications and effectiveness of current therapeutic approaches in treating TCA.

METHODS:

We performed a literature search in the PubMed and Scopus databases for studies published before December 31, 2022. The search was refined by combining search terms, examining relevant study references, and restricting publications to the English language. Following the search, 943 articles were retrieved, and two independent reviewers conducted a screening process.

RESULTS:

A review of various studies on pre- and intra-arrest prognostic factors showed that survival rates were higher when patients had an initial shockable rhythm. There were conflicting results regarding other prognostic factors, such as witnessed arrest, bystander cardiopulmonary resuscitation (CPR), and the use of prehospital or in-hospital epinephrine. Emergency thoracotomy was found to result in more favorable outcomes in cases of penetrating trauma than in those with blunt trauma. Resuscitative endovascular balloon occlusion of the aorta (REBOA) provides an advantage to emergency thoracotomy in terms of occupational safety for the operator as an alternative in managing hemorrhagic shock. When implemented in the setting of aortic occlusion, emergency thoracotomy and REBOA resulted in comparable mortality rates. Veno-venous extracorporeal life support (V-V ECLS) and veno-arterial extracorporeal life support (V-A ECLS) are viable options for treating respiratory failure and cardiogenic shock, respectively. In the context of traumatic injuries, V-V ECLS has been associated with higher rates of survival to discharge than V-A ECLS.

CONCLUSION:

TCA remains a significant challenge for emergency medical services due to its high morbidity and mortality rates. Pre- and intra-arrest prognostic factors can help identify patients who are likely to benefit from aggressive and resource-intensive resuscitation measures. Further research is needed to enhance guidelines for the clinical use of established and emerging therapeutic approaches that can help optimize treatment efficacy and ameliorate survival outcomes.

INTRODUCTION

Trauma remains a major contributor to mortality and morbidity in all age groups and predominantly affects children and young adults under 44 years old.[1,2] Despite decades of improvements in modern medical care, the survival rate of traumatic cardiac arrest (TCA) remains extremely low, ranging from 3.3% to 9.2%.[3-5] For those who survive, a large number of people will suffer from debilitating neurological outcomes.[5-7] Resource availability and allocation must be considered when deciding to pursue extreme resuscitative measures given the overall poor prognosis after TCA.[8]

Among adults, the survival rate is directly influenced by factors including the mechanism of injury and the time between injury and intervention.[9] Despite potentially dismal outcomes, several advancements have contributed to improvements in survival. Advancements have arisen from analyzing TCA as a separate entity from medical cardiac arrest. Once the unique pathophysiology of TCA was identified, advancements helped contribute to improved survival rates.[10]

Traumatic brain injury is the leading cause of death in trauma; however, the main preventable cause remains hemorrhagic shock, followed by other causes such as obstructive shock and hypoxia, which in most TCA cases can affect a healthy heart, unlike in medical cardiac arrest.[11] A healthy heart is an invaluable resource in regard to resuscitation efforts; thus, implementing resuscitation algorithms that account for this fact can shift the focus to addressing the underlying causes. As a result, contemporary TCA algorithms now prioritize addressing hemorrhagic shock and obstructive shock before addressing hypoxia to improve chances of survival.[12]

Understanding that TCA is a unique pathophysiology is critical for emergency providers. In this review, we aim to discuss factors associated with successful resuscitation, outline approaches to the management of TCA by type and highlight the role of different interventions based on current guidelines (Figure 1).

Figure 1.

Traumatic cardiac arrest algorithm. * REBOA is indicated in trauma patients with suspected hemorrhage below the diaphragm, an initial systolic pressure of 90 mmHg or lower, requiring ongoing massive transfusion and low suspicion of either cardiac, intrathoracic, head or neck injury. ATLS: advanced trauma life support; SBP: systolic blood pressure; REBOA: resuscitative endovascular balloon occlusion of the aorta; XABC: exsanguinating hemorrhage > airway > breathing > circulation.

METHODS

For this literature review, we searched the PubMed and Scopus databases to assess the literature on TCA. The terms “traumatic cardiac arrest”, “trauma”, and “cardiac arrest” were used. Boolean operators and medical subject headings (MeSH) terms were used to combine search terms, giving: (“traumatic” [All Fields] OR “traumatized” [All Fields] AND “heart arrest” [MeSH Terms] OR (“heart” [All Fields] AND “arrest” [All Fields]) OR “heart arrest” [All Fields] OR (“cardiac” [All Fields] AND “arrest” [All Fields]) OR “cardiac arrest” [All Fields]). Search results were further limited to English language, human, adult, and we included studies published before December 31, 2022. The results revealed 943 matches. Database searches were supplemented by screening the reference lists of relevant studies and reviews. In total, 49 studies were included in the review (Figure 2).

Figure 2.

Study identification, screening and inclusion flow chart. ED: mergency department.

Each title and abstract was assessed independently by two investigators according to the following criteria. Studies included randomized clinical trials, observational studies, and reviews. Expert opinion, commentary articles and editorials were excluded from this review. Additionally, we excluded articles not relating to emergent traumatic conditions or that did not include clinically relevant effects, such as those pertaining to effects at the cellular level. Both investigators needed to agree about the eligibility of each abstract before it could advance to the full-text review stage. When there was a discrepancy, the two investigators attempted to resolve the difference by consensus before involving a third investigator. The process of reaching agreement after full-text review on eligibility for inclusion in the analysis was similar. Therefore, all abstracts required agreement from at least two investigators before being included in the final analysis.

Each of the selected articles was read in its entirety with particularly close attention to the study design, sample size, classification of traumatic injuries, condition of the patients included, and the location of the study. This information was combined with each of the main conclusions in tabular fashion to provide a comprehensive summary of the selected studies. Studies that addressed settings outside of the emergency department (ED) were excluded. We used the web-based Covidence system to manage our narrative review (www.covidence.org, Melbourne, Australia). The data were reported as a consensus between investigators, so no interrater agreement was calculated.

RESULTS

Pre- and intra-arrest prognostic factors affecting survival

Given the high rates of morbidity and mortality in patients with TCA, patient selection for aggressive and resource intensive resuscitation must be assessed, especially considering other factors such as cost, scarcity of blood transfusion resources, and the infrastructure for transport and immediate resuscitative measures.[8,13] In a 2020 systematic review and meta-analysis by Tran et al,[9] which included a total of 53 studies and 37,528 patients, several prognostic factors were identified and analyzed before and during resuscitation. Primary outcomes of the study included survival to hospital discharge and survival to 30 d. This study found that cardiac motion on ultrasound, initial shockable rhythm, witnessed arrest, and bystander CPR were associated with higher odds of survival. The use of prehospital or intra-hospital epinephrine was associated with lower odds of survival. Sex and mechanism of injury did not affect survival.

More recently, a 2022 systematic review and meta-analysis by Vianen et al[14] also investigated prognostic factors associated with survival and favorable neurologic outcomes after traumatic arrest. It included a total of 36 studies and 51,722 patients. The results showed that overall mortality was 96.2%, and of those, only 43.5% had a favorable neurologic outcome. When comparing mortality rates of TCA where a physician was available on scene, mortality rate decreases from 97.2% to 93.9% and outcomes with favorable neurological outcome rises from 38% to 57%. The only factor that was associated with a higher odds of survival was having an initial shockable rhythm. Sex, mechanism of injury, witnessed arrest, bystander CPR, use of epinephrine, and prehospital intubation were not associated with survival.

According to the American Heart Association, epinephrine is a recommended medication for treating cardiac arrest;[15] however, its therapeutic effects in TCA remain controversial.[10] In a prospective study, Hosomi et al[16] investigated the effect of epinephrine administration at different time points after traumatic out-of-hospital cardiac arrest. It included a total of 2,024 adult patients. Epinephrine was administered at 4 different time points following arrest. The results demonstrated that one-month survival was the highest in patients who received epinephrine at the earliest time point, and the probability of survival decreased significantly for the patient who received epinephrine at the latest time point. When looking at the data in aggregate, a systematic review and meta-analysis by Wongtanasarasin et al[17] that included a total of 7,158 patients measured outcomes of epinephrine treatment overall despite administration timing on patients with TCA and showed no mortality benefits in terms of in-hospital survival or reported prehospital ROSC.

Emergency thoracotomy: historical perspective, indications, rationale, outcomes, and complications

The first description of a resuscitative thoracotomy was used in 1906. This technique was later pioneered by Beall and colleagues in 1961 as a method for immediate hemorrhage control and direct access for open cardiac massage and repair of injuries in trauma patients.[18-20]

Indications for emergency thoracotomy depend on the mechanism of injury and timing of loss of pulses and vital signs. Although several societies have recommendations regarding indications for this resuscitative maneuver, emergency thoracotomy is probably most useful in trauma patients with prehospital cardiac arrest from either penetrating or blunt injuries. In TCA from penetrating injuries, it is indicated in patients who are pulseless and receive less than 15 min of CPR after the injury. In TCA from blunt trauma, recommendations for emergency thoracotomy are in patients with arrest upon arrival or if the patient is pulseless but exhibits signs of life, such as pupillary response, spontaneous ventilation, or cardiac electrical activity. However, poor survival rates and neurological outcomes have been reported.[21,22]

The goals of this procedure are to relieve cardiac tamponade, access the heart muscle for injury repair and cardiac massage, and cross clamp the aorta to provide hemorrhage control below the level of occlusion. Open cardiac massage helps to augment/restore cardiac output once hemorrhage is replaced with blood transfusion. In cases of arrest due to ventricular fibrillation, internal defibrillation can also be used. Thoracotomy can provide access to major thoracic vessels and lung parenchyma for direct repair of injury.[23]

Even with the life-saving potential of emergency thoracotomy, this procedure can carry significant morbidity. Considering the invasive nature of this procedure, complications can be a direct result of the procedure, such as massive chest wall bleeding, damage to the heart on pericardiotomy, damage to the coronary arteries from repair, damage to the phrenic nerve, or damage to the esophagus during aortic cross clamping. Sequalae from aortic occlusion from cross clamping can include decreased perfusion to abdominal organs and the spinal cord. Other related complications include occupational injury to the operator in which blood-borne disease can be transmitted, so personal protective equipment is essential in performing this procedure.[24,25]

With regard to outcomes, sources have reported varied results of survival rate and poor neurologic outcome. A review published by the Eastern Association for the Surgery of Trauma in 2015, which combined a total of 72 studies and 10,238 patients, showed an overall survival rate of 8.5%, of which 85.7% were considered neurologically intact.[22] These figures differ in regard to the mechanism of injuries. Penetrating trauma has a more favorable outcome with a survival rate of 10.6%, of which 90.4% were considered neurologically intact. In contrast, blunt injuries have a survival rate of 2.3%, of which 59.4% of patients were considered neurologically intact. Favorable predictors of survival were the presence of vital signs and sinus cardiac rhythm.

Resuscitative endovascular balloon occlusion of the aorta (REBOA): background, historical view, indications, rationale, and outcomes, complications

A major contributor to traumatic arrest is hemorrhagic shock,[26] since circulatory volume is a core element in maintaining adequate systemic pressure for successful resuscitation. In such an environment, maintaining cardiac and cerebral blood flow is essential to achieve favorable outcomes. Resuscitative thoracotomy with aortic cross clamping achieves this goal; however, less invasive maneuvers could provide a more attractive therapeutic option. REBOA is a resuscitative measure that allows the control of blood flow in the proximal aorta by inflating a balloon in the aorta in a designated anatomical zone and redirecting the flow from the distal hemorrhage to perfuse cardiac and cerebral tissue.[27] Aortic occlusion serves to increase perfusion to the heart and the brain.[28] REBOA can be used in postpartum hemorrhage and nontraumatic hemorrhagic emergencies such as ruptured abdominal aneurysm.[29-31] For blunt and penetrating traumatic injuries, Brenner et al[32] first described the use of REBOA in end-stage hemorrhagic shock. REBOA can be a life-saving tool in cases of hemorrhage below the diaphragm.

Based on current guidelines, trauma patients with suspected hemorrhage below the diaphragm, an initial systolic pressure of 90 mmHg (1 mmHg=0.133 kPa) or lower, and requiring ongoing massive transfusion are candidates for REBOA. However, according to expert consensus, REBOA was not recommended in TCA or patients arriving with no pulse or no blood pressure. Excluded from these recommendations were patients with blunt and/or penetrating trauma to the abdomen or pelvis, with no palpable carotid pulse but with any organized electrocardiography rhythm or cardiac contraction on ultrasound.[33,34]

Placement of the inflated balloon is designated to two anatomical aortic zones (I, III), each performing a different function. Zone I is in the proximal aorta just distal to the takeoff of the left subclavian artery. Inflating the endovascular balloon here allows cessation of blood flow beyond this point. This may be life-saving in the event of severe intra-abdominal or retroperitoneal hemorrhage. Zone III is located in the distal aorta just above its bifurcation. Deploying the REBOA in this position allows cessation of blood flow in severe pelvic, inguinal or lower extremity hemorrhage. Balloon inflation is recommended not to exceed 30 min if placed in Zone I and 60 min if placed in Zone III to avoid ischemic injury distally. Alternatively, intermittent or partial REBOA are options for prolonging occlusion time while reducing ischemic effects.[33] The contraindication of REBOA according to a joint statement from the American College of Surgeons Committee on Trauma is in the setting of major thoracic hemorrhage or pericardial tamponade.[34] Other contraindications include traumatic brain injury and penetrating neck trauma, where occluding the descending aorta has the potential to increase the risk of brain or neck hemorrhage.[35]

Although REBOA is considered a less invasive procedure than emergency thoracotomy, REBOA-related complications still exist. According to a previous study,[36] complications were classified by procedural phases of REBOA. These can occur during arterial access, balloon inflation and occlusion, and removal of the sheath. Gaining arterial access can lead to vessel injury. Balloon-related injuries can occur if the balloon is inflated in the wrong location, decreasing distal organ perfusion. In terms of arterial occlusion, serious complications include ischemic organ injury and limb ischemia and can lead to worsening lactic acidosis. Upon removing the occlusion, ischemia-reperfusion can be observed. The removal of balloons and sheaths also carries the risk of arterial injury, dissection, or distal thrombosis. In a nationwide database from the American College of Surgeons Trauma Quality Improvement Program, serious but rare complications such as lower leg amputation and acute kidney injury were reported.[37]

Regarding REBOA-related outcomes in TCA, a report from the American Association for the Surgery of Trauma showed comparable mortality rates among TCA patients treated with REBOA and emergency thoracotomy with aortic occlusion.[38] A recent prospective observational study from the R Adams Cowley Shock Trauma Center reported mortality of 90% and ROSC of 58%.[39] Another prospective observational study from six USA level 1 trauma centers reported a similar rate of ROSC of 59% among TCA patients.[40] Recently, a case series from London’s Air Ambulance Service reported the use of REBOA in a physician-led pre-hospital care setting with significant improvement in blood pressure and reduction of hypovolemic cardiac arrest and early death due to exsanguination.[41] Future studies on REBOA utility in TCA and risk of ischemic complications can help guide decision-making in resuscitative care.

Emerging alternative treatment approaches: selective aortic arch perfusion (SAAP), extracorporeal life support (ECLS), and emergency preservation and resuscitation (EPR)

Even with invasive resuscitative measures, TCA mortality remains high, and survival can be at the risk of unfavorable neurologic outcomes. Since closed chest-CPR is ineffective due to hypovolemia from severe hemorrhage,[42] the introduction of REBOA as a less invasive option to buy time for more definitive surgical intervention has been shown to be a viable option. However, evidence on outcomes is limited, and complications can still occur. Alternative resuscitative approaches to improve survival must control hemorrhage and provide enough systemic blood pressure to perfuse vital organs. A recent review introduced emerging resuscitative strategies to address these factors, which included SAAP, ECLS, and EPR.[43]

SAAP is a technique aimed at improving survival in cardiac arrest. This method combines the technique of aortic occlusion in anatomical Zone I and direct aortic and femoral arterial access for extracorporeal perfusion with an oxygen-carrying fluid. This technique represents extracorporeal support isolated to the aortic arch and great vessels.[44] Laboratory models using SAAP with oxygenated hemoglobin-based oxygen carrier (HBOC), whole blood, and packed red blood cells (pRBC) have in fact shown successful ROSC after hemorrhage-induced TCA.[45,46] However, data on this concept are limited to animal models, as clinical studies have not yet occurred due to the lack of Food and Drug Administration (FDA)-clearance for this device.

ECLS, commonly known as extracorporeal membrane oxygenation (ECMO), is a well-known technique used to provide support in cases of respiratory and cardiac failure.[47] The use of veno-venous (V-V) ECMO in trauma in the setting of acute lung injury and refractory hypoxemia is well reported. The first description of V-V ECLS in a case of blunt trauma was in 1972. This form of support has been shown to be effective in combatting trauma casualties suffering from hypoxemia.^[48.49] Two retrospective studies demonstrated V-V ECLS to be associated with improved survival in trauma patients experiencing severe acute respiratory distress.[50,51] Veno-arterial (V-A) ECLS is useful in the setting of cardiogenic shock in trauma. A consideration of the patient’s ability to tolerate anticoagulation is important but not an absolute contraindication in all situations. A recent review on ECLS use in trauma patients showed that V-V ECLS was used in 71.4% of cases, while V-A ECLS was used in only 24.5%.[52] Another review on ECLS survival outcomes showed that V-V ECLS survival to discharge ranged from 56% to 89%, while V-A ECLS survival to discharge ranged from 42% to 63%.[53] The difference in survival is likely due to cardiopulmonary failure indicating V-A extracorporeal support rather than the procedure itself. Further evidence on V-A ECLS is needed to determine its effect and outcomes in treating TCA.

EPR is an approach currently being investigated in managing TCA. To decrease metabolic demand during circulatory arrest, the concept of EPR involves rapid cooling of the entire body, which is then followed by delayed resuscitation using full cardiopulmonary bypass (CPB) once the injury has been definitively managed.[54,55] Experimental laboratory studies and animal model studies have shown benefits in providing time to more definitive surgical hemostasis.[56,57] A grant for an investigational device exemption for a safety and feasibility clinical trial from the FDA has been awarded. The trial (EPR-CAT) aims to enroll subjects 18- to 65-year-old victims of penetrating trauma who have suffered a cardiac arrest shortly before hospital arrival in the ED or in the operation room.[58]

CONCLUSION

TCA remains a significant challenge in the field of emergency medicine. The current treatments for this condition have shown limited success rates. Established treatment modalities such as emergency thoracotomy and REBOA present viable treatment options to address hemorrhagic shock, but further research regarding ischemic risks and other complications is needed to guide appropriate use.