Ep 138 - Traumatic Cardiac Arrest with Prof Jason Smith RN

The Evolution of Traumatic Cardiac Arrest Management: Military Insights and Civilian Applications

Traumatic cardiac arrest (TCA) is a critical and often fatal condition encountered in both military and civilian emergency medicine. Historically, the prognosis for patients with TCA has been poor, leading many to believe that resuscitation efforts are largely futile. However, recent developments, particularly those arising from military experience, are challenging this perspective. In this post, we explore insights shared by Dr. Jason Smith, a consultant in emergency medicine and a seasoned military doctor, about the evolving understanding of TCA, including the role of chest compressions and the application of military practices in civilian settings.

Traumatic Cardiac Arrest: Insights from Military Experience

TCA is relatively rare in civilian settings, with major trauma centres like Plymouth seeing a case every one to two months. However, in military environments, where high-velocity injuries are more common, TCA occurs more frequently. Dr. Jason Smith’s experience in Afghanistan revealed that traumatic cardiac arrests happened as often as three to four times a week. This stark contrast has driven the development of specific management protocols in military settings, where hemorrhagic shock is the leading cause of TCA.

In these high-intensity environments, the focus is on immediate and aggressive interventions. These protocols, developed on the battlefield, have significantly improved outcomes and are now being adapted for civilian trauma centres, where they continue to challenge the longstanding belief that TCA is nearly always fatal.

From the Battlefield to the Emergency Room: Evolving TCA Management

Over the past decade, the management of TCA has undergone significant evolution, largely influenced by military practices. Dr. Smith’s team in Afghanistan developed a "bundle of care" designed to rapidly and effectively address the key factors leading to TCA. This bundle includes:

1. External Hemorrhage Control involves ensuring that tourniquets are properly applied and functioning, alongside other measures to control external bleeding.
2. Oxygenation and Ventilation: Rapid intubation and ventilation to maintain oxygen delivery to vital organs.
3. Bilateral Thoracostomies: Decompressing the chest on both sides to manage potential tension pneumothorax.
4. Rapid Volume Replacement: Administer warm blood and blood products intravenously or intraosseously to quickly replace lost volume.
5. Pelvic Binding: Applying a pelvic binder in cases of blunt trauma to reduce pelvic volume and control bleeding.
6. Consideration of Thoracotomy: In specific cases, such as penetrating trauma to the chest, thoracotomy is considered as a life-saving intervention.

This structured approach, honed in military contexts, has led to outcomes that are significantly better than those reported in civilian literature at the time. These practices are now being adapted for civilian use, where they are helping to improve survival rates for TCA patients.

Challenging Old Assumptions: New Data on TCA Survival

One of the most significant shifts in the perception of TCA has come from recent data showing that survival rates are not as dismal as previously thought. In military populations from Iraq and Afghanistan, survival rates from TCA have been reported at around 10.6%. Even more compelling is data from the UK’s TARN database, which indicates a 7.5% survival rate for civilian TCA cases, including those caused by blunt trauma.

These figures are comparable to survival rates for non-traumatic cardiac arrest, leading to a reassessment of TCA management. The traditional view that resuscitation in TCA is futile is increasingly being challenged by evidence that with the right interventions, survival is possible.

The Controversy Around Chest Compressions in TCA

One of the most hotly debated topics in TCA management is the role of closed chest compressions. In standard Advanced Life Support (ALS) protocols, chest compressions are a fundamental part of resuscitation. However, in the context of TCA, particularly hemorrhagic TCA, their effectiveness has been called into question.

Dr. Smith’s research has played a pivotal role in this debate. He observed that during resuscitation in Afghanistan, the use of a Belmont rapid infuser often resulted in alarms indicating that chest compressions were creating too much pressure inside the thorax, preventing effective blood transfusion. This led to the hypothesis that chest compressions might be not only ineffective but potentially harmful in hemorrhagic TCA.

To explore this hypothesis, Dr. Smith and his colleagues at DSTL Porton Down developed an animal model using swine to simulate TCA. The study aimed to replicate the conditions seen in hemorrhagic TCA by bleeding the animals to a mean arterial pressure (MAP) of 20 mmHg. The animals were then divided into groups to compare the outcomes of different resuscitation strategies, including chest compressions alone, blood transfusion alone, and combinations of the two.

Key Findings: Prioritizing Blood Over Compressions

The study’s results were revealing. Animals that received blood transfusions without chest compressions had significantly better outcomes than those that received chest compressions alone or in combination with blood transfusion. Specifically, all animals that received only chest compressions were dead by the end of the study, while those that received blood alone showed signs of return of spontaneous circulation (ROSC).

Moreover, when chest compressions were combined with blood transfusion, the results were mixed. While some animals achieved partial ROSC, the overall survival was lower than in the group that received blood alone. This led to the conclusion that in hemorrhagic TCA, chest compressions might be not only unnecessary but potentially detrimental.

These findings, while based on animal models, have significant implications for clinical practice. They suggest that in cases where haemorrhage is the primary cause of TCA, the focus should be on rapid volume replacement with blood and blood products rather than on chest compressions.

Translating Research into Practice

While Dr. Smith’s study provides compelling evidence, applying these findings to human practice requires careful consideration. The study’s limitations, including its reliance on animal models and the specific conditions of hemorrhagic TCA, mean that more research is needed to fully understand how these findings apply to diverse patient populations.

However, the study does provide a strong foundation for re-evaluating current protocols. In situations where haemorrhage is identified as the primary cause of TCA, emergency teams might consider prioritizing volume replacement over chest compressions, especially in environments where rapid blood transfusion is possible.

The challenge, as Dr. Smith noted, lies in training and protocol development. Chest compressions are deeply ingrained in resuscitation practice, and changing this mindset requires robust training and clear guidelines. Emergency departments and trauma centres need to prepare their teams for scenarios where the traditional approach might not be the best one, ensuring that all members are aligned in their approach to TCA management.

Conclusion: A New Paradigm for Traumatic Cardiac Arrest

The management of traumatic cardiac arrest is evolving, driven by insights from military medicine and supported by emerging data from civilian practice. While challenges remain, particularly in shifting entrenched practices around chest compressions, the future of TCA management looks promising. Survival rates once thought to be negligible, are improving as we better understand the mechanisms at play and refine our interventions accordingly.

For emergency medicine practitioners, staying informed about these developments is crucial. As more data becomes available and as we continue to learn from both military and civilian experiences, the protocols for TCA will undoubtedly continue to evolve. The days of viewing traumatic cardiac arrest as a futile scenario are fading. With the right approach, training, and tools, we can offer these patients a fighting chance at survival.

In summary, putting science into the argument has been a game-changer, and continuing to blend evidence with practice will be key to improving outcomes in this challenging area of emergency medicine.