In this study using a large multi-institutional database, we demonstrated an association between EMS transport time and survival after TCA. For patients with sustained TCA at arrival, the estimated chances of survival declined rapidly with time. After 15 min of transport time, the estimated survival rate of sustained TCA patients flattened and remained below 1%. Time can be one reasonable factor for considering termination of resuscitation in patients with sustained TCA, although clinical signs of life and type and severity of trauma should be taken into account clinically. To our knowledge, ours is the first report to define the survival curve of patients with TCA in a large, multi-institutional cohort.
The mortality of patients with TCA can vary depending on the treatment options available. Some TCA patients in our study experienced ROSC early in their contact with EMS or during transport, affecting the overall patient survival curve even beyond 15 min of transport time, with estimated survival estimates remaining at 5 to 6%. The basic life support and advanced procedures paramedics are allowed to use in the system [6], such as advanced airway management, intravenous line establishment, and administration of adrenaline, may contribute to some patients’ survival. TCA patients who had these effective procedures performed at the scene or during the transport with prehospital ROSC had a much higher proportion of survival at discharge compared to sustained TCA. Prehospital ROSC patients may have had airway/respiratory/neurological deterioration rather than exsanguination, conditions which can be stabilized with on-scene airway and respiratory management. However, we could not explore which type of injury caused TCA due to the limits of the database. Determining which of several early treatment options are the most effective for increasing survival chances beyond the 15 min time window may depend on the type of trauma endured, and will require further study. In the case of physician-staffed EMS, physicians can perform additional prehospital procedures, such as chest tube insertion and administration of red blood cells or blood plasma, that are potentially beneficial for patients with TCA [7,8,9]. Although still controversial, thoracotomy in the ED for open-chest CPR may increase the chances of survival, as demonstrated when Endo and colleagues compared open-chest versus closed-chest CPR in TCA patients with signs of life upon hospital arrival [10]. Resuscitative endovascular balloon occlusion of the aorta is increasingly used in patients with severe trauma and may also contribute to successfully treating TCA [11]. Further study is required to test whether these procedures and strategies may increase the critical time limit for TCA.
Despite advances in trauma care, survival rates for TCA patients who arrive at a trauma center with no signs of life remain low [12]. A 2012 systematic review demonstrated a 3.3% mortality rate for adult patients with TCA [13]. Duration of CPR is one crucial concern for terminating resuscitation, however the mechanism of injury and the physiological status of the patient should also factor into the decision to terminate resuscitation after TCA. As shown in our study, ROSC before arrival at the ED is a predictor for survival, and longer transport times did not reduce survival-to-discharge when ROSC was observed, indicating continued efforts should be devoted to these cases. Other studies have shown that an initial shockable rhythm, agonal breathing, or a corneal/pupil reflex may indicate improved survival odds [14,15,16,17]. Pulseless electrical activity (PEA) or preserved cardiac wall motion observed by ultrasound examination may also be predictive of survival and can be easily performed in the ED [18]. Different types of injury can cause TCA, and patients with obstructive causes (such as tension pneumothorax) tend to have a higher chance of survival compared with patients whose TCA was caused by exsanguination or severe brain injury [7, 19]. However, consideration of the type of injury was outside the scope of this study.
Making the decision to terminate resuscitation can be difficult. Although few TCA patients survive, even after more than 15 min of CPR [20], the number of patients who could be salvaged may be underestimated. However, showing the survival curve is necessary for the effective use of limited medical resources. In our emergency medical service system, paramedics are not legally permitted to terminate resuscitation in the field. The decision to terminate resuscitation is prolonged to reach the hospital, since some procedures and assessments are only available in the ED. Physicians should thoroughly examine clinical signs predictive of survival prior to considering resuscitation time when deciding to terminate sustained TCA.
The current study has some limitations. We could not obtain the exact duration of CA, and instead used EMS transport time as a surrogate, for most of the patients with sustained TCA actual CA duration is longer than this time window. However, this study demonstrated a survival curve which may be used as one factor to determine termination of resuscitative efforts after TCA. Our emergency service system generally does not allow cessation of resuscitation on scene. Therefore, the survival curve is mainly targeted for emergency department physicians or surgeons when considering termination of resuscitation. Transport times were fairly short, presumably because the majority of participating institutions are located in urban areas, conditions which may not be practical in rural areas. However, the initial time course may still be relevant for all TCA patients. Further study is needed to examine the effectiveness of prolonged efforts for patients in rural areas. Additionally, we could not obtain data for some potential indicators of survival such as pupillary reflexes or spontaneous movement. These indicators should be considered before withholding or withdrawing CPR. We also did not consider outcomes after advanced resuscitative treatments such as open-chest CPR or resuscitative endovascular balloon occlusion of the aorta. Neurological outcomes were not considered in our study, and some survivors of TCA have neurological impairment. Finally, as with all retrospective studies, data integrity, validity, and ascertainment bias are potential limitations.
