The primary finding of this research was that a long decision-TAE time resulted in a high risk of mortality. Moreover, although the actual TAE duration did not have a statistically significant influence on decision-TAE time, the interaction between TAE duration and decision-TAE time was statistically significant, indicating that TAE duration modified the effect of decision-TAE time on mortality.
Some reports have suggested the importance of early TAE for improving mortality [4, 15, 16, 25]. In clinical settings, there are many variations in the circumstances surrounding patient delivery to the ER, and the condition of the patient upon delivery [26, 27]. These variables include the presence of associated injuries, severity of said injuries, and differences in vital signs . Moreover, they may or may not have been transferred from another hospital and they may have received previous treatment by prehospital medical professionals [29, 30]. Physicians must decide upon a treatment plan for these patients taking these factors into consideration . Hence, the actual effectiveness of shortening the delay from decision making to actual TAE administration can be confirmed by analyzing the time from when the decision to administer TAE is made to when the TAE is performed and its effect on the outcomes .
Several studies have reported that the time to angioembolization is longer than the time to PPP, which may be in part due to the high availability of orthopedic surgeons as compared with that of interventional radiologists [7, 12, 32], and TAE may be delayed at night or on weekends based on reports of other catheter-based interventions [16, 33, 34]. In our institution, interventional radiologists and the equipment required for TAE are available 24 h a day, 365 days a year. Therefore, the availability of staff and/or equipment was not an issue in the present study. The overall decision-TAE time was 60 min, even after performing other resuscitation procedures. Although PPP may have advantages over TAE, namely that of early start time [7, 12], most patients with pelvic fracture, even if they are unstable, can be managed with primary TAE strategies at centers that have 24-h availability of interventional radiologists .
Other studies have reported the effectiveness of REBOA for patients with unstable pelvic fractures [8, 9]. In this study, there were seven (4.4%) cases of REBOA; however, there were no clear indications for REBOA in pelvic fracture patients. Moreover, the consensus on REBOA indications, ideal patient populations, and outcomes has not been decided even among trauma specialties ; therefore, further studies are needed. In our facility, we aim to complete TAE, including treatment of other bleeding injuries, within 60 min. Although we could not directly clarify the relationship between TAE duration and mortality, our intervention analysis showed that TAE duration modified the effect of decision-TAE time on mortality. Based on these results, it appears that patients with a decision-TAE time of 105 min or longer benefited from a long TAE duration, whereas patients with a decision-TAE time of < 105 min benefitted from a short TAE duration. When the decision-TAE time increased by 10 min from 105 to 115 min, the risk increased by 1.15, 1.1, and 1.08 times, respectively, for cases with TAE duration times of 40, 55, and 75 min. If the decision TAE time extended by an additional 10 min to 125 min, the risk increased by 1.3, 1.23, and 1.15 times, respectively. Conversely, when the decision-TAE time reduced by 10 min from 105 min to 95 min, the risk was 0.88, 0.9, and 0.93 times, respectively. If the TAE time was reduced from 105 min to 20 min, the risk increased by 0.77, 0.81, and 0.86 times, respectively. This suggests that a short decision-TAE time with a short procedure time could lead to improved mortality outcomes. To our knowledge, this is the first study to discuss the relationship between TAE duration and mortality, as there is only speculation in previous reports. Further studies need to be undertaken.
We could not confirm the factors that influenced the decision-TAE time, except for hospital transfer (Table 4). Based on these results, the expected parameters that could influence the severity of the patient’s condition, such as ISS, vital signs, and even associated injuries, were not related to decision-TAE time. In addition, the transferred patients underwent TAE within a short duration. These results indicate that fast CT scanning can reduce the decision-TAE time; hence, the development of fast imaging strategies is essential. Recently, there have been reports on the effectiveness of hybrid emergency room systems [37, 38], hybrid operation rooms , and mobile angiography systems  for treating trauma patients. These systems consist of an angiography-computed tomography (CT) machine in a trauma resuscitation room and thus have the potential to provide new evidence in this field.
This study has several limitations. First, the performance of the CT scan was dependent on the patient’s mode of admission. This meant that we could not determine the severity of the patient's condition based on the CT/DT stratification. Second, we could not clarify the actual durations of “decision time,” which means that other decision-TAE times could be established, and if this happens, the results would be changed. In fact, it is difficult to retrospectively ascertain the exact time when the decision to administer TAE is made, and we believe that the definition of decision-TAE time requires further discussion. Third, the result of this study cannot be generalized to other facilities that do not have the same interventional radiology coverage and equipment. Fourth, as the decision on treatment with REBOA was made by physicians, we could not analyze the impacts of REBOA in this study.