Observational management of Grade II or higher blunt traumatic thoracic aortic injury: 15 years of experience at a single suburban institution.

Background: We aimed to investigate the outcomes after delayed management of ≥ Grade II blunt traumatic thoracic aortic injury (BTAI).
Methods: Between January 2005 and December 2019, we retrospectively reviewed the medical records of 21 patients with ≥ Grade II thoracic aortic injury resulting from blunt trauma. Twelve patients underwent observation for the injury, whereas nine patients were transferred immediately after the diagnosis. Patients were divided into a nonoperative management group (n = 7) and delayed repair group (n = 5) based on whether they underwent thoracic endovascular aneurysm repair or surgery.
Results: The most common dissection type was DeBakey classification IIIa (n = 9). Five patients underwent delayed surgery (including aneurysm repair), with observation periods ranging from 1 day to 36 months. The delayed repair group exhibited higher injury severity scores than the nonoperative management group (n = 7). The nonoperative management group was followed-up with blood pressure management without a change in status for a period ranging from 3 to 96 months. Conclusions: Our findings indicated that conservative management may be appropriate for select patients with Grade II/III BTAI, especially those exhibiting hemodynamic stability with anti-impulse therapy and minimally sized pseudoaneurysms. However, further studies are required to identify the risk factors for injury progression and long-term outcomes. Copyright:

INTRODUCTION

Although blunt traumatic thoracic aortic injury (BTAI) occurs in less than 1% of patients involved in motor vehicle collisions, the condition is life-threatening and represents the second leading cause of death in such patients after head injury.[1] Previous studies have reported that the prehospital mortality rate among patients with BTAI is over 75%, and that up to 50% of patients die within the first 24 h following injury.[234] In addition, a wide range of concomitant injuries, such as major abdominal injury (29% of cases) and major head injury (31% of cases), are the challenges for the management of BTAI.[5]

In the currently accepted grading system, injuries are assigned to one of four categories: Grade I (intimal tear), Grade II (intramural hematoma), Grade III (pseudoaneurysm), and Grade IV (rupture).[6] Classically, the surgical repair technique requires a thoracotomy, aortic cross-clamping, cardiopulmonary bypass, and lengthy operative times. However, this technique is associated with high rates of mortality and paraplegia,[178] and a recent trend in the management of BTAI has changed the way in which patients with minimal aortic injury are managed.[89] The Society for Vascular Surgery (SVS) consensus guidelines on thoracic endovascular aneurysm repair (TEVAR) recommend expectant management with serial imaging for type I injuries, whereas types II to IV should be repaired.[6] However, these guidelines stated that the overall level of evidence was poor, necessitating further investigation.[6]

Delayed repair of Grade II or higher BTAI may be appropriate when coexisting trauma injuries can be managed and optimal resuscitation can be achieved.[610] However, few studies have investigated the delayed management of patients with high-grade BTAI.[11] In the present study, we aimed to describe our experience with and investigate the outcomes of delayed management of Grade II or higher BTAI in 12 patients treated at our institution over a 15-year period.

METHODS

We retrospectively reviewed the medical records of 21 patients with Grade II or higher BTAI treated at Chungbuk National University Hospital (CBNUH) between January 2005 and December 2019. Twelve patients underwent initial observational management for BTAI, whereas nine were transferred immediately after the diagnosis. Decisions regarding the timing of the procedure, TEVAR, or operative management were made by the attending trauma thoracic surgeon.

This study was approved by the Institutional Review Board of Chungbuk University Hospital (2021-03-005), who waived the requirement for informed consent due to the retrospective nature of the study.

Demographic data collected included age, sex, Injury Severity Score (ISS), Revised Trauma Score, trauma and ISS, initial systolic blood pressure (SBP), Glasgow Coma Scale score, mechanism of injury, and additional injuries. We reviewed all chest X-rays (CXR) for hemopneumothorax, rib fractures, and mediastinal widening findings. Mediastinal widening on CXR was defined as a width of at least 8 cm. Based on computed tomography (CT) imaging, the presence of mediastinal hematoma, sternum and manubrium fracture, and location of injury were identified. BTAI was classified into four grades in accordance with the clinical guidelines for treating thoracic aortic injury released by the SVS:[6] Grade I, intimal tear; Grade II, intramural hematoma; Grade III, pseudoaneurysm; Grade IV, rupture.

Patients were divided into a nonoperative management (NOM) group (n = 7) and a delayed repair group (n = 5) based on whether they underwent TEVAR or operative management. Because of the small sample size, nonparametric tests were used to analyze the variables. Statistical analysis was performed using the IBM SPSS Statistics version 23.0 (IBM Co. Armonk, NY). The numeric data are summarized as the mean, median, range, and interquartile range where appropriate. The categorical data were analyzed using a contingency table with Fisher's exact test. P < 0.05 was considered statistically significant.

RESULTS

A total of 12 patients with grade II or higher BTAI were initially managed through observation. The NOM group (n = 7) continued to undergo observational management for BTAI, whereas the delayed repair group (n = 5) underwent TEVAR or delayed operative management. The mean age of all patients was 60 ± 16.1 years, and there were no significant differences in age between the two groups (65 ± 16 years vs. 54 ± 15.0 years, P = 0.202). Men represented 50% of all patients, and there were no significant differences in the proportion of men between the two groups (71.4% vs. 20%). The most common mechanism of injury was car road traffic accidents (RTA), followed by pedestrian RTA, and fall-related injury, and there were no significant differences in the mechanism of injury between the two groups. Based on significant differences in ISS and SBP, our findings indicated that the delayed repair group exhibited more features of hemodynamic instability and higher injury severity than the NOM group [Table 1].

Table 1

Demographic characteristics of patients with blunt traumatic thoracic aortic injury

	Total (12), n (%)	NOM group (7), n (%)	Delayed repair group (5), n (%)	P
Age (years), mean±SD	60±16.1	65±16	54±15.0	0.202
Male	6 (50)	5 (71.4)	1 (20)	0.242
Underlying disease
HTN	1 (8.3)	1 (14.3)	0	1.000
DM	0	0	0	1.000
CAoD	1 (8.3)	1 (14.3)	0	1.000
CVA	1 (8.3)	1 (14.3)	0	1.000
SBP (mmHg), mean±SD	106±35	120±34	84±25	0.034
GCS, median (IQR)	14.5 (14-15)	15 (14-15)	14 (8.5-15)	0.311
ISS, mean±SD	33±13.4	27±11.8	42±10.7	0.048
RTS, mean±SD	7.29±1.205	7.76±0.142	6.63±1.744	0.038
TRISS (%), mean±SD	74±28	83±19	60±36	0.322
Injury mechanism
Pedestrian TA	3 (25)	2 (28.6)	1 (20)	0.663
In-car TA	4 (33.3)	2 (28.6)	2 (40)
Bike TA	1 (8.3)	0	1 (20)
Fall	3 (25)	2 (28.6)	1 (20)
Others	1 (8.3)	1 (14.3)	0
Elixhauser comorbidity index, mean±SD	1.3±3.45	0.3±1.38	2.8±5.02	0.331

NOM: Nonoperative management, SD: Standard deviation, HTN: Hypertension, DM: Diabetes mellitus, CAoD: Carotid artery occlusive disease, CVA: Cerebrovascular accident, SBP: Systolic blood pressure, GCS: Glasgow Coma Scale, ISS: Injury severity score, RTS: Revised trauma score, TRISS: Trauma and injury severity score, TA: Traffic accident, IQR: Interquartile range

In order of decreasing frequency, the most common associated injuries among all patients were extremity injury, spinal injury, and abdominal organ injury [Table 2]. In addition, extremity injury was more common in the delayed repair group, and there was a statistically significant difference between the two groups (28.6% vs. 100%, P = 0.028). Mediastinal widening on CXR was observed in six (50%) patients, although there were no significant differences between the two groups (37.5% vs. 75%, P = 0.273). Mediastinal hematoma on chest CT was identified only in the delayed repair group (n = 8), and there was a significant difference between the two groups (0% vs. 80%, P = 0.010). The most common dissection type was DeBakey classification IIIa (n = 9), and 10 patients had Grade III injury. There were no significant differences in dissection type or injury grade between the two groups.

Table 2

Radiologic characteristics of the nonoperative management and delayed repair groups

	Total (12), n (%)	NOM group (7), n (%)	Delayed repair group (5), n (%)	P
Associated injuries
Head injury	3 (25)	1 (14.3)	2 (40)	0.523
Intra-abdominal injury	5 (41.7)	2 (28.6)	3 (60)	0.558
Extremity injury	7 (58.3)	2 (28.6)	5 (100)	0.028
Spinal injury	6 (50)	3 (42.9)	3 (60)	1.000
Chest x-ray findings
Hemothorax	4 (33.3)	3 (37.5)	1 (25)	0.594
Pneumothorax	1 (8.3)	0	1 (25)	0.333
Rib fracture	6 (50)	2 (25)	4 (100)	0.030
Mediastinal widening	6 (50)	3 (37.5)	3 (75)	0.273
Lung contusion	5 (41.7)	2 (25)	3 (75)	0.152
Chest CT findings
Sternum and manubrium fracture	5 (41.7)	2 (28.6)	3 (60)	0.558
Mediastinal hematoma	4 (33.3)	0	4 (80)	0.010
DeBakey classification
I	2 (16.7)	1 (14.3)	1 (20)	1.000
IIIa	9 (75)	5 (71.4)	4 (80)
IIIb	1 (8.3)	1 (14.3)	0
Injury grade
II	2 (16.7)	2 (28.6)	0	0.470
III	10 (83.3)	5 (71.4)	5 (100)

NOM: Nonoperative management, CT: Computed tomography

The median observation period in the delayed repair group (n = 5) was 2 days (range: 1–549 days), whereas the median follow-up period without a change in status in the NOM group (n = 7) was 6 months (range: 3–96 months). Mortality was observed in two patients in the unstable injury group. Two patients in the delayed repair group died due to severe associated injuries before definitive aortic repair [Table 3].

Table 3

Clinical outcomes of the nonoperative management and delayed repair groups

	Total (12)	NOM group (7)	Delayed repair group (5)	P
Length of hospital stay (days), median (IQR)	21 (3-44)	41.5 (17.5-69.0)	3.0 (1.5-38.5)	0.177
Mortality, n (%)	2 (16.7)	0	2 (40)	0.182
Length of observation period (days), median (IQR)	165 (2.3-730)	180 (150-730)	2 (1-549)	0.064

NOM: Nonoperative management, IQR: Interquartile range

DISCUSSION

BTAI remains difficult to diagnose and manage, with early reports suggesting that 80%–90% of patients die at the scene.[312] A recent study[7] reported a 30-day survival rate of only 34% among patients who arrived with signs of life. Classically, BTAI has been treated through open surgical repair, which involves a thoracotomy, aortic cross-clamping, and cardiopulmonary bypass in some cases.[7] Over the past decade, there has been a transition in the management of aortic trauma from open surgical repair to endovascular repair.[16910] However, several studies have demonstrated the feasibility of conservative management for low-grade BTAI.[8131415] In addition, a recent study suggests a delayed strategy for BTAI because early aortic repair may worsen concurrent traumatic brain injury.[16]

As mentioned earlier, SVS consensus guidelines recommend expectant management with serial imaging for minimal aortic injury, while types II to IV should be repaired. However, the term “minimal aortic injury” does not make a clear distinction between an isolated intimal defect and a small pseudoaneurysm.[1] The natural history of minimal aortic injury is unclear as well. Osgood et al.[13] reported a very low risk of injury progression in patients with Grade I–II BTAI (2/42, 5%). It is likely that there remains substantial institution-to-institution variation in the management of these injuries. Many surgeons decide to repair BTAI due to concern over eventual injury progression, the potential for aneurysm development or rupture, and the high risk of loss to follow-up.[15]

In our study, 12 patients underwent initial observational management for BTAI. The NOM group was watched successfully for a median of 6 months without a change in aortic injury diameter, while the delayed repair group underwent TEVAR a median of 2 days after admission. Our analysis identified significant differences in hemodynamic instability, ISS, and mediastinal hematoma on chest CT between the two groups. According to the study of Hirose et al.,[17] traumatic aortic injury might be treatment without operation in patients with multiple associated injuries or severe comorbidity. A study of early outcomes among 29 patients who underwent planned NOM reported a survival rate of 97% at a median of 1.8 years.[18] They concluded that deliberate NOM of carefully selected patients with BTAI may be a reasonable alternative in patients with multisystem trauma. Harris et al.[19] recently reported that NOM of selected traumatic aortic pseudoaneurysm is common, particularly for lesions involving <50% of the aortic circumference, and that such management is associated with a minimal short-term risk of treatment failure or aortic-related mortality. These studies suggest that appropriately selected high-grade BTAIs (not Grade IV) do not require early repair and can be managed through careful observation.

This study has several limitations. The retrospective nature of the study and small sample size limit the quality of data, and the study lacks sufficient statistical power to determine whether differences are clinically relevant. As of early 2017, CBNUH had not become a high-volume facility. The regional trauma center for Chungbuk province was just opened at CBNUH in December 2017. Finally, the assessment of injury progression through repeated imaging was limited by the relatively short duration of the follow-up period.

CONCLUSIONS

We retrospectively reviewed the data for 12 patients with high-grade BTAI who underwent initial observational management. Our findings indicated that conservative management may be appropriate for select patients with Grade II or III BTAI, especially those exhibiting hemodynamic stability with anti-impulse therapy and minimally sized pseudoaneurysms. However, further studies are required to identify the risk factors for injury progression and long-term outcomes.

Research quality and ethics statement

This study was approved by the Institutional Review Board/Ethics Committee at Chungbuk University Hospital (Approval # 2021-03-005; Approval date August 26, 2021). The authors followed the applicable EQUATOR Network (http://www.equator-network.org/) guidelines, specifically the STROBE Guidelines, during the conduct of this research project.

Financial support and sponsorship

None.

Conflicts of interest

There are no conflicts of interest.