INTRODUCTION
Traumatic inferior vena cava (IVC) injuries are rare among traumatic abdominal injuries, accounting for fewer than 5% of penetrating injuries and 0.5% of blunt trauma injuries [1]. However, they are often fatal, with prehospital and in-hospital mortality rates of 30% to 50% and 20% to 66%, respectively [2].
There are various methods for treating traumatic IVC injuries, including surgery, vascular grafting, and even close monitoring, depending on the injury level and patient stability. Although IVC repair is the mainstay treatment, in cases where repair is challenging because of massive bleeding, difficult access to the injured site, or notable patient instability, ligation is a treatment option [3]. An atriocaval shunt can also be used to repair the retrohepatic IVC segment [4]. This variety of treatment methods illustrates the lack of consensus or guidelines, and survival rates have not significantly improved over time [5].
Currently, a higher level of injury, blunt trauma, and a lower Glasgow Coma Scale (GCS) score are associated with worse outcomes of traumatic IVC injuries [3,6–8]. However, relatively few cases of IVC injuries have been studied to identify the prognostic factors.
IVC injuries often require emergency treatment, and it can be difficult to collect data in those urgent situations. Moreover, IVC injuries are rare and information is scarce. In Korea, where the availability of authorized trauma centers is relatively recent, there have been few studies on traumatic IVC injuries, and most are case reports. Therefore, this study aimed to describe our experience with the surgical treatment of traumatic IVC injuries and to investigate the demographics, clinical profiles, and surgical outcomes of cases at a regional trauma center.
METHODS
Ethics statements
This study was reviewed and approved by the Institutional Review Board Dankook University Hospital (No. DKUH 2022-11-034). The requirement for informed consent was waived by the Institutional Review Board because this was a retrospective study and only anonymized data were used.
Description of participants
The medical records of patients admitted to a single regional trauma center for traumatic IVC injuries between January 2014 and March 2022 were retrospectively reviewed. Nineteen patients with IVC injuries were identified. Among them, one patient had an IVC contusion only, one patient had an unnamed vessel branch injured near the IVC, and one patient was transferred from another hospital after already undergoing repair. Thus, 16 patients were enrolled after the three above-mentioned patients were excluded. Of these 16 patients, two underwent medical treatment without surgery. Finally, 14 patients were enrolled for the analysis of surgical outcomes (Fig. 1). The surgical outcomes included overall mortality and 24-hour mortality. We aimed to identify the factors associated with these surgical outcomes and the differences between patients with injuries at the retrohepatic IVC or higher level and those with injuries at the subhepatic IVC level.
Data collection
Data regarding patient demographics, injury levels, initial clinical characteristics, initial laboratory values, treatments, and surgical outcomes were collected. The demographics included age, sex, body mass index (BMI), injury mechanism, cause of injury, prehospital time, Injury Severity Score (ISS), and Abbreviated Injury Scale for each body part. Initial clinical characteristics included systolic blood pressure (SBP), heart rate per minute, mean arterial pressure (MAP), and GCS score. Initial laboratory values included pH, partial pressure of arterial oxygen, serum lactate level, hemoglobin, and international normalized ratio. Treatment data included cardiopulmonary resuscitation (CPR) in the emergency room (ER), door-to-operating room (DTO) time, main treatment methods (direct repair, ligation, atriocaval shunt, observation, and others), amount of red blood cells (RBCs) transfused within the first 24 hours, and operation time. “Others” in the main treatment methods included procedures to stop bleeding such as gauze packing, direct manual compression, and resuscitative endovascular balloon occlusion of the aorta.
If the patient was intubated on arrival, the GCS verbal score was calculated using a linear regression model as follows [9]:
Derived verbal score = −0.3756 + motor score × (0.5713) + eye score × (0.4233)
The abdominal IVC was anatomically divided into five segments as follows: (1) suprahepatic IVC, from the upper margin of the hepatic veins to the lower margin of the diaphragm; (2) retrohepatic IVC, which is covered by the liver; (3) suprarenal IVC, from the upper margin of the renal vessels to the lower margin of the liver; (4) juxtarenal IVC, between the bilateral renal vessels; and (5) infrarenal IVC, from the bifurcation of the common iliac veins to the lower margin of the renal vessels (Fig. 2). In this study, subhepatic IVC included the IVC segments below the retrohepatic IVC.
Statistical analysis
Categorial variables were analyzed using the Fisher exact test and continuous variables were analyzed using the Mann-Whitney U-test. Continuous variables were expressed as median values (interquartile range, IQR). Statistical significance was set at P<0.05. Statistical analysis was conducted using R ver. 4.2.0 (R Foundation for Statistical Computing).
RESULTS
Demographics
Of the 16 patients who had traumatic IVC injury, 10 (62.5%) were male and 15 (93.8%) had blunt trauma. The most common cause of traumatic IVC injury was a car-driver traffic accident (six patients, 37.5%), followed by falls (three patients, 18.8%). The median patient age was 48 years (IQR, 40–68 years), BMI was 23.4 kg/m2 (IQR, 21.0–26.1 kg/m2), prehospital time was 92.5 minutes (IQR, 54.0–158.0 minutes), and ISS was 34 (IQR, 25–43) (Table 1). The most common injury level was the retrohepatic IVC (six patients, 37.5%), followed by the infrarenal IVC (five patients, 31.3%), suprarenal IVC (two patients, 12.5%), juxtarenal IVC (two patients, 12.5%), and suprahepatic IVC (one patient, 6.3%) (Fig. 2).
Clinical characteristics and initial laboratory findings
During admission, the median SBP and MAP values were 86.5 mmHg (IQR, 71.8–120.8 mmHg) and 60.5 mmHg (IQR, 54.7–85.3 mmHg), respectively. Patients had a moderate loss of consciousness (median GCS, 10; IQR, 6–15). The initial laboratory data showed acidosis (median pH, 7.31; IQR, 7.24–7.37) with hyperlactatemia (median lactate, 4.3 mmol/L; IQR, 2.2–7.5 mmol/L) (Table 1).
Treatment and surgical outcomes
Of the 16 patients studied, eight (50.0%) underwent direct repair, two (12.5%) were closely monitored (observation), one (6.3%) underwent ligation, and one (6.3%) underwent an atriocaval shunt. Furthermore, four patients (25.0%) underwent other damage control surgery, and three (18.8%) underwent CPR in the ER. The median DTO time was 72.5 minutes (IQR, 55.8–109.8 minutes) and the median number of RBC units transfused within the first 24 hours was 29.0 (IQR, 19.8–40.3). Of the two patients who were closely monitored, one had a pericaval hematoma at the infrarenal IVC level and received only an injection of tranexamic acid and fluid therapy because the hemodynamics were stable. The other patient was hypotensive on arrival and had extravasation at the retrohepatic IVC level. However, the hemodynamics became stable after an initial transfusion of 2 units of RBCs. The patient was then closely monitored during hospitalization and received additional transfusions (14 units of RBCs, 7 units of fresh-frozen plasma, and 30 units of platelet concentrate) and injections of tranexamic acid. Both patients that were closely monitored, eventually survived. Of the 14 patients who underwent surgery, 11 (78.6%) did not survive, nine of whom (64.3%) died within 24 hours of admission (Table 1).
Survivors who underwent damage control surgery
The five survivors who underwent surgical treatment for traumatic IVC injury are presented in Table 2. All patients were injured at the subhepatic IVC level and successfully underwent direct repairs (venorrhaphy) in the first operation. Three patients were discharged alive and the remaining two died. One patient died of severe brain injury on hospital day 11, and the other died of septic shock with pneumonia on hospital day 12.
Variables associated with surgical outcomes
A BMI >23.0 kg/m2 (P=0.046), a higher serum lactate level (P=0.043), and a shorter operation time (P=0.016) were significantly associated with overall mortality (Table 3). A higher BMI (P=0.050), higher serum lactate level (P=0.004), shorter operation time (P=0.005), and injury at the retrohepatic IVC or higher level (P=0.031) were significantly associated with 24-hour mortality in the univariate analysis (Table 3).
Comparison according to the injury level of the IVC
Younger age (P=0.028), higher BMI (P=0.005), more acidic pH (P=0.028) with higher lactatemia (P=0.012), higher hemoglobin level (P=0.012), and shorter DTO time (P=0.028) were significantly associated with injury at the retrohepatic IVC or higher level (Table 4). Although not statistically significant, the MAP was lower (P=0.081) in patients with an injury at the retrohepatic IVC or higher level, and CPR in the ER was performed more frequently in these patients (P=0.055). All patients with injuries at the retrohepatic IVC or higher level who underwent surgical treatment died within 24 hours of admission. In contrast, patients with subhepatic IVC injuries had a high rate of direct repair (75.0%) and a significantly low 24-hour mortality rate (37.5%, P=0.031) (Table 4).
DISCUSSION
In this study, the overall and 24-hour mortality rates after surgery were 78.6% and 64.3%, respectively. These outcomes are slightly worse than those noted in previous studies, where the overall mortality rates ranged between 20% and 70% [5,8,10–14]. The worse outcomes in this study are probably because 13 of the 14 patients who underwent surgery had blunt trauma, which is a known risk factor for mortality in traumatic IVC injury [7]. Of the nine deaths within 24 hours of admission seven developed cardiac arrest due to massive bleeding during the operation and did not recover. For the remaining two deceased patients, the operations ended with uncontrolled bleeding. Therefore, 24-hour mortality in this study indicated a failure of damage control.
Several prognostic factors associated with traumatic IVC injury have been reported. According to previous studies, a higher IVC injury level was a prognostic factor for mortality [3,8]. A recent meta-analysis revealed that blunt trauma and injury at the suprarenal or higher IVC level were prognostic factors for mortality in traumatic IVC injury [7]. It is difficult to expose the retrohepatic IVC segment as the liver is attached to the anterior surface of the IVC, and the major hepatic veins connect to this level; therefore, the mortality rate associated with a retrohepatic IVC injury can be as high as 90% [3]. Furthermore, in this study, compared to patients with injury at the subhepatic IVC, those with injury at the retrohepatic IVC or higher level showed worse 24-hour mortality rates in the univariate analysis. In a study of 16 cases, multiple logistic regression analysis revealed lower GCS scores to be an independent factor for mortality [6]. We found that higher BMI and serum lactate levels were associated with mortality. Obesity has been reported as an independent risk factor for mortality in blunt trauma patients because the kinetic energy applied to the patient is in proportion to the mass; thus, obesity may increase the energy and cause more severe injury [15]. A higher initial serum lactate level has been associated with higher injury severity and can predict massive hemorrhage in trauma patients [16]. However, because the currently available studies and this study have all had small sample sizes, further studies with a large population are required to confirm that these are prognostic factors for traumatic IVC injury.
The surgical treatments for IVC injuries vary depending on the location of the injury. In general, the first step is to expose the injured IVC segment and apply direct compression to the proximal and distal parts of the segment [1]. Direct repair can then be attempted following proximal and distal control of the injured IVC. However, when repair is difficult due to massive bleeding, ligation can be performed more quickly and easily for damage control [2]. In a study using data from the United States (2007 to 2014), excluding other-vessel injuries and severe extraperitoneal injuries, there was no difference in mortality between ligation and repair, and ligation was not an independent factor for mortality [17]. A recent meta-analysis showed that, compared with repair, ligation was associated with higher mortality. However, there was no significant difference in mortality rates for infrarenal IVC injuries [7]. Therefore, ligation appears to be a safe treatment option, particularly in infrarenal injuries. Nevertheless, we were unable to save a patient with an infrarenal IVC injury despite using ligation. For a retrohepatic IVC injury, liver mobilization may be required to expose the segment, but massive hemorrhage from the injury site can occur with this procedure [5]. Therefore, in a retrohepatic IVC injury, without active bleeding or with only a contained hematoma, perihepatic gauze packing without mobilization should be performed [1]. However, if packing fails to control the bleeding, direct repair of the injured site may be the only way to do so. Total hepatic vascular occlusion or an atriocaval shunt can be used to achieve a clear operative field during repair. Since subhepatic and suprahepatic IVC clamping for total hepatic vascular occlusion also blocks venous return, it may cause cardiac arrest. Therefore, additional aortic clamping at the supraceliac level or a venovenous bypass may be required, although outcomes have been reported to be poor [18,19]. Alternatively, an atriocaval shunt facilitates volume resuscitation during repair by isolating the injury site and maintaining venous return through a shunt using an endotracheal tube or a chest tube. As such, it can be used in a retrohepatic IVC injury with active bleeding, a large injury site, and extreme hemodynamic instability [4,5,20]. However, the reported outcomes of using an atriocaval shunt have also been unsatisfactory due to the severity of retrohepatic IVC injuries, the complexity of the procedure, the approach to the thorax, and delays in the decision to apply the procedure [4,20]. Richardson [21] reported a mortality rate of 88% in 412 patients with atriocaval shunts. We had one case of retrohepatic IVC injury for whom total hepatic vascular occlusion and an atriocaval shunt were ineffective. The patient was a 24-year-old man who was crushed by 2,000 kg of building material. Although venorrhaphy for a retrohepatic IVC injury was performed with total hepatic vascular occlusion, bleeding through an extended supradiaphragmatic IVC injury continued. By switching to an atriocaval shunt, the extended IVC injury was confirmed and venorrhaphy was successfully performed. Unfortunately, the patient did not survive because the delay in deciding to apply the atriocaval shunt resulted in significant blood loss (57 units of RBC were transfused during the operation). However, this case confirmed that an atriocaval shunt could be a better damage control tool than total hepatic vascular occlusion for primary repair of a retrohepatic IVC or higher level injury in terms of securing the operative field during massive bleeding.
There were some limitations to this study. First, it was a retrospective study; therefore, important variables affecting surgical outcomes may have been missed. Moreover, data extracted from a review of medical records are not very reliable. Second, this was a single-center study, making it difficult to generalize the results to the overall population of patients with traumatic IVC injuries. Third, the statistical power of this study was weak because the sample size was small (14 to 16 patients).
Subhepatic IVC injuries, which are easy to access, can be usually treated with a direct repair method. A systematic and multidisciplinary treatment strategy is required to deal with injuries at the retrohepatic IVC or higher level that are difficult to treat surgically. Since IVC injuries that require surgical treatment are rare, simulation training may be necessary to master the surgical skills needed for the complex damage control techniques (e.g., atriocaval shunt or ligation) and to understand their correct indications. This study described 14 cases in which surgical treatment was performed for IVC injury over a period of 9 years at a single institution. For a more comprehensive analysis, further studies are needed with larger populations and the participation of multiple centers.
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