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Original Article

Predictive indications of operation and mortality following renal trauma

Yang, Chia-Shena, c; Chen, Isaac Chun-Jenb; Wang, Chien-Yingb; Liu, Chen-Chib; Shih, Hsin-China, b, *; Huang, Mu-Shuna, b

Author Information
Journal of the Chinese Medical Association: January 2012 - Volume 75 - Issue 1 - p 21-24
doi: 10.1016/j.jcma.2011.11.002

    Abstract

    1. Introduction

    Nonoperative management of blunt trauma to solid intra-abdominal organs (e.g., the liver, spleen, and kidney) has been the first choice of care for many years.1,2 Mild and moderate blunt renal injuries can be managed nonoperatively with high success rates; however, nonoperative management of patients with high-grade renal injuries remains controversial.3 There is little debate regarding to the use of surgery to treat patients who are hemodynamically unstable and need immediate exploration. Controversy exists regarding the management of patients who are hemodynamically stable and have been diagnosed with a major renal injury by computed tomography (CT).1

    Moreover, the clinical outcomes of patients with blunt renal injuries that are accompanied with various associated injuries need to be clarified. The management of patients with renal injuries becomes increasingly complex in the face of multiple associated injuries. A few studies have examined coexisting injuries in order to determine their impact on nephrectomy rates.4–6 As solid organ injuries are increasingly managed using nonoperative techniques, the need for the early identification of injuries that require surgical intervention is becoming of paramount importance. Due to the potential complexity involved in the clinical outcomes of patients who experience renal trauma and multiple injuries, and as the prognostic factors regarding the mortality of renal trauma remain unclear, we investigated the predictive factors associated with the possibility of surgical intervention and outcomes in trauma patients with renal injuries.

    2. Methods

    This clinical observation study retrospectively reviewed the clinical characteristics of adult patients (age ≥ 18 years) who had sustained renal injuries during 1996–2006. The enrolled patients were primarily managed in our hospital, a university medical center located in northern Taiwan. Patients were brought to our emergency department and were initially resuscitated according to the advanced trauma life support guidelines provided by the American College of Surgeons. Patients who were suspected of having blunt abdominal trauma were managed using a sonogram, according to the screening procedure and algorithm provided in our previous report.7 Stable patients who were found to have positive sonographic findings (e.g., any intra-abdominal fluid collection, including perirenal fluid) received a CT scan afterward. Patients who were found to have solid organ injuries, including renal trauma, that did not require surgical indication received nonoperative treatment. They were observed in the intensive care unit for at least 24 hours and transferred to an ordinary ward when their condition stabilized.

    Data collected from the trauma registry and the medical records included demographics, injury mechanism, blood pressure, hemoglobin, heart rate upon admission and after resuscitation, operative procedures, and associated extra- and intra-abdominal injuries and outcomes. Injury severity score (ISS),8 renal injury scale (RIS) score,9 Glasgow coma scale (GCS) score, and abbreviated injury scale (AIS) score were calculated for each patient. This study was approved by the institutional review board of our hospital.

    2.1. Statistical analysis

    Comparisons of the patient characteristics (including operation and mortality) were performed using the two-tailed Student’s t test for continuous variables and the Chi-square test for categorical variables. Variables associated with p value <0.05 on univariate analysis were incorporated into the multivariate analysis, which was performed using logistic regression modeling. Any independent risk factors identified in the final model were presented in terms of the odds ratios (OR), including 95% confidence intervals (CI). SPSS version 17.0 (SPSS Inc., Chicago, IL, USA) for Windows was used to analyze all numerical and categorical data obtained for this study.

    3. Results

    3.1. Demographic characteristics

    From 1996–2006, 73 patients who were diagnosed with renal injuries and initially admitted to our hospital were enrolled in this study. This included 55 males (75.34%) and 18 females (24.66%), with a mean age of 37.71 ± 19.35 years (Table 1). The major mechanisms of injury were motor vehicle accidents (MVA) for 45 patients (61.64%), falling accident for 15 patients (20.55%), and a high falling (≥6 m) accident for 10 patients (13.70%). There were three patients (4.11%) who were injured by a penetrating mechanism; two of the injuries were incurred by knife stabs and the other one occurred via a gunshot. Seven patients (9.59%) required operative exploration before a renal procedure could be performed, and four died (overall mortality rate: 5.48%) as a result. GCS, ISS, blood pressure, heart rate, and hemoglobin levels are shown in Table 1. Nine patients were classified with severe injuries (ISS ≥ 16), including four (6%) of the 66 nonoperative patients and five (71.4%) of the seven operative patients. Three of the four (75%) mortalities suffered from a severe injury.

    Table 1
    Table 1:
    Clinical characteristics of nonoperative and operative patients.

    Renal injuries were diagnosed by CT scan and all patients were hemodynamically unstable on presentation. Sonograms were then taken. The average RIS score was 2.22 ± 1.12. There were 64 patients (87.68%) with low-grade renal injuries (RIS I, II, or III) and nine (12.33%) with high-grade renal trauma (RIS IV or V).

    3.2. Nonoperation versus operation groups

    There were 66 patients who underwent conservative management and seven who underwent surgical management. Compared with the patients who received nonoperative treatment, patients who required an operation had a higher ISS, higher RIS score, lower hemoglobin levels, and lower blood pressure upon admission to the ER (Table 1). When these data were analyzed by binary variables, such as ISS ≥ 16 (OR = 12; p = 0.011), RIS ≥ 4 (OR = 16.27; p = 0.003), SBP < 90 (OR = 1.83; p = 0.014), and if a blood transfusion was required (OR = 28; p = 0.001), these variables were significantly correlated with the necessity of an operation, as determined by univariate analysis. Multivariate analysis determined that ISS ≥ 16 (OR = 44.67; p = 0.002) and RIS ≥ 4 (OR = 19.52; p = 0.02) are independent predictors of operative management (Table 2).

    Table 2
    Table 2:
    Clinical variables correlated with operation.

    3.3. Survivor versus nonsurvivor groups

    The clinical characteristics and trauma scores of the survivors and nonsurvivors are shown in Table 3. Four patients (5.48%) died of shock and multiple organ failure. Three of them had severe head injuries (AIS ≥ 3). One patient, who suffered from a severe fall (≥6 m), died of intracranial hemorrhage on the 11th day after admission. The other patient with severe head injury, along with another patient with severe chest and abdomen injuries, was involved in a motor vehicle accident and was in shock upon arrival. All of these patients died within 1 day after admission. Three of the nonsurviving patients presented with deep coma status (i.e., GCS score of 3). The other patient, who was conscious upon arrival, was a 79-year-old who suffered from a severe penetrating injury to the abdomen that required a nephrectomy; he died of multiple organ failure in the intensive care unit on the 67th day after admission. This patient presented with the most stable vital signs upon arrival (SBP = 175 mmHg), but also the most severe renal injury (RIS = 4) that required an operation. The development of multiple organ failure may have been due to the patient’s old of age, which ultimately resulted in his death.

    Table 3
    Table 3:
    Clinical characteristics of surviving and nonsurviving patients.

    Nonsurvivors had a higher ISS, lower GCS, higher heart rate, and lower hemoglobin levels. When these data were analyzed using binary variables, ISS ≥ 16, GCS < 8, SBP < 90 mmHg, heart rate ≥ 110/min, hemoglobin < 10 g/dl, and the requirement of a blood transfusion were significantly correlated with mortality by univariate analysis. Multivariate analysis indicated ISS ≥ 16 and GCS < 8 as significant predictors of mortality (Table 4).

    Table 4
    Table 4:
    Clinical variables correlated with mortality.

    3.4. Associated injuries

    The majority of the patients presented with associated injuries along with their renal injuries. A total of 33 patients (45.21%) had associated intra-abdominal injuries, including injuries to the liver in 18 patients (24.66%), injuries to the spleen in 11 patients (15.107%), injuries to the pancreas in two patients (2.74%), and bowel injuries in two patients (2.74%). The extra-abdominal organ injuries included head and neck injuries in 15 patients (20.55%), facial injuries in eight (10.96%), injuries to the thorax in 27 (36.99%), injuries to the extremities in 20 patients (27.45%), and injuries to the external surface in five patients (6.85%).

    4. Discussion

    Renal trauma occurs in 8–10% of all abdominal injuries, with blunt renal trauma accounting for the majority of the injuries to the kidney.10,11 Bozeman et al suggested that blunt trauma is the cause of renal injury in 80–90% of cases.3 Many factors influence the nature and injury severity of renal trauma patients, including age, gender, cause of injury, and associated injuries, including those to the intra- or extra- abdominal organs. In recent decades, the suggested treatment for renal trauma patients has shifted more toward nonoperative options. The success rate of nonoperative management ranges from 60–90%.12–16 Patients with minor renal injuries (i.e., grades I or II) have a better success rate, up to 90%. For patients with renal trauma that does not involve the renal vessels, the nonoperative success rate is higher, up to 95%.17 Demetriades et al suggested that renal injuries are theoretically more amenable to nonoperative management than other intra-abdominal solid organ injuries.1 The reason may be due to the retroperitoneal position of the kidneys, which may contain bleeding, and to their rich blood supply, which may promote healing even after severe parenchymal injury. In addition, the retroperitoneal space can limit the amount of blood that accumulates in this area, allowing blood clots to cover the laceration.

    Despite the trend toward nonoperative management of renal trauma, those patients who are injured by penetrating mechanisms are more likely to undergo a laparotomy for the management of associated intra-abdominal injuries regardless of their hemodynamic status.18 Another factor that must be considered before surgery is the injury grade of the kidney. High-grade lesions require surgical exploration.18–20 Davis et al demonstrated that overall injury severity, severity of renal injury grade, hemodynamic instability, and transfusion requirements are predictive of nephrectomy after both blunt and penetrating traumas.15 Baverstock et al suggested that grade V injuries still result in a nephrectomy rate of 90.9% and, in patients with hemodynamic instability the rate is 100%.18

    Our present study found that the success rate of nonoperative treatment was 91.3%. We also found that higher injury severity, including higher ISS and higher RIS, was significantly associated with the need for an operation. Furthermore, our study demonstrated that higher ISS and lower GCS are highly correlated with nonsurviving patients. The coma scale might be influenced by severe head injuries, in addition to low blood perfusion to the brain. Although shock was related to nonsurvival, our study showed that ISS ≥ 16 and GCS < 8 are the two main predictors of final mortality.

    CT has emerged in recent years as an effective tool that can provide an accurate assessment of the extent of injuries and is invaluable for making management-related decisions. Thall et al reported that CT is the best imaging modality for the staging and management of renal trauma.21 In recent years, the aggressive use of angiography with transcatheter embolization has been advocated as an effective adjunct for the salvage of high-grade renal lacerations.22 Fu et al demonstrated that patients with contrast extravasation on CT scans, i.e., patients with discontinuous Gerota’s fascia and pararenal hematoma expansion in blunt renal trauma, is associated with the need for angioembolization. Early angioembolization should be considered in patients with blunt renal traumas who present with severe associated traumas.23

    Several limitations of the present study need to be declared. Besides the innate character of a retrospective study, the small number of mortality cases may have resulted in an inaccurate conclusion. For example, the limited number (nine cases) of high-grade renal injuries (RIS ≧ 4) in present study might have resulted in bias when comparing the operation (seven cases) and nonoperation (66 cases) groups. However, our study emphasizes the importance of aggressive treatment for treating patients with severe injury by renal trauma.

    In conclusion, based on the results of our study, ISS ≥ 16 and RIS ≥ 4 are predictive factors for an operation, and higher injury severity (ISS ≥ 16), lower consciousness level (GCS < 8) are significantly associated with mortality in trauma patients with renal injuries.

    References

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    Keywords:

    nonoperative treatment; outcome; renal injury

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