M. Margaret Knudson

Prospective Study of Blunt Aortic Injury: Multicenter Trial of the American Association for the Surgery of Trauma

BACKGROUND Blunt aortic injury is a major cause of death from blunt trauma. Evolution of diagnostic techniques and methods of operative repair have altered the management and posed new questions in recent years. METHODS This study was a prospectively conducted multi-center trial involving 50 trauma centers in North America under the direction of the Multi-institutional Trial Committee of the American Association for the Surgery of Trauma. RESULTS There were 274 blunt aortic injury cases studied over 2.5 years, of which 81% were caused by automobile crashes. Chest computed tomography and transesophageal echocardiography were applied in 88 and 30 cases, respectively, and were 75 and 80% diagnostic, respectively. Two hundred seven stable patients underwent planned thoracotomy and repair. Clamp and sew technique was used in 73 (35%) and bypass techniques in 134 (65%). Overall mortality was 31%, with 63% of deaths being attributable to aortic rupture; mortality was not affected by method of repair. Paraplegia occurred postoperatively in 8.7%. Logistic regression analysis demonstrated clamp and sew (p = 0.002) and aortic cross clamp time of > or = 30 minutes (p = 0.01) to be associated with development of postoperative paraplegia. CONCLUSIONS Rupture after hospital admission remains a major problem. Although newer diagnostic techniques are being applied, at this time aortography remains the diagnostic standard. Aortic cross clamp time beyond 30 minutes was associated with paraplegia; bypass techniques, which provide distal aortic perfusion, produced significantly lower paraplegia rates than the clamp and sew approach.

Status of nonoperative management of blunt hepatic injuries in 1995: a multicenter experience with 404 patients

INTRODUCTION Nonoperative management is presently considered the treatment modality of choice in over 50% of adult patients sustaining blunt hepatic trauma who meet inclusion criteria. A multicenter study was retrospectively undertaken to assess whether the combined experiences at level I trauma centers could validate the currently reported high success rate, low morbidity, and virtually nonexistent mortality associated with this approach. Thirteen level I trauma centers accrued 404 adult patients sustaining blunt hepatic injuries managed nonoperatively over the last 5 years. Seventy-two percent of the injuries resulted from motor vehicle crashes. The mean injury severity score for the entire group was 20.2 (range, 4-75), and the American Association for the Surgery of Trauma-computerized axial tomography scan grading was as follows: grade I, 19% (n = 76); grade II, 31% (n = 124); grade III, 36% (n = 146); grade IV, 10% (n = 42); and grade V, 4% (n = 16). There were 27 deaths (7%) in the series, with 59% directly related to head trauma. Only two deaths (0.4%) could be attributed to hepatic injury. Twenty-one (5%) complications were documented, with the most common being hemorrhage, occurring in 14 (3.5%). Only 3 (0.7%) of these 14 patients required surgical intervention, 6 were treated by transfusions alone (0.5 to 5 U), 4 underwent angio-embolization, and 1 was further observed. Other complications included 2 bilomas and 3 perihepatic abscesses (all drained percutaneously). Two small bowel injuries were initially missed (0.5%), and diagnosed 2 and 3 days after admission. Overall, 6 patients required operative intervention: 3 for hemorrhage, 2 for missed enteric injuries, and 1 for persistent sepsis after unsuccessful percutaneous drainage. Average length of stay was 13 days. Nonoperative management of blunt hepatic injuries is clearly the treatment modality of choice in hemodynamically stable patients, irrespective of grade of injury or degree of hemoperitoneum. Current data would suggest that 50 to 80% (47% in this series) of all adult patients with blunt hepatic injuries are candidates for this form of therapy. Exactly 98.5% of patients analyzed in this study successfully avoided operative intervention. Bleeding complications are infrequently encountered (3.5%) and can often be managed nonoperatively. Although grades IV and V injuries composed 14% of the series, they represented 66.6% of the patients requiring operative intervention and thus merit constant re-evaluation and close observation in critical care units. The optimal time for follow-up computerized axial tomography scanning seems to be within 7 to 10 days after injury.

Thromboembolism after trauma: an analysis of 1602 episodes from the American College of Surgeons National Trauma Data Bank

Objective:Venous thromboembolic events (VTE) are potentially preventable causes of morbidity and mortality after injury. We hypothesized that the current clinical incidence of VTE is relatively low and that VTE risk factors could be identified. Methods:We queried the ACS National Trauma Data Bank for episodes of deep venous thrombosis (DVT) and/or pulmonary embolism (PE). We examined demographic data, VTE risk factors, outcomes, and VTE prophylaxis measures in patients admitted to the 131 contributing trauma centers. Results:From a total of 450,375 patients, 1602 (0.36%) had a VTE (998 DVT, 522 PE, 82 both), for an incidence of 0.36%. Ninety percent of patients with VTE had 1 of the 9 risk factors commonly associated with VTE. Six risk factors found to be independently significant in multivariate logistic regression for VTE were age ≥40 years (odds ratio [OR] 2.01; 95% confidence interval [CI] 1.74 to 2.32), lower extremity fracture with AIS ≥3 (OR 1.92; 95% CI 1.64 to 2.26), head injury with AIS ≥3 (OR 1.24; 95% CI 1.05 to 1.46), ventilator days >3 (OR 8.08; 95% CI 6.86 to 9.52), venous injury (OR 3.56; 95% CI 2.22 to 5.72), and a major operative procedure (OR 1.53; 95% CI 1.30 to 1.80). Vena cava filters were placed in 3,883 patients, 86% as PE prophylaxis, including in 410 patients without an identifiable risk factor for VTE. Conclusions:Patients who need VTE prophylaxis after trauma can be identified based on risk factors. The use of prophylactic vena cava filters should be re-examined.

Thromboembolism following multiple trauma.

The true incidence of thromboembolic complications following multiple trauma is unknown, and no method of prophylaxis has been shown to be both safe and effective in managing seriously injured patients. In this prospective study, 113 trauma patients were assigned on admission to receive either low-dose heparin (LDH), (5,000 U subcutaneously every 12 hours) or to wear sequential compression devices (SCDs) as prophylaxis against the development of deep venous thrombosis (DVT). Both groups of patients were serially studied with duplex venous ultrasound imaging to detect thrombus in the veins of the thigh. Ventilation-perfusion lung scans and pulmonary angiograms were performed when pulmonary embolism (PE) was suspected clinically. There were 12 patients who had thromboembolic complications, including 9 of 76 in the SCD group (12%) and 3 of 37 in the LDH group (8%). Five patients had DVT only, four had PE without detectable DVT, and three had both DVT and PE. None of the patients with PE died, and there were no major complications associated with either method of prophylaxis. Compared with the patients who did not develop DVT/PE, those with thromboembolic complications were older (49 +/- 23 vs. 36 +/- 17 years, p less than 0.02), spent more hospital days immobilized (24 +/- 15 vs. 10 +/- 13 days, p less than 0.001), received more transfusions (11 +/- 12 vs. 3 +/- 5 U, p less than 0.001) and had clotting abnormalities on admission, as demonstrated by prolonged PTT values (39 +/- 28 vs. 26 +/- 5 seconds, p less than 0.001). It appears that there is an identifiable subgroup of injured patients at highest risk for PE who warrant both prophylaxis and close surveillance for DVT.

Use of Low Molecular Weight Heparin in Preventing Thromboembolism in Trauma Patients

OBJECTIVE To investigate the safety and effectiveness of low molecular weight heparin (LMWH) in preventing deep venous thrombosis (DVT) in high-risk trauma patients, compared with mechanical methods of prophylaxis. DESIGN A prospective randomized trial conducted over a 19-month period in an urban, academic trauma center. METHODS All trauma patients with the following risk factors for the development of DVT were considered for enrollment in this study: any injury with an Abbreviated Injury Scale score > or = 3; major head injury (Glasgow Coma Scale score < or = 8); spine, pelvic, or lower extremity fractures; acute venous injury; or age > 50 years. After a screening venous duplex examination, the patients were assigned to a Heparin versus No-Heparin group, depending upon the presence of injuries precluding the use of heparin. In the Heparin group, the patients were then randomized to receive either LMWH or optimal mechanical compression (defined as bilateral sequential gradient pneumatic compression (SCD) or, in the presence of lower extremity injuries precluding the use of the SCD, the arteriovenous impulse (AVI) compression system). All the patients in the No-Heparin group received optimal compression. Enrolled patients underwent sequential duplex examinations every 5 to 7 days until discharge. RESULTS Of the 487 consecutive patients initially enrolled in this study, 372 were available for at least the first two duplex examinations and comprise the study population. Only nine (2.4%) patients developed DVT, compared with the predicted 9.1% rate in high-risk trauma patients receiving no prophylaxis (p = 0.037). Of the 120 patients who were randomized to receive LMWH, only one (0.8%) developed DVT. In the SCD group, there were 5 of 199 patients (2.5%) with DVT, and 3 of 53 (5.7%) in the AVI group. One patient with DVT also had clinical symptoms of pulmonary embolism, but there were no deaths secondary to pulmonary embolism. There was one major bleeding complication potentially associated with the use of LMWH. CONCLUSIONS The administration of LMWH is a safe and extremely effective method of preventing DVT in high-risk trauma patients. When heparin is contraindicated, aggressive attempts at mechanical compression are warranted.

The role of ultrasound in patients with possible penetrating cardiac wounds: a prospective multicenter study.

BACKGROUND Ultrasound is quickly becoming part of the trauma surgeons practice, but its role in the patient with a penetrating truncal injury is not well defined. The purpose of this study was to evaluate the accuracy of emergency ultrasound as it was introduced into five Level I trauma centers for the diagnosis of acute hemopericardium. METHODS Surgeons or cardiologists (four centers) and technicians (one center) performed pericardial ultrasound examinations on patients with penetrating truncal wounds. By protocol, patients with positive examinations underwent immediate operation. Vital signs, base deficit, time from examination to operation, operative findings, treatment, and outcome were recorded. RESULTS Pericardial ultrasound examinations were performed in 261 patients. There were 225 (86.2%) true-negative, 29 (11.1%) true-positive, 0 false-negative, and 7 (2.7%) false-positive examinations, resulting in sensitivity of 100%, specificity of 96.9%, and accuracy of 97.3%. The mean time from ultrasound to operation was 12.1+/-5 minutes. CONCLUSION Ultrasound should be the initial modality for the evaluation of patients with penetrating precordial wounds because it is accurate and rapid.

Prevention of venous thromboembolism in trauma patients.

Trauma patients are at risk for thromboembolic complications, but effective methods of prophylaxis have not been established for this heterogenous population. In this prospective trial, 400 trauma patients were assigned to one of three groups, depending upon their injuries, and randomized within each group to a treatment mode: Group I: sequential gradient pneumatic leg compression (SCD), low-dose subcutaneous heparin (H), or control (C); Group II: H or C; Group III: SCD or C. Venous duplex ultrasound examinations were performed on admission and weekly thereafter. Of the 251 patients who completed the study, 15 (6%) developed lower extremity venous thrombosis and two additional patients developed pulmonary embolism (one fatal). Significant risk factors associated with the development of thromboembolism included immobilization > 3 days, age 30 years or older, and the presence of pelvic or lower extremity fractures. In patients with neurotrauma who cannot receive heparin (Group III), the SCD was more effective than control in preventing DVT (p = 0.057). Neither H nor SCD appeared to offer protection for the other groups of trauma patients, but surveillance with ultrasound examinations allowed for prompt recognition and treatment of occult deep vein thrombosis.

Death in the operating room: An analysis of a multi-center experience

To characterize causes of death in the operating room (OR) following major trauma, a retrospective review of admissions to eight academic trauma centers was conducted to define the etiology of death and challenges for improvement in outcome. Five hundred thirty seven OR deaths of 72,151 admissions were reviewed for mechanism of injury, physiologic findings, resuscitation, patterns of injury, surgical procedures, cause of death, and preventability. Blunt injuries accounted for 61% of all injuries, gunshot wounds (GSW) accounted for 74% of penetrating injuries. Sixty two percent of all patients arrived in shock. Average blood pressure (BP) was 52 mm Hg at the scene and 60 mm Hg on admission, with the period of shock > 10 minutes in 74%. Only 56% were resuscitated to a BP > 90 mm Hg before surgery. Average time to the OR was 30.1 minutes and mean best postresuscitation pH was 7.18. Mean best OR temperature was 32.2 degrees C. Recurrent injury patterns judged as the primary cause of patient death included head/neck injury (16.4%), chest injury (27.4%), and abdominal injury (53.4%). Actual cause of death was bleeding (82%), cerebral herniation (14.5%), and air emboli (2.2%). A different strategy for improved outcome was identified in 54 patients with the following conclusions: (1) delayed transfer to the OR remains a problem with significant BP deterioration during delay, particularly following interfacility transfer; (2) staged injury isolation and repair to allow better resuscitation and warming may lead to improved results; (3) combined thoraco-abdominal injuries, particularly with thoracic aortic disruption, often require a different sequence of management; (4) aggressive evaluation of retroperitoneal hematomas is essential; (5) OR management of severe liver injuries remains a technical challenge with better endpoints for packing needed; and (6) resuscitative thoracotomy applied to OR patients in extremis from exsanguination offers little.

NONOPERATIVE MANAGEMENT OF SOLID ORGAN INJURIES: Past, Present, and Future

All patients with injuries to the solid organs of the abdomen and who are hemodynamically stable should be considered candidates for nonoperative management after their injuries have been staged by abdominal CT scanning, but because the CT stage of the injury does not always predict which patients require laparotomy, these patients must remain under the care of experienced trauma surgeons who can not only recognize the presence of an associated hollow viscus injury in need of repair but also will be readily available to operate if the nonoperative approach fails. Until continued bleeding can be safely ruled out, a period of close monitoring in an ICU-like setting seems warranted. Although delayed bleeding from the liver seems extremely rare, delayed rupture of the spleen and continued hemorrhage into the retroperitoneum from an injured kidney are not unusual, so patients with splenic and renal injuries should be considered candidates for repeat imaging procedures before discharge. Others likely to benefit from a second look at their injuries include patients with subcapsular hematomas, patients with recognized extravasation on the initial scan, and athletes anxious to return to contact sports. Experience from major trauma centers suggests that the incidence of missed intestinal injuries is low in adults and children managed nonoperatively, but surgeons must be diligent in monitoring for increasing abdominal pain, abdominal distention, vomiting, and signs of inflammation, which may be delayed manifestations of intestinal disruption. Patients with vascular injuries (grade V injuries to the spleen, liver, or kidney) may be candidates for radiologic procedures, such as angioembolization or stenting, but some of these patients are best served by immediate laparotomy. Selected patients with penetrating injuries may also be candidates for the nonoperative approach, but further research in this area is needed before this approach can be widely embraced. As we approach the year 2000, the nonoperative approach to hepatic, splenic, and renal injuries will continue to have a major role in the treatment of trauma patients. Currently, the morbidity and mortality rates of nonoperative management are acceptably low, but surgeons still must monitor their results carefully as they apply these methods more liberally among injured patients.

Outcome after major renovascular injuries: a Western trauma association multicenter report.

BACKGROUND Major renal vascular injuries are uncommon and are frequently associated with a poor outcome. In addition to renal dysfunction, posttraumatic renovascular hypertension may result, although the true incidence of this complication is unknown. The objective of this study was to describe the factors contributing to outcome after major renovascular trauma. We hypothesized that the highest percentage of renal salvage would be achieved by minimizing the time from injury to repair. METHODS This was a retrospective chart review over a 16-year period conducted at six university trauma centers of patients with American Association for the Surgery of Trauma grade IV/V renal injuries surviving longer than 24 hours. Postinjury renal function with poor outcome was defined as renal failure requiring dialysis, serum creatinine greater than or equal to 2 mg/dL, renal scan showing less than 25% function of the injured kidney, postinjury hypertension requiring treatment, or delayed nephrectomy. Data collected for analysis included demographics, mechanism of injury, presence of shock, presence of hematuria, associated injuries, type of renal injury (major artery, renal vein, segmental artery), type of repair (primary vascular repair, revascularization, observation, nephrectomy), time from injury to definitive renal surgery, and type of surgeon performing the operation (urologist, vascular surgeon, trauma surgeon). RESULTS Eighty-nine patients met inclusion criteria; 49% were injured from blunt mechanisms. Patients with blunt injuries were 2.29 times more likely to have a poor outcome compared with those with penetrating injuries. Similarly, the odds ratio of having a poor outcome with a grade V injury (n = 32) versus grade IV (n = 57) was 2.2 (p = 0.085). Arterial repairs had significantly worse outcomes than vein repairs (p = 0.005). Neither the time to definitive surgery nor the operating surgeons specialty significantly affected outcome. Ten percent (nine patients) developed hypertension or renal failure postoperatively: three had immediate nephrectomies, four had arterial repairs with one intraoperative failure requiring nephrectomy, and two were observed. Of the 20 good outcomes for grade V injuries, 15 had immediate nephrectomy, 1 had a renal artery repair, 1 had a bypass graft, 1 underwent a partial nephrectomy, and 2 were observed. CONCLUSION Factors associated with a poor outcome following renovascular injuries include blunt trauma, the presence of a grade V injury, and an attempted arterial repair. Patients with blunt major vascular injuries (grade V) are likely to have associated major parenchymal disruption, which contributes to the poor function of the revascularized kidney. These patients may be best served by immediate nephrectomy, provided that there is a functioning contralateral kidney.