Penetrating esophageal injuries: multicenter study of the American Association for the Surgery of Trauma.

OBJECTIVE: The purpose of this study was to define the period of time after which delays in management incurred by investigations cause increased morbidity and mortality. The outcome study is intended to correlate time with death from esophageal causes, overall complications, esophageal related complications, and surgical intensive care unit length of stay. METHODS: This was a retrospective multicenter study involving 34 trauma centers in the United States, under the auspices of the American Association for the Surgery of Trauma Multi-institutional Trials Committee over a span of 10.5 years. Patients surviving to reach the operating room (OR) were divided into two groups: those that underwent diagnostic studies to identify their injuries (preoperative evaluation group) and those that went immediately to the OR (no preoperative evaluation group). Statistical methods included Fisher's exact test, Student's T test, and logistic regression analysis. RESULTS: The study involved 405 patients: 355 male patients (86.5%) and 50 female patients (13.5%). The mean Revised Trauma Score was 6.3, the mean Injury Severity Score was 28, and the mean time interval to the OR was 6.5 hours. There were associated injuries in 356 patients (88%), and an overall complication rate of 53.5%. Overall mortality was 78 of 405 (19%). Three hundred forty-six patients survived to reach the OR: 171 in the preoperative evaluation group and 175 in the no preoperative evaluation group. No statistically significant differences were noted in the two groups in the following parameters: number of patients, age, Injury Severity Score, admission blood pressure, anatomic location of injury (cervical or thoracic), surgical management (primary repair, resection and anastomosis, resection and diversion, flaps), number of associated injuries, and mortality. Average length of time to the OR was 13 hours in the preoperative evaluation group versus 1 hour in the no preoperative evaluation group (p < 0.001). Overall complications occurred in 134 in the preoperative evaluation group versus 87 in the no preoperative evaluation group (p < 0.001), and 74 (41%) esophageal related complications occurred in the preoperative evaluation group versus 32 (19%) in the no preoperative evaluation group (p = 0.003). Mean surgical intensive care unit length of stay was 11 days in the preoperative evaluation group versus 7 days in the no preoperative evaluation group (p = 0.012). Logistic regression analysis identified as independent risk factors for the development of esophageal related complications included time delays in preoperative evaluation (odds ratio, 3.13), American Association for the Surgery of Trauma Organ Injury Scale grade >2 (odds ratio, 2.62), and resection and diversion (odds ratio, 4.47). CONCLUSION: Esophageal injuries carry a high morbidity and mortality. Increased esophageal related morbidity occurs with the diagnostic workup and its inherent delay in operative repair of these injuries. For centers practicing selective management of penetrating neck injuries and transmediastinal gunshot wounds, rapid diagnosis and definitive repair should be made a high priority.

Helical computed tomographic scan in the evaluation of mediastinal gunshot wounds.

BACKGROUND: The standard evaluation of mediastinal gunshot wounds usually requires angiography and either esophagoscopy or esophagography. In the present study, we have evaluated the role of helical computed tomographic (CT) scanning in reducing the need for angiographic and esophageal studies. METHODS: This was a prospective study of patients with mediastinal gunshot wounds who were hemodynamically stable and would otherwise require angiography and esophageal evaluation. All patients underwent CT scan of the chest with intravenous contrast to delineate the missile trajectory. If the missile tract was in close proximity to the aorta, great vessels, or esophagus, then traditional evaluation with angiographic or esophageal evaluation was pursued. RESULTS: A total of 24 patients met the inclusion criteria and underwent CT scan evaluation of their mediastinal gunshot wounds. One patient was taken for sternotomy to remove a missile embedded in the myocardium solely on the basis of the result of the CT scan. Because of proximity of the bullet tract, 12 patients required additional evaluation with eight angiograms and nine esophageal studies. One of these patients had a positive angiogram (bullet resting against the ascending aorta) and underwent sternotomy for missile removal; all other studies were negative. The remaining 11 patients were found to have well-defined missile tracts that approached neither the aorta nor the esophagus, and no additional evaluation was pursued. There were no missed mediastinal injuries in this group. Overall, 12 of 24 patients (50%) had a change in management (either received an operation or avoided additional radiographic or endoscopic evaluation) on the basis of the CT scan. CONCLUSION: The helical CT scan provides a rapid, readily available, noninvasive means to evaluate missile trajectories. This permits accurate assessment of potential mediastinal injury and reduces the need for routine angiographic and esophageal studies.

Nonskeletal cervical spine injuries: epidemiology and diagnostic pitfalls.

BACKGROUND: Cervical spine injuries are the most commonly missed severe injuries with serious implications for the patient and physician. The diagnosis of subluxations or spinal cord injuries in the absence of vertebral fractures, especially in unevaluable patients, poses a major challenge. The objective of this study was to study the incidence and type of cervical spine trauma according to mechanism of injury; identify problems and pitfalls in the diagnosis of nonskeletal cervical spine injuries. METHODS: Retrospective study of all C-spine injuries caused by traffic accidents or falls admitted over a 5-year period at a large Level I trauma center. Data were obtained from the trauma registry, review of patient charts, and radiology reports. RESULTS: During the study period, there were 14,755 admissions due to traffic injuries or falls who met trauma center criteria. There were 292 patients with C-spine injuries, for an overall incidence of 2.0% (3.4% in car occupants, 2.8% for pedestrians, 1.9% for motorcycle riders, and 0.9% for falls). The incidence of C-spine injuries in patients with a Glasgow Coma Scale score of 13 to 15 was 1.4%, 9 to 12 was 6.8%, and in < or =8 was 10.2% (p < 0.05). Of C-spine injuries, 85.6% (250 patients) were a vertebral fracture, 10.6% of the injuries (31 patients) were subluxation without fractures, and 3.8% (11 patients) were an isolated spinal cord injury without fracture or subluxation. Of the 31 patients with isolated subluxations, one-third required an early endotracheal intubation before clinical evaluation of the spine, because of associated severe head injury or hypotension. Adequate lateral C-spine films diagnosed or suspected 30 of the 31 subluxations (96.8%). The combination of plain films and computed tomographic (CT) scan diagnosed or suspected all injuries. Of the 11 patients with isolated cord injury, 27.3% required early intubation before clinical evaluation of the spine. The diagnosis of cord injury was made on admission in only five patients (45.5%). In three patients, the neurologic examination on admission was normal and neurologic deficits appeared a few hours later. In the remaining three patients (two intubated, one intoxicated), the diagnosis was missed clinically and radiologically. CONCLUSIONS: Isolated nonskeletal C-spine injuries are rare but potentially catastrophic because of the high incidence of neurologic deficits and missed diagnosis. In subluxations, the combination of an adequate lateral film and CT scan was reliable in diagnosing or highly suspecting the injury. A large prospective study is needed to confirm these findings, before a recommendation is made to remove the cervical collar if the findings of these investigations are normal. However, in isolated cord injuries, the diagnosis was often missed because of associated severe head trauma and the low sensitivity of the plain films and CT scans.

Approach to the management of complex hepatic injuries.

BACKGROUND: Complex hepatic injuries American Association for the Surgery of Trauma Organ Injury Scale grades IV and V incur high mortality rate ranging from 40 to 80%, respectively. The objective of this study is to assess the clinical experience with an aggressive approach to the management of these, the most complex of hepatic injuries. METHODS: This is a retrospective 6-year study (1992-1997) at an American College of Surgeons urban Level I trauma center of patients sustaining complex hepatic injuries whose interventions included surgery, angiographic embolization, endoscopic retrograde cholangiopancreatography plus biliary stenting and percutaneous computed tomographic-guided drainage. The main outcome measure was survival. RESULTS: A total of 22 patients sustaining complex hepatic injuries; mean age of 26 years (range, 10-52 years), mean Revised Trauma Scale score of 9.9, mean Injury Severity Score of 32 (range, 16-75), American Association for the Surgery of Trauma - Organ Injury Scale grade IV (13 cases); grade V (9 cases). Mean estimated blood loss was 4,600 mL; mean number of units of blood transfused was 15. The patients underwent the following interventions: surgery (n = 22), re-operated (n = 13), mean number of operations 1.6 (range, 1-4), extensive hepatotomy and hepatorrhaphy (n = 17), nonanatomic resection (n = 7), formal hepatectomy (n = 4), packing (n = 10), direct approach to hepatic veins (n = 3); angiographic embolization (n = 15); endoscopic retrograde cholangiopancreatography and stenting (n = 5); computed tomographic guided drainage (n = 6). Mean length of stay in the intensive care unit was 21 days (range, 2-134 days), mean hospital length of stay was 40 days (range, 2-147 days). Overall mortality rate was 14% (3 of 22 cases), hepatic mortality rate was 9% (2 of 22 cases), mortality rate by injury grade was 8% grade IV (1 of 13 cases) and 22% grade V (2 of 9 cases). CONCLUSION: In this select patient population, improvements in mortality rates can be achieved with an aggressive approach to the management of complex hepatic injuries, including surgery, early packing, angiographic embolization, endoscopic retrograde cholangiopancreatography and stenting of biliary leaks, and drainage of hepatic abscesses.

Operative management and outcome of 302 abdominal vascular injuries.

BACKGROUND: Abdominal vascular injuries incur high mortality rates. The purposes of this study are (1) review institutional experience, (2) determine additive effect on mortality of multiple vessel injuries, (3) determine mortality of combined arterial and venous injuries, and (4) correlate mortality with American Association for the Surgery of Trauma-Organ Injury Scale (AAST-OIS) for abdominal vascular injury. METHODS: A retrospective 6-year study was made at an urban level I trauma center of patients with abdominal vascular injuries. Main outcome measure was survival. RESULTS: (1) There was a total of 302 patients, mean age 28, mean Injury Severity Score (ISS) 25 (range 4 to 75). Mechanism of injury was penetrating in 266 (88%), blunt in 36 (12%). Emergency Department thoracotomy was done in 43 of 302 (14%), 504 vessels were injured: arteries 238(47%), veins 266(53%). Surgical management was ligation 245, primary repair 141, prosthetic interposition grafts 24, autogenous 2. Overall mortality was 162 of 302 (54%). (2) Mortality multiple vessels injured: 1 vessel 160 (45%), 2 vessels 102 (60%), 3 vessels 33 (73%), >4 vessels 5 (100%). Mortality arterial injuries: aorta isolated (I) 78% versus combined with other arterial injuries (C) 82.4%, superior mesenteric artery (SMA) I 47.6% versus C 71.4%, iliac I 53% versus C 72.7%, renal I 37.5% versus C 66.7%. Venous injuries: inferior vena cava (IVC) isolated (I) 70% versus combined with other venous injuries (C) 77.7%, superior mesenteric vein (SMV) I 52.7% versus C 65%, IMV I 16% versus C 50%. (3) Specific mortality combined arterial and venous injuries: aorta plus IVC 93%, SMA plus SMV 43%, iliac artery plus vein 45.5%. (4) Mortality versus AAST-OIS: grade II 25%, grade III 32%, grade IV 65%, grade V 88%. CONCLUSION: Abdominal vascular injuries are highly lethal. Multiple arterial and venous injuries increase mortality. Mortality correlates with AAST-OIS for abdominal vascular injury.

Traumatic injury to the superior mesenteric artery.

BACKGROUND: Superior mesenteric artery (SMA) injuries are rare and devastating injuries incurring very high mortality rates. It is the purpose of this study to review our experience with these injuries, to analyze Fullen's classification based on anatomical zone and injury grade for its predictive value, and to correlate the American Association for the Surgery of Trauma-Organ Injury Scale (AAST-OIS) for abdominal vascular injury with mortality. METHODS: Retrospective study was made over a 65-month period of all patients sustaining SMA injuries in an urban level I trauma center. RESULTS: Thirty-five patients, mean age 31, had a mean Revised Trauma Score of 5.86 and a mean Injurity Severity Score of 23. Mechanisms of injury were penetrating 27 (77%) and blunt 8 (23%). Mean admission systolic blood pressure was 85 mm Hg. Mean estimated blood loss was 8,500 mL and mean total fluid replacement 17,000 mL. Operating room findings were retroperitoneal hematoma in 34 (97%) and "black bowel" in 2 (6%). Number of associated injuries was nonvascular, mean 4.2, and vascular, mean 1.5. Surgical management consisted of ligation in 18 (51%), primary repair in 14 (40%), and interposition graft in 2 (6%). Overall mortality was 19 of 35 (54%). Mortality versus Fullen's zones was zone I, 100%, zone II, 43%, and zones III and IV, 25%. Mortality versus Fullen's ischemia grade was grade 1, 89%, grade 2, 58%, grade 3, 100%, and grade 4, 19%. Mortality versus AAST-OIS: was grade 1, 0%, grade II, 20%, grade III, 0%, grade IV, 59%, and grade V, 88%. CONCLUSIONS: SMA injuries are highly lethal. Most deaths are due to exsanguination. A higher number of associated vascular injuries increases mortality. "Black bowel" is an uncommon finding. Both Fullen's anatomical zones and the AAST-OIS for abdominal vascular injuries correlate with mortality. Fullen's ischemia grade does not.

Complex repair for the management of duodenal injuries.

The management of duodenal injuries is a subject of ongoing debate. In this study we attempt to describe duodenum-related morbidity (DRM) after primary repair or complex repair (CR) and to identify risk factors for development of complications. The medical records of 145 consecutive patients admitted to Los Angeles County + University of Southern California Medical Center with duodenal injuries between January 1991 and December 1997 were reviewed. Fifty-four (37%) died within 24 hours of admission because of associated injuries. The remaining 91 were subjected to univariate and multivariate analysis. Of them, 66 (72.5%) developed complications and 3 (3%) died. CR was used in 32 (35%) patients and with increasing frequency as the grade of duodenal injury increased. DRM rate was overall low (9%) and not different between low-grade and high-grade duodenal injuries. This occurred despite a significant increase in Injury Severity Score and abdominal Abbreviated Injury Score in patients with more severe duodenal injuries. Patients with overall complications had higher Injury Severity Scores, higher abdominal Abbreviated Injury Scores, and more severe duodenal injuries. We conclude that duodenal injuries are frequently associated with other highly lethal injuries. Liberal use of CR in patients with more severe duodenal injuries prevents DRM.

Compartment ablation analysis of the insulin-responsive glucose transporter (GLUT4) in 3T3-L1 adipocytes.

The translocation of a unique facilitative glucose transporter isoform (GLUT4) from an intracellular site to the plasma membrane accounts for the large insulin-dependent increase in glucose transport observed in muscle and adipose tissue. The intracellular location of GLUT4 in the basal state and the pathway by which it reaches the cell surface upon insulin stimulation are unclear. Here, we have examined the colocalization of GLUT4 with the transferrin receptor, a protein which is known to recycle through the endosomal system. Using an anti-GLUT4 monoclonal antibody we immunoisolated a vesicular fraction from an intracellular membrane fraction of 3T3-L1 adipocytes that contained > 90% of the immunoreactive GLUT4 found in this fraction, but only 40% of the transferrin receptor (TfR). These results suggest only a limited degree of colocalization of these proteins. Using a technique to cross-link and render insoluble ("ablate') intracellular compartments containing the TfR by means of a transferrin-horseradish peroxidase conjugate (Tf-HRP), we further examined the relationship between the endosomal recycling pathway and the intracellular compartment containing GLUT4 in these cells. Incubation of non-stimulated cells with Tf-HRP for 3 h at 37 degrees C resulted in quantitative ablation of the intracellular TfR, GLUT1 and mannose-6-phosphate receptor and a shift in the density of Rab5-positive membranes. In contrast, only 40% of intracellular GLUT4 was ablated under the same conditions. Ablation was specific for the endosomal system as there was no significant ablation of either TGN38 or lgp120, which are markers for the trans Golgi reticulum and lysosomes respectively. Subcellular fractionation analysis revealed that most of the ablated pools of GLUT4 and TfR were found in the intracellular membrane fraction. The extent of ablation of GLUT4 from the intracellular fraction was unchanged in cells which were insulin-stimulated prior to ablation, whereas GLUT1 exhibited increased ablation in insulin-stimulated cells. Pretreatment of adipocytes with okadaic acid, an inhibitor of Type-I and -IIa phosphatases, increased GLUT4 ablation in the presence of insulin, consistent with okadaic acid increasing the internalization of GLUT4 from the plasma membrane under these conditions. Using a combination of subcellular fractionation, vesicle immunoadsorption and compartment ablation using the Tf-HRP conjugate we have been able to resolve overlapping but distinct intracellular distributions of the TfR and GLUT4 in adipocytes. At least three separate compartments were identified: TfR-positive/GLUT4-negative. TfR-negative/GLUT4-positive, and TfR-positive/GLUT4-positive, as defined by the relative abundance of these two markers. We propose that the TfR-negative/GLUT4-positive compartment, which contains approximately 60% of the intracellular GLUT4, represents a specialized intracellular compartment that is withdrawn from the endosomal system. The biosynthesis and characteristics of this compartment may be fundamental to the unique insulin regulation of GLUT4.

Characterization of the intracellular GLUT-4 compartment.

Insulin stimulates glucose transport in muscle and adipose tissue by triggering the translocation of the glucose transporter GLUT-4 from intracellular vesicles to the cell surface. In the present study we have attempted to characterize the intracellular GLUT-4 compartment using vesicle immunoadsorption. Silver staining of this fraction indicates that this compartment contains numerous polypeptides that exhibit a marked change in mobility upon treatment with reducing agents. The polypeptide composition of GLUT-4-containing vesicles isolated from a variety of insulin-sensitive cell types, including heart, adipose tissue, skeletal muscle and 3T3-L1 adipocytes, is similar. In addition, the polypeptide composition of the GLUT-4 compartment isolated from CHO cells transfected with GLUT-4 resembles that observed in insulin-sensitive cells. Two major proteins in this vesicle fraction isolated from all cell types are the transferrin receptor (TfR) and the mannose 6-phosphate/IGF II receptor (MPR). Furthermore, vesicles immunoadsorbed from adipocytes, with antibodies specific for GLUT-4 and the TfR, also show conservation in their overall polypeptide composition. Protein micro sequencing of a major 80 kDa polypeptide enriched in the GLUT-4 compartment isolated from skeletal muscle revealed this protein to be rat transferrin. These data indicate that there is a close relationship between the intracellular GLUT-4 compartment and the endosomal system. Future studies will be required to determine if it is possible to isolate subcompartments within this system to determine if GLUT-4 is targeted to a specialized secretory compartment in insulin-sensitive cells or simply a subdomain within recycling endosomes.

Immunocytochemical and biochemical studies of GLUT4 in rat skeletal muscle.

In muscle and adipocytes, glucose transport is regulated by the translocation of insulin regulatable glucose transporters (GLUT4) between an intracellular compartment and the cell surface. In these studies we have characterized the cellular compartments containing GLUT4 in rat skeletal muscle. Immunocytochemical studies showed that in unstimulated muscle, GLUT4 was not present in surface membranes. Tubulo-vesicular structures clustered in the trans Golgi reticulum were enriched in GLUT4. GLUT4 underwent translocation to the sarcolemma in response to combined stimulation with insulin and exercise. Using immunoisolation, the intracellular GLUT4 vesicles (IRGTV) were purified 300-fold over the cell homogenate. IRGTV from unstimulated muscle were not enriched in markers specific for the sarcolemma, transverse tubules, sarcoplasmic reticulum or mitochondria; this was confirmed using gel filtration chromatography. Insulin resulted in a 40% decrease in GLUT4 levels in IRGTV confirming that this represents the intracellular compartment of GLUT4. GLUT4 is a major component of the IRGTV, constituting at least 5% of total vesicle protein. A subset of polypeptides are also markedly enriched in the muscle IRGTV. In conclusion, these data suggest that translocation of GLUT4 from intracellular tubulo-vesicular structures is the major mechanism by which insulin and exercise regulate muscle glucose transport.

Central hemodynamics during progressive upper- and lower-body exercise and recovery.

The purpose of this study was to compare stroke volume (SV) and myocardial contractility responses during and immediately after upper- and lower-body exercise. Nine men (mean 28 yr, 78 kg) completed progressive intensity discontinuous tests on both an arm crank and cycle ergometer. Exercise for each power output (PO) was 7 min with 20-min rest periods interspersed. Impedance cardiography was used to measure cardiac output (Q), SV, and contractility on a beat-by-beat basis during exercise and a 15-s recovery period. Q increased linearly, and total peripheral resistance decreased exponentially with increasing PO levels. During recovery from exercise, the Q and heart rate (HR) values decreased immediately at all PO levels. When the exercise VO2 exceeded 1.0 1 X min-1, SV fell significantly during recovery for both exercise modes. In general, the recovery myocardial contractility indices remained similar to exercise values. It was concluded that immediately after low intensities of exercise, Q decreases because of a fall in HR. After moderate- and high-intensity exercise, Q decreases because of a fall in both HR and SV.

Blood flow and metabolism during isometric contractions in cat skeletal muscle.

The muscle blood flow, oxygen uptake, carbon dioxide production, muscle and blood lactate, muscle ATP, creatinine phosphate, glycogen, and venous pH were measured in the soleus (a slow-twitch muscle) and the medial gastrocnemius (a fast-twitch muscle) of the cat during fatiguing isometric exercise. Five tensions were examined: 10, 25, 50, 75, and 100% of the initial strength of the muscles (tetanic tension of the unfatigued muscle). Contractions were either sustained to fatigue or, for tensions of 10 and 25% initial strength of the soleus muscle, were sustained for 3 min. Analysis of the blood flow and metabolites from these muscles showed that the soleus was heavily dependent on its blood supply, using aerobic metabolism as the predominant pathway, whereas the medial gastrocnemius muscle seemed to use anaerobic metabolism even at low isometric tensions.

Muscle fiber recruitment and blood pressure response to isometric exercise.

Blood pressure was recorded during fatiguing and nonfatiguing isometric contractions of a slow-twitch muscle (the soleus) and a mixed muscle (the medial gastrocnemius) of the cat. Four tensions were examined in each muscle; 10, 25, 40, and 70% of the muscle's initial strength (tetanic tension of the unfatigued muscle). All experiments were also repeated at two muscle temperatures, 28 and 38 degrees C. For the soleus muscle, there was no change in the blood pressure during isometric contractions. For the medial gastrocnemius muscle, both the systolic and diastolic blood pressure increased markedly when either all or just the fast-twitch motor units were stimulated; however, when only the slow-twitch motor units were stimulated, a lower pressor response was observed. Venous blood samples were drawn before, during, and after fatiguing and nonfatiguing contractions of both muscles to determine the K+ concentration in the venous blood. The mean increase in the K+ concentration during contractions was 0.6 meq/l for the slow-twitch motor units of the soleus and 5.1 meq/l for the motor units in the medial gastrocnemius.