Management of traumatic lung injury: a Western Trauma Association Multicenter review.

BACKGROUND: Improved outcomes following lung injury have been reported using "lung sparing" techniques. METHODS: A retrospective multicenter 4-year review of patients who underwent lung resection following injury was performed. Resections were categorized as "minor" (suture, wedge resection, tractotomy) or "major" (lobectomy or pneumonectomy). Injury severity, Abbreviated Injury Scale (AIS) score, and outcome were recorded. RESULTS: One hundred forty-three patients (28 blunt, 115 penetrating) underwent lung resection after sustaining an injury. Minor resections were used in 75% of cases, in patients with less severe thoracic injury (chest AIS scores "minor" 3.8 +/- 0.9 vs. "major" 4.3 +/- 0.7, p = 0.02). Mortality increased with each step of increasing complexity of the surgical technique (RR, 1.8; CI, 1.4-2.2): suture alone, 9% mortality; tractotomy, 13%; wedge resection, 30%; lobectomy, 43%; and pneumonectomy, 50%. Regression analysis demonstrated that blunt mechanism, lower blood pressure at thoracotomy, and increasing amount of the lung resection were each independently associated with mortality. CONCLUSION: Blunt traumatic lung injury has higher mortality primarily due to associated extrathoracic injuries. Major resections are required more commonly than previously reported. While "minor" resections, if feasible, are associated with improved outcome, trauma surgeons should be facile in a wide range of technical procedures for the management of lung injuries.

Hypotension, hypoxia, and head injury: frequency, duration, and consequences.

BACKGROUND: Retrospective studies have suggested an association between systemic hypotension and hypoxia and worsened outcome from traumatic brain injury. Little is known, however, about the frequency and duration of these potentially preventable causes of secondary brain injury. HYPOTHESIS: Early episodes of hypoxia and hypotension occurring during initial resuscitation will have a significant impact on outcome following traumatic brain injury. DESIGN: Prospective cohort study. SETTING: Urban level I trauma center. PATIENTS: Patients with a traumatic brain injury who had a Glasgow Coma Score of 12 or less within the first 24 hours of admission to the hospital and computed tomographic scan results demonstrating intracranial pathologic features. Patients who died in the emergency department were excluded from the study. MAIN OUTCOME MEASURES: Automated blood pressure and pulse oximetry readings were collected prospectively from the time of arrival through initial resuscitation. The number and duration of hypotensive (systolic blood pressure, < or =90 mm Hg) and hypoxic (oxygen saturation, < or =92%) events were analyzed for their association with mortality and neurological outcome. RESULTS: One hundred seven patients met the enrollment criteria (median Glasgow Coma Score, 7). Overall mortality was 43%. Twenty-six patients (24%) had hypotension while in the emergency department, with an average of 1.5 episodes per patient (mean duration, 9.1 minutes). Of these 26 patients with hypotension, 17 (65%) died (P =.01). When the number of hypotensive episodes increased from 1 to 2 or more, the odds ratio for death increased from 2.1 to 8.1. Forty-one patients (38%) had hypoxia, with an average of 2.1 episodes per patient (mean duration, 8.7 minutes). Of these 41 patients with hypoxia, 18 (44%) died (P =.68). CONCLUSIONS: Hypotension, but not hypoxia, occurring in the initial phase of resuscitation is significantly (P =.009) associated with increased mortality following brain injury, even when episodes are relatively short. These prospective data reinforce the need for early continuous monitoring and improved treatment of hypotension in brain-injured patients.

Helmet laws and motorcycle rider death rates.

We investigated motorcycle rider death rates between states with full motorcycle helmet laws and those without. This was done using both unadjusted bivariate analyses and multivariate random-effects generalized least squares regression models of rider death rates. Multivariate models were adjusted for the competing influences of several explanatory variables, including the existence of a motorcycle helmet law. From 1994 to 1996, states with helmet laws experienced a median death rate of 6.20 riders per 10000 registered motorcycles and states without helmet laws experienced a median death rate of 5.07 riders per 10000 registered motorcycles (P = 0.008). After controlling for other factors that affect motorcycle rider fatalities (most notably population density and temperature), death rates in states with full helmet laws were shown to be lower on average than deaths rates in states without full helmet laws (P = 0.740). Our study weakens the claim that rider death rates are significantly lower in states without full motorcycle helmet laws.

Surgeons and injury prevention: what you don't know can hurt you!

BACKGROUND: The most effective treatment for traumatic injuries is to prevent them from occurring. Currently, few surgeons receive any formal training in injury' control and prevention. This study was designed to test the knowledge of injury prevention principles among practicing surgeons, in order to identify areas in need of intensified educational efforts. STUDY DESIGN: Survey questions designed by members of the American College of Surgeons Committee on Trauma were programmed into a specialized touch-screen computer, which was displayed at four different surgery and trauma meetings, including the ACS Clinical Congress in 1999 and 2000. Participants were questioned about their knowledge of trauma epidemiology, bicycle helmet effectiveness, child safety seat usage, suicide, and domestic violence. RESULTS: Seventy-nine surveys were completed by surgeons, including 33 specializing in trauma care, and by 106 nurses attending trauma courses. Overall, the percentage of correct answers was 50%. There were no significant differences in survey scores between trauma surgeons and general surgeons, although both scored higher than trauma nurses. Areas where knowledge deficits were the most apparent included proper use of child safety seats, the effectiveness of airbags, the prevalence of suicide, and the annual cost of injury in America. CONCLUSIONS: The majority of practicing surgeons and nurses, including those working at trauma centers, are unaware of the basic concepts of injury prevention. Advancements in the field of injury control will require efforts to educate medical professionals and the public.

Timing of urgent thoracotomy for hemorrhage after trauma: a multicenter study.

HYPOTHESIS: It is possible to quantify an amount of thoracic hemorrhage, after blunt and penetrating injury, at which delay of thoracotomy is associated with increased mortality. DESIGN: A retrospective case series. SETTING: Five urban trauma centers. STUDY SELECTION: Patients undergoing urgent thoracotomy (within 48 hours of injury) for hemorrhage (excluding emergency department thoracotomy). DATA EXTRACTION: Respective registries identified patients who underwent urgent thoracotomy. Injury characteristics, initial and subsequent chest tube outputs, time before thoracotomy, and outcomes were evaluated. MAIN OUTCOME MEASURE: Death. RESULTS: One hundred fifty-seven patients (36 with blunt and 121 with penetrating injuries) underwent urgent thoracotomy for hemorrhage between January 1, 1995, and December 31, 1998. Mortality correlated with mean (+/- SD) Injury Severity Score (38 +/- 19 vs 22 +/- 12.6 for survivors; P<.01) and mechanism (24 [67%] for blunt vs 21 [17%] for penetrating injuries; P<.01). Mortality increased as total chest blood loss increased, with the risk for death at blood loss of 1500 mL being 3 times greater than at 500 mL. Blunt-injured patients waited a significantly longer time to thoracotomy than penetrating-injured patients (4.4 +/- 9.0 h vs 1.6 +/- 3.0 h; P =.02) and also had a greater total chest tube output before thoracotomy (2220 +/- 1235 mL vs 1438 +/- 747 mL; P =.001). CONCLUSIONS: The risk for death increases linearly with total chest hemorrhage after thoracic injury. Thoracotomy is indicated when total chest tube output exceeds 1500 mL within 24 hours, regardless of injury mechanism.

Down's syndrome, precocious puberty, and transverse vaginal septum: an unusual cause of abdominal pain.

Hematocolpos should be considered in adolescent girls who present with lower abdominal pain, a pelvic mass, and primary amenorrhea. The authors describe a rare case of a young child with Down's syndrome, precocious puberty, and hematocolpos caused by a transverse vaginal septum. The diagnosis was facilitated using a combination of computed tomography and ultrasound scanning. J Pediatr Surg 36:641-643.

Carbon dioxide reactivity and pressure autoregulation of brain tissue oxygen.

OBJECTIVE: To describe the normal relationships between brain tissue oxygen tension (PbrO2) and physiological parameters of systemic blood pressure and CO2 concentrations. METHODS: Licox Clark-type oxygen probes (GMS mbH, Kiel, Germany) were inserted in the frontal white matter of 12 swine maintained under general anesthesia with a 1.0 fraction of inspired oxygen (FiO2). In seven swine, alterations in end-tidal carbon dioxide (ET-CO2) concentration (range, 13-72 mm Hg) were induced via hyperventilation or instillation of CO2 into the ventilation circuit. In nine swine, mean arterial pressure (MAP) (range, 33-200 mm Hg) was altered; phenylephrine was used to induce hypertension, and a nitroprusside-esmolol combination or systemic hemorrhage was used for hypotension. Quantitative cerebral blood flow (CBF) was measured in two animals by using a thermal diffusion probe. RESULTS: Mean baseline PbrO2 was 41.9 +/- 11.3 mm Hg. PbrO2 varied linearly with changes in ET-CO2, ranging from 20 to 60 mm Hg (r2 = 0.70). The minimum PbrO2 with hypocarbia was 5.9 mm Hg, and the maximum PbrO2 with hypercarbia was 132.4 mm Hg. PbrO2 varied with MAP in a sigmoid fashion suggestive of pressure autoregulation between 60 and 150 mm Hg (r2 = 0.72). The minimum PbrO2 with hypotension was 1.4 mm Hg, and the maximum PbrO2 with hypertension was 97.2 mm Hg. In addition, CBF correlated linearly with PbrO2 during CO2 reactivity testing (r2 = 0.84). CONCLUSION: In the uninjured brain, PbrO2 exhibits CO2 reactivity and pressure autoregulation. The relationship of PbrO2 with ET-CO2 and MAP appears to be similar to those historically established for CBF with ET-CO2 and MAP. This suggests that, under normal conditions, PbrO2 is strongly influenced by factors that regulate CBF.

State helmet laws and motorcycle rider death rates.

Motorcycles are the most dangerous form of motorized transportation. Per vehicle miles traveled, motorcyclists are about 3 times as likely as passenger car occupants to be injured in a crash, and 16 times as likely to die. Because the majority of these deaths are caused by head injury, safety advocates have recommended mandatory use of motorcycle helmets. Others contend that state laws mandating helmet use infringe on motorcyclists' rights, and question whether such laws really reduce motorcycle deaths and injury. Scientific evidence cannot address the appropriate balance between personal freedom and public safety, but it can address the effectiveness of mandatory helmet laws. This Issue Brief summarizes a new analysis of the effects of motorcycle helmet laws on death rates, and points out the need to account for other potential factors when comparing death rates across states.

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 surgeon's 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.

Significance of minimal or no intraperitoneal fluid visible on CT scan associated with blunt liver and splenic injuries: a multicenter analysis.

BACKGROUND: The use of ultrasound (U/S) for the evaluation of patients with blunt abdominal trauma is gaining increasing acceptance. Patients who would have undergone computed tomographic (CT) scan may now be evaluated solely with U/S. Solid organ injuries with minimal or no free fluid may be missed by surgeon sonographers. OBJECTIVE: The purpose of this study was to describe the incidence and clinical importance of liver and splenic injuries with minimal or no free intraperitoneal fluid visible on CT scan. We hypothesized that these solid organ injuries occur infrequently and are of minor clinical significance. METHODS: Patient records and CT scans were reviewed for the presence of and outcome associated with blunt liver and splenic injuries with minimal (<250 mL) or no free fluid detected by an attending radiologist. Data were collected from six major trauma centers during a 4-year period before the introduction of U/S and included demographics, grade of injury (American Association for the Surgery of Trauma scale), need for operative intervention, and outcome. RESULTS: A total of 938 patients with liver and splenic injuries were identified. In this group, 11% of liver injuries and 12% of splenic injuries had no free fluid visible on CT scan and could be missed by diagnostic peritoneal lavage or U/S. Of the 938 patients, 267 (28%) met the inclusion criteria; 161 had injury to the spleen and 125 had injury to the liver. In the 267 patients studied, 97% of the injuries were managed nonoperatively. However, 8 patients (3%) required operative intervention for bleeding. Compared with the liver, the spleen was significantly more likely to bleed (p = 0.01), but the grade of splenic injury was not related to the risk for hemorrhage (p = 0.051). CONCLUSION: Data from this study suggest that injuries to the liver or spleen with minimal or no intraperitoneal fluid visible on CT scan occur more frequently than predicted but usually are of minimal clinical significance. However, patients with splenic injuries may be missed by abdominal U/S. We found a 5% associated risk of bleeding. Therefore, abdominal U/S should not be used as the sole diagnostic modality in all stable patients at risk for blunt abdominal injury.

Cerebral oxygenation during hemorrhagic shock: perils of hyperventilation and the therapeutic potential of hypoventilation.

OBJECTIVES: Prophylactic hyperventilation of patients with head injuries worsens outcome, presumably by exacerbating tissue hypoxia. Oxygen tension in brain tissue (PbrO2) provides a direct measurement of cerebral metabolic substrate delivery and varies with changing end-tidal carbon dioxide tension (ETCO2) and mean arterial pressure. However, the effects of hyperventilation and hypoventilation on PbrO2 during hemorrhagic shock are not known. The aim of this study was to examine the effects of alteration in ventilation on PbrO2 in hemorrhaged swine. METHODS: Clark-type polarographic probes were inserted into the brain tissue of seven swine to measure PbrO2 directly. To examine the effects of alterations in ventilation on hemorrhage-induced hypotension, swine were hemorrhaged to 50% estimated blood volume and PbrO2 was monitored during hyperventilation (RR = 30) and hypoventilation (RR = 4). RESULTS: After the 50% hemorrhage, PbrO2 declined rapidly from 39.8 +/- 4.6 mm Hg to 11.4 +/- 2.2 mm Hg. Hyperventilation resulted in a further 56% mean decrease in PbrO2. Hypoventilation produced a 166% mean increase in PbrO2. These changes were significant (p = 0.001) for absolute and percentage differences from baseline. CONCLUSION: During hemorrhage, alterations in ventilation significantly changed PbrO2: hyperventilation increased brain-tissue hypoxia whereas hypoventilation alleviated it. This finding suggests that hyperventilation has deleterious effects on brain oxygenation in patients with hemorrhagic shock and those with head trauma. Conversely, hypoventilation with resultant hypercapnia may actually help resolve hemorrhagic shock-induced cerebral hypoxia.

Training residents using simulation technology: experience with ultrasound for trauma.

BACKGROUND: The need for surgeons to become proficient in performing and interpreting ultrasound examinations has been well recognized in recent years, but providing standardized training remains a significant challenge. The UltraSim (MedSim, Ft. Lauderdale, Fla) ultrasound simulator is a modified ultrasound machine that stores patient data in three-dimensional images. By scanning on the UltraSim mannequin, the student can reconstruct these images in real-time, eliminating the need for finding normal and abnormal models, while providing an objective method of both teaching and testing. The objective of this study was to compare the posttest results between residents trained on a real-time ultrasound simulator versus those trained in a traditional hands-on patient format. We hypothesized that both methods of teaching would yield similar results as judged by performance on the interpretive portion of a standardized posttest. It is designed as a prospective, cohort study from two university trauma centers involving residents at the beginning of their first or second postgraduate year of training. The main outcome measure was performance on a standardized posttest, which included interpretation of ultrasound cases recorded on videotape. METHODS: Students first took a written pretest to evaluate their baseline knowledge of ultrasound physics as well as their ability to interpret basic ultrasound images. The didactic portion of the course used the same teaching materials for all residents and included lectures on ultrasound physics, ultrasound use in trauma/critical care, and a series of instructional videos. This didactic session was followed by 1 hour for each student of hands-on training on medical models/medical patients (group I) or by training on the ultrasound simulator (group II). The pretest was repeated at the completion of the course (posttest). Data were stratified by postgraduate year, i.e., PG1 or PG2. RESULTS: A total of 74 residents were trained and tested in this study (PG1 = 48, PG2 = 26). All residents showed significant improvement in their pretest and posttest scores (p = 0.00) in both their knowledge of ultrasound physics and in their interpretation of ultrasound images. Importantly, we could not demonstrate any significant difference between groups trained on models/patients (group I) versus those trained on the simulator (group II) when comparing their posttest interpretation of ultrasound images presented on videotapes (PG1, group I mean score 6.9 +/- 1.4 vs. PG1, group II mean score 6.5 +/- 1.6, p = 0.32; PG2, group I mean score 7.7 +/- 1.4 vs. PG2, group II mean score 7.9 +/- 1.2, p = 0.70). CONCLUSION: The use of a simulator is a convenient and objective method of introducing ultrasound to surgery residents and compares favorably with the experience gained with traditional hands-on patient models.

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

BACKGROUND: Ultrasound is quickly becoming part of the trauma surgeon's 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.

Brain tissue oxygenation during hemorrhagic shock, resuscitation, and alterations in ventilation.

OBJECTIVES: Recently developed polarographic microelectrodes permit continuous, reliable monitoring of oxygen tension in brain tissue (PbrO2). The aim of this study was to investigate the feasibility and utility of directly monitoring PbrO2 in cerebral tissue during changes in oxygenation or ventilation and during hemorrhagic shock and resuscitation. We also sought to develop a model in which treatment protocols could be evaluated using PbrO2 as an end point. METHODS: Licox Clark-type polarographic probes were inserted in the brain tissue of 16 swine to monitor PbrO2. In eight swine, changes in PbrO2 were observed over a range of fractional concentrations of inspired O2 (FiO2) as well as during periods of hyperventilation and hypoventilation. In eight other swine, PbrO2 was monitored during a graded hemorrhage of up to 70% estimated blood volume and during the resuscitation period. RESULTS: When FiO2 was elevated to 100%, PbrO2 increased from a baseline of 15+/-2 mm Hg to 36+/-11 mm Hg. Hyperventilation while breathing 100% oxygen resulted in a 40% decrease in PbrO2 (p < 0.05), whereas hypoventilation increased PbrO2 to 88 mm Hg (p < 0.01). A graded hemorrhage to 50% estimated blood volume significantly reduced PbrO2, mean arterial pressure, and intracranial pressure (p < 0.01). Continued hemorrhage to 70% estimated blood volume resulted in a PbrO2 of 2.9+/-1.5 mm Hg. After resuscitation, PbrO2 was significantly elevated, reaching 65+/-13 mm Hg (p < 0.01), whereas mean arterial pressure and cerebral perfusion pressure simply returned to baseline. CONCLUSION: Directly measured PbrO2 was highly responsive to changes in FiO2, ventilatory rate, and blood volume in this experimental model. In particular, hypoventilation significantly increased PbrO2, whereas hyperventilation had the opposite effect. The postresuscitation increase in PbrO2 may reflect changes in both O2 delivery and O2 metabolism. These experiments set the stage for future investigations of a variety of resuscitation protocols in both normal and injured brain.

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.

Fasciotomy, chronic venous insufficiency, and the calf muscle pump.

OBJECTIVE: To test the hypothesis that fasciotomy may impair the function of the calf muscle pump, which in turn could result in the development of chronic venous insufficiency. DESIGN: A cohort study of patients with a history of lower extremity fasciotomy. SETTING: An urban trauma center. PATIENTS: Seventeen of the 83 patients identified through trauma, vascular, and/or orthopedic registries consented to participation in this study. INTERVENTIONS: Participating patients completed a study questionnaire, and then underwent a complete vascular examination, including air plethysmographic (APG) assessment. Patients with a history of venous injuries were also studied with color flow duplex venous imaging. MAIN OUTCOME MEASURES: Function of the calf muscle pump as measured by APG, and evidence of chronic venous insufficiency as measured by APG, findings on clinical examination, and by venous ultrasonography. RESULTS: Seventeen patients completed the study, including 8 with a history of vascular injuries, 6 with old fractures, and 3 who had undergone fasciotomy for soft tissue infections. The time from injury to examination ranged from 5 months to 20 years. Eight patients had signs or symptoms of venous insufficiency, the severity of which appeared to be time dependent. The APG data showed significant mean differences between fasciotomy and control extremities in ejection fraction (P<.001) and residual volume fraction (P<.001), both measures of calf muscle pump function. There were no significant changes in venous filling index, a measure of venous reflux, or in outflow fraction, which correlates with venous obstruction. There were no differences in APG variables between patients with vascular injuries vs those with orthopedic or soft tissue injuries. CONCLUSIONS: Lower extremity fasciotomy impairs long-term calf muscle pump function, as measured by APG, in patients with and without vascular injuries. These patients are at risk for the long-term development of chronic venous insufficiency following lower extremity trauma.

The surgeon's use of ultrasound in the acute setting.

As the role of the general surgeon continues to evolve, the surgeon's use of ultrasound will surely influence practice patterns, particularly for the evaluation of patients in the acute setting. With the use of real-time imaging, the surgeon receives "instantaneous" information to augment the physical examination, narrow the differential diagnosis, or initiate an intervention. With select ultrasound examinations, the surgeon can rapidly evaluate adult and pediatric patients who present with an acute abdomen, especially those in shock. In the hands of the surgeon, this noninvasive bedside tool can more accurately assess the presence, depth, and extent of an abscess, confirm complete aspiration, or diagnose wound dehiscence before it is apparent on physical examination. Ultrasound is so accurate for the diagnosis of pyloric stenosis that it has essentially replaced the upper gastrointestinal series in most institutions. The surgeon's use of ultrasound to detect a pleural effusion has virtually replaced the lateral decubitus film. Furthermore, an ultrasound-guided thoracentesis not only facilitates the procedure but improves its safety. Many ICUs now have protocols in place to perform routine duplex surveillance of those patients who are considered at high risk for the development of thromboembolic complications. As surgeons become more facile with ultrasound, it is anticipated that other uses will develop to further enhance its value for the assessment of patients in the acute setting.

Long-term results of lower-extremity venous injuries.

OBJECTIVES: To compare the long-term venous function of ligated, simple, and complex repairs and to assess long-term patency in repaired veins. DESIGN: A cohort study of patients with lower-extremity venous injuries treated during a 7-year period. SETTING: A level I urban trauma center. PATIENTS: Twenty-one of the 79 patients with a history of lower-extremity venous injury identified via the trauma registry consented to outpatient evaluation. INTERVENTION: Participating patients underwent a through vascular examination that included color flow duplex venous imaging and air plethysmographic assessment. MAIN OUTCOME MEASURES: The patency of venous repairs, the incidence of chronic deep venous thrombosis, and evidence of chronic venous insufficiency. RESULTS: The venous injuries included 5 iliac, 10 femoral, and 6 popliteal. Six of these injuries were ligated, 11 injuries were simply repaired (lateral venorrhaphy or end-to-end), and 4 were repaired with complex interposition grafts. All repairs were patent, with no evidence of deep venous thrombosis by color flow duplex venous imaging. Seventeen of the 21 patients had symptoms, color flow duplex venous imaging findings, and air plethysmographic data consistent with chronic venous insufficiency, including significant mean differences (P < .03) in outflow fraction, outflow fraction with compression, venous filling index, and residual volume fraction, when compared with the uninjured extremity. The most profound changes followed complex repairs and perioperative fasciotomies. CONCLUSIONS: While the long-term patency of venous repairs is excellent, most patients demonstrate evidence of chronic venous insufficiency after either ligation or repair. Complex venous repairs and fasciotomy are associated with the most severe functional changes.

Use of tissue oxygen tension measurements during resuscitation from hemorrhagic shock.

BACKGROUND: Tissue oxygen tension can be measured directly in selected organ beds, and these measurements may be more sensitive in assessing the adequacy of resuscitation than global physiologic parameters. We hypothesized that heart tissue oxygen tension would be an important marker for the severity of ischemic insult to the heart during hemorrhagic shock. We further hypothesized that gut oxygen tension measured in the jejunum would prove to be a better measure of splanchnic hypoperfusion than intramucosal pH (pHi). METHODS: Tissue oxygen probes were inserted directly into the myocardium of the left ventricle and into the lumen of the proximal jejunum in 10 anesthetized swine. A pHi catheter was introduced into the stomach. The animals were subjected to a controlled hemorrhage of 50% of estimated blood volume. Gut and cardiac oxygen were monitored continuously during hemorrhage and resuscitation, which was performed with shed blood and crystalloid. RESULTS: While gut O2 and pHi trended together, we were unable to establish a correlation between changes in these two variables during hemorrhage and resuscitation. Heart PO2 decreased significantly during hemorrhage, but surpassed baseline values after resuscitation, a finding not seen in gut PO2. No standard physiologic variables reliably predicted changes in heart PO2 during these experiments. CONCLUSIONS: Tissue oxygen tensions measurements are highly responsive to changes induced during graded hemorrhagic shock and resuscitation. Gut PO2 and pHi appear to be measuring different physiologic processes in the gastrointestinal tract. The compensatory ability of the heart far exceeds that of the gut after ischemic insult. This hemorrhagic shock model appears feasible for the study of various methods of resuscitation.

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.