Operative Management of Aerodigestive Injuries: Improved Survival Over two Decades

INTRODUCTION

Non-iatrogenic aerodigestive injuries are infrequent but potentially fatal. We hypothesize that advances in management and adoption of innovative therapies resulted in improved survival.

METHODS

Trauma registry review at a university Level 1 center from 2000 to 2020 that identified adults with aerodigestive injuries requiring operative or endoluminal intervention. Demographics, injuries, operations, and outcomes were abstracted. Univariate analysis was performed, P < .05 was statistically significant.

RESULTS

95 patients had 105 injuries: 68 tracheal and 37 esophageal (including 10 combined). Mean age 30.9 (± 14), 87.4% male, 82.1% penetrating, and 28.4% with vascular injuries. Median ISS, chest AIS, admission BP, Shock Index, and lactate were 26 (16-34), 4 (3-4), 132 (113-149) mmHg, .8 (.7-1.1), and 3.1 (2.4-5.6) mmol/L, respectively. There were 46 cervical and 22 thoracic airway injuries; 5 patients in extremis required preoperative ECMO. 66 airway injuries were surgically repaired and 2 definitively managed with endobronchial stents. There were 24 cervical, 11 thoracic, 2 abdominal esophageal injuries-all repaired surgically. Combined tracheoesophageal injuries were individually managed and buttressed. 4 airway complications were successfully managed, and 11 esophageal complications managed conservatively, stented, or resected. Mortality was 9.6%, half from intraoperative hemorrhage. Specific mortality: tracheobronchial 8.8%, esophageal 10.8%, and combined 20%. Mortality was significantly associated with higher ISS (P = .01), vascular injury (P = .007), blunt mechanism (P = .01), bronchial injury (P = .01), and years 2000-2010 (P = .03), but not combined tracheobronchial injury.

CONCLUSION

Mortality is associated with several variables, including vascular trauma and years 2000-2010. The use of ECMO and endoluminal stents in highly selected patients and institutional experience may account for 97.8% survival over the past decade.

Early Veno-venous Extracorporeal Membrane Oxygenation is an Effective Strategy for Traumatically Injured Patients Presenting with Refractory Respiratory Failure

BACKGROUND

Veno-venous extracorporeal membrane oxygenation (VV ECMO) is used for respiratory failure when standard therapy fails. Optimal trauma care requires patients be stable enough to undergo procedures. Early VV ECMO (EVV) to stabilize trauma patients with respiratory failure as part of resuscitation could facilitate additional care. As VV ECMO technology is portable and prehospital cannulation possible, it could also be used in austere environments. We hypothesize that EVV facilitates injury care without worsening survival.

METHODS

Our single center, retrospective cohort study included all trauma patients between January 1, 2014, and August 1, 2022, who were placed on VV ECMO. EVV was defined as cannulation ≤48 hours from arrival with subsequent operation for injuries. Data were analyzed with descriptive statistics. Parametric or nonparametric statistics were used based on the nature of the data. After testing for normality, significance was defined as a p < 0.05. Logistic regression diagnostics were performed.

RESULTS

Seventy-five patients were identified and 57 (76%) underwent EVV. There was no difference in survival between the EVV and non-EVV groups (70% v 61%, p = 0.47). Age, race, and gender did not differ between EVV survivors and non-survivors. Time to cannulation (4.5 h v 8 h, p = 0.39) and injury severity scores (34 v 29, p = 0.74) were similar. EVV survivors had lower lactic acid levels pre-cannulation (3.9 mmol/L v 11.9 mmol/L, p < 0.001). A multivariable logistic regression analysis examining admission and pre-cannulation laboratory and hemodynamic values demonstrated that lower pre-cannulation lactic acid levels predicted survival (OR 1.2, 95% CI 1.02-1.5, p = 0.03) with a significant inflection point of 7.4 mmol/L corresponding to decreased survival at hospital discharge.

CONCLUSIONS

Patients undergoing EVV did not have increased mortality compared to the overall trauma VV ECMO population. EVV resulted in ventilatory stabilization that allowed subsequent procedural treatment of injuries.

LEVEL OF EVIDENCE

Therapeutic Care/Management, IV.

Contemporary Management and Outcomes of Injuries to the Inferior Vena Cava: A Prospective Multicenter Trial From PROspective Observational Vascular Injury Treatment

INTRODUCTION

Injuries to the inferior vena cava (IVC), while uncommon, have a high mortality despite modern advances. The goal of this study is to describe the diagnosis and management in the largest available prospective data set of vascular injuries across anatomic levels of IVC injury.

METHODS

The American Association for the Surgery of Trauma PROspective Observational Vascular Injury Treatment (PROOVIT) registry was queried from November 2013 to January 2019. Demographics, diagnostic modalities, injury patterns, and management strategies were recorded and analyzed. Comparisons between anatomic levels were made using non-parametric Wilcoxon rank-sum statistics.

RESULTS

140 patients from 19 institutions were identified; median age was 30 years old (IQR 23-41), 75% were male, and 62% had penetrating mechanism. The suprarenal IVC group was associated with blunt mechanism (53% vs 32%, P = .02), had lower admission systolic blood pressure, pH, Glasgow Coma Scale (GCS), and higher ISS and thorax and abdomen AIS than the infrarenal injury group. Injuries were managed with open repair (70%) and ligation (30% overall; infrarenal 37% vs suprarenal 13%, P = .01). Endovascular therapy was used in 2% of cases. Overall mortality was 42% (infrarenal 33% vs suprarenal 66%, P<.001). Among survivors, there was no difference in first 24-hour PRBC transfusion requirement, or hospital or ICU length of stay.

CONCLUSIONS

Current PROOVIT registry data demonstrate continued use of ligation extending to the suprarenal IVC, limited adoption of endovascular management, and no dramatic increase in overall survival compared to previously published studies. Survival is likely related to IVC injury location and total injury burden.

Mortality Risk Assessment in COVID-19 Venovenous Extracorporeal Membrane Oxygenation

Background

A life-threatening complication of coronavirus disease 2019 (COVID-19) is acute respiratory distress syndrome (ARDS) refractory to conventional management. Venovenous (VV) extracorporeal membrane oxygenation (ECMO) (VV-ECMO) is used to support patients with ARDS in whom conventional management fails. Scoring systems to predict mortality in VV-ECMO remain unvalidated in COVID-19 ARDS. This report describes a large single-center experience with VV-ECMO in COVID-19 and assesses the utility of standard risk calculators.

Methods

A retrospective review of a prospective database of all patients with COVID-19 who underwent VV-ECMO cannulation between March 15 and June 27, 2020 at a single academic center was performed. Demographic, clinical, and ECMO characteristics were collected. The primary outcome was in-hospital mortality; survivor and nonsurvivor cohorts were compared by using univariate and bivariate analyses.

Results

Forty patients who had COVID-19 and underwent ECMO were identified. Of the 33 patients (82.5%) in whom ECMO had been discontinued at the time of analysis, 18 patients (54.5%) survived to hospital discharge, and 15 (45.5%) died during ECMO. Nonsurvivors presented with a statistically significant higher Prediction of Survival on ECMO Therapy (PRESET)-Score (mean ± SD, 8.33 ± 0.8 vs 6.17 ± 1.8; P = .001). The PRESET score demonstrated accurate mortality prediction. All patients with a PRESET-Score of 6 or lowers survived, and a score of 7 or higher was associated with a dramatic increase in mortality.

Conclusions

These results suggest that favorable outcomes are possible in patients with COVID-19 who undergo ECMO at high-volume centers. This study demonstrated an association between the PRESET-Score and survival in patients with COVID-19 who underwent VV-ECMO. Standard risk calculators may aid in appropriate selection of patients with COVID-19 ARDS for ECMO.

Single Center Experience With Veno-Venous Extracorporeal Membrane Oxygenation in Patients With Traumatic Brain Injury

METHODS

We retrospectively reviewed TBI patients ≥ 18 years of age treated with VV-ECMO. The primary outcome was survival to discharge. Secondary outcomes included progression of intracranial hemorrhage, bleeding complications, and episodes of oxygenator thrombosis requiring exchange. Medians and interquartile ranges were reported where appropriate.

RESULTS

13 TBI patients received VV-ECMO support during the study period. The median age was 28 years (Interquartile range (IQR) 25-37.5) and 85% were men. Median admission Glasgow coma scale was 5 (IQR 3-13.5). Median injury severity score (ISS) was 48 (IQR 33.5-66). Median pre-ECMO PaO2:FiO2 ratio was 58 (IQR 47-74.5). Five (38.4%) patients survived to discharge. Six patients (46%) received systemic A/C while on ECMO. No patient had worsening of intracranial hemorrhage on computed tomography imaging. There were two bleeding complications in patients on A/C, neither was related to TBI. Four patients required an oxygenator change; 2 in patients on A/C.

CONCLUSION

VV-ECMO appears safe with TBI. We have demonstrated that A/C can be withheld without increased complications. Traumatic brain injury should not be considered an absolute contraindication to the use of VV-ECMO for severe respiratory failure and should be decided on a case by case basis. Additional research is needed to confirm these preliminary findings.

Admission Physiology vs Blood Pressure: Predicting the Need for Operating Room Thoracotomy after Penetrating Thoracic Trauma

BACKGROUND

Approximately 15% of patients with penetrating thoracic trauma require an emergency center or operating room thoracotomy, usually for hemodynamic instability or persistent hemorrhage. The hypothesis in this study was that admission physiology, not vital signs, predicts the need for operating room thoracotomy.

STUDY DESIGN

We conducted a trauma registry review, 2002 to 2017, of adult patients undergoing operating room thoracotomy within 6 hours of admission (emergency department thoracotomies excluded). Demographics, injuries, admission physiology, time to operating room (OR), operations, and outcomes were reviewed. Data are reported as mean (SD) or median (IQR).

RESULTS

Of the 301 consecutive patients in this 15-year review, 75.6% were male, mean age was 31.1 years (11.5), and 41.5% had gunshot wounds. The median Injury Severity Score was 25 (range 16 to 29), time to operating room was 38 minutes (interquartile range [IQR] 19 to 105 minutes), and 21.9% had a thoracic damage control operation. Mean admission systolic blood pressure was 115 mmHg (SD 37 mmHg), with only 23.9% <90 mmHg; however, admission pH 7.22 (SD 0.14), base deficit 7.6 (SD 6.1), and lactate 7.2 (SD 4.5) were markedly abnormal. Overall, there were 136 (45.2%) patients with significant pulmonary injuries treated with 112 major nonanatomic resections, 17 lobectomies, and 7 pneumonectomies; respective mortalities were 2.7%, 11.8%, and 42.9%. There were 100 (33.2%) cardiac, 30 (9.9%) great vessel, 14 (4.7%) aerodigestive, and 58 (19%) combined thoracic injuries. Mortalities for cardiac, great vessel, and aerodigestive injuries were 7%, 0%, and 14.3%, respectively. Overall mortality was 6.6%, 15.2% after damage control, and 4.3% for all others.

CONCLUSIONS

Shock characterized by acidosis, but not hypotension, is the most common presentation in patients who will need operating room thoracotomy after penetrating thoracic trauma. Survival rates are excellent unless a pneumonectomy or damage control thoracotomy is required.

Blunt Thoracic Aortic Injury: Endovascular Repair Is Now the Standard

BACKGROUND

Incidence and treatment of blunt thoracic aortic injury (BTAI) has evolved, likely from improved imaging and emergence of endovascular techniques; however, multicenter data demonstrating this are lacking. We examined trends in incidence, management, and outcomes in BTAI.

STUDY DESIGN

The American College of Surgeons National Trauma Databank (2003 to 2013) was used to identify adults with BTAI. Management was categorized as nonoperative repair, open aortic repair (OAR), or thoracic endovascular repair (TEVAR). Outcomes included demographics, management, and outcomes.

RESULTS

There were 3,774 patients. Median age was 46.0 years (interquartile range [IQR] 29.3, 62.0 years), with 70.8% males, and median Injury Severity Score (ISS) of 34.0 (IQR 26.0, 45.0). The number of BTAIs diagnosed over the decade increased 196.8% (p < 0.001), median ISS decreased from 38 to 33 (p < 0.001), and significantly more patients were treated at a level I trauma center (p < 0.001). After FDA approval of TEVAR devices, there was a significant increase in endovascular repair overall (1.0% to 30.6%, p < 0.001) and in those treated operatively (0.0% to 94.9%, p < 0.001), with a marked decrease in OAR. Use of TEVAR was associated with significantly reduced median ICU LOS (9.0 vs 12.0 days, p = 0.048) and mortality (9.3% vs 16.6%; p = 0.015) compared with OAR. In modern BTAI care, TEVAR has nearly completely replaced OAR.

CONCLUSIONS

The diagnosis of BTAI has increased, likely due to more sensitive imaging. Nearly 70% of patients get nonoperative care. Treatment with TEVAR improves outcomes relative to OAR. Part of the proportional increase in TEVAR use may represent overtreatment of lower grade BTAI amenable to medical management, and warrants further investigation.

Veno-Venous Extracorporeal Membrane Oxygenation (VV ECMO) for Acute Respiratory Failure Following Injury: Outcomes in a High-Volume Adult Trauma Center with a Dedicated Unit for VV ECMO

INTRODUCTION

The use of veno-venous extracorporeal membrane oxygenation (VV ECMO) has increased over the past decade. The purpose of this study was to evaluate outcomes in adult trauma patients requiring VV ECMO.

METHODS

Data were collected on adult trauma patients admitted between January 1, 2015, and November 1, 2016. Demographics, injury-specific data, ECMO data, and survival to discharge were recorded. Medians [interquartile range (IQR)] were reported. A p value ≤0.05 was considered statistically significant.

RESULTS

Eighteen patients required VV ECMO during the study period. Median age was 28.5 years (IQR 24-43). Median injury severity score (ISS) was 27 (IQR 21-41); median PaO₂/FiO₂ (P/F) prior to ECMO cannulation was 61 (IQR 50-70). Median time from injury to cannulation was 3 (IQR 0-6) days. Median duration of ECMO was 266 (IQR 177-379) hours. Survival to discharge was 78%. Survivors had a significantly higher ISS (p = 0.03), longer intensive care unit length of stay (ICU LOS) (p < 0.0004), hospital LOS (p < 0.000004), and time on the ventilator (p < 0.0003). Median time of injury to cannulation was significantly longer in patients who survived to discharge (p = 0.01). There was no difference in P/F ratio prior to cannulation (p = ns).

CONCLUSION

We have demonstrated improved outcome of patients requiring VV ECMO following injury compared to historical data. Although shorter time from injury to cannulation for VV ECMO was associated with death, select patients who meet criteria for VV ECMO early following injury should be referred/transferred to a tertiary care facility that specializes in trauma and ECMO care.

The Influence of Carbohydrate Structure on the Clearance of Recombinant Tissue-Type Plasminogen Activator

Modification of the carbohydrate structures of recombinant tissue-type plasminogen activator (rt-PA) can increase or decrease its rate of clearance in rabbits. When rt-PA was treated with sodium periodate to oxidize carbohydrate residues, the rate of clearance was decreased from 9.6 ± 1.9 ml min−1 kg−1 to 3.5 ± 0.6 ml min−1 kg−1 (mean ± SD, n = 5). A similar change in the clearance of rt-PA was introduced by the use of endo-β-N-acetyl- glucosaminidase H (Endo-H), which selectively removes high mannose asparagine-linked oligosaccharides; the clearance of Endo-H-treated rt-PA was 5.0 ± 0.5 ml min−1 kg−1. A mutant of rt-PA was produced with an amino acid substitution at position 117 (Asn replaced with Gin) to remove a potential glycosylation site that normally contains a high mannose structure. The clearance of this material was also decreased, similar to the periodate and Endo-H-treated rt-PA. Conversely, when rt-PA was produced in the CHO 15B cell line, which can produce only high mannose oligosaccharide structures on glycoproteins, the clearance was increased by a factor of 1.8. These results demonstrate that the removal of rt-PA from the blood depends significantly upon the nature of its oligosaccharide structures.

Nonoperative Damage Control: The Use of Extracorporeal Membrane Oxygenation in Traumatic Bronchial Avulsion as a Bridge to Definitive Operation

The conventional treatment for an avulsed bronchus is emergent thoracotomy and repair or lobectomy. The principles of damage control thoracic operations include initial hemorrhage control with delayed definite repair after physiologic resuscitation. We report a multiply injured patient with avulsion of the left lower lobe bronchus. Profound acidosis, hypercarbia, and hypoxia precluded an emergent operation, and venovenous extracorporeal membrane oxygenation (V-V ECMO) was used for organ support during physiologic resuscitation. After the achievement of physiologic repletion, a thoracotomy and lobectomy were performed while the patient was supported by V-V ECMO.

Critical Care Resuscitation Unit: An Innovative Solution to Expedite Transfer of Patients with Time-Sensitive Critical Illness

BACKGROUND

Time-sensitive, critical surgical illnesses require care at specialized centers. Trauma systems facilitate patient transport to designated trauma centers, but formal systems for nontraumatic critical illness do not exist. We created the critical care resuscitation unit to expedite transfers of adult critically ill patients with time-sensitive conditions to a quaternary academic medical center, hypothesizing that this would decrease time to transfer, increase transfer volume, and improve outcomes.

STUDY DESIGN

Critical care transfers to the University of Maryland Medical Center during the first year of the critical care resuscitation unit (July 2013 to June 2014) were compared with a previous year (July 2011 to June 2012). Times from transfer request to arrival and operating room and hospital mortality were compared.

RESULTS

There was a 64.5% increase in transfers with a 93.6% increase in critically ill surgical patients. For patients requiring operation, median time to arrival and operating room (118 vs 223 minutes and 1,113 vs 3,424 minutes, respectively; p < 0.001 for both) and median hospital length of stay (13 vs 17 days; p < 0.001) were reduced significantly. There was a nonsignificant trend toward lower mortality (14.6% vs 16.5%; p = 0.27).

CONCLUSIONS

The critical care resuscitation unit dramatically increased the volume of critically ill surgical patients. It decreased transfer times, increased volume, and, for those who required urgent operation, decreased time from initial referral to operating room. This benefit seems to be most marked in patients needing urgent operation. This might be a paradigm shift expediting the transfer of patients with time-sensitive critical illness to an appropriately resourced specialty center.

A new aortic injury score predicts early rupture more accurately than clinical assessment

OBJECTIVE

The optimal timing for repair of a high-grade blunt thoracic aortic injury (BTAI) is uncertain. Delayed repair is common and associated with improved outcomes, but some lesions may rupture during observation. To determine optimal patient selection for appropriate management, we developed a pilot clinical risk score to evaluate aortic stability and predict rupture.

METHODS

Patients presenting in stable condition with Society for Vascular Surgery grade III or IV BTAI diagnosed on computed tomography (CT) were retrospectively reviewed. To determine clinical and radiographic factors associated with aortic rupture, patients progressing to aortic rupture (defined by contrast extravasation on CT or on operative or autopsy findings) were compared with those who had no intervention ≤48 hours of admission. A model targeting 100% sensitivity for rupture was generated and internally validated by bootstrap analysis. Clinical utility was tested by comparison with clinical assessment by surgeons experienced in BTAI management who were provided with CT images and clinical data but were blinded to outcome.

RESULTS

The derivation cohort included 18 patients whose aorta ruptured and 31 with stable BTAI. There was no difference in age, gender, injury mechanism, nonchest injury severity, blood pressure, or Glasgow Coma Scale on admission between patient groups. As dichotomous factors, admission lactate >4 mM, posterior mediastinal hematoma >10 mm, and lesion/normal aortic diameter ratio >1.4 on the admission CT were independently associated with aortic rupture. The model had an area under the receiver operator curve of .97, and in the presence of any two factors, was 100% sensitive and 84% specific for predicting aortic rupture. No aortic lesions ruptured in patients with fewer than two factors. In contrast, clinical assessment had lower accuracy (65% vs 90% total accuracy, P < .01).

CONCLUSIONS

This novel risk score can be applied on admission using clinically relevant factors that incorporate patient physiology, size of the aortic lesion, and extent of the mediastinal hematoma. The model reliably identifies and distinguishes patients with high-grade BTAI who are at risk for early rupture from those with stable lesions. Although preliminary, because it is more accurate than clinical assessment alone, the score may improve patient selection for emergency or delayed intervention.

Post-traumatic empyema: aetiology, surgery and outcome in 125 consecutive patients

INTRODUCTION

Empyema remains a potentially serious condition with multiple etiologies including post-pneumonic, post-resection, and post-traumatic. There are few studies describing the latter. We reviewed our experience at a high volume trauma centre in injured patients with empyema, examining pre-operative status, surgical procedures, pathogens and outcome.

METHODS

Retrospective trauma registry review, from 9/01 to 4/10. Empyema was defined as culture positive pleural fluid or purulence at operation. Data collected included demographics, injury mechanism, thoracic injuries, organ dysfunction, pathogens isolated, surgical procedures, outcomes and follow up.

RESULTS

One hundred twenty-five consecutive patients with empyema were identified. Average injury severity score and age were 27.3 and 37.2 years respectively; 89.6% were male, 63.2% sustained blunt chest trauma. Time from injury to diagnosis averaged 12.1 days. All underwent decortication; 80% by thoracotomy, the remainder thoracoscopically. At operation over half were mechanically ventilated and 13.6% required vasoactive infusions. Monomicrobial cultures with Gram positive cocci predominating were obtained in 44%, 48% had polymicrobial cultures and 18.4% had a ruptured lung abscess. There were five deaths (4%); two occurring after a ruptured lung abscess. Recurrent empyema occurred in 6.4%, all successfully treated by re-operation or catheter drainage. Intensive care and hospital stays were 18.1 and 30.6 days respectively. All survivors achieved resolution of empyema.

CONCLUSIONS

Trauma patients with empyema represent a subset of severely injured critically ill patients with diverse pathogens and polymicrobial flora. Appropriate surgical management and specific antibiotic therapy yields excellent results with acceptable risk. A ruptured lung abscess may be the aetiology of the post-traumatic empyema in a subset of patients and may represent an increased operative risk.

Assessing Behind Armor Blunt Trauma in Accordance With the National Institute of Justice Standard for Personal Body Armor Protection Using Finite Element Modeling

BACKGROUND

To assess the possibility of injury as a result of behind armor blunt trauma (BABT), a study was undertaken to determine the conditions necessary to produce the 44-mm clay deformation as set forth in the National Institute of Justice (NIJ) Standard 0101.04. These energy levels were then applied to a three-dimensional Human Torso Finite Element Model (HTFEM) with soft armor vest. An examination will be made of tissue stresses to determine the effects of the increased kinetic energy levels on the probability of injury.

METHODS

A clay finite element model (CFEM) was created with a material model that required nonlinear properties for clay. To determine these properties empirically, the results from the CFEM were matched with experimental drop tests. A soft armor vest was modeled over the clay to create a vest over clay block finite element model (VCFEM) and empirical methods were again used to obtain material properties for the vest from experimental ballistic testing. Once the properties for the vest and clay had been obtained, the kinetic energy required to produce a 44-mm deformation in the VCFEM was determined through ballistic testing. The resulting kinetic energy was then used in the HTFEM to evaluate the probability of BABT.

RESULTS

The VCFEM, with determined clay and vest material properties, was exercised with the equivalent of a 9-mm (8-gm) projectile at various impact velocities. The 44-mm clay deformation was produced with a velocity of 785 m/s. This impact condition (9-mm projectile at 785 m/s) was used in ballistic exercises of the HTFEM, which was modeled with high-strain rate human tissue properties for the organs. The impact zones were over the sternum anterior to T6 and over the liver. The principal stresses in both soft and hard tissue at both locations exceeded the tissue tensile strength.

CONCLUSIONS

This study indicates that although NIJ standard 0101.04 may be a good guide to soft armor failure, it may not be as good a guide in BABT, especially at large projectile kinetic energies. Further studies, both numerical and experimental, are needed to assist in predicting injury using the NIJ standard.

Retrograde Esophageal Intubation

Intrathoracic esophageal injury can be treated using conventional surgical techniques, including buttressed closure, T-tube drainage, resection, and exclusion with diversion. If esophageal replacement is necessary, stomach, left or right colon, and jejunum are commonly used conduits. Problems arise when esophageal drainage and diversion is necessary in patients with prior gastrectomy. This problem compounds when planning esophageal reconstruction in those with previous colectomy because preserving esophageal length is crucial. We developed the technique of retrograde esophageal intubation, and we have successfully used it in three patients requiring total or near total gastrectomy and concomitant colon resection as part of damage control laparotomy. The injuries resulted from penetrating trauma in two patients and a failed gastric bypass in one. The technique involved retrograde placement of an Ewald tube through the skin into the open, distal esophagus, creating a controlled esoghagocutaneous fistula. The restoration of gastrointestinal continuity was performed 6 months after the initial injury. The reconstructive procedure was based on the precise anatomy involved. Esophagogastrostomy, loop gastrojejunostomy, and Roux-en-Y esophojejunostomy were used in one patient. Each developed an anastomotic leak, which all resolved with simple drainage. Retrograde esophageal intubation is simple, can be used long term, and allows control of esophageal secretions without cervical esophagostomy. Esophageal length is preserved and can be used as part of a damage control operation.

Retrograde esophageal intubation

Intrathoracic esophageal injury can be treated using conventional surgical techniques, including buttressed closure, T-tube drainage, resection, and exclusion with diversion. If esophageal replacement is necessary, stomach, left or right colon, and jejunum are commonly used conduits. Problems arise when esophageal drainage and diversion is necessary in patients with prior gastrectomy. This problem compounds when planning esophageal reconstruction in those with previous colectomy because preserving esophageal length is crucial. We developed the technique of retrograde esophageal intubation, and we have successfully used it in three patients requiring total or near total gastrectomy and concomitant colon resection as part of damage control laparotomy. The injuries resulted from penetrating trauma in two patients and a failed gastric bypass in one. The technique involved retrograde placement of an Ewald tube through the skin into the open, distal esophagus, creating a controlled esoghagocutaneous fistula. The restoration of gastrointestinal continuity was performed 6 months after the initial injury. The reconstructive procedure was based on the precise anatomy involved. Esophagogastrostomy, loop gastrojejunostomy, and Roux-en-Y esophojejunostomy were used in one patient. Each developed an anastomotic leak, which all resolved with simple drainage. Retrograde esophageal intubation is simple, can be used long-term, and allows control of esophageal secretions without cervical esophagostomy. Esophageal length is preserved and can be used as part of a damage control operation.

Computational and experimental models of the human torso for non-penetrating ballistic impact

Both computational finite element and experimental models of the human torso have been developed for ballistic impact testing. The human torso finite element model (HTFEM), including the thoracic skeletal structure and organs, was created in the finite element code LS-DYNA. The skeletal structure was assumed to be linear-elastic while all internal organs were modeled as viscoelastic. A physical human surrogate torso model (HSTM) was developed using biosimulant materials and the same anthropometry as the HTFEM. The HSTM response to impact was recorded with piezoresistive pressure sensors molded into the heart, liver and stomach and an accelerometer attached to the sternum. For experimentation, the HSTM was outfitted with National Institute of Justice (NIJ) Level I, IIa, II and IIIa soft armor vests. Twenty-six ballistic tests targeting the HSTM heart and liver were conducted with 22 caliber ammunition at a velocity of 329 m/s and 9 mm ammunition at velocities of 332, 358 and 430 m/s. The HSTM pressure response repeatability was found to vary by less than 10% for similar impact conditions. A comparison of the HSTM and HTFEM response showed similar pressure profiles and less than 35% peak pressure difference for organs near the ballistic impact point. Furthermore, the peak sternum accelerations of the HSTM and HTFEM varied by less than 10% for impacts over the sternum. These models provide comparative tools for determining the thoracic response to ballistic impact and could be used to evaluate soft body armor design and efficacy, determine thoracic injury mechanisms and assist with injury prevention.

Risk Factors Associated with Pelvic Fractures Sustained in Motor Vehicle Collisions Involving Newer Vehicles

BACKGROUND

Despite advances in automotive safety, pelvic fractures caused by motor vehicle collisions remain a significant cause of mortality, morbidity, and functional disability. This study was designed to evaluate epidemiologic and biomechanic risk factors associated with pelvic fractures resulting from motor vehicle collisions. We utilized the Crash Injury Research Engineering Network (CIREN) database to identify these risk factors in newer vehicles.

METHODS

Data were prospectively collected at the ten CIREN centers from 1996 to 2005. Specific data were then abstracted on all patients, biomechanic crash characteristics, and injuries sustained. Patients involved in a frontal or near-side lateral impact with pelvic fractures were compared with those without. Univariate analysis was performed using a chi2 analysis. Logistic regression was used to identify significant risk factors in a multivariate analysis to control for confounding associations.

RESULTS

Of the 1,851 patients studied, 511 (27.6%) had a pelvic fracture. The overall mortality was 17%. Injury specific factors associated with pelvic fracture were higher Injury Severity Score (ISS) and fatality of the patient. Biomechanic factors associated with the risk of pelvic fracture included; no airbag deployment (p < 0.001), smaller vehicle (p = 0.05), and lateral deformation location (p < 0.001). When stratified by vehicle deformation location, logistic regression models revealed statically significant variables in a frontal impact which included; higher body mass index, higher ISS, large patient vehicle, no seatbelt use, and higher deltaV. For near-side lateral impacts, multivariate analysis revealed statistically significant variables of lower body mass index, higher ISS, female sex, small vehicle size, and higher deltaV.

CONCLUSIONS

Even in newer vehicles with federally mandated safety features, pelvic fractures remain a common injury. Pelvic fractures may serve as a marker of crash severity and specific crash characteristics are associated with pelvic fractures. Lateral crashes are significantly more likely to result in a pelvic fracture and, therefore, prevention of pelvic fractures should focus on improving occupant safety in near-side lateral impacts. Recognition of other associations should lead researchers to further investigate causative factors that will ultimately result in improved vehicle design.

Spent Bullet in the Bronchus

Penetrating tracheal trauma, although infrequent, varies from minor to life-threatening injuries. Serious injury often results from airway compromise or significant associated esophageal or vascular trauma. Tracheal injuries resulting in a retained ballistic fragment in the airway have been infrequently reported. We report the successful treatment of a patient with a gunshot wound to the anterior cervical trachea resulting in a spent bullet lodged in the left lower lobe bronchus.

Traumatic Hemoptysis Treated With Recombinant Human Factor VIIa

Blunt thoracic trauma resulting in massive hemoptysis is rare. Although there are several indications for the administration of recombinant factor VIIa, we are unaware of a report of its utilization in the treatment of hemoptysis following chest trauma. We report a case of the successful use of factor VIIa in the treatment of life-threatening hemoptysis secondary to blunt force thoracic injury and traumatic coagulopathy.

Modeling the Effect of Non-Penetrating Ballistic Impact As a Means of Detecting Behind Armor Blunt Trauma

BACKGROUND

According to the National Institute of Justice (NIJ) Standard 0101.04, the maximum deformation a soft armor vest can undergo without penetration is 44 mm. However, this does not take into account the effect of the pressure wave or energy transferred to the organs within the torso due to behind armor blunt trauma (BABT). Therefore, a study was undertaken to develop a finite element model (FEM) to study these effects.

METHODS

A finite element model (FEM) of the human thorax; complete with musculoskeletal structure and internal organs (heart, liver, lungs and stomach), intercostal muscle and skin, has been developed in LS-DYNA. A Kevlar vest was modeled on the chest to simulate non-penetrating ballistic impact.

RESULTS

Using a projectile modeled with a size and mass equivalent to a 9 mm (124 grain) bullet at 360 and 425 m/s, four impacts were simulated against NIJ Level II and Level IIIa Kevlar vests at the midsternum and right thorax. At the same velocity, the pressures decreased by a factor of 3 and the energy absorbed by the organs decreased by a factor of 6 for the NIJ Level II and Level IIIa vests, respectively. As the projectile velocity increased, the peak pressures increased by a factor of 3 while the energy absorbed by the organs increased by a factor of 4.

CONCLUSIONS

The resulting pressure profiles and kinetic energy exhibited by the respective organs indicate this model may be useful in identifying mechanisms of injury as well as organs at an elevated injury risk as a result of BABT.

A report of the treatment of coronary artery aneurysm without cardiopulmonary bypass

Coronary artery aneurysm (CAA) is a fairly rare pathologic entity whose exact incidence is unknown but has been reported from 1.4% in autopsy series [Daoud, 1963] to 4.9% in the Coronary Artery Surgery Registry [Swaye, 1984]. While atherosclerosis is the most common cause of true coronary artery aneurysms, pseudoaneurysms most often occur as complications of percutaneous transluminal coronary angioplasty (PTCA) or directional artherectomy [Dralle, 1995]. We report the successful treatment of a coronary artery aneurysm with comcomitant coronary revascularization without the use of cardiopulmonary bypass in a patient with impaired pulmonary and myocardial function. The use of an intracoronary shunt, previously described by one of the authors (EW), facilitated the surgical procedure [Franzone 1977].

A convenient microscale colorimetric method for terminal galactose on immunoglobulins

A new approach for quantitative determination of terminal galactose (Gal) residues of immunoglobulins was developed by combining exoglycosidase digestion with the classical colorimetric estimation of reducing sugars. The ferricyanide colorimetric method was modified to increase the stability of the chromophore (Prussian blue) and adapted to determine the amount of terminal Gal residues present in immunoglobulins. The method involves the release of covalently bound Gal from immunoglobulins by Diplococcus pneumoniae beta-D-galactosidase (specific for beta(1,4) linked galactose), removal of the glycoprotein and enzyme from the reaction mixture by heat denaturation or ethanol precipitation, followed by colorimetric measurement of the released sugar using the ferricyanide assay. The ferricyanide method was modified to enhance the solubility and stability of the chromophore by increasing the concentration of aqueous sulfuric acid and sodium dodecyl sulfate (SDS). The linear range of the modified method was from approximately 11 to 111 microM Gal. Typical variation in assay results was on the order of 5%. Using the modified method, the terminal Gal content of a recombinant chimeric monoclonal antibody (anti-CD20, rIgG) expressed in Chinese hamster ovary (CHO) cells was determined and evaluated for batch-to-batch consistency. The method was used to optimize pH, time, temperature, and enzyme concentration for beta-galactosidase digestion for maximal release of terminal Gal residues from rIgG.

Preparation, isolation, and characterization of cutin monomers and oligomers from tomato peels

Cutin in tomato peels was depolymerized in methanolic base to yield cutin monomers or a mixture of cutin oligomers. These products were isolated by typical solvent extraction methods or by precipitation, and the isolates were characterized by chromatographic and spectroscopic analyses. It was determined that the compositions of the isolates from both isolation procedures were similar, although solvent extraction gave higher yields. However, the precipitation method, which is easy to carry out and avoids the use of undesirable organic solvents, may be preferable in commercial processes for recovering these compounds.

Chromatography of recombinant proteins

Variants of intact polypeptides/proteins ranging in mass from 6,500 to 70,000 Da were easily separated using reversed-phaseHPLC (rpHPLC) or affinity chromatography. A variant of rhlGF-I, where the racemization of a serine residue was detected in the intact molecule, was resolved from rhlGF-I within 25 minutes by rpHPLC. Other variants of rhlGF-I separated by this method include methionine sulphoxide at position 59, des Gly1, des Gly1Pro2, Glu for Asp substitution at position 20 and incorrectly folded IGF-I. For rhDNase (approximately 40 kDa), affinity chromatography was able to clearly resolve three different amino acids (Asn, Asp and iso-Asp) at position 74 of the intact glycoprotein. The presence or absence of O-linked sugars on Thr -37 of recombinant human thrombopoietin was rapidly demonstrated by rpHPLC. While the separation of these types of variants is essential, the demonstration of biological activity is critical for designing specifications that allow the administration of these proteins into humans. Once a correlation exists between the variant and its biological activity, control of the manufacturing process can be better achieved with analytical methodology.

Popliteal pseudoaneurysm following total knee arthroplasty

Arterial injuries complicating total knee arthroplasty are rare but may result in significant morbidity. There are three reports of popliteal artery pseudoaneurysm resulting from arterial trauma during total knee replacement. We report a case of a popliteal pseudoaneurysm with rupture into the surrounding muscle, its evaluation, and successful repair 5 months after arthroplasty.

Thoracic splenosis

Thoracic splenosis is a rare pathologic entity resulting from seeding of splenic tissue in the pleural cavity after thoracoabdominal trauma. A 45-year-old man with a history of splenectomy secondary to abdominal trauma presented with a left lung mass and an inconclusive tissue diagnosis after needle biopsy. Thoracic splenosis was not suspected preoperatively, considered on an intraoperative frozen section, and established on permanent pathologic biopsy specimens obtained during thoracotomy. A history of thoracoabdominal trauma, combined with radiologic and radionuclide imaging studies, may establish the diagnosis without thoracotomy.

The structure of the exopolysaccharide of Pseudomonas fluorescens strain H13

An acidic exopolysaccharide was isolated from P. fluorescens strain H13. The structure of the polysaccharide repeating unit was determined using chemical methods and 1D and 2D NMR techniques. The repeating unit was characterized as a trisaccharide composed of D-glucose, 2-acetamido-2-deoxy-D-glucose and 4-O-acetyl-2-acetamido-2-deoxy-D-mannuronic acid.

Carbohydrate structures of human tissue plasminogen activator expressed in Chinese hamster ovary cells

Recombinant human tissue plasminogen activator (rt-PA), produced by expression in Chinese hamster ovary cells, is a fibrin-specific plasminogen activator which has been approved for clinical use in the treatment of myocardial infarction. In this study, the structures of the Asn-linked oligosaccharides of Chinese hamster ovary-expressed rt-PA have been elucidated. High mannose and hybrid oligosaccharides were released from the protein by endoglycosidase H digestion, whereas N-acetyllactosamine-type ("complex") oligosaccharides were released by peptide:N-glycosidase F digestion. The oligosaccharides were fractionated by gel permeation chromatography and anion exchange high performance liquid chromatography (HPLC), and their structures were analyzed by composition and methylation analysis, high pH anion exchange chromatography, fast atom bombardment-mass spectrometry (FAB-MS), and 500-MHz 1H NMR spectroscopy. High mannose oligosaccharides were found to account for 38% of the total carbohydrate content of rt-PA and consisted of Man5GlcNAc2, Man6GlcNAc2, and Man7GlcNAc2 in the ratio 1.8:1.7:1. Two hybrid oligosaccharides were identified and accounted for 3% of the carbohydrate of rt-PA. The N-acetyllactosamine-type oligosaccharides were found to comprise diantennary (34% of total carbohydrate), 2,4-branched triantennary (11%), 2,6-branched triantennary (9%), and tetraantennary (5%) structures. Sialylation of these oligosaccharides was by alpha (2----3) linkages to galactose. Most (greater than 90%) of the N-acetyllactosamine-type structures contained fucose alpha (1----6) linked to the Asn-linked N-acetylglucosamine residue. The distribution of oligosaccharide structures at individual glycosylation sites (Asn residues 117, 184, and 448) was also determined. rt-PA exists as two variants that differ by the presence (type I) or absence (type II) of carbohydrate at Asn-184. Tryptic glycopeptides were isolated by reversed phase high performance liquid chromatography and treated with peptide:N-glycosidase F. The oligosaccharides released from each glycosylation site were analyzed by high pH anion exchange chromatography. By this analysis, Asn-117 was demonstrated to carry exclusively high mannose oligosaccharides. When glycosylated, Asn-184 carried diantennary, 2,4-branched triantennary, 2,6-branched triantennary, and tetraantennary N- acetyllactosamine oligosaccharides in the ratio 9.0:4.5:1.4:1. Asn- 448 carried the same types of oligosaccharides, but in the ratio 7.5:1.6:2.1:1. The distributions of Asn-linked oligosaccharides at positions 117 and 448 were found not to be affected by the presence or absence of carbohydrate at position 184. The relevance of the

The influence of carbohydrate structure on the clearance of recombinant tissue-type plasminogen activator

Modification of the carbohydrate structures of recombinant tissue-type plasminogen activator (rt-PA) can increase or decrease its rate of clearance in rabbits. When rt-PA was treated with sodium periodate to oxidize carbohydrate residues, the rate of clearance was decreased from 9.6 +/- 1.9 ml min-1 kg-1 to 3.5 +/- 0.6 ml min-1 kg-1 (mean +/- SD, n = 5). A similar change in the clearance of rt-PA was introduced by the use of endo-beta-N-acetyl-glucosaminidase H (Endo-H), which selectively removes high mannose asparagine-linked oligosaccharides; the clearance of Endo-H-treated rt-PA was 5.0 +/- 0.5 ml min-1 kg-1. A mutant of rt-PA was produced with an amino acid substitution at position 117 (Asn replaced with Gln) to remove a potential glycosylation site that normally contains a high mannose structure. The clearance of this material was also decreased, similar to the periodate and Endo-H-treated rt-PA. Conversely, when rt-PA was produced in the CHO 15B cell line, which can produce only high mannose oligosaccharide structures on glycoproteins, the clearance was increased by a factor of 1.8. These results demonstrate that the removal of rt-PA from the blood depends significantly upon the nature of its oligosaccharide structures.

Tumor necrosis factor (cachectin) is an endogenous pyrogen and induces production of interleukin 1

Recombinant human tumor necrosis factor (rTNF alpha) injected intravenously into rabbits produces a rapid-onset, monophasic fever indistinguishable from the fever produced by rIL-1. On a weight basis (1 microgram/kg) rTNF alpha and rIL-1 produce the same amount of fever and induce comparable levels of PGE2 in rabbit hypothalamic cells in vitro; like IL-1, TNF fever is blocked by drugs that inhibit cyclooxygenase. At higher doses (10 micrograms/kg) rTNF alpha produces biphasic fevers. The first fever reaches peak elevation 45-55 min after bolus injection and likely represents a direct action on the thermoregulatory center. During the second fever peak (3 h later), a circulating endogenous pyrogen can be shown present using passive transfer of plasma into fresh rabbits. This likely represents the in vivo induction of IL-1. In vitro, rTNF alpha induces the release of IL-1 activity from human mononuclear cells with maximal production observed at 50-100 ng/ml of rTNF alpha. In addition, rTNF alpha and rIFN-gamma have a synergistic effect on IL-1 production. The biological activity of rTNF alpha could be distinguished from IL-1 in three ways: the monophasic pyrogenic activity of rIL-1 was destroyed at 70 degrees C, whereas rTNF alpha remained active; anti-IL-1 neutralized IL-1 but did recognize rTNF alpha or natural cachectin nor neutralize its cytotoxic effect; and unlike IL-1, rTNF alpha was not active in the mitogen-stimulated T cell proliferation assay. The possibility that endotoxin was responsible for rTNF alpha fever and/or the induction of IL-1 was ruled-out in several studies: rTNF alpha produced fever in the endotoxin-resistant C3H/HeJ mice; the IL-1-inducing property of rTNF alpha was destroyed either by heat (70 degrees C) or trypsinization, and was unaffected by polymyxin B; pyrogenic tolerance to daily injections of rTNF alpha did not occur; levels of endotoxin, as determined in the Limulus amebocyte lysate, were below the minimum rabbit pyrogen dose; and these levels of endotoxin were confirmed by gas chromatography/mass spectrometry analysis for the presence of beta-hydroxymyristic acid. Although rTNF alpha is not active in T cell proliferation assays, it may mimic IL-1 in a T cell assay, since high concentrations of rTNF alpha induced IL-1 from epithelial or macrophagic cells in the thymocyte preparations. These studies show that TNF (cachectin) is another endogenous pyrogen which, like IL-1 and IFN-alpha, directly stimulate hypothalamic PGE2 synthesis. In addition, rTNF alpha is an endogenous inducer of IL-1.(ABSTRACT TRUNCATED AT 400 WORDS)

The protective effect of profound hypothermia on the canine central nervous system during one hour of circulatory arrest

Circulatory arrest during profound hypothermia is a safe technique of cardiac surgery when used in selected instances. Despite its proven safety, the degree of cerebral protection offered by this technique is still poorly defined. Ten dogs anesthetized with Pentothal (thiopental sodium) were surface cooled to 32 degrees C. They were placed on cardiopulmonary bypass, cooled to 13 degrees C (cerebral temperature), and then underwent one hour of circulatory arrest. At the end of the arrest period, the dogs were rewarmed, resuscitated, and successfully weaned from bypass. A control group of 6 dogs were subjected to the same protocol but without the one-hour period of circulatory arrest. There were no group differences in animal weight, duration of surface cooling, cardiopulmonary bypass, or rewarming, mean flow, or mean arterial pressure. After a 7-day observation period, the dogs were killed with rapid tissue fixation using formalin. No neurological deficits were noted in any of the dogs during the observation period. The fixed brains were examined by a neuropathologist. No gross or microscopic evidence of cerebral hypoxia was seen in any of the animals. We conclude that one hour of circulatory arrest under profoundly hypothermic temperatures produces no detectable neurological changes or histological evidence of cerebral hypoxia.