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Background Patients who undergo cholecystectomy often do so for diagnoses related to the sequelae of gallstones. Many patients present acutely, requiring urgent removal due to complications of cholelithiasis. This study aims to characterize the patient population likely to present acutely during ongoing workup for cholelithiasis to better identify those who may benefit from expedited care. Methods Medical records of all adult patients who underwent cholecystectomy for indications related to cholelithiasis between 2015 and 2016 were reviewed retrospectively. Qualitative data was analyzed using Chi square test and quantitative data was analyzed using independent t-tests. Results One hundred and seventy-four cholecystectomies were performed. Overall, 74.2% of the procedures were done electively while 25.8% were done urgently. And 42.2% of patients who underwent acute surgical intervention had evidence of prior workup. Patients requiring urgent intervention during ongoing diagnostic evaluation were more likely to have initially presented to an emergency department (ED) than another provider (68.4% vs 31.3%, P < .001) and had an odds ratio of 4.7 for undergoing acute intervention if they initially presented to the ED. They also tended to be more temporally remote from their initial diagnosis (119 ± 142 vs 74.6 ± 68.2 days, P < .19) relative to those who underwent elective operations. Discussion Patients who require urgent intervention during ongoing workup for cholelithiasis have prolonged courses of care and present to the ED more often for initial evaluation when compared to those who undergo elective intervention. These findings suggest that an emphasis on expedited workup of cholelithiasis and early surgical referral may be warranted, especially for those who initially present in the ED.

Appendicitis is one of the most common surgically treated diseases in the world. CT scans are often over-utilized and ordered before a surgeon has evaluated the patient. Our aim was to develop a tool using machine learning (ML) algorithms that would help determine if there would be benefit in obtaining a CT scan prior to surgeon consultation. Retrospective chart review of 100 randomly selected cases who underwent appendectomy and 100 randomly selected controls was completed. Variables included components of the patient’s history, laboratory values, CT readings, and pathology. Pathology was used as the gold standard for appendicitis diagnosis. All variables were then used to build the ML algorithms. Random Forest (RF), Support Vector Machine (SVM), and Bayesian Network Classifiers (BNC) models with and without CT scan results were trained and compared to CT scan results alone and the Alvarado score using area under the Receiver Operator Curve (ROC), sensitivity, and specificity measures as well as calibration indices from 500 bootstrapped samples. Among the cases that underwent appendectomy, 88% had pathology-confirmed appendicitis. All the ML algorithms had better sensitivity, specificity, and ROC than the Alvarado score. SVM with and without CT had the best indices and could predict if imaging would aid in appendicitis diagnosis. This study demonstrated that SVM with and without CT results can be used for selective imaging in the diagnosis of appendicitis. This study serves as the initial step and proof-of-concept to externally validate these results with larger and more diverse patient population.

The pathophysiology of the inflammatory response after major trauma is complex, and the magnitude correlates with severity of tissue injury and outcomes. Study of infection-mediated immune pathways has demonstrated that cellular microRNAs may modulate the inflammatory response. The authors hypothesize that the expression of microRNAs would correlate to complicated recoveries in polytrauma patients (PtPs). METHODS: Polytrauma patients enrolled in the prospective observational Tissue and Data Acquisition Protocol with Injury Severity Score of >15 were selected for this study. Polytrauma patients were divided into complicated recoveries and uncomplicated recovery groups. Polytrauma patients' blood samples were obtained at the time of admission (T0). Established biomarkers of systemic inflammation, including cytokines and chemokines, were measured using multiplexed Luminex-based methods, and novel microRNAs were measured in plasma samples using multiplex RNA hybridization. RESULTS: Polytrauma patients (n = 180) had high Injury Severity Score (26 [20–34]) and complicated recovery rate of 33%. MicroRNAs were lower in PtPs at T0 compared with healthy controls, and bivariate analysis demonstrated that variations of microRNAs correlated with age, race, comorbidities, venous thromboembolism, pulmonary complications, complicated recovery, and mortality. Positive correlations were noted between microRNAs and interleukin 10, vascular endothelial growth factor, Acute Physiology and Chronic Health Evaluation, and Sequential Organ Failure Assessment scores. Multivariable Lasso regression analysis of predictors of complicated recovery based on microRNAs, cytokines, and chemokines revealed that miR-21-3p and monocyte chemoattractant protein-1 were predictive of complicated recovery with an area under the curve of 0.78. CONCLUSION: Systemic microRNAs were associated with poor outcomes in PtPs, and results are consistent with previously described trends in critically ill patients. These early biomarkers of inflammation might provide predictive utility in early complicated recovery diagnosis and prognosis. Because of their potential to regulate immune responses, microRNAs may provide therapeutic targets for immunomodulation. LEVEL OF EVIDENCE: Diagnostic Tests/Criteria; Level II.

Background The incidence of underlying malignancy in appendicitis ranges between 0.5% and 1.7%. We sought to identify the subset of patients with appendicitis who are at increased risk of appendiceal malignancy. Methods Using the Eastern Association for the Surgery of Trauma Multicenter Study of the Treatment of Appendicitis in America: Acute, Perforated, and Gangrenous database, we included all patients from 28 centers undergoing immediate, delayed, or interval appendectomy between 2017 and 2018. Univariate then multivariable analyses were performed to compare patients with and without malignancy and to identify independent demographic, clinical, laboratory, and/or radiological predictors of malignancy. Akaike information criteria for regression models were used to evaluate goodness of fit. Results A total of 3,293 patients were included. The median age was 38 (27–53) years, and 46.5% were female patients. On pathology, 48 (1.5%) had an underlying malignancy (adenocarcinoma [60.4%], neuroendocrine [37.5%], and lymphoma [2.1%]). Patients with malignancy were older (56 [34.5–67] vs 37 [27–52] years, P 40 years with an appendiceal diameter >10 mm on computed tomography was 2.95% compared with 0.97% in patients ≤40 years old with appendiceal diameter ≤10 mm. The corresponding risk ratio for that population was 3.03 (95% confidence interval: 1.24–7.42; P = .02). Conclusion The combination of age >40 and an appendiceal diameter >10 mm is associated with a greater than 3-fold increased risk of malignancy in patients presenting with appendicitis.

IntroductionPelvic fractures are a common occurrence in combat trauma. However, the fracture pattern and management within the most recent conflicts, i.e. Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF), have yet to be described, especially in the context of dismounted complex blast injury. Our goal was to identify the incidence, patterns of injury and management of pelvic fractures.MethodsWe conducted a retrospective review on all combat-injured patients who arrived at our military treatment hospital between November 2010 and November 2012. Basic demographics, Young-Burgess fracture pattern classification and treatment strategies were examined.ResultsOf 562 patients identified within the study time period, 14% (81 of 562) were found to have a pelvic fracture. The vast majority (85%) were secondary to an improvised explosive device. The average Injury Severity Score for patients with pelvic fracture was 31±12 and 70% were classified as open. Of the 228 patients with any traumatic lower extremity amputation, 23% had pelvic fractures, while 30% of patients with bilateral above-knee amputations also sustained a pelvic fracture. The most common Young-Burgess injury pattern was anteroposterior compression (APC) (57%), followed by lateral compression (LC) (36%) and vertical shear (VS) (7%). Only 2% (nine of 562) of all patients were recorded as having pelvic binders placed in the prehospital setting. 49% of patients with pelvic fracture required procedural therapy, the most common of which was placement of a pelvic external fixator (34 of 40; 85%), followed by preperitoneal packing (16 of 40; 40%) and angioembolisation (three of 40; 0.75%). 17 (42.5%) patients required combinations of these three treatment modalities, the majority of which were a combination of external fixator and preperitoneal packing. The likelihood to need procedural therapy was impacted by injury pattern, as 72% of patients with an APC injury, 100% of patients with a VS injury and 25% of patients with an LC injury required procedural therapy.ConclusionsPelvic fractures were common concomitant injuries following blast-induced traumatic lower extremity amputations. APC was the most common pelvic fracture pattern identified. While procedural therapy was frequent, the majority of patients underwent conservative therapy. However, placement of an external fixator was the most frequently used modality. Considering angioembolisation was used in less than 1% of cases, in the forward deployed military environment, management should focus on pelvic external fixation±preperitoneal packing. Finally, prehospital pelvic binder application may be an area for further process improvement.

IntroductionThe purpose of this study was to evaluate the utilization of pelvic binders, the proper placement of binders, and to determine any differences in blood product transfusions between combat casualties with and without a pelvic binder identified on initial imaging immediately after the injury.MethodsWe conducted a retrospective review of all combat-injured patients who arrived at our military treatment hospital between 2010 and 2012 with a documented pelvic fracture. Initial imaging (X-ray or computed tomography) immediately after injury were evaluated by 2 independent radiologists. Young-Burgess (YB) classification, pelvic diastasis, correct binder placement over the greater trochanters, and the presence of a pelvic external fixator (ex-fix) was recorded. Injury severity score (ISS), whole blood, and blood component therapy administered within the first 24-hours after injury were compared between casualties with and without a pelvic binder.Results39 casualties had overseas imaging to confirm and radiographically classify a YB pelvic ring injury. The most common fracture patterns were anteroposterior (53%) and lateral compression (28%). 49% (19/39) did not have a binder or ex-fix identified on initial imaging or in any documentation after injury. Ten patients had a binder, with 30% positioned incorrectly over the iliac crest. ISS (34 ± 1.6) was not statistically different between the binder and the no-binder group. Pubic symphysis diastasis was significantly lower in the binder group (1.4 ± 0.2 vs 3.7 ± 0.5, P < .001). There was a trend toward decreased 24-hour total blood products between the binder and no-binder groups (75 ± 11 vs 82 ± 13, P = .67). This was due to less cryoprecipitate in the binder group (6 ± 2 vs 19 ± 5, P = .01).ConclusionsPelvic binder placement in combat trauma may be inconsistent and an important area for continued training. While 24-hour total transfusions do not appear to be different, no-binder patients received significantly more cryoprecipitate.

Background Tranexamic acid (TXA) may be a useful adjunct for military patients with severe traumatic brain injury (TBI). These patients are often treated in austere settings without immediate access to neurosurgical intervention. The purpose of this study was to evaluate any association between TXA use and progression of intracranial hemorrhage (ICH), neurologic outcomes, and venous thromboembolism (VTE) in TBI. Methods This was a retrospective cohort study of military casualties from October 2010 to December 2015 who were transferred to a military treatment facility (MTF) in the United States. Data collected included: demographics, types of injuries, initial and interval head computerized tomography (CT) scans, Glasgow Coma Scores (GCS), and six-month Glasgow Outcome Scores (GOS). Results were stratified based on TXA administration, progression of ICH, and VTE. Results Of the 687 active duty service members reviewed, 71 patients had ICH (10.3%). Most casualties were injured in a blast (80.3%), with 36 patients (50.7%) sustaining a penetrating TBI. Mean ISS was 28.2 ± 12.3. Nine patients (12.7%) received a massive transfusion within 24 h of injury, and TXA was administered to 14 (19.7%) casualties. Patients that received TXA had lower initial reported GCS (9.2 ± 4.4 vs. 12.5 ± 3.4, p = 0.003), similar discharge GCS (13.3 ± 4.0 vs. 13.8 ± 3.2, p = 0.58), and a larger improvement between initial and discharge GCS (3.7 ± 3.9 vs. 1.3 ± 3.1, p = 0.02). However, there was no difference in mortality (7.1% vs. 7.0%, p = 1.00), progression of ICH (45.5% vs. 14.7%, p = 0.09), frequency of cranial decompression (50.0% vs. 42.1%, p = 0.76), or mean GOS (3.5 ± 0.9 vs. 3.8 ± 1.0, p = 0.13). Patients administered TXA had a higher rate of VTE (35.7% vs. 7.0%, p = 0.01). On multivariate analysis, however, TXA was not independently associated with VTE. Conclusions Patients that received TXA were associated with an improvement in GCS but not in progression of ICH or GOS. TXA was not independently associated with VTE, although this may be related to a paucity of patients receiving TXA. Decisions about TXA administration in military casualties with ICH should be considered in the context of the availability of neurosurgical intervention as well as severity of extracranial injuries and need for massive transfusion.

Introduction As combat-related trauma decreases, there remains an increasing need to maintain the ability to care for trauma victims from other casualty events around the world (e.g., terrorism, natural disasters, and infrastructure failures). During these events, military surgeons often work closely with their civilian counterparts, often in austere and expeditionary contexts. In these environments, the primary aim of the surgical team is to implement damage control principles to avert blood loss, optimize oxygenation, and improve survival. Upper-extremity vascular injuries are associated with high rates of morbidity and mortality resulting from exsanguination and ischemic complications; however, fatalities may be avoided if hemorrhage is rapidly controlled. In austere contexts, deployed surgical teams typically include one general surgeon and one orthopedic surgeon, neither of which have acquired the expertise to manage these vascular injuries. The purpose of this study was to examine the baseline capabilities of general surgeons and orthopedic surgeons to surgically expose and control axillary and brachial arteries and to determine if the abilities of both groups could be increased through a focused cadaver-based training intervention. Methods This study received IRB approval at our institution. Study methods included the use of cadavers for baseline assessment of procedural capabilities to expose and control axillary and brachial vessels, followed by 1:1 procedural training and posttraining re-assessment of procedural capabilities. Inferential analyses included ANOVA/MANOVA for within- and between-group effects (P Results Study outcomes demonstrated significant differences between the baseline performance abilities of the two groups, with general surgeons outperforming orthopedic surgeons. Before training, neither group reached performance benchmarks for overall or critical procedural abilities in exposing axillary and brachial vessels. Training led to increased abilities for both groups. There were statistically significant gains for overall procedural abilities, as well as for critical procedural elements that are directly associated with morbidity and mortality. These outcomes were consistent for both general and orthopedic surgeons. Effect sizes ranged between medium (general surgeons) and very large (orthopedic surgeons). Conclusion There was a baseline capability gap for both general surgeons and orthopedic surgeons to surgically expose and control the axillary and brachial vessels. Outcomes from the course suggest that the methodology facilitates the acquisition of accurate and independent vascular procedural capabilities in the management of upper-extremity trauma injuries. The impact of this training for surgeons situated in expeditionary or remote contexts has direct relevance for caring for victims of extremity trauma. These outcomes underscore the need to train all surgeons serving in rural, remote, expeditionary, combat, or global health contexts to be able to competently manage extremity trauma and concurrent vascular injuries to increase the quality of care in those settings.

IntroductionVenous thromboembolism (VTE) is a frequent complication of trauma associated with high mortality and morbidity. Clinicians lack appropriate tools for stratifying trauma patients for VTE, thus have yet to be able to predict when to intervene. We aimed to compare random forest (RF) and logistic regression (LR) predictive modelling for VTE using (1) clinical measures alone, (2) serum biomarkers alone and (3) clinical measures plus serum biomarkers.MethodsData were collected from 73 military casualties with at least one extremity wound and prospectively enrolled in an observational study between 2007 and 2012. Clinical and serum cytokine data were collected. Modelling was performed with RF and LR based on the presence or absence of deep vein thrombosis (DVT) and/or pulmonary embolism (PE). For comparison, LR was also performed on the final variables from the RF model. Sensitivity/specificity and area under the curve (AUC) were reported.ResultsOf the 73 patients (median Injury Severity Score=16), nine (12.3%) developed VTE, four (5.5%) with DVT, four (5.5%) with PE, and one (1.4%) with both DVT and PE. In all sets of predictive models, RF outperformed LR. The best RF model generated with clinical and serum biomarkers included five variables (interleukin-15, monokine induced by gamma, vascular endothelial growth factor, total blood products at resuscitation and presence of soft tissue injury) and had an AUC of 0.946, sensitivity of 0.992 and specificity of 0.838.ConclusionsVTE may be predicted by clinical and molecular biomarkers in trauma patients. This will allow the development of clinical decision support tools which can help inform the management of high-risk patients for VTE.

Tools to assist clinicians in predicting pneumonia could lead to a significant decline in morbidity. Therefore, we sought to develop a model in combat trauma patients for identifying those at highest risk of pneumonia. This was a retrospective study of 73 primarily blast-injured casualties with combat extremity wounds. Binary classification models for pneumonia prediction were developed with measurements of injury severity from the Abbreviated Injury Scale (AIS), transfusion blood products received before arrival at Walter Reed National Military Medical Center (WRNMMC), and serum protein levels. Predictive models were generated with leave-one-out-cross-validation using the variable selection method of backward elimination (BE) and the machine learning algorithms of random forests (RF) and logistic regression (LR). BE was attempted with two predictor sets: (1) all variables and (2) serum proteins alone. Incidence of pneumonia was 12% (n = 9). Different variable sets were produced by BE when considering all variables and just serum proteins alone. BE selected the variables ISS, AIS chest, and cryoprecipitate within the first 24 h following injury for the first predictor set 1 and FGF-basic, IL-2R, and IL-6 for predictor set 2. Using both variable sets, a RF was generated with AUCs of 0.95 and 0.87—both higher than LR algorithms. Advanced modeling allowed for the identification of clinical and biomarker data predictive of pneumonia in a cohort of predominantly blast-injured combat trauma patients. The generalizability of the models developed here will require an external validation dataset.

Newly-graduated military general surgeons often find themselves isolated at sea, solely responsible for all surgical care of several thousand sailors, regardless of the surgical specialty training required for any individual procedure. This educational need assessment explored trends in afloat surgical care over the last 25 years, and assessed trainees' preparedness for their expected role as an isolated surgeon.A sample of deidentified US Navy Ship's Surgeon case logs were reviewed to determine afloat case load trends in 5 common afloat case categories (urologic/gynecologic, anorectal, hernia, appendectomy, and hand/orthopedic/trauma) from 1990s to 2017. Individual procedures were mapped to American College of Surgeons/Military Health System Knowledge, Skills, and Attitudes line items to ensure afloat-relevant skills were identified. Recent military resident case logs were then compared with afloat cases to evaluate relevant trainee experience.US Navy ships at sea from 1995 to 2017.US Navy afloat-deployed surgeons, totaling 1340 cases within the study period.Case log analysis of 1340 surgeries, comprising200 months at sea, reflected 46 named procedures; 34 of 46 (74%) correlated to an intraoperative knowledge, skills, and attitudes item. The most common surgeries were vasectomy, (304 of 1340, 23%). No difference in case mix was apparent comparing pre- and post-2000 deployments (representing afloat laparoscopic integration) in 4 of 5 categories, while hernias proportionally declined. Case volume per deployment markedly declined overall (p0.001) and in each category. Resident case log analysis from 2012 to 2016 showed experience was limited in urologic/gynecologic, orthopedic, and open appendectomy categories.No formal case repository exists for afloat surgery, making detailed analysis problematic. Current training provides excellent surgical education but minimal exposure to rare-but-real cases expected on deployments, which may not translate to competency for the isolated, afloat surgeon. Military surgical leadership should embrace training for these cases and assertively invest in the development of the military's newest surgeons.

BACKGROUND Surgical site infections (SSIs) are well-recognized complications after exploratory laparotomy for abdominal trauma; however, little is known about SSI development after exploration for battlefield abdominal trauma. We examined SSI risk factors after exploratory laparotomy among combat casualties. METHODS Military personnel with combat injuries sustained in Iraq and Afghanistan (June 2009 to May 2014) who underwent laparotomy and were evacuated to participating US military hospitals were included. Log-binominal regression was used to identify SSI risk factors. RESULTS Of 4,304 combat casualties, 341 patients underwent a total of 1,053 laparotomies. Abdominal SSIs were diagnosed in 49 patients (14.4%): 8% with organ space SSI, 4% with deep incisional SSI, and 4% with superficial SSIs (4 patients had multiple SSIs). Patients with SSIs had more colorectal (p < 0.001), small bowel (p = 0.010), duodenum (p = 0.006), pancreas (p = 0.032), and abdominal vascular injuries (p = 0.040), as well as prolonged open abdomen (p = 0.004) and more infections diagnosed before the SSI (or final exploratory laparotomy) versus non-SSI patients (p < 0.001). Sustaining colorectal injuries (risk ratio [RR], 3.20; 95% confidence interval [CI], 1.58-6.45), duodenum injuries (RR, 6.71; 95% CI, 1.73-25.58), and being diagnosed with prior infections (RR, 10.34; 95% CI, 5.05-21.10) were independently associated with any SSI development. For either organ space or deep incisional SSIs, non-intra-abdominal infections, fecal diversion, and duodenum injuries were independently associated, while being injured via an improvised explosive device was associated with reduced likelihood compared with penetrating nonblast (e.g., gunshot wounds) injuries. Non-intra-abdominal infections and hypotension were independently associated with organ space SSIs development alone, while sustaining blast injuries were associated with reduced likelihood. CONCLUSION Despite severity of injuries and the battlefield environment, the combat casualty laparotomy SSI rate is relatively low at 14%, with similar risk factors and rates reported following severe civilian trauma. LEVEL OF EVIDENCE Epidemiological, level III.

Objectives To evaluate early activation of latent viruses in polytrauma patients and consider prognostic value of viral micro-RNAs in these patients. Design This was a subset analysis from a prospectively collected multicenter trauma database. Blood samples were obtained upon admission to the trauma bay (T0), and trauma metrics and recovery data were collected. Setting Two civilian Level 1 Trauma Centers and one Military Treatment Facility. Patients Adult polytrauma patients with Injury Severity Scores greater than or equal to 16 and available T0 plasma samples were included in this study. Patients with ICU admission greater than 14 days, mechanical ventilation greater than 7 days, or mortality within 28 days were considered to have a complicated recovery. Interventions None. Measurements and main results Polytrauma patients (n = 180) were identified, and complicated recovery was noted in 33%. Plasma samples from T0 underwent reverse transcriptase-quantitative polymerase chain reaction analysis for Kaposi's sarcoma-associated herpesvirus micro-RNAs (miR-K12_10b and miRK-12-12) and Epstein-Barr virus-associated micro-RNA (miR-BHRF-1), as well as Luminex multiplex array analysis for established mediators of inflammation. Ninety-eight percent of polytrauma patients were found to have detectable Kaposi's sarcoma-associated herpesvirus and Epstein-Barr virus micro-RNAs at T0, whereas healthy controls demonstrated 0% and 100% detection rate for Kaposi's sarcoma-associated herpesvirus and Epstein-Barr virus, respectively. Univariate analysis revealed associations between viral micro-RNAs and polytrauma patients' age, race, and postinjury complications. Multivariate least absolute shrinkage and selection operator analysis of clinical variables and systemic biomarkers at T0 revealed that interleukin-10 was the strongest predictor of all viral micro-RNAs. Multivariate least absolute shrinkage and selection operator analysis of systemic biomarkers as predictors of complicated recovery at T0 demonstrated that miR-BHRF-1, miR-K12-12, monocyte chemoattractant protein-1, and hepatocyte growth factor were independent predictors of complicated recovery with a model complicated recovery prediction area under the curve of 0.81. Conclusions Viral micro-RNAs were detected within hours of injury and correlated with poor outcomes in polytrauma patients. Our findings suggest that transcription of viral micro-RNAs occurs early in the response to trauma and may be associated with the biological processes involved in polytrauma-induced complicated recovery.

Lung herniation is a rare pathology seen after trauma. A case of acquired lung hernia is presented after blunt thoracic trauma that was repaired primarily. Surgical management and decision-making for this process are discussed.

Background Surgeons in resource-limited environments often provide care outside the expected scope of current general surgery training. Geographically isolated patients may be unwilling or unable to travel for specialty care. These same patients also present with life-threatening emergencies beyond the typical breadth of a general surgeon's practice, in hospitals with limited professional and material support. This review characterizes the unique role of isolated surgeons, so individual surgeons and health care organizations may focus professional development resources more efficiently, with the ultimate goal of improved patient care. Methods We performed a scoping review of the isolated surgeon, reviewing 25 years of literature regarding isolated US civilian and military surgeons. We examined emerging themes regarding the definition of an isolated surgeon, the scope of surgical practice beyond current training norms, and training gaps identified by surgeons in an isolated role. Results From 904 articles identified, we included 91 for final review. No prior definition exists for the isolated surgeon, although multiple definitions describe rural surgeons, patients, or hospitals; we propose an initial definition from consistent themes in the literature. Isolated surgeons across varied practice settings consistently performed relatively large volumes of cases of, and identified training gaps in, orthopedic, obstetric and gynecologic, urologic, and vascular surgery subspecialties. Life-threatening, “rare-but-real” cases in the above and neurosurgical disciplines are uncommon, but consistent across practice settings. Conclusions This review represents the largest examination of the isolated surgeon in the current literature. Clarifying the identity, practice components, and training gaps of the isolated surgeon represent the first step in formalizing support for this small but critical group of surgeons and their patients.

Low-cost iron-based CO2 hydrogenation catalysts have shown promise as a viable route to the production of value-added hydrocarbon building blocks. It is envisioned that these hydrocarbons will be used to augment industrial chemical processes and produce drop-in replacement operational fuel. To this end, the U.S. Naval Research Laboratory (NRL) has been designing, testing, modeling, and evaluating CO2 hydrogenation catalysts in a laboratory-scale fixed-bed environment. To transition from the laboratory to a commercial process, the catalyst viability and performance must be evaluated at scale. The performance of a Macrolite&reg, supported iron-based catalyst in a commercial-scale fixed-bed modular reactor prototype was evaluated under different reactor feed rates and product recycling conditions. CO2 conversion increased from 26% to as high as 69% by recycling a portion of the product stream and CO selectivity was greatly reduced from 45% to 9% in favor of hydrocarbon production. In addition, the catalyst was successfully regenerated for optimum performance. Catalyst characterization by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), along with modeling and kinetic analysis, highlighted the potential challenges and benefits associated with scaling-up catalyst materials and processes for industrial implementation.

Background It has been well established that ultrasound (US) is the initial screening tool for children with suspected acute appendicitis. However, computed tomography (CT) has become the standard screening modality for adults presenting with abdominal pain. A recent review of National Surgical Quality Improvement Program (NSQIP) data revealed US is being utilized as a screening modality in adults. We aimed to assess the diagnostic performance of US in evaluating adults with acute appendicitis. Study Design The American College of Surgeons NSQIP and NSQIP Procedure Targeted Data Files were accessed and examined for all patients in 2016 and 2017 who received an US and underwent an appendectomy. The US results were then correlated to the pathology in order to determine the diagnostic performance. Additionally, we identified predictors for indeterminate and false negative US results. Results Our study included 3607 appendectomy patients of which 1135 (30%) had an indeterminate US, 683 (18%) had an US not consistent with appendicitis, and 1789 (49%) had an US consistent with appendicitis. Sensitivity and Specificity were 74.3% and 53.0%, respectively. Positive Predictive Value (PPV) and Negative Predictive Value (NPV) were 95.9% and 12.2%, respectively. On regression analysis, clinically relevant predictors for false negative and indeterminate studies included age, sex, and BMI. Conclusions Ultrasound is an effective initial imaging modality for acute appendicitis in the adult population. Females, age >30 y, and elevated BMI were more likely to have indeterminate or false negative results. These patients may benefit from CT as their initial screening test.

BACKGROUND: Tranexamic acid (TXA) may be a useful adjunct for military patients with severe traumatic brain injury (TBI). These patients are often treated in austere settings without immediate access to neurosurgical intervention. The purpose of this study was to evaluate any association between TXA use and progression of intracranial hemorrhage (ICH), neurologic outcomes, and venous thromboembolism (VTE) in TBI.METHODS: This was a retrospective cohort study of combat casualties from October 2010 to December 2015 who were transferred to a military treatment facility (MTF) in the United States. Data collected included: demographics, types of injuries, initial and interval head computerized tomography (CT) scans, Glasgow Coma Scores (GCS), and six-month Glasgow Outcome Scores (GOS). Results were stratified based on TXA administration, progression of ICH, and VTE.RESULTS: Of the 687 active duty service members reviewed, 71 patients had ICH (10.3%). Most casualties were injured in a blast (80.3%), with 36 patients (50.7%) sustaining a penetrating TBI. Mean ISS was 28.2 ± 12.3. Nine patients (12.7%) received a massive transfusion within 24 hours of injury, and TXA was administered to 14 (19.7%) casualties. Patients that received TXA had lower initial reported GCS (9.2 ± 4.4 vs. 12.5 ± 3.4, p=0.003), similar discharge GCS (13.3 ±4.0 vs. 13.8±3.2, p=0.58), and a larger improvement between initial and discharge GCS (3.7±3.9 vs. 1.3±3.1, p=0.02). However, there was no difference in mortality (7.1% vs. 7.0%, p=1.00), progression of ICH (45.5% vs. 14.7%, p=0.09), frequency of cranial decompression (50.0% vs. 42.1%, p=0.76), or mean GOS (3.5±0.9 vs. 3.8±1.0, p=0.13). Patients administered TXA had a higher rate of VTE (35.7% vs. 7.0%, p=0.01). On multivariate analysis, however, TXA was not independently associated with VTE.CONCLUSIONS: Patients that received TXA were associated with an improvement in GCS but not in progression of ICH or GOS. TXA was not independently associated with VTE, although this may be related to a paucity of patients receiving TXA. Decisions about TXA administration in combat casualties with ICH should be considered in the context of the availability of neurosurgical intervention as well as severity of extracranial injuries and need for massive transfusion.

Heterotopic ossification (HO) is defined as ectopic bone formation around joints and in soft tissues following trauma, particularly blast-related extremity injuries, thermal injuries, central nerve injuries, or orthopaedic surgeries, leading to increased pain and diminished quality of life. Current treatment options include pharmacotherapy with non-steroidal anti-inflammatory drugs, radiotherapy, and surgical excision, but these treatments have limited efficacy and have associated complication profiles. In contrast, small molecule inhibitors have been shown to have higher specificity and less systemic cytotoxicity. Previous studies have shown that bone morphogenetic protein (BMP) signaling and downstream non-canonical (SMAD-independent) BMP signaling mediated induction of TGF-β activated kinase-1 (TAK1) contributes to HO. In the current study, small molecule inhibition of TAK1, NG-25, was evaluated for its efficacy in limiting ectopic bone formation following a rat blast-associated lower limb trauma and a murine burn tenotomy injury model. A significant decrease in total HO volume in the rat blast injury model was observed by microCT imaging with no systemic complications following NG-25 therapy. Furthermore, tissue-resident mesenchymal progenitor cells (MPCs) harvested from rats treated with NG-25 demonstrated decreased proliferation, limited osteogenic differentiation capacity, and reduced gene expression of Tac1, Col10a1, Ibsp, Smad3, and Sox2 (P < 0.05). Single cell RNA-sequencing of murine cells harvested from the injury site in a burn tenotomy injury model showed increased expression of these genes in MPCs during stages of chondrogenic differentiation. Additional in vitro cell cultures of murine tissue-resident MPCs and osteochondrogenic progenitors (OCPs) treated with NG-25 demonstrated reduced chondrogenic differentiation by 10.2-fold (P < 0.001) and 133.3-fold (P < 0.001), respectively, as well as associated reduction in chondrogenic gene expression. Induction of HO in Tak1 knockout mice demonstrated a 7.1-fold (P < 0.001) and 2.7-fold reduction (P < 0.001) in chondrogenic differentiation of murine MPCs and OCPs, respectively, with reduced chondrogenic gene expression. Together, our in vivo models and in vitro cell culture studies demonstrate the importance of TAK1 signaling in chondrogenic differentiation and HO formation and suggest that small molecule inhibition of TAK1 is a promising therapy to limit the formation and progression of HO.

The purpose of this study is to compare end-tidal carbon dioxide (EtCO2) during resuscitation of open-chest cardiac massage (OCCM) with aortic cross-clamp (ACC) versus receiving resuscitative endovascular balloon occlusion of the aorta (REBOA) with closed-chest compressions (CCCs). Patients who received REBOA were compared with patients receiving OCCM for traumatic arrest using continuous vital sign monitoring and videography. Thirty-three patients were enrolled in the REBOA group and 18 patients were enrolled in the OCCM group. Of the total patients, 86.3 per cent were male with a mean age of 36.2 ± 13.9 years. Ninety-four percent of patients suffered penetrating trauma in the OCCM group compared with 30.3 per cent of the REBOA group ( P = 2 values, but mean, median, peak, and final EtCO2 values were lower in OCCM ( P < 0.005). During CPR after AO, the initial, mean, and median values were higher with REBOA ( P = 0.015, 0.036, and 0.038). The rate of return of spontaneous circulation was higher in REBOA versus OCCM (20/33 [60.1%] vs 5/18 [33.3%]; P = 0.04), and REBOA patients survived to operative intervention more frequently ( P = 0.038). REBOA patients had greater total cardiac compression fraction (CCF) before AO than OCCM (85.3 ± 12.7% vs 35.2 ± 18.6%, P < 0.0001) and after AO (88.3 ± 7.8% vs 71.9 ± 24.4%, P = 0.0052). REBOA patients have higher EtCO2 and cardiac compression fraction before and after AO compared with patients who receive OCCM.

Background During the past decade of conflict, numerous patients with combat-associated injuries required the formation of an ostomy. However, outcomes in those patients undergoing ostomy reversal have yet to be analyzed. We review the experience and identify risk factors for complications after ostomy reversal in a series of patients with combat injuries at our military treatment facility. Study Design A retrospective review of patients with combat-associated injuries managed with a diverting ostomy who underwent ostomy reversal at our military treatment facility during a 13-year period. Demographic and clinical data were collected for all patients and postoperative complications were identified. Multivariate analysis was performed to identify independent risk factors for complications after reversal. Complication rates were calculated for 90-day periods of time after ostomy creation and best-fit curve analysis was conducted. Results Ninety-nine patients were identified who underwent ostomy reversal. Forty patients (40.4%) suffered a post-reversal complication. On multivariate analysis, older age (odds ratio 1.11/y; p = 0.038), severe perineal injury indication for diversion (odds ratio 4.37; p = 0.028), and increased time interval between ostomy creation and reversal (odds ratio 1.005/d; p = 0.037), were independently associated with postoperative complications. A cubic regression best fit quarterly complication rate data (R2 0.526; p Conclusions Ostomy reversal in patients wounded in combat is a major undertaking with a high complication rate. The finding of a shorter interval from ostomy creation to reversal independently associated with a reduction in complications provides a modifiable risk factor to guide future practice and potentially reduce complications. Our modeling suggests reversal in the 3- to 6-month time frame can have the lowest rate of complications. Future research to reduce complications is indicated, especially in older patients with perineal wounds.

The nature of many combat wounds puts patients at a high risk of developing deep venous thrombosis (DVT) and pulmonary embolism (PE), which fall under the broader disease category of venous thromboembolism (VTE). In addition to the hypercoagulable state induced by trauma, massive injuries to the extremities, prolonged immobility, and long fixed wing transport times to higher echelons of care are unique risk factors for venous thromboembolism in the combat-injured patient. These risk factors mandate aggressive prophylaxis for DVT and PE that can effectively be achieved by the use of lower extremity sequential compression devices and low dose unfractionated heparin or low molecular weight heparin. In addition, inferior vena cava filters are often used for PE prophylaxis when chemical DVT prophylaxis fails or is contraindicated. The following Department of Defense (DoD) Joint Trauma System (JTS) Clinical Practice Guideline (CPG) discusses the current recommendations for the prevention of DVT and PE including the use of inferior vena cava filters (IVCFs).

The intent of this study was to characterize the management and subsequent complications of combat injury tube thoracostomies and to determine risk factors for the development of pneumonia (PNA) and retained hemothorax (RH). One hundred fifteen patients with 173 tube thoracostomies met the inclusion criteria and were analyzed. The mean injury severity score was 30.8 1 11.6, 23.5 per cent had traumatic amputations, 49.7 per cent had a hemothorax, and 50.3 per cent had a pneumothorax as indications for tube thoracostomy (TT) placement. Within 24 hours of injury, 89.6 per cent were intubated, the majority (54%) were injured by improvised explosive devices, 35.6 per cent sustained rib fractures, and 12.2 per cent had a diaphragm injury. A mean of 1.5 1 0.7(range 1–4) tube thoracostomies were placed, 18.3 per cent of patients had bilateral tube thoracostomies, and the average TT duration was 6.7 1 3.9 days. The incidence of PNA was 27 per cent (n = 31), RH was 9.6 per cent (n = 11), and empyema was 1.7 per cent (n = 2). Multivariable analysis identified the duration of ventilation [OR 1.2, 95% confidence interval (CI): 1.097–1.313, P < 0.001] as independently associated with the development of PNA. Bilateral TT placement (OR 3.848, 95% CI: 1.219–12.143, P = 0.0216) and injury severity score (OR 1.050, 95% CI: 1.001–1.102, P = 0.0443) were independently associated with PNA development when a patient was intubated for eight days or less. The number of tube thoracostomies placed (OR 3.08, 95% CI: 1.03–9.18, P = 0.0439) was independently associated with the development of RH. Further research is warranted to identify modifiable risk factors to reduce the incidence of PNA and RH in patients with TT placed for traumatic injuries.

The objective of this study was to describe the natural history of primary pulmonary thrombus (PPT) in combat casualties. This was a retrospective study of casualties treated at a major military treatment facility from 2010 to 2012. Patients with a downrange chest CTwere included. CTs were reviewed by two independent, blinded radiologists to confirm PPTon initial imaging. Follow-up CTs, if obtained, were also independently reviewed to determine the extent of clot burden. Two hundred and forty-nine casualties with a downrange, acceptable quality chest CT were included. 9 per cent (23/249) of patients sustained PPT. Thirty nine per cent (9/23) were initially treated with therapeutic anticoagulation (AC). Conversely, 61 per cent (14/23) arrived to our military treatment facility without AC. Seven arriving without AC-developed pulmonary symptoms during their hospitalization and had interval chest CTs. Of those, three had no evidence of pulmonary thrombus. The other four had subsegmental filling defects and three were started AC whereas one had an IVC (Inferior Vena Cava) filter inserted. In total, 11/23 (48%) PPT patients were managed without AC and discharged without complications. This is the first study attempting to look at PPT natural history. There were no adverse sequelae from managing PPT without AC. Further studies are warranted to further characterize PPT.

The purpose of this review is to give an overview of recent updates in the management of traumatic brain injury (TBI) in military settings. Studies from the recent conflicts in Central and Southwest Asia have demonstrated that appropriate aggressive neurosurgical intervention in austere settings has been associated with improved outcomes. Modern management of military TBI has evolved from the era of Cushing in WWI to damage control and rapid aeromedical evacuation today. Aggressive management of severe injuries has been shown to increase survival. These interventions have included an emphasis on measures to reduce secondary brain injury—aggressive cranial decompression, addressing intracranial vascular injuries, and aeromedical evacuation to facilities with neurosurgical capability. Additionally, advances in the screening of mild TBI have led to increased awareness of the prevalence of this injury and potential associated long-term effects.

Introduction Chest injuries occur in a significant portion of trauma patients and hemothorax is a common result. While the initial management of traumatic hemothorax is most commonly treated with tube thoracostomy, the management of retained hemothorax is a subject of debate. Recent literature has proposed different methods for treating or preventing retained hemothorax, yet the approach to this pathology is not straightforward. Methods The literature was reviewed for relevant studies regarding the prevention and management of post-traumatic retained hemothorax. What follows is a review of the recent literature and an algorithm for the approach to treating a traumatic retained hemothorax. Results Identifying a traumatic retained hemothorax and preventing subsequent complications such as pneumonia, empyema, and fibrothorax are significant issues faced by surgeons. Studies for preventing retained hemothorax have focused on initial chest tube size, location, and peri-procedural placement conditions, as well as thoracic lavage. Several treatment modalities exist, including second drainage procedure and intra-pleural fibrinolytic drug instillation, but video-assisted thoracoscopic surgery is the most common and successful approach. Regardless of the approach to evacuation, early intervention is paramount. Conclusion Further studies will help characterize appropriate candidates, timing, treatment modalities, and guide therapy for retained hemothorax.

Background Established animal trauma models are limited in recapitulating the pathophysiology of human traumatic injury. Herein, we characterize the physiologic insult and inflammatory response in two clinically relevant non-human primate (NHP) trauma models. Methods Mauritian Cynomolgus Macaques underwent either a laparoscopic closed abdomen liver injury (laparoscopic 60% left-lobe hepatectomy) in an established uncontrolled severe hemorrhage model (THM), or a polytrauma hemorrhage model (PHM) involving combined liver and bowel injury, uncontrolled severe hemorrhage as well as an open full-thickness cutaneous flank wound. Fixed volume resuscitation strategies were employed in the THM and goal directed resuscitation was used in the PHM. Complete peripheral blood and critical clinical chemistry parameters, serum biomarkers of systemic inflammation, tissue perfusion parameters, as well as survival, were compared between the models throughout the 2-week study period. Results NHPs in both the THM (n = 7) and the PHM (n = 21) demonstrated tissue hypoperfusion (peak lactate 6.3 ± 0.71 mmol/L) with end organ injury (peak creatinine 3.08 ± 0.69 mg/dL) from a similar liver injury (60% left hemi-hepatectomy), though the PHM NHPs had a significantly higher blood loss (68.1% ± 12.7% vs. 34.3% ± 2.3%, p = 0.02), lower platelet counts (59 ± 25 vs. 205 ± 46 K/uL, p = 0.03) and a trend towards higher mortality (90.5% vs. 33.3%, p = 0.09). The inflammatory response was robust in both models with peak cytokine (IL-6 > 6000-fold above baseline) and peak leukocyte values (WBC 27 K/uL) typically occurring around t = 240 min from the time of hepatic injury. A more robust systemic inflammatory response was appreciated in the PHM resulting in marked elevations in peak serum IL-6 (7887 ± 2521 pg/mL vs.1076 ± 4833 pg/mL, p = 0.02), IL-1ra (34,499 ± 5987 pg/mL vs. 2511 ± 1228 pg/mL, p

The remote military installation at Diego Garcia is used as an economic and strategic example of the many possible future naval or commercial sites and scenarios that could be utilized for the production of sustainable low carbon fuel from non-fossil electrical energy. In addition to photovoltaic (PV) and wind electrical sources, this analysis includes light water reactors (LWRs) on mobile platforms as the main electrical energy source. Using published capital cost estimates and a range of solar and wind renewable electrical energy scenarios, costs ranging between $6.40 and $12.57 per gallon of standard fuel are estimated for a 129,000 gallons/day fuel process. The cost estimate for a floating nuclear electrical scenario is between $4.66 and $9.47 per gallon. Larger area potential sites of strategic naval and/or commercial importance such as Guam and Djibouti provide additional operational scenarios. Most importantly these military examples provide a framework for how such a process could be used commercially to supply stored energy as a sustainable fuel source for remote countries poor in fossil fuel resources. This information may also be used by policy analysts to support alternative energy implementation strategies and greatly expand the naval and commercial role in nuclear and renewable energy aimed at sustainable production of low carbon fuel.

Objectives: In combat casualty care, tranexamic acid (TXA) is administered as part of initial resuscitation effort; however, conflicting data exist as to whether TXA contributes to increased risk of venous thromboembolism (VTE). The purpose of this study is to determine what factors increase risk of pulmonary embolism after combat-related orthopaedic trauma and whether administration of TXA is an independent risk factor for major thromboembolic events. Setting: United States Military Trauma Centers. Patients: Combat casualties with orthopaedic injuries treated at any US military trauma center for traumatic injuries sustained from January 2011 through December 2015. In total, 493 patients were identified. Intervention: None. Main Outcome Measures: Occurrence of major thromboembolic events, defined as segmental or greater pulmonary embolism or thromboembolism-associated pulseless electrical activity. Results: Regression analysis revealed TXA administration, traumatic amputation, acute kidney failure, and hypertension to be associated with the development of a major thromboembolic event for all models. Injury characteristics independently associated with risk of major VTE were Injury Severity Score 23 or greater, traumatic amputation, and vertebral fracture. The best performing model utilized had an area under curve = 0.84, a sensitivity=0.72, and a specificity=0.84. Conclusions: TXA is an independent risk factor for major VTE after combat-related Orthopaedic injury. Injury factors including severe trauma, major extremity amputation, and vertebral fracture should prompt suspicion for increased risk of major thromboembolic events and increased threshold for TXA use if no major hemorrhage is present. Level of evidence: III, Prognostic Study

Background The National Surgical Quality Improvement Program (NSQIP) has become a prevalent tool for quality improvement. At our tertiary military hospital, NSQIP collects 20% of eligible cases. We implemented an emergency general surgery (EGS) registry to prospectively review all EGS cases. We compared our EGS registry with NSQIP, hypothesizing that NSQIP sampling under-represents EGS outcomes. Methods A formal EGS Process Improvement Program was implemented in 2016. From 2016 to 2018, the four most common operations were laparoscopic appendectomy, laparoscopic cholecystectomy, surgery for small bowel obstruction, and nonelective hernia repair. Outcomes were compared between the EGS registry and NSQIP abstracted cases. Results In 2016, the EGS registry identified 11/112 (9.8%) patients with a complication. National Surgical Quality Improvement Program abstracted 16% of EGS cases with 16.7% (3/18) of patients having a complication. In 2017, the EGS registry identified 10/87 (11.5%) cases with complications. National Surgical Quality Improvement Program abstracted 23% of EGS with zero complications. In 2018, the EGS registry identified 9.5% of 74 cases with complications. National Surgical Quality Improvement Program abstracted 15% of EGS cases with zero complications. Conclusions National Surgical Quality Improvement Program did not capture many important EGS outcomes. In 2 of 3 years, NSQIP did not identify a single complication for EGS. National Surgical Quality Improvement Program alone may be insufficient to target EGS improvements.

Background Abdominal injuries historically account for 13% of battlefield surgical procedures. We examined the occurrence of exploratory laparotomies and subsequent abdominal surgical site infections (SSIs) among combat casualties. Methods Military personnel injured during deployment (2009-2014) were included if they required a laparotomy for combat-related trauma and were evacuated to Landstuhl Regional Medical Center, Germany, before being transferred to participating US military hospitals. Results Of 4304 combat casualties, 341 (7.9%) underwent laparotomy. Including re-explorations, 1053 laparotomies (median, 2; interquartile range, 1-3; range, 1-28) were performed with 58% occurring within the combat zone. Forty-nine (14.4%) patients had abdominal SSIs (four with multiple SSIs): 27 (7.9%) with deep space SSIs, 14 (4.1%) with a deep incisional SSI, and 12 (3.5%) a superficial incisional SSI. Patients with abdominal SSIs had larger volume of blood transfusions (median, 24 versus 14 units), more laparotomies (median, 4 versus 2), and more hollow viscus injuries (74% versus 45%) than patients without abdominal SSIs. Abdominal closure occurred after 10 d for 12% of the patients with SSI versus 2% of patients without SSI. Mesh adjuncts were used to achieve fascial closure in 20.4% and 2.1% of patients with and without SSI, respectively. Survival was 98% and 96% in patients with and without SSIs, respectively. Conclusions Less than 10% of combat casualties in the modern era required abdominal exploration and most were severely injured with hollow viscus injuries and required massive transfusions. Despite the extensive contamination from battlefield injuries, the SSI proportion is consistent with civilian rates and survival was high.

Damage control is the process of counteracting an unfavorable situation in order to curtail losses. First utilized by the United States Navy, a “damage controlman” was responsible for temporary salvage of a vessel under duress so that it could make its way to a port for formal repairs. This principle, rapid salvage to stabilize long enough for definitive repair, was adopted by numerous surgical fields and is now considered the gold standard in the care of significantly injured patients. This concept encompasses the entirety of patient care from the point of injury and initial resuscitation to the control of hemorrhage and contamination to stabilization in the critical care unit and back to the operating room for definitive anatomic repair. In this chapter, we will review the history of damage control, provide a guide to damage control procedures with specific focus on blast injuries, and reinforce the necessity of proper damage control resuscitation in concert with the surgical interventions.