Contemporary Trends in Physician Utilization Rates of CEA and CAS for Asymptomatic Carotid Stenosis among Medicare Beneficiaries.

BACKGROUND: Carotid revascularization for asymptomatic carotid artery stenosis (ACAS) has become increasingly controversial in the past few decades as the best medical therapy has improved. The aim of this study was to assess and define contemporary trends in the rate of carotid revascularization procedures for ACAS in the United States and to characterize outlier physicians performing a higher rate of asymptomatic revascularization compared to their peers. METHODS: We used 100% Medicare fee-for-service claims to identify all patients who were newly diagnosed with ACAS between 01/2011-06/2018. Patients with symptomatic carotid artery stenosis, those with prior carotid revascularization, and surgeons who performed ≤10 CEAs during the study period were excluded. We used a hierarchical multivariable logistic regression model to evaluate patient and physician characteristics associated with undergoing a carotid endarterectomy or carotid artery stent procedure within 3 months after the initial diagnosis of ACAS. We also assessed temporal trends in carotid revascularization rates over time using the Cochran-Armitage Trend Test. RESULTS: Overall, 795,512 patients (median age 73.9 years, 50.9% male, 87.6% white) had a first-time diagnosis of ACAS during the study period, of which 23,481 (3.0%) underwent carotid revascularization within 3 months. There was a significant decline in overall carotid artery revascularization rates over time (2011: 3.2% vs. 2018: 2.1%; P < 0.001). The median and mean physician-specific carotid revascularization rates were 2.0% (IQR 0.0%-6.3%) and 4.7% ± 7.1%, respectively. Three-hundred and fifty physicians (5.2%) had carotid revascularization rates ≥19%, which was more than 2 standard deviations above the mean. After adjusting for patient-level characteristics, physician-level variables associated with carotid revascularization for newly diagnosed ACAS included male sex (adjusted OR 1.59, 95% CI 1.35-1.89), more years in practice (≥31 vs. <10 years, aOR 1.64, 95% CI 1.32-2.04), rural practice location (aOR 1.34, 95% CI 1.18-1.52), Southern region practice location (versus Northeast, aOR 1.54, 95% CI 1.39-1.69), and lower volume of ACAS patients (lower versus upper tertile, aOR 2.62, 95% CI 2.39-2.89). Cardiothoracic surgeons had a 1.52-fold higher odds of carotid revascularization compared to vascular surgeons (95% CI 1.36-1.68), whereas cardiologists and radiologists had lower intervention rates (both, P < 0.05). CONCLUSIONS: The current early revascularization rate for newly diagnosed ACAS is <5% among proceduralists in the United States, and has been decreasing steadily since 2014. There are particular physician-level characteristics that are associated with higher rates of carotid revascularization that cannot be fully contextualized without high-level contemporary outcomes data to guide decision making in ACAS.

Recurrent bacteremia: A 10-year retrospective study in combat-related burn casualties.

INTRODUCTION: Surviving the first episode of bacteremia predisposes burn casualties to its recurrence. Herein, we investigate the incidence, mortality, bacteriology, and source of infection of recurrent bacteremia in military burn casualties admitted to the U.S. Army Institute of Surgical Research Burn Center over a 10year period. METHODS: Bacteremia was defined as the growth of Gram-positive or Gram-negative organisms in a blood culture that excluded probable skin contaminants. Recurrent bacteremia was defined as a subsequent episode of bacteremia ≥7 days after the first episode. Polymicrobial bacteremia was the presence of more than one pathogen in the same blood culture. Bacteremia was attributed to UTI, pneumonia, or wound sepsis. All other bacteremias were considered non-attributable bloodstream infections. Univariate and multivariate analyses determined factors predictive of clinical outcome. RESULTS: Out of 952 combat-related burn casualties screened, 166 cases were identified; 63% (non-recurrent) and 37% (recurrent) with median time to recurrence of 20 days. Univariate and multivariate analysis showed that the mortality rate was two and nine-fold, respectively, higher with recurrent bacteremia. Univariate analysis found that except for urinary tract infection, large burn size (>20%), 3rd degree burns, increased injuiry severity, perineal burns, and mechanical ventilator days were independent factors predictive of recurrence of bacteremia as well as increased mortality in the recurrent bacteremia cohort. Acinetobacter baumannii complex (63%) was prevalent in the non-recurrent group, while Klebsiella pneumoniae (46% vs. 30%) and Pseudomonas aeruginosa (35% vs. 26%) were prevalent in recurrent bacteremia. Half of the recurrent bacteremia cases were polymicrobial, compared to 9% in non-recurrent bacteremia. Pneumonia was prevalent in non-recurrent bacteremia (38%) and a combination of pneumonia and wound sepsis (29%) in recurrent bacteremia casualties. CONCLUSIONS: Recurrent bacteremia increases mortality in military burn casualties. Additional research is needed to address and mitigate the underlying causes, thereby improving survival.

Using the injury severity score to adjust for comorbid trauma may be double counting burns: implications for burn research.

BACKGROUND: The injury severity score considers burn size and inhalation injury in estimating overall anatomical injury severity. Models that adjust for injury severity score in addition to total burn size and inhalation injury may therefore be double counting the risk from these individual burn characteristics, and obscuring (or overemphasizing) the contribution of risk from each source. The primary aim of this study was to compare differences in the estimated mortality risk of burn trauma using the traditional injury severity score (ISS) calculation and the non-burn injury severity score (NBISS) to examine how separating out the risk attributable to the burn injury versus other trauma changes the interpretation and clinical assessment. METHODS: Among U.S. casualties sustaining burns during combat operations in Iraq and Afghanistan from March 2003 to October 2013, we performed a retrospective cohort study. Unadjusted, adjusted, and weighted Cox proportional hazards models were performed to estimate the risk of age, burn injury severity, and non-burn injury severity on mortality. Weighted hazard ratios and adjusted survival curves were performed using non-parametric inverse probability weighting. RESULTS: Our final sample consisted of 902 service members with a mortality proportion of 5.7% (n=51). Adjusting for non-burn trauma with traditional ISS attenuated the risk of percent total body surface area burned (%TBSA) by 20% when modeled continuously [HR (95% CI): 1.27 (1.10-1.32) vs. 1.07 (0.99-1.15]. However, the adjusted model using NBISS only attenuated the associated mortality risk of burn size by 5% [HR (95% CI): 1.22 (1.12-1.34)] and had a similar model fit (AIC: 484.2 vs. 478.6). For the weighted Cox proportional hazards models, the risk from a large burn (%TBSA≥60) was also attenuated when adjusting for ISS [HR (95% CI): 2.80 (1.18-6.64)] compared to the model adjusting for NBISS [HR (95% CI): 5.63 (2.79-11.35)]. CONCLUSION: Our analysis comparing the use of traditional ISS and NBISS to measure comorbid non-burn trauma resulted in different interpretations for the effect of %TBSA on subsequent mortality. Our results suggest that the association of %TBSA with death can be obscured by the inclusion of traditional ISS. Therefore, we recommend using NBISS when constructing statistical models in this patient population.

Extracorporeal Filtration of Potassium in a Swine Model of Bilateral Hindlimb Ischemia-Reperfusion Injury With Severe Acute Hyperkalemia.

Introduction: Options for the treatment of hyperkalemia in the pre-hospital setting are limited, particularly in the context of natural disaster or during combat operations. Contemporary interventions require extensive resources and technical expertise. Here we examined the potential for a simple, field deployable bridge-dialysis as a countermeasure for acute hyperkalemia induced by prolonged ischemia-reperfusion. Methods: Twenty female swine were randomized into two experimental groups undergoing a 2-hour bilateral hindlimb ischemia-reperfusion injury. Subsequent to injury, hemoperfusion was performed in the presence (Column) and absence (Sham Control) of a high-affinity potassium-binding column (CytoSorbents, Monmouth Junction, NJ, USA). Serial blood gas and chemistries were sampled. Primary endpoint was changed in serum potassium concentrations post-injury and filtration. Results: Serum potassium was significantly elevated following ischemia-reperfusion injury in both groups (149% (12) and 150% (22), p < 0.05 vs respective baseline values). There were no differences observed between groups in respect to physiologic parameters; mean arterial pressure, heart rate, systemic vascular resistance, cardiac output, or central venous oxygenation. Filtration resulted in a significant relative decrease in potassium compared with controls after the first hour as determined by repeated measures two-way ANOVA (p < 0.0001) which continued through end of the study. Significant thrombocytopenia was observed in animals undergoing filtration with a mean reduction in platelets measured at T = 480 minutes (168 × 103µL, p < 0.0001 vs baseline). Conclusions: We demonstrate that serum potassium can be filtered via hemoperfusion utilizing a simple extracorporeal potassium-binding platform, though evolution of this technology will be required to achieve meaningful reduction of potassium in clinically significant hyperkalemia after trauma.

Rectal Trauma: Evidence-Based Practices.

The management of rectal trauma has often been lumped in with colon trauma when, in fact, it is a unique entity. The anatomic nature of the rectum (with its intra- and extraperitoneal segments) lends itself to unique circumstances when it comes to management and treatment. From the four Ds (debridement, drainage, diversion, and distal irrigation), the management of rectal trauma has made some strides in light of the experiences coming out of the recent conflicts overseas as well as some rethinking of dogma. This article will serve to review the anatomy and types of injuries associated with rectal trauma. A treatment algorithm will also be presented based on our current literature review. We will also address controversial points and attempt to give our opinion in an effort to provide an update on an age-old problem.

Hyperkalemia in Combat Casualties: Implications for Delayed Evacuation.

OBJECTIVE: Fixed facilities and rapid global evacuation ensured that delayed complications of trauma, such as hyperkalemia, occurred late in the evacuation chain where renal replacement therapies were available. However, future conflicts or humanitarian disasters may involve prolonged evacuation times. We sought to quantify one potential risk of delayed evacuation by assessing hyperkalemia in combat casualties. METHODS: Retrospective study of military members admitted to intensive care units in Iraq and Afghanistan from February 1, 2002, to February 1, 2011. This study was approved by the U.S. Army Medical Research and Materiel Command Institutional Review Board. Demographics, injury severity score, burn injury, mechanism of injury, vital signs, creatinine, and potassium were collected. Logistic regression models were used to identify incidence and risk factors for hyperkalemia. RESULTS: Of 6,011 patient records, 1,472 had sufficient data to be included for analysis. Hyperkalemia occurred in 5.8% of patients. Those with hyperkalemia had higher injury severity scores, higher shock index, were more likely to have acute kidney injury, and were more likely to die. On multivariate analysis, acute kidney injury and shock index were significantly associated with the development of hyperkalemia. In a subgroup of patients with data on creatine kinase, rhabdomyolysis was associated with hyperkalemia in the univariate model, but was not significant after adjustment. CONCLUSION: Hyperkalemia occurred in 5.8% of patients in our cohort of critically injured combat casualties. The development of hyperkalemia was independently associated with acute kidney injury and shock index. In future conflicts, with prolonged evacuation times, mitigation strategies should be developed to treat hyperkalemia in casualties before arrival at definitive care.

Hemodynamic effects of the Abdominal Aortic and Junctional Tourniquet in a hemorrhagic swine model.

BACKGROUND: Torso hemorrhage constitutes a leading cause of battlefield mortality. The Abdominal Aortic and Junctional Tourniquet (AAJT) uses a pneumatic bladder to compress the aorta reducing pelvic and lower extremity perfusion; however, concern exists over the risk of caval compression exacerbating hypotension after application. METHODS: Male swine (70-90 kg) were randomized into four groups of 10: presence or absence of hemorrhage and AAJT placement. After a 40% hemorrhage, a 15-min period of hypovolemia was observed before the AAJT application. All animals received two 500 mL boluses of Hextend separated by 30 min. Cardiovascular, pulmonary, and oxygenation values were compared among groups. RESULTS: The AAJT was effective in reducing blood flow to the femoral arteries in both hemorrhaged and nonhemorrhaged animals (P < 0.001 for both groups). Hemorrhage resulted in significant decrease in mean arterial pressure compared with sham controls (23.5 ± 2.4 versus 61.6 ± 7.8 mm Hg, respectively, P < 0.001). AAJT application, compared with untreated controls, resulted in a significant increase in mean arterial pressure and systemic vascular resistance but not in cardiac output, oxygenation, and central venous pressure. Furthermore, no indication of overresuscitation injury was present as evidenced by pulmonary artery pressure and pulmonary histology. CONCLUSIONS: AAJT application in an animal model of severe shock results in a favorable hemodynamic profile because of afterload support. The present study did not demonstrate any adverse consequences because of caval compression, bowel injury, or pulmonary dysfunction. In addition, there does not appear to be any particular intravenous fluid economy achieved by AAJT application.

Burns to the genitalia, perineum, and buttocks increase the risk of death among U.S. service members sustaining combat-related burns in Iraq and Afghanistan.

PURPOSE: Among service members injured in Iraq and Afghanistan, to determine the risk of mortality associated with combat-related burns to the genitalia, perineum, and buttocks. MATERIALS AND METHODS: The prospectively maintained burn registry from the United States Army Institute of Surgical Research was retrospectively reviewed to identify all service members with combat-related burns sustained in Iraq and Afghanistan from March 2003 to October 2013. The two primary risk factors of interest were (1) any burn to the genitals, perineum, and/or buttocks (PB) and (2) burns involving the entire perineal, genital, and buttock region (complete PB). Cox proportional hazard models were used to estimate the risk of mortality for both primary risk factors, and adjusted for severe non-burn-related trauma, percent of burn over total body surface area (TBSA), inhalational injury, time to urinary tract infection, and time to bacteremia. A post-hoc analysis was performed to explore the potential effect modification of TBSA burned on the relationship between PB and mortality. RESULTS: Among the 902 U.S. service members with combat-related burns sustained during the study period, 226 (25.0%) had involvement of the genitalia, perineum, and/or buttocks. Complete PB was associated with a crude risk of mortality (HR: 5.3; 2.9-9.7), but not an adjusted risk (HR=1.8; 0.8-4.0). However, TBSA burned was identified as a potential negative effect modifier. Among patients with burns <60% TBSA, sustaining a complete PB conferred an adjusted risk of death (HR=2.7; 1.1-6.8). Further, patients with a perineal burn had a five-fold increased incidence of bacteremia. In adjusted models, each event of bacteremia increased the risk of mortality by 92% (HR 1.92; 1.39-2.65). Perineal burns were associated with a two-fold increased incidence of severe non-burn related trauma that also doubled mortality risk in adjusted models (HR 2.29; 1.23-4.27). CONCLUSIONS: Among those with relatively survivable combat-related burns (<60% TBSA), genital/perineal/buttock involvement increases the risk of death. Bacteremia may account for part of this increased risk, but does not fully explain the independent risk associated with perineal burns.

Antimicrobial-bonded graft patency in the setting of a polymicrobial infection in swine (Sus scrofa).

BACKGROUND: Polytetrafluoroethylene (PTFE) and Dacron are commonly used as arterial conduits in vascular trauma or infection when vein interposition graft may not be available. This study used a previously validated large animal model of polymicrobial infection to assess the patency and infectious resistance of a novel, antibiotic-impregnated graft material compared with PTFE and Dacron. METHODS: Forty-eight animals were placed into five groups for a 21-day survival period. A 6-mm PTFE, Dacron, or antimicrobial-bonded graft was used to replace the iliac artery and then inoculated with 1 × 107 colonies/mL of genetically labeled Pseudomonas aeruginosa and Staphylococcus aureus. Native vessels with and without contamination served as control groups. The primary end points were graft patency (determined by duplex ultrasound and necropsy) and graft infection (culture with molecular analysis). Secondary end points included physiologic measurements, blood cultures, laboratory data, and histopathology. RESULTS: At 21 days, 50% of PTFE, 62.5% of Dacron, and 100% of the antimicrobial-bonded grafts remained patent (P = .04). PTFE and Dacron had an equivalent number of overall infections, 87.5% and 75%, respectively (P = 1.0). There was no significant difference of infectious organisms between standard materials. The infection rate of the antimicrobial-bonded graft (25%) was significantly less than that of both PTFE and Dacron (P < .01), and all of these infections were secondary to P. aeruginosa. Clinical data did not vary significantly between groups. There were no mortalities in the protocol secondary to graft blowout or sepsis. CONCLUSIONS: The antimicrobial-bonded graft material outperformed standard PTFE and Dacron in the setting of polymicrobial infection with regard to graft patency and infection. The novel prosthetic material appears to be resistant to infection with S. aureus and to limit the growth of P. aeruginosa. Additional studies are recommended to explore the role of this antibiotic-bonded graft for use in the setting of vascular infection or trauma.

Quality of Life in United States Veterans With Combat-Related Ostomies From Iraq and Afghanistan.

OBJECTIVE: Assess the impact of ostomy formation on quality of life for U.S. Service Members. METHODS: U.S. personnel sustaining colorectal trauma from 2003 to 2011 were identified using the Department of Defense Trauma Registry. A cross-sectional observational study was conducted utilizing prospective interviews with standard survey instruments. Primary outcome measures were the Stoma Quality of Life Scale and Veterans RAND 36 scores and subjective responses. Patients with colorectal trauma not requiring ostomy served as controls. RESULTS: Of 177 available patients, 90 (50.8%) male veterans consented to participate (55 ostomy, 35 control). No significant differences were observed between ostomy and control groups for Injury Severity Score (25.6 ± 9.9 vs. 22.9 ± 11.8, p = 0.26) or mechanism of injury (blast: 55 vs. 52%, p = 0.75); nonostomates had fewer anorectal injuries (3.2 vs. 47.9%, p < 0.01). Median follow-up was 6.7 years. Veterans RAND-36 Physical and Mental Component Scores were similar between groups. About 45.8% of ostomates were willing-to-trade a median of 10 years (interquartile range = 5-15) of their remaining life for gastrointestinal continuity. At last follow-up, 95.9% of respondents' combat-related ostomies were reversed with a median duration of 6 (range = 3-19) months diverted. CONCLUSIONS: Ostomy creation in a combat environment remains safe and does not have a quantifiable impact on long-term quality of life.

Prosthetic Graft Patency in the Setting of a Polymicrobial Infection in Swine (Sus scrofa).

BACKGROUND: In the setting of vascular injury, vein interposition graft is the preferred conduit, but may have limited availability. This study seeks to develop a large animal model assessing the graft performance of polytetrafluoroethylene (PTFE) and Dacron in the setting of a polymicrobial infection. METHODS: Thirty-seven animals were placed into 4 groups for a 21-day survival period. Six-millimeter PTFE or Dacron interposition grafts were placed in the right iliac artery with a standardized bacterial inoculation. Native vessel with and without contamination served as control groups. The inoculant was 1 × 107 of genetically labeled Pseudomonas aeruginosa and Staphylococcus aureus. The primary end points were graft patency (determined by duplex ultrasound and necropsy) and graft infection (culture with molecular analysis). Secondary end points included physiological measurements, blood cultures, laboratory data, and histopathology. RESULTS: PTFE and Dacron had similar infection rates of 85.7% and 75%, respectively. There was no significant difference in infectious organisms between graft materials. PTFE and Dacron exhibited bacterial ingrowth and transmigration to the intraluminal portion of the conduit. Forty-five percent of the Dacron group and 40% of the PTFE group remained patent at postoperative day 21 (P = 0.98). Clinical data, including white blood cell count, percent neutrophils, and lactate, did not vary significantly between groups. CONCLUSIONS: PTFE and Dacron perform similarly in terms of infection rates and graft failure as both have a propensity toward bacterial ingrowth and occlusion when compared with controls. This is a valid animal model to assess graft performance in the setting of polymicrobial infection and provides an avenue for studying novel prosthetic conduits.

Reciprocal Risk of Acute Kidney Injury and Acute Respiratory Distress Syndrome in Critically Ill Burn Patients.

OBJECTIVE: To evaluate the association between acute respiratory distress syndrome and acute kidney injury with respect to their contributions to mortality in critically ill patients. DESIGN: Retrospective analysis of consecutive adult burn patients requiring mechanical ventilation. SETTING: A 16-bed burn ICU at tertiary military teaching hospital. PATIENTS: Adult patients more than 18 years old requiring mechanical ventilation during their initial admission to our burn ICU from January 1, 2003, to December 31, 2011. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A total 830 patients were included, of whom 48.2% had acute kidney injury (n = 400). These patients had a 73% increased risk of developing acute respiratory distress syndrome after controlling for age, gender, total body surface area burned, and inhalation injury (hazard ratio, 1.73; 95% CI, 1.18-2.54; p = 0.005). In a reciprocal multivariate analysis, acute respiratory distress syndrome (n = 299; 36%) demonstrated a strong trend toward developing acute kidney injury (hazard ratio, 1.39; 95% CI, 0.99-1.95; p = 0.05). There was a 24% overall in-hospital mortality (n = 198). After adjusting for the aforementioned confounders, both acute kidney injury (hazard ratio, 3.73; 95% CI, 2.39-5.82; p < 0.001) and acute respiratory distress syndrome (hazard ratio, 2.16; 95% CI, 1.58-2.94; p < 0.001) significantly contributed to mortality. Age, total body surface area burned, and inhalation injury were also significantly associated with increased mortality. CONCLUSIONS: Acute kidney injury increases the risk of acute respiratory distress syndrome in mechanically ventilated burn patients, whereas acute respiratory distress syndrome similarly demonstrates a strong trend toward the development of acute kidney injury. Acute kidney injury and acute respiratory distress syndrome are both independent risks for subsequent death. Future research should look at this interplay for possible early interventions.

Simulation and qualitative analysis of glucose variability, mean glucose, and hypoglycemia after subcutaneous insulin therapy for stress hyperglycemia.

BACKGROUND: The critically ill can have persistent dysglycemia during the "subacute" recovery phase of their illness because of altered gene expression; it is also not uncommon for these patients to receive continuous enteral nutrition during this time. The optimal short-acting subcutaneous insulin therapy that should be used in this clinical scenario, however, is unknown. Our aim was to conduct a qualitative numerical study of the glucose-insulin dynamics within this patient population to answer the above question. This analysis may help clinicians design a relevant clinical trial. METHODS: Eight virtual patients with stress hyperglycemia were simulated by means of a mathematical model. Each virtual patient had a different combination of insulin resistance and insulin deficiency that defined their unique stress hyperglycemia state; the rate of gluconeogenesis was also doubled. The patients received 25 injections of subcutaneous regular or Lispro insulin (0-6 U) with 3 rates of continuous nutrition. The main outcome measurements were the change in mean glucose concentration, the change in glucose variability, and hypoglycemic episodes. These end points were interpreted by how the ultradian oscillations of glucose concentration were affected by each insulin preparation. RESULTS: Subcutaneous regular insulin lowered both mean glucose concentrations and glucose variability in a linear fashion. No hypoglycemic episodes were noted. Although subcutaneous Lispro insulin lowered mean glucose concentrations, glucose variability increased in a nonlinear fashion. In patients with high insulin resistance and nutrition at goal, "rebound hyperglycemia" was noted after the insulin analog was rapidly metabolized. When the nutritional source was removed, hypoglycemia tended to occur at higher Lispro insulin doses. Finally, patients with severe insulin resistance seemed the most sensitive to insulin concentration changes. CONCLUSIONS: Subcutaneous regular insulin consistently lowered mean glucose concentrations and glucose variability; its linear dose-response curve rendered the preparation better suited for a sliding-scale protocol. The longer duration of action of subcutaneous regular insulin resulted in better glycemic-control metrics for patients who were continuously postprandial. Clinical trials are needed to examine whether these numerical results represent the glucose-insulin dynamics that occur in intensive care units; if present, their clinical effects should be evaluated.

Rhabdomyolysis among critically ill combat casualties: Associations with acute kidney injury and mortality.

BACKGROUND: Rhabdomyolysis has been associated with poor outcomes in patients with traumatic injury, especially in the setting of acute kidney injury (AKI). However, rhabdomyolysis has not been systematically examined in a large cohort of combat casualties injured in the wars in Iraq and Afghanistan. METHODS: We conducted a retrospective study of casualties injured during combat operations in Iraq and Afghanistan who were initially admitted to the intensive care unit from February 1, 2002, to February 1, 2011. Information on age, sex, Abbreviated Injury Scale (AIS) score, Injury Severity Score (ISS), mechanism of injury, shock index, creatine kinase, and serum creatinine were collected. These variables were examined via multivariate logistic and Cox regression analyses to determine factors independently associated with rhabdomyolysis, AKI, and death. RESULTS: Of 6,011 admissions identified, a total of 2,109 patients met inclusion criteria and were included for analysis. Rhabdomyolysis, defined as creatine kinase greater than 5,000 U/L, was present in 656 subjects (31.1%). Risk factors for rhabdomyolysis identified on multivariable analysis included injuries to the abdomen and extremities, increased ISS, male sex, explosive mechanism of injury, and shock index greater than 0.9. After adjustment, patients with rhabdomyolysis had a greater than twofold increase in the odds of AKI. In the analysis for mortality, rhabdomyolysis was significantly associated with death until AKI was added, at which point it lost statistical significance. CONCLUSION: We found that rhabdomyolysis is associated with the development of AKI in combat casualties. While rhabdomyolysis was strongly associated with mortality on the univariate model and in conjunction with both ISS and age, it was not associated with mortality after the inclusion of AKI. This suggests that the effect of rhabdomyolysis on mortality may be mediated by AKI. LEVEL OF EVIDENCE: Prognostic and epidemiologic study, level III.

Comparison of Subcutaneous Regular Insulin and Lispro Insulin in Diabetics Receiving Continuous Nutrition: A Numerical Study.

BACKGROUND: Optimal management of non-critically ill patients with diabetes maintained on continuous enteral feeding (CEN) is poorly defined. Subcutaneous (SQ) lispro and SQ regular insulin were compared in a simulated type 1 and type 2 diabetic patient receiving CEN. METHOD: A glucose-insulin feedback mathematical model was employed to simulate type 1 and type 2 diabetic patients on CEN. Each patient received 25 SQ injections of regular insulin or insulin lispro, ranging from 0-6 U. Primary endpoints were the change in mean glucose concentration (MGC) and change in glucose variability (GV); hypoglycemic episodes were also reported. The model was first validated against patient data. RESULTS: Both SQ insulin preparations linearly decreased MGC, however, SQ regular insulin decreased GV whereas SQ lispro tended to increase GV. Hourly glucose concentration measurements were needed to capture the increase in GV. In the type 2 diabetic patient, "rebound hyperglycemia" occurred after SQ lispro was rapidly metabolized. Although neither SQ insulin preparation caused hypoglycemia, SQ lispro significantly lowered MGC compared to SQ regular insulin. Thus, it may be more likely to cause hypoglycemia. Analyses of the detailed glucose concentration versus time data suggest that the inferior performance of lispro resulted from its shorter duration of action. Finally, the effects of both insulin preparations persisted beyond their duration of actions in the type 2 diabetic patient. CONCLUSIONS: Subcutaneous regular insulin may be the short-acting insulin preparation of choice for this subset of diabetic patients. Clinical trial is required before a definitive recommendation can be made.

A diagnostic evolution: surgical experience with popliteal artery entrapment syndrome at a military tertiary referral center.

BACKGROUND: Popliteal artery entrapment syndrome (PAES) is an increasingly encountered disorder that typically presents as claudication in young and active individuals. However, despite the increased recognition, accurate preoperative diagnosis can be difficult. The objective of this study was to describe the surgical assessment and outcomes of patients treated for PAES. METHODS: Retrospective case series of all patients managed surgically for a diagnosis of PAES at the San Antonio Military Medical Center from 2005 to 2013. RESULTS: Over 8 years, PAES was surgically treated in 25 consecutive limbs of 15 patients (mean age, 35; range, 21-49) in a military tertiary medical center. Type III was the most common variant (n = 13, 52%), followed by type VI (n = 7, 28%). Most patients presented with class I or II ischemia (88%), with anterolateral symptoms (56%), and were referred by orthopedics (66%). Diagnostic work-up included stress ankle-brachial indices, magnetic resonance imaging (MRI) and provocative angiography. Sixty-three percent of limbs with negative MRI demonstrated findings consistent with either type III or V PAES. Tendon release was used in those with types III and V, whereas liberal myectomy was used in those with types I, II, or VI. Two patients required revascularization. At a median follow-up of 126 days (range, 25 days-7 years), 83% of patients with type III demonstrated partial resolution of symptoms. Only 27% of patients without an identifiable muscle slip had clinical improvement. CONCLUSIONS: Despite modern imaging, open surgical exploration remains the definitive diagnostic modality for PAES. Patients with a muscular or tendinous slip identified intraoperatively have the best clinical outcomes. Those with no identifiable muscle slip (functional entrapment) are less likely to demonstrate clinical improvement. Further evaluation on outcomes in the management in PAES is warranted.

A technique for endograft relining of a type IV endoleak using a surgeon-modified internal gate.

Type IV endoleaks represent a rare etiology of late endograft failure; however, depending on the location, they can be extremely challenging to repair with endovascular solutions. We present a method of endograft relining that preserves antegrade limb perfusion, avoids extra-anatomic reconstructions, and ensures complete endograft exclusion.

Mechanism of stent failure in a patient with fibromuscular dysplasia following renal artery stenting.

Endovascular techniques used in the management of renal artery stenosis (RAS) have unique complications, to include stent facture, thrombosis, aneurysm formation, migration, and in-stent restenosis. Described here is an unusual complication of renal artery obstruction and recurrent hypertension without progressive loss of renal function, secondary to intermittent arterial kinking with respiratory and cardiac motion in a patient with fibromuscular dysplasia. This mechanical complication has implication not only in successful endovascular treatment of RAS, but raises questions regarding the alterations in dynamic motion with the cardio-respiratory cycle in stented visceral arteries in other vascular pathologies requiring renal artery stenting (i.e., juxtarenal or pararenal aortic aneurysms).

Validation of the Short Musculoskeletal Function Assessment in patients with battlefield-related extremity vascular injuries.

OBJECTIVE: Vascular extremity injuries can be a significant burden on a patient's long-term quality of life. Currently, no limb-specific surveys have been used to quantify the relation between injury pattern and the resultant physical or psychological impact. The objective of this study was to validate the use of the Short Musculoskeletal Function Assessment (SMFA) in the setting of extremity vascular injury. METHODS: The Joint Theater Trauma Registry was queried and filtered for U.S. troops with an extremity vascular injury isolated to a single limb. Injury and management data were obtained, and the SMFA was administered after patient contact and consent. Validity was analyzed by characterization of SMFA score distribution, correlation with 36-Item Short Form Health Survey (SF-36) scores, and assessment of its discriminative capability to external measures of injury severity (ie, Injury Severity Score [ISS], Mangled Extremity Severity Score [MESS], and Medicare Part A disability qualification). RESULTS: At mean follow-up of 5 years, 164 patients (median age, 25 years; interquartile range, 22-31 years) completed both surveys. The overall SMFA Dysfunction Index was 24.8 ± 15.2 (range, 0-78; skewness, 0.60; floor/ceiling effect, 0%-1.2%; and nonresponse, 0%), and the overall Bother Index was 29.4 ± 20.2 (range, 0-96; skewness, 0.58; floor/ceiling effect, 0%-4.3%; and nonresponse, 0.6%). SF-36 physical component summary scores correlated inversely with the Dysfunction Index (r = -0.64; P < .01), whereas mental component summary scores correlated inversely with the Bother Index (r = -0.59; P < .01). No difference was found in reported scores between those considered severely injured (ISS > 15) and those not severely injured (ISS ≤ 15). However, those with mangled extremities (MESS ≥ 7) reported higher Dysfunction and Bother indices than those with lower scores (P < .05). In addition, patients considered disabled (per Medicare Part A qualifications) reported higher Dysfunction and Bother indices compared with those not considered disabled (P < .05). CONCLUSIONS: Use of the SMFA is validated in those with extremity vascular injuries, and it should be considered an adjunctive tool in evaluating long-term patient outcomes.

Magnetic resonance imaging: occult popliteal artery entrapment syndrome in a young soldier.

BACKGROUND: Popliteal artery entrapment syndrome (PAES) is frequently misdiagnosed because of symptom overlap with other conditions and lack of a definitive diagnostic modality. The incidence is widely variable, although it should be considered in all patients under 50 years with symptoms of lower extremity claudication. Long-term sequelae of PAES include critical limb ischemia, arterial occlusion, and aneurysm formation caused by repetitive external compression. METHODS: We review the case of a 27-year-old soldier originally treated for exertional compartment syndrome with fasciotomies without relief of symptoms. Magnetic resonance imaging (MRI) failed to demonstrate an aberrant slip of the gastrocnemius muscle, which was ultimately found and released on surgical exploration. RESULTS: Surgical exploration and release of an aberrant band of gastrocnemius muscle through a medial approach resulted in significant relief of symptoms and improvement of walking distance. CONCLUSIONS: Healthy athletes without peripheral vascular disease and symptomatic calf and foot claudication should have an early referral to vascular surgery. The risk of false-negative MRI warrants further investigation into provocative, noninvasive imaging modalities to properly classify PAES. This report reviews the literature to discuss the diagnostic challenges, natural history of disease, and surgical interventions for PAES.