Canagliflozin Mitigates Acute Kidney Injury Secondary to Resuscitative Endovascular Balloon Occlusion of the Aorta in a Porcine Model of Hemorrhagic Shock.

OBJECTIVE: We investigated the potential of acute canagliflozin administration to mitigate acute kidney injury (AKI) and attenuate deleterious pro-inflammatory cytokine release in a clinically relevant swine model of severe renal ischemia reperfusion injury (IRI) induced by hemorrhage and aortic occlusion. BACKGROUND: Long-term canagliflozin use attenuates renal function decline and reduces AKI in diabetes mellitus and heart failure patients. Whilst several reports indicate prophylactic SGLT2 inhibition prevents AKI in IRI, the efficacy of acute administration on IRI and inflammation is not known. METHODS: Female swine (n=16) underwent controlled hemorrhage of 25% blood volume, followed by 90 min of aortic occlusion at the level of the renal ostia (via Resuscitative Endovascular Balloon Occlusion of the Aorta). A single 300 mg dose of oral canagliflozin or vehicle (saline) was delivered 5 mins into aortic occlusion. Hemodynamic monitoring, markers of renal function (serum creatinine, blood urea nitrogen, proteinuria and urinary neutrophil gelatinase-associated lipocalin) and serum cytokine concentrations (including interleukins: IL-1RA, IL-6, IL-8, IL-10, IL-18; and Tumor necrosis factor alpha) were analyzed after IRI, and during a 6h critical care phase. RESULTS: Compared to controls, animals receiving canagliflozin had less severe AKI, improved creatinine clearance, reduced proteinuria, and significantly lower tubular damage as evidenced by histopathology and urinary NGAL. Furthermore, the pro-inflammatory cytokine IL-6 was markedly attenuated without reduction in anti-inflammatory cytokines (IL-1RA and IL-10). CONCLUSIONS: A single dose of canagliflozin administered shortly into ischemic insult mitigates AKI and attenuates harmful pro-inflammatory cytokine release following trauma or surgery. These findings suggest a potential novel therapeutic role for canagliflozin in mitigating the effects of renal IRI worthy of further investigation.

The degree of aortic occlusion in the setting of trauma alters the extent of acute kidney injury associated with mitochondrial preservation.

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is used to control noncompressible hemorrhage not addressed with traditional tourniquets. However, REBOA is associated with acute kidney injury (AKI) and subsequent mortality in severely injured trauma patients. Here, we investigated how the degree of aortic occlusion altered the extent of AKI in a porcine model. Female Yorkshire-cross swine (n = 16, 68.1 ± 0.7 kg) were anesthetized and had carotid and bilateral femoral arteries accessed for REBOA insertion and distal and proximal blood pressure monitoring. Through a laparotomy, a 6-cm liver laceration was performed and balloon inflation was performed in zone 1 of the aorta for 90 min, during which animals were randomized to target distal mean arterial pressures of 25 or 45 mmHg via balloon volume adjustment. Blood draws were taken at baseline, end of occlusion, and time of death, at which point renal tissues were harvested 6 h after balloon deflation for histological and molecular analyses. Renal blood flow was lower in the 25-mmHg group (48.5 ± 18.3 mL/min) than in the 45-mmHg group (177.9 ± 27.2 mL/min) during the occlusion phase, which recovered and was not different after balloon deflation. AKI was more severe in the 25-mmHg group, as evidenced by circulating creatinine, blood urea nitrogen, and urinary neutrophil gelatinase-associated lipocalin. The 25-mmHg group had increased tubular necrosis, lower renal citrate synthase activity, increased tissue and circulating syndecan-1, and elevated systemic inflammatory cytokines. The extent of renal ischemia-induced AKI is associated with the magnitude of mitochondrial biomass and systemic inflammation, highlighting potential mechanistic targets to combine with partial REBOA strategies to prevent AKI.NEW & NOTEWORTHY Large animal models of ischemia-reperfusion acute kidney injury (IR-AKI) are lacking. This report establishes a titratable IR-AKI model in swine in which a balloon catheter can be used to alter distal pressures experienced by the kidney, thus controlling renal blood flow. Lower blood flow results in greater renal dysfunction and structural damage, as well as lower mitochondrial biomass, elevated systemic inflammation, and vascular dysfunction.

A Novel Sutureless Anastomotic Device in a Swine Model: A Proof of Concept Study.

INTRODUCTION: Vascular reconstruction requires technical expertise and is often time consuming. As a novel alternative to traditional hand-sewn vascular anastomoses, the VasoLock (VL), is a nonabsorbable, sutureless anastomosis device with traction anchors designed to hold free artery ends together. These anchors do not penetrate the vessel wall but adhere by leveraging the elasticity of the vessels to fasten blood vessels together. This pilot study assesses the performance and patency of this novel device in a porcine model of femoral artery injury. METHODS: Female swine (n = 7) underwent femoral artery exposure for a total of 10 VL implanted. Study animals underwent hemodilution to a target hematocrit of 15% and ROTEM was used to assess coagulopathy, followed by an arterial injury via transection. The VL was inserted without any sutures. Flow-probe monitors were positioned proximal and distal to the device and flow rates were measured continuously for a total of 90 min. Flow was analyzed and presented as a ratio of distal to proximal flow with the slope of this ratio across time subsequently determined. Angiographic assessment was completed to evaluate for patency and technical complications after 90 min of implant. RESULTS: The average animal weight was 44.1 ± 3.2 kg. The average mean arterial pressure at the time of implant was 51.2 ± 7.8 mmHg, median heart rate was 77.4 (IQR = 77.25-157.4) beats per minute, and average temperature was 36.1 ± 1.5°C. The baseline hematocrit was 13.5 ± 3.0%, average pH was 7.20 ± 0.1, average clotting time was 154.1 ± 58.7 s and average clot formation time was 103.4 ± 10.9 s all demonstrating the acidotic, hypothermic, and coagulopathic state of the swine at the time of insertion. During the 90-min observation period, the average flow gradient identified across the VL was 0.99 ± 0.24, indicating no significant change in flow across the VL. The average slope of the gradients was 0.0005 (P = 0.22), suggesting the ratio of proximal and distal flow did not change over the 90 min. Following 90 min of dwell time, all VL were patent without technical complication. Angiographic assessment at 90 min demonstrated no evidence of dissection, device migration, arterial extravasation, or thromboembolism with any of the 10 devices. CONCLUSIONS: This pilot study demonstrated technical feasibility of the novel VL device over a 90-min observation period. All VL were patent and no negative events or complications were identified. This technology demonstrated significant promise in a coagulopathic state: additional investigation, involving long-term survival, is warranted for further validation.

Lower Extremity Extracorporeal Distal Revascularization in a Swine Model of Prolonged Extremity Ischemia.

BACKGROUND: Acute arterial occlusion of the lower extremity is a time-dependent emergency that requires prompt revascularization. Lower extremity extracorporeal distal revascularization (LEEDR) is a technique that can be initiated bedside when definitive therapy is delayed. The aim of this study is to evaluate this technique in a swine model of prolonged extremity ischemia. METHODS: Anesthetized swine underwent right femoral and left posterior tibial artery cannulation, left iliac venous flow monitoring (mL/min), and continuous left anterior compartment pressure (CP) monitoring (mm Hg). The iliac artery was clamped for 6 hr. LEEDR animals underwent 5 hr of extracorporeal femoral-to-tibial blood flow at 150 mL/min; controls had no intervention. At 6 hr, LEEDR was discontinued, iliac flow restored, and anterior CP monitored for 3 hr. RESULTS: Baseline characteristics were similar across both the groups. Iliac clamping saw an expected fall in iliac venous flow (258 ± 30 to 82 ± 19; P < 0.001). LEEDR resulted in a rise in iliac venous flow (82 ± 20 to 181 ± 16; P < 0.001); control arm flow remained reduced (71 ± 8; P < 0.001). Once inflow was restored, venous flow returned to baseline. Revascularization provoked a higher peak CP in the control arm versus in the LEEDR group (25 ± 5 vs. 6 ± 1; P = 0.02). CONCLUSIONS: An extracorporeal circuit can temporarily revascularize an extremity in a swine model of prolonged ischemia, mitigating reperfusion injury and maintaining normal CPs. This concept should undergo further evaluation as a bedside tool to mitigate extremity ischemia prior to definitive revascularization.

Impact of Ischemia Duration on Lower Limb Salvage in Combat Casualties.

INTRODUCTION: The 6-hour threshold to revascularization of an ischemic limb is ubiquitous in the trauma literature, however, contemporary evidence suggests that this threshold should be less. This study aims to characterize the relationship between the duration of limb ischemia and successful limb salvage following lower extremity arterial trauma. METHODS: This is a cohort study of the United States and UK military service members injured while serving in Iraq or Afghanistan between 2003 and 2013. Consecutive patients who sustained iliac, femoral, or popliteal artery injuries, and underwent surgery to attempt revascularization, were included. The association between limb outcome and the duration of limb ischemia was assessed using the Kaplan-Meier method. RESULTS: One hundred twenty-two patients (129 limbs) who sustained iliac (2.3%), femoral (56.6%), and popliteal (41.1%) arterial injuries were included. Overall, 87 limbs (67.4%) were successfully salvaged. The probability of limb salvage was 86.0% when ischemia was ≤1 hour; 68.3% when between 1 and 3 hours; 56.3% when between 3 and 6 hours; and 6.7% when >6 hours ( P <0.0001). Shock more than doubled the risk of failed limb salvage [hazard ratio=2.42 (95% confidence interval: 1.27-4.62)]. CONCLUSIONS: Limb salvage is critically dependent on the duration of ischemia with a 10% reduction in the probability of successful limb salvage for every hour delay to revascularization. The presence of shock significantly worsens this relationship. Military trauma systems should prioritize rapid hemorrhage control and early limb revascularization within 1 hour of injury.

Revascularization of acute inferior vena cava thrombosis and atresia in an adolescent.

Inferior vena cava (IVC) anomalies will remain silent until collateralized venous drainage has been lost. The initial signs can be subtle, including back pain, and are often missed initially until progressive changes toward motor weakness, phlegmasia cerulea dolens, and/or renal impairment have occurred. We have presented a case of acute occlusion of an atretic IVC and infrarenal collateral drainage in an adolescent patient, who had been treated with successful thrombolysis, thrombectomy, and endovascular revascularization for IVC stenting and reconstruction.

Preliminary Experience With the Human Acellular Vessel: A Descriptive Case Series Detailing Early Use of a Bioengineered Blood Vessel for Arterial Repair.

BACKGROUND: An infection-resistant, immediately available conduit for trauma and urgent vascular reconstruction remains a critical need for successful limb salvage. While autologous vein remains the gold standard, vein-limited patients and size mismatch are common issues. The Human Acellular Vessel (HAV) (Humacyte, Inc., Durham, NC) is a bioengineered conduit with off-the-shelf availability and resistance to infection, ideal characteristics for patients with challenging revascularization scenarios. This report describes HAV implantation in patients with complex limb-threatening ischemia and limited conduit options who may have otherwise faced limb loss. METHODS: The Food and Drug Administration (FDA) expanded-access program was used to allow urgent implantation of the HAV for arterial reconstruction. Electronic medical records were reviewed with extraction of relevant data including patient demographics, surgical implantation, patency, infectious complications, and mortality. RESULTS: The HAV was implanted in 8 patients requiring vascular reconstruction. Graft or soft tissue infection was present in 2 patients. One patient with severe penetrating pelvic injury had 4 HAV placed to repair bilateral external iliac artery and vein injuries. There was 1 technical failure due to poor outflow, 2 patients died unrelated to HAV use, and 5 lower extremity bypasses maintained patency at an average of 11.4 months (range: 4-20 months). No HAV infectious complications were identified. CONCLUSIONS: This report is the first United States series describing early outcomes using the HAV under the FDA expanded-access program for urgent vascular reconstruction. The HAV demonstrates resistance to infection, reliable patency, and offers surgeons an immediate option when confronted with complex revascularization scenarios. Assessment of long-term outcomes will be important for future studies.

Surgical Deep Vein Arterialization: Adding to the Armamentarium of Complex Limb Salvage.

BACKGROUND: Patients with severe peripheral arterial disease with limited or nonexistent arterial runoff, the so-called "desert foot", challenge efforts at limb preservation. Deep vein arterialization (DVA) involves incorporating a venous target as an outflow to achieve revascularization in these complex patients. We report outcomes in an initial series of patients undergoing DVA as a component of surgical bypass. METHODS: Over a 2-year period, 10 patients underwent bypass incorporating DVA due to severely disadvantaged runoff using a heparin-bonded expanded polytetrafluoroethylene conduit. Indications for surgery included tissue loss (8) or ischemic rest pain (2) in patients who had failed endovascular (3) or surgical (7) revascularization. Inflow arteries for bypass ranged from external iliac to below knee popliteal. Outflow anastomoses incorporated a common ostium arteriovenous fistula between anterior tibial (5), posterior tibial (2), peroneal (1) or plantaris pedis (2) arteries, and corresponding tibial veins. Prior to anastomotic completion, tibial vein valves were lysed to allow venous arterialization by a way of retrograde flow. Postoperative medical regimen included dual antiplatelet (2), antiplatelet plus anticoagulation (7), or anticoagulation alone (1). RESULTS: Primary patency was maintained in 7 of 10 grafts (average: 4.1 months, range: 1-18 months). Limb salvage was achieved in 8 of 10 patients (average: 6 months, range: 1-18 months). Two below knee amputations were performed after graft occlusion due to extensive tissue loss and infection, whereas 1 patient maintained limb salvage despite graft occlusion after successful wound healing. CONCLUSIONS: This initial experience describes surgical DVA using a prosthetic conduit in conjunction with an arteriovenous fistula at the distal anastomosis in patients with threatened limb loss and severely disadvantaged tibial runoff. Although evidence for long-term efficacy is uncertain, preliminary outcomes warrant further investigation as this technique may allow for surgical revascularization resulting in limb preservation for patients with no other alternative than amputation.

Maximizing Benefit of Virtual Learning: Lessons From the Coronavirus Disease 2019 Pandemic.

INTRODUCTION: The coronavirus disease 2019 pandemic has profoundly impacted surgical education. We assessed resident perceptions of our virtual academic program, which consists of daily lectures or case conferences held via a videoconferencing platform. METHODS: A survey evaluating attitudes and practices for virtual academics was administered to general surgery residents. A focus group was conducted to identify benefits, barriers to engagement, and opportunities for improvement for virtual education. A total of 19 residents completed the education survey, and seven residents participated in the focus group. RESULTS: While expressing preference toward in-person academics (84.2%), residents felt the virtual academics were of good quality (median rating 4/5) and preferred virtual academics to no academic sessions (94.7%). Of respondents, 57.9% believe that the coronavirus pandemic negatively impacted their surgical education. They believe their American Board of Surgery In-Training Examination preparation was not impacted. Residents preferred using a computer over a phone for academics (79% versus 16%). The focus group identified the benefits of virtual academics, including the ability to participate while away and having recordings available. Areas for improvement included reinforcement of protected time for academics, requiring cameras be on, increasing in-lecture polls, and creation of an online repository of recordings for review. Residents hoped a virtual component of academics and recordings would continue past the pandemic. CONCLUSIONS: Although virtual academics are not the preferred mode of learning in our residency, there are multiple unintended benefits. We recommend a hybrid academic model with in-person didactics and recorded video for later review.

Early Fasciotomy and Limb Salvage and Complications in Military Lower Extremity Vascular Injury.

BACKGROUND: Military guidelines endorse early fasciotomy after revascularization of lower extremity injuries to prevent compartment syndrome, but the real-world impact is unknown. We assessed the association between fasciotomy and amputation and limb complications among lower extremitys with vascular injury. METHODS: A retrospectively collected lower extremity injury database was queried for limbs undergoing attempted salvage with vascular procedure (2004-2012). Limbs were categorized as having undergone fasciotomy or not. Injury and treatment characteristics were collected, as were intervention timing data when available. The primary outcome measure was amputation. Multivariate models examined the impact of fasciotomy on limb outcomes. RESULTS: Inclusion criteria were met by 515 limbs, 335 (65%) with fasciotomy (median 7.7 h postinjury). Of 212 limbs, 174 (84%) with timing data had fasciotomy within 30 min of initial surgery. Compartment syndrome and suspicion of elevated pressure was documented in 127 limbs (25%; 122 had fasciotomy). Tourniquet and shunt use, fracture, multiple arterial and combined arteriovenous injuries, popliteal involvement, and graft reconstruction were more common in fasciotomy limbs. Isolated venous injury and vascular ligation were more common in nonfasciotomy limbs. Fasciotomy timing was not associated with amputation. Controlling for limb injury severity, fasciotomy was not associated with amputation but was associated with limb infection, motor dysfunction, and contracture. Sixty-three percent of fasciotomies were open for >7 d, and 43% had multiple closure procedures. Fasciotomy revision (17%) was not associated with increased amputation or complications. CONCLUSIONS: Fasciotomy after military lower extremity vascular injury is predominantly performed early, frequently without documented compartment pressure elevation. Early fasciotomy is generally performed in severely injured limbs with a subsequent high rate of limb complications.

Using Technology to Maintain the Education of Residents During the COVID-19 Pandemic.

BACKGROUND: The COVID-19 pandemic presents a unique challenge to surgical residency programs. Due to the restrictions recommended by the Centers for Disease Control and Prevention and other organizations, the educational landscape for surgical residents is rapidly changing. In addition, the time course of these changes is undefined. METHODS: We attempt to define the scope of the problem of maintaining surgical resident education while maintaining the safety of residents, educators, and patients. Within the basic framework of limiting in-person gatherings, postponing or canceling elective operations in hospitals, and limiting rotations between sites, we propose innovative solutions to maintain rigorous education. RESULTS: We propose several innovative solutions including the flipped classroom model, online practice questions, teleconferencing in place of in-person lectures, involving residents in telemedicine clinics, procedural simulation, and the facilitated use of surgical videos. Although there is no substitute for hands-on learning through operative experience and direct patient care, these may be ways to mitigate the loss of learning exposure during this time. CONCLUSIONS: These innovative solutions utilizing technology may help to bridge the educational gap for surgical residents during this unprecedented circumstance. The support of national organizations may be beneficial in maintaining rigorous surgical education.

Analysis of Limb Outcomes by Management of Concomitant Vein Injury in Military Popliteal Artery Trauma.

BACKGROUND: Despite aggressive limb salvage attempts, military popliteal artery injuries are associated with high amputation rates. Combined arterial and venous injuries present a management dilemma for military surgeons in austere settings, and the impact of vein injury management strategy on limb outcomes is not clear. METHODS: Military casualties sustaining combined ipsilateral popliteal artery and vein injuries from 2003 to 2016 were identified from a military vascular injury database. Limbs were grouped based on whether venous ligation or repair was initially performed. The primary outcome was secondary amputation; the secondary outcomes included limb and vascular/graft complications. RESULTS: Fifty-six limbs were included; of which, 27 (48%) were managed with vein ligation and 29 (52%) with repair. Veins were repaired primarily in 13 (45%) cases with the remainder being treated with interposition grafts. Median injury severity score was higher in the ligation group (19 vs 15, P = 0.09), but vascular and concomitant limb injury characteristics were similar. Amputation rates did not differ by vein treatment (45% repair vs. 41% ligation, P = 0.76), and this held with injuries above and below the knee considered independently. Most (71%) amputations were performed <30 days from injury. Amputation was indicated more frequently for vascular repair failure in the ligated group (55% vs 15%, P = 0.04). Four graft infections were all in the repair group (P = 0.07 vs ligation). Arterial graft complications were more frequent with vein repair (45%) than ligation (30%), but this did not reach significance (P = 0.24). Only one deep vein thrombosis was diagnosed in each group (P = 0.96). CONCLUSIONS: Type of management of concomitant popliteal vein injury was not associated with early or late amputation in this series of military popliteal artery injuries. Vein injury management may have had implications for the development of arterial graft and limb complications, however. Surgical decision-making regarding popliteal vein treatment should balance short-term contingencies with long-term limb salvage issues.

Impact of Staged Vascular Management on Limb Outcomes in Wartime Femoropopliteal Arterial Injury.

BACKGROUND: By necessity, wartime arterial injuries undergo staged management. Initial procedures may occur at a forward surgical team (role 2), where temporary shunts can be placed before transfer to a larger field hospital (role 3) for definitive reconstruction. Our objective was to evaluate the impact of staging femoropopliteal injury care on limb outcomes. METHODS: A military vascular injury database was queried for Iraq/Afghanistan casualties with femoropopliteal arterial injuries undergoing attempted reconstruction (2004-2012). Cases were grouped by initial arterial management: shunt placed at role 2 (R2SHUNT), reconstruction at role 2 (R2RECON), and initial management at role 3 (R3MGT). The primary outcome was limb salvage; secondary outcomes were limb-specific complications. Descriptive and intergroup comparative statistics were performed with significance defined at P ≤ 0.05. RESULTS: Of 257 cases, all but 4 had definitive reconstruction before evacuation to Germany (median, 2 days): 46 R2SHUNT, 84 R2RECON, and 127 R3MGT; median Mangled Extremity Severity Score was 6 for all groups. R2SHUNT had median extremity Abbreviated Injury Scale--vascular of 4 (other groups, 3; P < 0.05) and was more likely to have concomitant venous injury and to undergo fasciotomy. Shunts were used for 5 ± 3 hr. About 24% of R2RECON repairs were revised at role 3. Limb salvage rate of 80% was similar between groups, and 62% of amputations performed within 48 hr of injury. Rates of limb and composite graft complications were similar between groups. Thrombosis was more common in R2SHUNT (22%) than R2RECONST (6%) or R3MGT (12%) (P = 0.03). Late (>48 hr) thrombosis rates were similar, whereas 60% of R2SHUNT thromboses occurred on day of injury (P = 0.003 vs. 25% and 0%). CONCLUSIONS: Staged femoropopliteal injury care is associated with similar limb salvage to initial role 3 management. Early thrombosis is likely because of shunt failure but does not lead to limb loss. Current military practice guidelines are appropriate and may inform civilian vascular injury management protocols.

Venovenous bypass using continuous renal replacement therapy and endovascular inferior vena cava reconstruction to treat bilateral massive iliocaval deep venous thrombosis.

Many inferior vena cava (IVC) anomalies remain asymptomatic because of collateral circulation, but thrombosis of these channels can cause acute deep venous thrombosis with serious sequelae. For those with threatened limbs, anticoagulation is the mainstay of treatment, with endovascular pharmacomechanical thrombolysis replacing open surgical thrombectomy. Described is a severe case of massive iliocaval deep venous thrombosis with bilateral lower extremity Rutherford IIb acute limb ischemia in a patient with congenital IVC atresia. After initial thrombolysis, endovascular IVC reconstruction was accomplished to decompress the lower extremities. The patient ultimately required a right through-knee amputation but remains ambulatory with a prosthetic.

Attrition Rate in Military General Surgery GME and Effect on Quality of Military Programs.

INTRODUCTION: The attrition rate in civilian general surgery Graduate Medical Education (GME) is estimated at 20%, while estimates of attrition in military general surgery (MGS) GME programs using the same methodology are nearly twice that. We sought to identify the true attrition rate in MGS GME, identify factors influencing attrition, and examine the relationship between attrition and quality of MGS GME. METHODS: Deidentified data were collected on categorical general surgery residents matriculating from 2010 to 2013 from all 12 MGS residency programs. Information gathered included gender, medical degree, marital status, location of program, presence of a military-related interruption in training, and age at start of the categorical contract. For those who did not graduate, data on postgraduate year at time of attrition, reasons for attrition, and deficiencies in core competencies were solicited. To assess the effect of true attrition rate on graduate performance, we compared the published 5-year American Board of Surgery qualifying exam/certifying exam first time pass rates between military and civilian programs. RESULTS: One hundred eighty-four categorical residents matriculated from 2010 to 2013. Fifty six (31.5 %) were women, 151 (62.1%) were MD's, 103 (56%) were married, 172 (93.5%) were less than 35 years old, and 33 (17.9%) had a military-related interruption in training. Nineteen individuals left residency prior to graduation (15 resigned, 2 resigned in lieu of termination, 2 terminated) for an overall attrition rate of 10.3%. The most common year for attrition was PGY-3 (31.6%) and most common reason for resignation was changing to a different subspecialty (73.3%). Men and women had equal attrition rates (10.3%), and there was no meaningful difference between MD's and DO's (9.9% vs 12.1%, p = 0.71) or region of training (10.6% East vs 9.1% West, p = 0.73). However, those who were not married, had a militarily mandated interruption in training and started their categorical training over the age of 35 had higher attrition rates (married 5.6%, not married 15%, p = 0.04, interruption 16% vs no interruption 9%, p = 0.1; Age ≥ 35 33.3% vs age < 35 6.7%, p < 0.01). Comparison of American Board of Surgery (ABS) first time pass rates over a similar time period showed that military programs performed statistically discernibly better than civilian programs (82% ± 12 vs 75% ± 13, p = 0.047). CONCLUSIONS: Previous used methodology over estimates the attrition rate in MGS GME. The lower rate in MGS programs results in a high level of graduate performance as measured by ABS pass rates. Interruption in training and especially marital status and age ≥ 35 appear to be potential predictors of attrition. Components of MGS GME training and selection processes might inform efforts to reduce attrition and improve performance in civilian surgical GME.

Successful Use of Nellix and Endovascular Aortic Sealing Technology for Treatment of Aortic Rupture in a Porcine Model.

BACKGROUND: Endovascular aortic sealing (EVAS) represents a recent transformation in approach for treatment of aortic aneurysms. Initial reporting has shown that EVAS using the Nellix device is safe with similar complication rates to standard endovascular aortic repair (EVAR). What remains unknown is how EVAS technology will behave in the ruptured setting. The purpose of this report is to discuss how EVAS system and endobag technology behave when deployed in a porcine model of aortic rupture. METHODS: A controlled left retroperitoneal rupture was created in 20 large swine. Following rupture, an EVAS system was deployed across the rupture site to seal the area. The primary end point was seal from ongoing hemorrhage. Other parameters were examined to include endobag extravasation, aortic wall pressure measurements and device behavior in a live tissue model. RESULTS: Of the EVAS systems used, 15 Nellix (Endologix, Irvine, CA) devices and 5 novel EVAS systems were used. Of the correctly deployed devices, 100% sealed the rupture (n = 19). One device was deployed above the rupture site, and seal was not achieved secondary to malpositioning. Endobag extravasation was seen with an average protrusion of 7.7 mm. No other areas of aortic injury were noted secondary to endobag trauma. Pressure recording from behind the endobag indicates loss of pulsatile flow to the aortic wall with polymer curing. CONCLUSIONS: Endovascular aortic sealing for rupture is feasible and performs well in a porcine model of aortic rupture. Polymer extravasation is seen and may be controllable by the implanter. Once the polymer has cured, pulsatile aortic wall pressure is no longer present. EVAS represents an emerging technology for treatment of aortic rupture.

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.

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.

Technical aspects of branched graft aortic reconstruction in patients with connective tissue disorders.

Connective tissue disorders (CTDs) predispose patients to dilation of the entire aorta, resulting in the development of extensive aneurysms. Aortic reconstruction in CTD patients can be challenging and demands specific approaches to ensure initial success and lasting stability of aortic repair. Herein, we describe technical approaches to aortic reconstruction in patients with CTDs and briefly report our outcomes on the use of branched grafts for reconstruction in this unique population of patients. We conclude that aortic reconstruction in CTD patients with branched grafts can be performed safely, with a low morbidity and mortality and excellent branch patency. Branched surgical grafts should be used preferentially over the inclusion patch technique during open repair to minimize the late development of patch aneurysms.

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.