Implications and Late Outcomes of Type II Endoleaks After Endovascular Aneurysm Repair.

OBJECTIVE: Type II endoleaks (T2EL) are the most common cause of reintervention after endovascular aneurysm repair (EVAR). While most resolve spontaneously, the long-term implications of T2EL remain elusive. We aim to evaluate the impact of persistent and late T2EL on clinical outcomes after EVAR. METHODS: Single institution retrospective review of patients who underwent EVAR for degenerative infrarenal abdominal aortic aneurysm between January 2010 and June 2022 with no Type I (T1EL) or III (T3EL) endoleak seen at EVAR completion. Patients were categorized based on T2EL status. Group 1 included patients with never detected or transient T2EL (detected at EVAR completion but not after). Group 2 encompassed persistent T2EL (seen at EVAR completion and again during follow-up) and late T2EL (detected for the first time at any point during follow-up). Time-to-event analysis was conducted using a time-dependent approach to T2EL status. Primary outcomes included freedom from sac enlargement (SE), aneurysm-related reinterventions, and overall survival. RESULTS: 803 patients met inclusion criteria. Group 1 included 418 patients (52%), of which 85% had no T2EL and 15% had transient T2EL. Group 2 had 385 patients; 23% had persistent T2EL, and 77% developed a new T2EL. Patients in group 1 had a higher prevalence of smoking (88% vs. 83%; p<0.001), COPD (33% vs. 25%; p=0.008), chronic kidney disease (13% vs. 8%; p=0.021) and a higher mean SVS score (7 vs. 6 points; p=0.049). No differences were found in aneurysm diameter or morphology. Mean follow-up was 5 years for the entire cohort. In Group 2, 58 patients (15%) underwent T2EL treatment, most commonly transarterial embolization. At 10 years after EVAR, Group 2 was associated with lower freedom from SE (p<0.001) and AAA-related reinterventions (p<0.001) and comparable overall survival (p=0.42). More T1EL were detected during follow-up in Group 2 (6 [1%] vs. 20 [5%]; p=0.004), with 15 (75%) of these detected at a median of 3 years after the T2EL. No difference between groups was observed in explant (0.7% vs. 2.1%; p=0.130) or aneurysm rupture (0.5% vs. 1.3%; p=0.269) rates. CONCLUSION: One-half of patients treated with infrarenal EVAR developed persistent/late T2ELs, which are associated with a higher risk of sac enlargement and reinterventions. No difference in overall survival or aneurysm rupture risk was seen at 10 years, based on T2EL status or T2EL intervention. A conservative approach to T2EL may be appropriate for most patients with absent T1EL or T3EL.

Skull and Scalp En-Bloc Harvest Protects Calvarial Perfusion: A Cadaveric Study.

BACKGROUND: Calvarial defects are severe injuries that can result from a wide array of etiologies. Reconstructive modalities for these clinical challenges include autologous bone grafting or cranioplasty with biocompatible alloplastic materials. Unfortunately, both approaches are limited by factors such as donor site morbidly, tissue availability, and infection. Calvarial transplantation offers the potential opportunity to address skull defect form and functional needs by replacing "like-with-like" tissue but remains poorly investigated. METHODS: Three adult human cadavers underwent circumferential dissection and osteotomy to raise the entire scalp and skull en-bloc. The vascular pedicles of the scalp were assessed for patency and perfused with color dye, iohexol contrast agent for computed tomography (CT) angiography, and indocyanine green for SPY-Portable Handheld Imager assessment of perfusion to the skull. RESULTS: Gross changes were appreciated to the scalp with color dye, but not to bone. CT angiography and SPY-Portable Handheld Imager assessment confirmed perfusion from the vessels of the scalp to the skull beyond midline. CONCLUSION: Calvarial transplantation may be a technically viable option for skull defect reconstruction that requires vascularized composite tissues (bone and soft tissue) for optimal outcomes.

Outcomes of lower extremity arterial bypass using the Human Acellular Vessel in patients with chronic limb-threatening ischemia.

OBJECTIVE: Patients with chronic limb-threatening ischemia (CLTI) and no great saphenous vein to use as a conduit for arterial bypass have a high risk for amputation despite advances in medical and endovascular therapies. This report presents findings from a U.S. Food and Drug Administration (FDA) supported study of the Human Acellular Vessel (HAV) (Humacyte Inc.) used as a conduit for arterial bypass in patients with CLTI and inadequate or absent autologous conduit. METHODS: The HAV is a 6-mm, 40-cm vessel created from human vascular smooth muscle cells seeded onto a polyglycolic acid scaffold pulsed in a bioreactor for 8 weeks as cells proliferate and the scaffold dissolves. The resultant vessel is decellularized, creating a nonimmunogenic conduit composed of collagen, elastin, and extracellular matrix. The FDA issued an Investigational New Drug for an intermediate-sized, single-center study of the HAV under the agency's Expanded Access Program in patients with advanced CLTI and inadequate or absent autologous conduit. Technical results and clinical outcomes were analyzed and reported. RESULTS: Between March 2021 and July 2023, 29 patients (20 males; mean age, 71 ± 11 years) underwent limb salvage operation using the HAV as a bypass conduit. Most patients had advanced CLTI (Rutherford class 5/6 in 72%; wound, ischemia, and foot infection stage 3/4 in 83%), and 97% had previously failed revascularization(s) of the extremity. Two HAVs were sewn together to attain the needed bypass length in 24 patients (83%). Bypasses were to tibial arteries in 23 patients (79%) and to the popliteal artery in 6 (21%). Technical success was 100%, and the 30-day mortality rate was 7% (2 patients). With 100% follow-up (median, 9.3 months), the limb salvage rate was 86% (25/29 patients). There were 16 reinterventions to restore secondary patency, of which 15 (94%) were successful. Primary and secondary patency of the HAV at 9 months were 59% and 71%, respectively. CONCLUSIONS: The HAV has demonstrated short- to intermediate-term safety and efficacy as an arterial bypass conduit in a complex cohort of patients with limb-threatening ischemia and no autologous options. This experience using the FDA's Expanded Access Program provides real-world data to inform regulatory deliberations and future trials of the HAV, including the study of the vessel as a first-line bypass conduit in less severe cases of chronic limb ischemia.

Prehospital Resuscitation: What Should It Be?

Prehospital resuscitation is a dynamic field now being energized by new technologies and a shift in thinking regarding intravascular resuscitation. Growing evidence discourages use of intravenous (IV) crystalloid and colloid solutions in trauma, whereas blood products, particularly whole blood, are becoming preferred. Although randomized clinical trials validating definitive resuscitative protocols are still lacking, most preclinical and clinical indicators support this approach. In addition, emerging technologies such as external and endovascular hemorrhage control devices and extracorporeal perfusion are now being used routinely, even in the prehospital setting in many countries, generating new lines of emerging investigations for trauma specialists.

Identifying temporal variations in burn admissions.

BACKGROUND: Variations in admission patterns have been previously identified in non-elective surgical services, but minimal data on the subject exists with respect to burn admissions. Improved understanding of the temporal pattern of burn admissions could inform resource utilization and clinical staffing. We hypothesize that burn admissions have a predictable temporal distribution with regard to the time of day, day of week, and season of year in which they present. STUDY DESIGN: A retrospective, cohort observational study of a single burn center from 7/1/2016 to 3/31/2021 was performed on all admissions to the burn surgery service. Demographics, burn characteristics, and temporal data of burn admissions were collected. Bivariate absolute and relative frequency data was captured and plotted for all patients who met inclusion criteria. Heat-maps were created to visually represent the relative admission frequency by time of day and day of week. Frequency analysis grouped by total body surface area against time of day and relative encounters against day of year was performed. RESULTS: 2213 burn patient encounters were analyzed, averaging 1.28 burns per day. The nadir of burn admissions was from 07:00 and 08:00, with progressive increase in the rate of admissions over the day. Admissions peaked in the 15:00 hour and then plateaued until midnight (p<0.001). There was no association between day of week in the burn admission distribution (p>0.05), though weekend admissions skewed slightly later (p = 0.025). No annual, cyclical trend in burn admissions was identified, suggesting that there is no predictable seasonality to burn admissions, though individual holidays were not assessed. CONCLUSION: Temporal variations in burn admissions exist, including a peak admission window late in the day. Furthermore, we did not find a predictable annual pattern to use in guiding staffing and resource allocation. This differs from findings in trauma, which identified admission peaks on the weekends and an annual cycle that peaks in spring and summer.

Acute management of mesenteric emergencies: Tailoring the solution to the problem.

Acute mesenteric ischemia (AMI) constitutes a life-threatening problem that can result in death, multiorgan failure, and severe nutritional disability. Although AMI is a rare cause of acute abdominal emergencies, ranging between 1 and 2 individuals per 10,000, the morbidity and mortality rates are high. Arterial embolic etiology composes nearly one-half of AMIs, with a sudden onset of severe abdominal pain considered the most common symptom. Arterial thrombosis is the second most common cause of AMI, which presents similarly to arterial embolic AMI, although often more severe due to anatomic differences. Veno-occlusive causes of AMI are the third most common and are associated with an insidious onset of vague abdominal pain. Each patient is unique, and the treatment plan should be tailored to their individual needs. This may include considering the patient's age, comorbidities, and overall health, as well as their preferences and personal circumstances. A multidisciplinary approach involving specialists from different fields, such as surgeons, interventional radiologists, and intensivists, is recommended for the best possible outcome. Potential challenges in tailoring an optimal treatment plan for AMI may include delayed diagnosis, limited availability of specialized care, or patient factors that make some interventions less feasible. Addressing these challenges requires a proactive and collaborative approach, with regular review and adjustment of the treatment plan as needed to ensure the best possible outcome for each patient.

Thoracic Endovascular Aortic RepairAcutely Augments Left Ventricular Biomechanics in An Animal Model: A Mechanism for Postoperative Heart Failure and Hypertension.

BACKGROUND: Thoracic aortic stent grafts are thought to decrease aortic compliance and may contribute to hypertension and heart failure after thoracic endovascular aortic repair (TEVAR). Left ventricular (LV) biomechanics immediately after TEVAR, however, have not been quantified. Pressure-volume (PV) loop analysis provides gold-standard LV functional information. The aim of this study is to use an LV PV loop catheter and analysis to characterize the LV biomechanics before and acutely after TEVAR. METHODS: Anesthetized Yorkshire swine (N = 6) were percutaneously instrumented with an LV PV loop catheter. A 20 mm × 10 cm stent graft was deployed distal to the left subclavian via the femoral artery under fluoroscopy. Cardiac biomechanics were assessed before and after TEVAR. As a sensitivity analysis, inferior vena cava occlusion with PV loop assessment was performed pre and post-TEVAR in 1 animal to obtain preload and afterload-independent end-systolic and end-diastolic PV relationships (ESPVR and EDPVR). RESULTS: All animals underwent successful instrumentation and TEVAR. Post-TEVAR, all 6 animals had higher mean LV ESP (106 vs. 118 mm Hg, P = 0.04), with no change in the EDPVR. inferior vena cava occlusion also moved the ESPVR curve upward and leftward, indicating increased LV work per unit time. There was no augmentation of EDPVR following TEVAR (P > 0.05). Postmortem exams in all animals revealed appropriate stent placement and no technical complications. CONCLUSIONS: TEVAR was associated with an acute increase in LV end-systolic pressure and shift in the ESPVR, indicating increased ventricular work. This data provides potential mechanistic insights into the development of post-TEVAR hypertension and heart failure. Future stent graft innovation should focus on minimizing the changes in cardiac physiology.

Association of Year of Surgery and Carotid Stenting Outcomes in High-risk Patients, 2015-2021.

This cohort study quantifies the yearly trends and outcomes of transcarotid artery revascularization vs transfemoral carotid artery stenting among high-risk patients from 2015 to 2021.

Transcarotid artery revascularization in blunt carotid injury.

Introduction: Transcarotid artery revascularization (TCAR) with flow reversal has substantially changed the management of carotid artery stenosis, enabling an endovascular approach with a periprocedural stroke rate as low as or lower than that of open carotid surgery. The use of TCAR for blunt carotid artery injury has not yet been described. Methods: A review of the use of TCAR for blunt carotid artery injury was performed at a single center from October 2020 to August 2021. The patient demographics, mechanism of injury, and outcomes were collected and compared. Results: Ten carotid stents were placed via TCAR in eight patients for hemodynamically significant blunt carotid artery injuries. No periprocedural neurologic events occurred, and all stents remained patent during short-term follow-up. Conclusions: TCAR is feasible and safe in the management of significant blunt carotid artery injuries. More data are needed regarding the long-term outcomes and ideal surveillance intervals.

How to TEVAR swine for scientific research: Technical, anatomic, and device considerations to translate human TEVAR techniques into the large animal laboratory.

OBJECTIVE: Thoracic Endovascular Aortic Repair (TEVAR) is well established in humans. Despite widespread use, additional research questions related to thoracic aortic stenting and endovascular innovation require large animal models. Translating human TEVAR devices and techniques into animal models, however, is a challenge even for experienced endovascular surgeons looking to develop a large animal TEVAR model.This article describes swine-specific strategies to deploy human TEVAR stent grafts, delineate how to select, size, prepare, and re-use human stents and deployment systems in swine, and how to translate human imaging modalities to large animal TEVAR. METHODS: We describe a selection of related TEVAR models and techniques in Yorkshire swine to support scientific inquiry. This includes an animal husbandry and pre-operative preparation and planning program. All imaged specimens in this paper are castrated male Yorkshire swine in the 60-80 kg range and underwent TEVAR with the Medtronic Navion stent and deployment system. RESULTS: To study human aortic stent grafts in swine, the animals generally must be at least 50 kgs to guarantee a 2 cm internal aortic diameter at the left subclavian, and for the iliac arteries to accommodate the human deployment system. Swine will have longer torsos and shorter iliofemoral segments than a human of the same weight which can make human deployment systems too short to reach the left subclavian from the femoral arteries in larger animals. We provide techniques to overcome this, including open iliac access or upside-down carotid TEVAR, which may be particularly useful if the scientific data would be confounded by iliofemoral access.Unlike humans that present clinically with axial imaging, swine will generally not have preoperative imaging, and many translational research laboratories do not have access to inexpensive preoperative CT, or any intraoperative CT scanning, which we are fortunate to have. We describe, therefore, several strategies for imaging in this setting including TEVAR via C-arm fluoroscopy and with or without in-laboratory CT scanning. Due to the low-resource setting of most large animal laboratories, as compared to a human hybrid room, we also describe several techniques to reduce cost and reuse materials, including the stent grafts, which at the end of non-survival experiments can be recovered during necropsy, cleaned, reinserted into the deployment device and reused on additional animals. CONCLUSIONS: This article describes a collection of related techniques and tips to translate human TEVAR imaging, sizing/selection, deployment, and anatomy to swine research. Using this framework alone, an experienced human vascular or endovascular surgeon may develop a complete aortic stenting animal model with strategies for scientific data acquisition.

Exploring Intra-arterial Contrast Administration for Intraoperative Imaging Using a Swine Model.

Intraoperative computed tomography (CT) imaging with endovascular delivery of intra-arterial (IA) contrast could potentially provide higher attenuation with lower contrast volumes than intravenous (IV) administration. We aimed to compare IA and IV contrast use for organ-specific CT abdominal imaging. Five anesthetized swine had external jugular and brachial artery access with ascending aortic pigtail placement. An IV protocol was 100 mL at 5 mL/sec over 20 sec vs 50 mL of IA contrast at 5 mL/sec over 10 sec. Region-of-interest markers were applied to anatomical regions to measure attenuation (HU) over time. IA and IV contrast protocols achieved adequate aortic opacification (IA, 455 ± 289 vs IV, 450 ± 114 HU). The IA contrast aortic attenuation curve reached peak attenuation compared with IV contrast (IA, 8 vs 23 sec; P < .001). Time to peak attenuation was similar between IA and IV contrast in the portal vein (IA, 38 vs IV, 42 sec, P = .25). IA administration achieved a superior contrast-to-noise ratio (CNR) in less time compared with IV (R2 = .94; P < .001). IA contrast achieved adequate opacification with less bolus broadening and a superior CNR compared with IV contrast while using a smaller contrast volume for directed organ-directed imaging.

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.

A Pilot Machine Learning Study Using Trauma Admission Data to Identify Risk for High Length of Stay.

INTRODUCTION: Trauma patients have diverse resource needs due to variable mechanisms and injury patterns. The aim of this study was to build a tool that uses only data available at time of admission to predict prolonged hospital length of stay (LOS). METHODS: Data was collected from the trauma registry at an urban level one adult trauma center and included patients from 1/1/2014 to 3/31/2019. Trauma patients with one or fewer days LOS were excluded. Single layer and deep artificial neural networks were trained to identify patients in the top quartile of LOS and optimized on area under the receiver operator characteristic curve (AUROC). The predictive performance of the model was assessed on a separate test set using binary classification measures of accuracy, precision, and error. RESULTS: 2953 admitted trauma patients with more than one-day LOS were included in this study. They were 70% male, 60% white, and averaged 47 years-old (SD: 21). 28% were penetrating trauma. Median length of stay was 5 days (IQR 3-9). For prediction of prolonged LOS, the deep neural network achieved an AUROC of 0.80 (95% CI: 0.786-0.814) specificity was 0.95, sensitivity was 0.32, with an overall accuracy of 0.79. CONCLUSION: Machine learning can predict, with excellent specificity, trauma patients who will have prolonged length of stay with only physiologic and demographic data available at the time of admission. These patients may benefit from additional resources with respect to disposition planning at the time of admission.

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

INTRODUCTION: Injuries to the inferior vena cava (IVC), while uncommon, have a high mortality despite modern advances. The goal of this study is to describe the diagnosis and management in the largest available prospective data set of vascular injuries across anatomic levels of IVC injury. METHODS: The American Association for the Surgery of Trauma PROspective Observational Vascular Injury Treatment (PROOVIT) registry was queried from November 2013 to January 2019. Demographics, diagnostic modalities, injury patterns, and management strategies were recorded and analyzed. Comparisons between anatomic levels were made using non-parametric Wilcoxon rank-sum statistics. RESULTS: 140 patients from 19 institutions were identified; median age was 30 years old (IQR 23-41), 75% were male, and 62% had penetrating mechanism. The suprarenal IVC group was associated with blunt mechanism (53% vs 32%, P = .02), had lower admission systolic blood pressure, pH, Glasgow Coma Scale (GCS), and higher ISS and thorax and abdomen AIS than the infrarenal injury group. Injuries were managed with open repair (70%) and ligation (30% overall; infrarenal 37% vs suprarenal 13%, P = .01). Endovascular therapy was used in 2% of cases. Overall mortality was 42% (infrarenal 33% vs suprarenal 66%, P<.001). Among survivors, there was no difference in first 24-hour PRBC transfusion requirement, or hospital or ICU length of stay. CONCLUSIONS: Current PROOVIT registry data demonstrate continued use of ligation extending to the suprarenal IVC, limited adoption of endovascular management, and no dramatic increase in overall survival compared to previously published studies. Survival is likely related to IVC injury location and total injury burden.

Postoperative antiplatelet and/or anticoagulation use does not impact complication or reintervention rates after vein repair of arterial injury: A PROOVIT study.

INTRODUCTION: The use of antiplatelet (AP) and anticoagulation (AC) therapy after autogenous vein repair of traumatic arterial injury is controversial. The hypothesis in this study was that there is no difference in early postoperative outcomes regardless of whether AC, AP, both, or neither are used. METHODS: The American Association for the Surgery of Trauma (AAST) PROspective Observational Vascular Injury Treatment (PROOVIT) registry was queried from November, 2013, to January, 2019, for arterial injuries repaired with a vein graft. Demographics and injury characteristics were compared. Need for in-hospital reoperation was the primary outcome in this four-arm study, assessed with two ordinal logistic regression models (1. no therapy vs. AC only vs. AC and AP; 2. no therapy vs. AP only vs. AC and AP). RESULTS: 373 patients (52 no therapy, 88 AP only, 77 AC only, 156 both) from 19 centers with recorded Injury Severity Scores (ISS) were identified. Patients who received no therapy were younger than those who received AP (27.0 vs. 34.2, p = 0.02), had higher transfusion requirement (p < 0.01 between all groups) and a different distribution of anatomic injury (p < 0.01). After controlling for age, sex, ISS, platelet count, hemoglobin, pH, lactate, INR, transfusion requirement and anatomic location, there was no association with postoperative medical therapy and in-hospital operative reintervention, or any secondary outcome, including thrombosis (p = 0.67, p = 0.22). CONCLUSIONS: Neither AC nor AP alone, nor in combination, impact complication rate after arterial repair with autologous vein. These patients can be safely treated with or without antithrombotics, recognizing that this study did not demonstrate a beneficial effect.

Lower Extremity Staged Revascularization (LESR) as a new innovative concept for lower extremity salvage in acute popliteal artery injuries: a hypothesis.

Popliteal artery injury following knee dislocation is associated with significant morbidity and high amputation rates. The complex and multi-disciplinary input required to manage this injury effectively can take time to arrange, prolonging the time to revascularization. Furthermore, open surgical bypass or interposition graft can be technically challenging in the acute setting, further prolonging ischemic time.Temporary intravascular shunts can be used to temporarily restore flow but require surgical exposure which takes time. Endovascular techniques can decrease the time to revascularization; however, endovascular popliteal stent-grafting is controversial because the biomechanical forces relating to flexion and extension of the knee may increase the risk of stent thrombosis. An ideal operation would result in rapid revascularization, eventually leading to a definitive and durable surgical solution.We hypothesize that a staged approach combing extracorporeal shunting, temporary endovascular covered stent placement, external fixation of bony injury, and definitive open repair provides for a superior approach to popliteal artery injury than current standard of care. We term this approach lower extremity staged revascularization (LESR) and the aim is to minimize the known factors contributing to poor outcomes after traumatic popliteal artery injury.

The Role of Endovascular Repair of Popliteal Arterial Injuries in the Acute Setting.

BACKGROUND: The role of endovascular surgery in the treatment of popliteal arterial injuries is not well established. As with other popliteal pathology, open repair has traditionally been considered the gold standard. As data has accumulated and technology advanced, however, a reassessment of the role of endovascular surgery is warranted. The aim of this study is to perform a noninferiority comparison of open versus endovascular management of traumatic popliteal injuries. Our hypothesis is that endovascular management is noninferior to open management of traumatic popliteal injuries. METHODS: The National Trauma Data Bank was searched for adult patients from 2002-2016 for isolated popliteal arterial injury. The study used a standard noninferiority methodology to compare rates of amputation and compartment syndrome between endovascular and open surgery. Margins for noninferiority were established using established published rates of complications: 17.1% for amputations and 23.0% for compartment syndrome. Endovascular intervention would be considered noninferior to open surgery if the lower bound confidence of the complication proportion (endo/open complication rate) was greater than the predefined noninferiority margin. RESULTS: A total of 3,698 patients met inclusion criteria, with blunt injury accounting for 2,117 (57%) and penetrating injury accounting for 1,581 (43%). Within the blunt group, 1,976 (93.3%) underwent open and 141 (6.7%) endovascular surgery. The rate of compartment syndrome (percentage and 95% confidence interval) after surgery for open repair was 9.9 (8.6-11.2) and 6.4 (3.2-11.3) for endovascular repair. The complication proportion is 64.6 (59.7-69.5). The rate of amputation for open repair was 15.7 (14.2-17.4) and 14.2 (9.2-20.6) for endovascular repair. The complication proportion is 90.4 (87.4-93.4). Within the penetrating group, 1,525 (96.5%) underwent open repair and 56 (3.5%) endovascular surgery. The rate of compartment syndrome after surgery for open repair was 14.9 (13.2-16.7) and 5.4 (1.5-13.6) for endovascular repair. The complication proportion is 36.2 (31.3-41.1). The rate of amputation for open repair was 4.3 (3.3-5.4) and 3.6 (0.7-11.0) for endovascular repair. The complication proportion is 83.7 (75.3-90.6). CONCLUSIONS: These data suggests that endovascular repair of popliteal artery injury may be noninferior to open repair with respect to limb preservation. Further examination of endovascular repair in popliteal artery injury is warranted.

The Underlying Cardiovascular Mechanisms of Resuscitation and Injury of REBOA and Partial REBOA.

Introduction: Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) is used for aortic control in hemorrhagic shock despite little quantification of its mechanism of resuscitation or cardiac injury. The goal of this study was to use pressure-volume (PV) loop analysis and direct coronary blood flow measurements to describe the physiologic changes associated with the clinical use of REBOA. Methods: Swine underwent surgical and vascular access to measure left ventricular PV loops and left coronary flow in hemorrhagic shock and subsequent placement of occlusive REBOA, partial REBOA, and no REBOA. PV loop characteristics and coronary flow are compared graphically with PV loops and coronary waveforms, and quantitatively with measures of the end systolic and end pressure volume relationship, and coronary flow parameters, with accounting for multiple comparisons. Results: Hemorrhagic shock was induced in five male swine (mean 53.6 ± 3.6 kg) as demonstrated by reduction of stroke work (baseline: 3.1 vs. shock: 1.2 L*mmHg, p < 0.01) and end systolic pressure (ESP; 109.8 vs. 59.6 mmHg, p < 0.01). ESP increased with full REBOA (178.4 mmHg; p < 0.01), but only moderately with partial REBOA (103.0 mmHg, p < 0.01 compared to shock). End systolic elastance was augmented from baseline to shock (1.01 vs. 0.39 ml/mmHg, p < 0.01) as well as shock compared to REBOA (4.50 ml/mmHg, p < 0.01) and partial REBOA (3.22 ml/mmHg, p = 0.01). Percent time in antegrade coronary flow decreased in shock (94%-71.8%, p < 0.01) but was rescued with REBOA. Peak flow increased with REBOA (271 vs. shock: 93 ml/min, p < 0.01) as did total flow (peak: 2136, baseline: 424 ml/min, p < 0.01). REBOA did not augment the end diastolic pressure volume relationship. Conclusion: REBOA increases afterload to facilitate resuscitation, but the penalty is supraphysiologic coronary flows and imposed increase in LV contractility to maintain cardiac output. Partial REBOA balances the increased afterload with improved aortic system compliance to prevent injury.

Characterizing Brain Perfusion in a Swine Model of Raised Intracranial Pressure.

INTRODUCTION: Perfusion of the brain is critical, but this can be compromised due to focal space occupying lesions (SOL). SOLs can raise intracranial pressure (ICP), resulting in reduced cerebral blood flow (CBF). Most gyrencephalic models of brain injury focus on parenchymal injury, with few models of acutely elevated ICP. We hypothesized that we could employ a SOL technique to develop a titratable ICP model and sought to quantitate the resulting decrease in brain perfusion. METHODS: Six swine were anesthetized and instrumented. A Fogarty balloon catheter was inserted intracranially. Blood CO2 partial pressure was maintained between 35 and 45 mmHg. The Fogarty balloon was infused with normal saline at 1 mL/min to ICP targets of 10, 20, 30, and 40 mmHg. CBF (mL/100 g/min) were assessed at each ICP level using computed tomography perfusion (CTP). Data are presented as the mean ± standard deviation with all pressures measured in mmHg. CBF values were compared between baseline and each ICP level using analysis of variance. RESULTS: Baseline ICP was 5 ± 2 and systolic blood pressure was 106 ± 7. Balloon volumes (mL) required to achieve each incremental ICP level were 2.4 ± 0.5, 4.9 ± 1.7, 7.6 ± 1.6, and 9.9 ± 1.7. CBF decreased with each raised ICP level, with CBF being significantly less than baseline at ICP values of 30 (56.1 ± 34.7 versus 20.6 ± 11.0, P < 0.05) and 40 (56.1 ± 34.7 versus 6.5 ± 10.6, P < 0.05). CONCLUSIONS: An intracranial balloon catheter can be used to increase ICP, delivering a proportionate reduction in CBF. This model can be used in the future studies to examine adjuncts that manipulate intracranial pressure and their effect on brain perfusion.

Less Operating and More Overtriage: National Trends in Interfacility Transfer of Facial Fracture Patients.

BACKGROUND: The purpose of this study was to characterize demographics, injury patterns, and initial management trends of facial fracture patients who were subject to interfacility transfer. METHODS: Using the National Trauma Data Bank from 2007 to 2015, facial fracture patients arriving by interfacility transfer were included in the study. RESULTS: Over 9 years, 171,618 patients were included, with 37.5 percent having an isolated facial injury. Isolated facial injury patients tended to be younger, less frequently white, more frequently assaulted, and more frequently underwent facial fracture operative repair during the index admission (all, p < 0.001). From 2007 to 2015, insurance coverage increased from 54.6 to 79.0 percent (R2 = 0.90, p < 0.001). In addition, there was a 45 percent proportional increase in patients 50 to 89 years of age compared to a 20 percent decrease in patients 0 to 39 years of age (both, R2 = 0.99, p < 0.001). The proportion of transfer patients with isolated facial injury increased over the study period (32.0 to 39.4 percent, R2 = 0.90, p < 0.001); however, there was a decline in operative intervention (29.5 to 22.1 percent, R2 = 0.94, p < 0.001) and a 151 percent increase in the proportion discharged from the emergency department upon transfer arrival (R2 = 0.99, p < 0.001). CONCLUSIONS: Facial fracture patients subject to interfacility transfer comprise a wide array of demographics and injury patterns, with most having concomitant injuries and only a minority undergoing immediate operative intervention. Over time, this demographic has become older, sustained more isolated facial injury, and undergone fewer immediate operative interventions and is more frequently insured and more frequently discharged from the emergency department upon transfer arrival, reflecting increasing rates of secondary overtriage.