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.

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.

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 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.

Intensive Care Unit Bypass for Robotic-Assisted Single-Vessel Coronary Artery Bypass Grafting.

BACKGROUND: Fast-track and enhanced recovery after cardiac surgical procedures have shown reductions in intensive care unit (ICU) and hospital lengths of stay, with unchanged outcomes. However, cost reduction by an ultra-fast-track protocol after minimally invasive cardiac operations, without compromising clinical benefits, has yet to be demonstrated. METHODS: A total of 215 consecutive patients underwent robotic-assisted coronary artery bypass grafting, with 156 preoperatively stratified into conventional ICU recovery vs 59 candidates for a defined ICU-bypass protocol involving recovery room and floor care. Of these, 40 candidates completed the protocol, and 19 had conversion-to-ICU recovery. Because of right-skewed distribution, inpatient cost was log-transformed, and linear regression models were constructed to estimate geometric mean ratios (GMRs) comparing inpatient cost for these groups (conventional ICU recovery, ICU-bypass, conversion-to-ICU recovery), adjusted for The Society of Thoracic Surgeons Predicted Risk of Mortality score. RESULTS: Compared with the conventional ICU group, the ICU-bypass group conferred a 15% reduction in total inpatient (GMR, 0.85; P = .0007) and a 14% reduction in total variable direct costs (GMR, 0.86; P = .003). Compared with the conventional ICU group, the ICU-bypass and conversion-to-ICU groups had similar net hospital stay reductions (1.6-1.7 days). Relative to the conventional ICU group, ICU and floor duration were shortened after conversion to ICU, with a trend to reduced costs. Cardiac arrest, 30-day mortality, and stroke were absent, and other key adverse events did not differ between groups. CONCLUSIONS: A selective, successful ultra-fast-track ICU-bypass protocol for robotic-assisted coronary artery bypass grafting reduces inpatient cost without affecting short-term outcomes. Conversion-to-ICU recovery also maintains outcomes and trends toward reduced costs.

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.

Evaluating the regulation of transporter proteins and P-glycoprotein in rats with cholestasis and its implication for digoxin clearance.

BACKGROUND: Cardiac and hepatic functionality are intertwined in a multifaceted relationship. Pathologic processes involving one may affect the other through a variety of mechanisms, including hemodynamic and membrane transport effects. AIM: To better understand the effect of extrahepatic cholestasis on regulations of membrane transporters involving digoxin and its implication for digoxin clearance. METHODS: Twelve adult rats were included in this study; baseline hepatic and renal laboratory values and digoxin pharmacokinetic (PK) studies were established before evenly dividing them into two groups to undergo bile duct ligation (BDL) or a sham procedure. After 7 d repeat digoxin PK studies were completed and tissue samples were taken to determine the expressions of cell membrane transport proteins by quantitative western blot and real-time polymerase chain reaction. Data were analyzed using SigmaStat 3.5. Means between pre-surgery and post-surgery in the same experimental group were compared by paired t-test, while independent t-test was employed to compare the means between sham and BDL groups. RESULTS: Digoxin clearance was decreased and liver function, but not renal function, was impaired in BDL rats. BDL resulted in significant up-regulation of multidrug resistance 1 expression in the liver and kidney and its down-regulation in the small intestine. Organic anion transporting polypeptides (OATP)1A4 was up-regulated in the liver but down-regulated in intestine after BDL. OATP4C1 expression was markedly increased in the kidney following BDL. CONCLUSION: The results suggest that cell membrane transporters of digoxin are regulated during extrahepatic cholestasis. These regulations are favorable for increasing digoxin excretion in the kidney and decreasing its absorption from the intestine to compensate for reduced digoxin clearance due to cholestasis.

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.

Open chest selective aortic arch perfusion vs open cardiac massage as a means of perfusion during in exsanguination cardiac arrest: a comparison of coronary hemodynamics in swine.

AIM: To describe and compare the aortic-right atrial pressure (AoP-RAP) gradients and mean coronary perfusion pressures (CPPs) generated during open chest selective aortic arch perfusion (OCSAAP) with those generated during open cardiac massage (OCM) in hypovolemic swine. METHODS: Ten male Hanford swine utilized in a prior poly-trauma study were included in the study. Animals were rendered hypovolemic via a 30% volume bleed. Upon confirmation of death, animals underwent immediate clamshell thoracotomy and aortic cross-clamping followed by 5 min of OCM. A catheter suitable for OCSAAP was then inserted into the aorta and animals underwent 1 min of OCSAAP at a rate of 10 mL/kg/min. Aortic and right atrial pressures were recorded continuously using solid-state blood pressure catheters. Representative 10-s intervals from each resuscitation method were extracted. Hemodynamic parameters including AoP-RAP gradients and CPPs were calculated and compared. RESULTS: At baseline, time from death to intervention was significantly shorter for OCM. However, mean CPPs and AoP-RAP gradients were significantly higher in animals undergoing OCSAAP. 98% of OCSAAP segments had a mean CPP > 15, compared to 35% of OCM intervals. While OCM had a significant negative correlation between time to intervention and maximum CPP, this correlation was not significant for OCSAAP. CONCLUSION: OCSAAP generates favorable and potentially time-resistant pressure gradients when compared to those generated by OCM. Further investigation of the technique of OCSAAP is warranted, as it may have potential utility as a therapy during resuscitative thoracotomy (RT).

An estrogen (17α-ethinyl estradiol-3-sulfate) reduces mortality in a swine model of multiple injuries and hemorrhagic shock.

BACKGROUND: Although 17α-ethinyl estradiol-3-sulfate (EES) reduces mortality in animal models of controlled hemorrhage, its role in a clinically relevant injury model is unknown. We assessed the impact of EES in a swine model of multiple injuries and hemorrhage. METHODS: The study was performed under Good Laboratory Practice, with 30 male uncastrated swine (25-50 kg) subjected to tibial fracture, pulmonary contusion, and 30% controlled hemorrhage for an hour. Animals were randomized to one of five EES doses: 0 (control), 0.3, 1, 3, and 5 mg/kg, administered postinjury. Subjects received no resuscitation and were observed for 6 hours or until death. Survival data were analyzed using Cox-proportional hazard regression. Left ventricular pressure-volume loops were used to derive preload recruitable stroke work as a measure of cardiac inotropy. Immediate postinjury preload recruitable stroke work values were compared with values at 1 hour post-drug administration. RESULTS: Six-hour survival for the 0, 0.3, 1, 3, and 5 mg/kg groups was 0%, 50%, 33.3%, 16.7%, and 0%, respectively. Following Cox regression, the hazard (95% confidence interval) of death was significantly reduced in the 0.3 (0.22 [0.05-0.93]) and 1 (0.24 [0.06-0.89]) mg/kg groups but not the 3 (0.49 [0.15-1.64]) and 5 (0.46 [0.14-1.47]) mg/kg groups. Mean survival time was significantly extended in the 1 mg/kg group (246 minutes) versus the 0 mg/kg group (96 minutes) (p = 0.04, t test). At 1 hour post-drug administration, inotropy was significantly higher than postinjury values in the 0.3 and 1 mg/kg groups (p = 0.003 and p < 0.001, respectively). Inotropy was unchanged in the 3 and 5 mg/kg groups but significantly depressed in the control (p = 0.022). CONCLUSION: Administration of EES even in the absence of fluid resuscitation reduces mortality and improves cardiac inotropy in a clinically relevant swine model of multiple injuries and hemorrhage. These findings support the need for a clinical trial in human trauma patients.

In-hospital outcomes in autogenous vein versus synthetic graft interposition for traumatic arterial injury: A propensity-matched cohort from PROOVIT.

BACKGROUND: The ideal conduit for traumatic arterial repair is controversial. Autologous vein was compared with synthetic interposition grafts in the acute setting. The primary outcome was in-hospital reoperation or endovascular intervention. METHODS: The American Association for the Surgery of Trauma PROspective Observational Vascular Injury Treatment registry from November 2013 to January 2019 was queried for arterial injuries requiring interposition vein or graft repair. Patients with no recorded Injury Severity Score were excluded, and multiple imputation was used for other missing data. Patients treated with synthetic grafts (SGs) were propensity matched to patients with vein grafts (VGs) to account for preoperative differences. RESULTS: Four hundred sixty from 19 institutions were identified, with 402 undergoing VG and 58 SG. In the SG group, 45 were PTFE grafts, 5 were Dacron, and 8 had other conduits. The SG group was more severely injured at admission with more gunshot wounds and higher mean Injury Severity Score, lactate, and first-24-hour transfusion requirement. In addition, the SG cohort had significantly lower admission systolic blood pressure, pH, and hemoglobin. After propensity matching, 51 patients with SG were matched with 87 patients with VG. There were no differences in demographics, clinical parameters, or diagnostic evaluation techniques postmatch. The need for reoperation or endovascular intervention between the matched groups was equivalent (18%; p = 0.8). There was no difference in any secondary outcome including thrombosis, stenosis, pseudoaneurysm, infection, or embolic event, and hospital and intensive care unit length of stay were the same. CONCLUSION: American Association for the Surgery of Trauma PROspective Observational Vascular Injury Treatment registry data demonstrate that SGs are used in more critically ill patients. After controlling for relevant clinical factors and propensity matching, there is no in-hospital difference in rate of reoperation or endovascular intervention, or any secondary outcome between VG and SG. LEVEL OF EVIDENCE: Prognostic and Epidemiolgic, Level III.

Development of a computed tomography perfusion protocol to support large animal resuscitation research.

BACKGROUND: Adequate cerebral perfusion is crucial for a positive neurological outcome in trauma; however, it is difficult to characterize in the acute setting with noninvasive methods. Intra-arterial computed tomography perfusion may offer a solution. The aim of this study was to develop an intra-arterial computed tomography perfusion protocol for resuscitation research. METHODS: The study examined intra-arterial contrast administration for computed tomography perfusion (CTP) acquisition. It consisted of three phases: intra-arterial contrast dose finding, evaluation of reproducibility, and evaluation during hypotension. Blood pressure and laser Doppler flow data were collected. In phase 1, animals underwent CTPs using several intra-arterial contrast injection protocols. In phase 2, animals underwent two CTPs 7 hours apart using the 2.5 mL/s for 3-second protocol. In phase 3, animals underwent CTPs at several pressures following a computer-controlled bleed including euvolemia and at systolic pressures of 60, 40, and 20 mm Hg. Phase 1 CTPs were evaluated for contrast-to-noise ratio. In phase 2, CTPs were compared within each animal and with laser Doppler flow using linear regression. Phase 3 CTPs were graphed against systolic pressure and fitted with a nonlinear fit. RESULTS: The protocol using 2.5mL/s for 3 seconds was optimal, demonstrating a contrast-to-noise ratio of 40.1 and a superior arterial input function curve compared with the 1 mL/s bolus. Cerebral blood flow demonstrated high concordance between baseline and end of study CTPs (R2 = 0.82, p < 0.001). Cerebral blood flow also compared moderately well against laser Doppler flow during 8 (R2 = 0.53, p = 0.03); however, laser Doppler flow did not perform well during hypovolemia, and the favorable concordance was not maintained (R2 = 0.45, p = 0.06). Cerebral blood flow was graphed against systolic blood pressure and fitted with a nonlinear fit (R2 = 0.95, p = 0.003). CONCLUSION: Computed tomography perfusion using intra-arterial contrast injection may offer a novel alternative to traditional CTP protocols that could prove a useful additional tool in the setting of resuscitation research.