Utility of Motor Evoked Potentials in Contemporary Open Thoracoabdominal Aortic Repair

OBJECTIVES

Paraplegia remains one of the major complications of contemporary open thoracoabdominal aortic aneurysm (TAAA) repair. Intraoperative motor-evoked potentials (MEPs) act as a surrogate measure for spinal cord homeostasis. The purpose of this study was to evaluate the results of intraoperative neuromonitoring in contemporary TAAA repair and its association with postoperative spinal cord ischemia.

METHODS

Patients who underwent open type 2 or 3 TAAA or completion aortic repair utilizing intraoperative neuromonitoring were identified between May 2006 and November 2023. Patient demographics, comorbidities, indication for the procedure, procedural details, and outcomes were recorded. The groups were divided based on type of repair, and univariate statistics were then utilized to evaluate the association of these metrics versus the type of repair.

RESULTS

Seventy-nine patients underwent open type 2 (N=41) and 3 (N=23) TAAA and completion aortic (N=15; open in 14, endovascular in 1) repairs by a single surgeon. The cohort was predominantly male (N=48, 60.8%) with a mean age of 52.5±16.2 years. There was a high incidence of hypertension (N=53, 67.1%), smoking history (N=42, 53.1%), and connective tissue disorders (N=37, 46.8%). Operative indications included dissection-related (N=50, 63.3%) and degenerative (N=26, 32.9%) TAAA and dissection-related malperfusion (N=3, 3.8%). Left heart bypass was often (N=73, 92.4%) utilized for distal aortic perfusion, and cerebrospinal fluid drainage (N=77, 97.5%) was a common adjunct. MEPs were classified as no change (N=43, 54.4%), reversible change (N=26, 32.9%), irreversible change (N=4, 5.1%), and unreliable (N=6, 7.6%). MEP changes were predominantly bilateral (N=70, 88.6%) and occurred most often during repair of the abdominal aortic segment (N= 13, 16.5%). The median number of replaced vertebral levels was associated with MEP changes (P=0.013). SCI was only observed in repairs greater than 6 replaced vertebral levels with an overall frequency of 17.7%. It was most prevalent in completion aortic repairs (26.7%). Immediate and delayed SCI occurred in 10.1% and 7.6% of patients, respectively; it was most commonly (71.8%) reversible. Permanent paraplegia occurred in 4 patients (5.1%), with equal immediate and delayed onsets. MEPs demonstrated poor sensitivity (53.9%) and specificity (62.3%) for SCI, however there was a high negative predictive value (86.4%) in this population. In-hospital mortality occurred in 5 (6.3%).

CONCLUSIONS

No changes in intraoperative MEPs are highly predictive of spinal cord homeostasis. The number of replaced vertebral levels and previous aortic repair should guide intraoperative neuroprotective measures including intercostal reimplantation and should take precedence over intraoperative monitoring, especially when MEP changes occur.

Raising Systemic Blood Pressure to Delay Irreversible Intestinal Ischemia in a Swine Model of Proximal Superior Mesenteric ArteryOcclusion

INTRODUCTION

Acute proximal superior mesenteric artery (SMA) occlusion is highly lethal, and adjuncts are needed to mitigate ischemic injury until definitive therapy. We hypothesized that raising mean arterial pressure (MAP) >90 mmHg with norepinephrine may delay irreversible bowel ischemia by increasing gastroduodenal artery (GDA) flow despite possible pressor-induced vasospasm.

METHODS

12 anesthetized swine underwent laparotomy, GDA flow probe placement, and proximal SMA exposure and clamping. Animals were randomized between conventional therapy (CT) versus targeted MAP >90 mmHg (MAP push; MP) where norepinephrine was titrated after 45 min of SMA occlusion. Animals were followed until bowel death or 4 h. Kaplan-Meier bowel survival, mean normalized GDA flow, and histology were compared.

RESULTS

12 swine (mean 57.8 ± 7.6 kgs) were included, six per group. Baseline weight, HR, MAP and GDA flows were not different. Within 5 min following SMA clamping, all 12 animals had an increase in MAP without other intervention from 81.7 to 105.5 mmHg (29.1%, P < 0.01) with a concomitant 74.9% increase in GDA flow as compared to baseline (P < 0.01). Beyond 45 min postclamp, MAP was greater in the MP group as intended, as were GDA flows. Median time to irreversibly ischemic bowel was 31% longer for MAP push animals (CT: 178 versus MP: 233 min, P = 0.006), Hazard Ratio of CT 8.85 (95% CI: 1.86-42.06); 3/6 MP animals versus 0/6 CT animals with bowel survived to predetermined end point.

CONCLUSIONS

In this swine model of acute complete proximal SMA occlusion, increasing MAP >90 mmHg with norepinephrine was associated with an increase in macrovascular blood flow through the GDA and bowel survival. Norepinephrine was not associated with worse bowel survival and a MAP push may increase the time window where ischemic bowel can be salvaged.

Technical and analytical approach to biventricular pressure-volume loops in swine including a completely endovascular, percutaneous closed-chest large animal model

Pressure-volume (PV) loop analysis is a sophisticated invasive approach to quantifying load-dependent and independent measures of cardiac function. Biventricular (BV) PV loops allow left and right ventricular function to be quantified simultaneously and independently, which is important for conditions and certain physiologic states, such as ventricular decoupling or acute physiologic changes. BV PV loops can be performed in an entirely endovascular, percutaneous, and closed-chest setting. This technique is helpful in a survival animal model, as a percutaneous monitoring system during endovascular device experiments, or in cases where chest wall compliance is being tested or may be a confounder. In this article, we describe the end-to-end implementation of a completely endovascular, totally percutaneous, and closed-chest large animal model to obtain contemporaneous BV PV loops in 40 to 70 kg swine. We describe the associated surgical and technical challenges and our solutions to obtaining endovascular BV PV loops, closed-chest cardiac output, and stroke volume (including validation of the correction factor necessary for thermodilution), as well as how to perform endovascular inferior vena cava occlusion in this swine model. We also include techniques for data acquisition and analysis that are required for this method.

Automatic 1-year follow-up appointment creation and reminders can improve long-term follow-up after carotid revascularization

BACKGROUND

Long-term follow-up (LTFU) following carotid revascularization is important for post-surgical care, stroke risk optimization and post-market surveillance of new technologies.

METHODS

We instituted a quality improvement project to improve LTFU rates for carotid revascularizations (primary outcome) by scheduling perioperative and one-year follow-up appointments at time of surgery discharge. A temporal trends analysis (Q1 2019 through Q1 2022), multivariable regression, and interrupted time series (ITS) were performed to compare pre-post intervention LTFU rates.

RESULTS

269 consecutive patients were included (151 pre-intervention, 118 post-intervention; mean 71 ​± ​12 years-old, 39% female, 77% White). The overall LTFU rate improved (64.9%-78.8%; P ​= ​0.013) after the intervention. After controlling for patient factors, procedures performed after the intervention were associated with increased odds of being seen for 1-year follow-up (OR: 2.2 95%CI: 1.2-4.0). Quarterly ITS analysis corroborated this relationship (P ​= ​0.01).

CONCLUSIONS

Time-of-surgery appointment creation and automated patient reminders can improve LTFU rates following carotid revascularizations.

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.

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.

Current Management of Intermittent Claudication

Peripheral artery disease (PAD) is a common condition representing a spectrum of clinical disease. Intermittent claudication, which is defined as PAD with lower extremity pain on exertion that resolves with rest, represents mild-to-moderate PAD. Intermittent claudication is associated with a low risk of limb loss long-term but is a significant marker of systemic cardiovascular risk. Here, we describe the workup, diagnosis, and management of intermittent claudication.

Mature artificial intelligence- and machine learning-enabled medical tools impacting vascular surgical care: A scoping review of late-stage, US Food and Drug Administration-approved or cleared technologies relevant to vascular surgeons

Artificial intelligence and machine learning (AI/ML)-enabled tools are shifting from theoretical or research-only applications to mature, clinically useful tools. The goal of this article was to provide a scoping review of the most mature AI/ML-enabled technologies reviewed and cleared by the US Food and Drug Administration relevant to the field of vascular surgery. Despite decades of slow progress, this landscape is now evolving rapidly, with more than 100 AI/ML-powered tools being approved by the US Food and Drug Administration each year. Within the field of vascular surgery specifically, this review identified 17 companies with mature technologies that have at least one US Food and Drug Administration clearance, all occurring between 2016 and 2022. The maturation of these technologies appears to be accelerating, with improving regulatory clarity and clinical uptake. The early AI/ML-powered devices extend or amplify clinically entrenched platform technologies and tend to be focused on the diagnosis or evaluation of time-sensitive, clinically important pathologies (eg, reading Digital Imaging and Communications in Medicine-compliant computed tomography images to identify pulmonary embolism), or when physician efficiency or time savings is improved (eg, preoperative planning and intraoperative guidance). The majority (>75%) of these technologies are at the intersection of radiology and vascular surgery. It is becoming increasingly important that the contemporary vascular surgeon understands this shifting paradigm, as these once-nascent technologies are finally maturing and will be encountered with increasingly regularity in daily clinical practice.

A 10-Year Analysis of Representation of Women in Patent Applications and NIH Funding in Vascular Surgery

BACKGROUND

There has been an increasing focus on gender disparities in the medical field and in the field of vascular surgery specifically. We aimed to characterize gender representation in vascular surgery innovation over the past 10 years, using metrics of patents and National Institutes of Health (NIH) support.

METHODS

We performed a retrospective review of all vascular-related patent filings (Google Scholar) and NIH-funded grants (NIH RePORTER) over a 10-year period (January 1st, 2012, to December 31st, 2021). Gender-API (Application Programming Interface) was used to identify the gender of the inventors, with manual confirmation of a 10% random sample. Gender representation for patent inventors and grant principal investigators (PIs) were compared using Chi-squared and Student's t-tests as appropriate. Yearly temporal changes in representation were analyzed using Wilcoxon signed-rank tests and linear regression analyses.

RESULTS

We identified 2,992 unique vascular device patents with 6,093 associated inventors over 10 years. Women were underrepresented in patent authorship overall (11.5%), and were least likely to be listed as first inventor (8.9%) and most commonly fourth and fifth inventors (15.5% and 14.1%, respectively) compared to men. There was no significant change in representation of women inventors over time (-0.2% females per year, 95% confidence interval (CI) -0.54 to 0.10). We identified 1736 total unique NIH grants, with 23.8% of funded projects having women PIs. There was an increase in the proportion of women PIs over time (+1.31% per year, 95% CI 0.784 to 1.855; P < 0.001). Projects with women PIs received mean total awards that were significantly lower than projects with men PIs ($350,485 ± $220,072 vs. $451,493 ± $411,040; P < 0.001), but the overall ratio of funding:women investigators improved over time (+$11,531 per year, 95% CI $6,167 to $16,895; P = 0.0011).

CONCLUSIONS

While we have made strides in increasing the number of women in the surgical research space, there is still room for improvement in funding parity. In addition, we found substantial and persistent room for improvement in representation of women in surgical innovation. As we enter a new frontier of surgery hallmarked by equalizing gender representation, these data should serve as a call-to-action for initiative aimed at rebuilding the foundation of surgical innovations upon equal gender representation.

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.

Endovascular stenting techniques for blunt carotid injury

OBJECTIVES

While methods of endovascular carotid artery stenting have improved over time, concerns surrounding the safety and efficacy of stenting for blunt carotid injury (BCI) remain. This study aims to present our approach to carotid artery stenting (CAS) by incorporating new technologies such as flow-diverting stents and circuits.

METHODS

There is no robust evidence to support routine carotid artery stenting; however, there are several therapeutic options and approaches for treating BCI that currently require an individualized approach. Endovascular stenting and specific stent selection are largely dictated by the disease process the surgeon intends to treat. We will discuss patient selection, medical management, and the most common revascularization techniques, including transfemoral stenting, trans-carotid arterial revascularization using flow reversal, and stent-assisting coiling.

RESULTS

It must be stressed that endovascular intervention is not an alternative to or preclusive of antithrombotic or anticoagulant therapy. In the setting of BCI, transfemoral CAS is most appropriate in patients who are symptomatic, have a rapidly progressing or large lesion, and do not have a soft thrombus present due to risk of embolism. Unlike transfemoral CAS, TCAR offers an elegant solution for embolic protection when patients have a soft thrombus present. In the case of a large pseudoaneurysm, we perform stent-assisted coiling.

CONCLUSIONS

We practice selective endovascular intervention, stenting lesions that are flow-limiting or have large or rapidly expanding pseudoaneurysms, and only in patients for whom anticoagulation and antiplatelet agents are not contraindicated. As technology and investigation progress, the concerns regarding the safety and the role of endovascular intervention in the treatment of BCI will be more clearly defined.

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.

Corrigendum: Implementation of a patient-centered remote wound monitoring system for management of diabetic foot ulcers

[This corrects the article DOI: 10.3389/fendo.2023.1157518.].

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.

Implementation of a patient-centered remote wound monitoring system for management of diabetic foot ulcers

Background

Regular clinical assessment is critical to optimize lower extremity wound healing. However, family and work obligations, socioeconomic, transportation, and time barriers often limit patient follow-up. We assessed the feasibility of a novel, patient-centered, remote wound management system (Healthy.io Minuteful for Wound Digital Management System) for the surveillance of lower extremity wounds.

Methods

We enrolled 25 patients from our outpatient multidisciplinary limb preservation clinic with a diabetic foot ulcer, who had undergone revascularization and podiatric interventions prior to enrollment. Patients and their caregivers were instructed on how to use the digital management system and asked to perform one at-home wound scan per week for a total of 8 weeks using a smartphone application. We collected prospective data on patient engagement, smartphone app useability, and patient satisfaction.

Results

Twenty-five patients (mean age 65.5 ± 13.7 years, 60.0% male, 52.0% Black) were enrolled over 3 months. Mean baseline wound area was 18.0 ± 15.2 cm2, 24.0% of patients were recovering from osteomyelitis, and post-surgical WiFi stage was 1 in 24.0%, 2 in 40.0%, 3 in 28.0%, and 4 in 8.00% of patients. We provided a smartphone to 28.0% of patients who did not have access to one that was compatible with the technology. Wound scans were obtained by patients (40.0%) and caregivers (60.0%). Overall, 179 wound scans were submitted through the app. The mean number of wound scans acquired per patient was 0.72 ± 0.63 per week, for a total mean of 5.80 ± 5.30 scans over the course of 8 weeks. Use of the digital wound management system triggered an early change in wound management for 36.0% of patients. Patient satisfaction was high; 94.0% of patients reported the system was useful.

Conclusion

The Healthy.io Minuteful for Wound Digital Management System is a feasible means of remote wound monitoring for use by patients and/or their caregivers.

Contemporary management and time to revascularization in upper extremity arterial injury

INTRODUCTION

Upper extremity arterial injury is associated with significant morbidity and mortality for trauma patients, but there is a paucity of data to guide the clinician in the management of these injuries. The goals of this review were to characterize the demographics, presentation, clinical management, and outcomes, and to evaluate how time to intervention associates with outcomes in trauma patients with upper extremity vascular injuries.

METHODS

The National Trauma Data Bank (NTDB) Research Data Set for the years 2007-2016 was queried in order to identify adult patients (age ≥ 18) with an upper extremity arterial injury. Patients with brachiocephalic, subclavian, axillary, or brachial artery injury using the 1998 and 2005 versions of the Abbreviated Injury Scale were included. Patients with non-survivable injuries to the brain, traumatic amputation, or other major arterial injuries to the torso or lower extremities were excluded.

RESULTS

The data from 7908 patients with upper extremity arterial injuries was reviewed. Of those, 5407 (68.4%) underwent repair of the injured artery. The median Injury Severity Score (ISS) was 10 (IQR = 7-18), and 7.7% of patients had a severe ISS (≥ 25). Median time to repair was 120 min (IQR = 60-240 min). Management was open repair in 52.3%, endovascular repair in 7.3%, and combined open and endovascular repairs in 8.8%; amputation occurred in 1.8% and non-operative management was used in 31.6% of patients. Blunt mechanism of injury, crush injury, concomitant fractures/dislocations, and nerve injuries were associated with amputation, whereas simultaneous venous injury was not. There was a significant decrease in the rate of amputation when patients undergoing surgical revascularization did so within 90 min of injury (P = 0.007).

CONCLUSION

Injuries to arteries of the upper extremity are managed with open repair, endovascular repair, and, rarely, amputation. Expeditious transport to the operating room for revascularization is the key for limb salvage.

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.

Females are less likely to receive best medical therapy for stroke prevention before and after carotid revascularization than males

BACKGROUND

Current professional guidelines recommend best medical therapy (BMT) with statin agents and antiplatelet therapy for primary and secondary stroke prevention in patients with carotid artery stenosis. We aimed to assess the association of patient sex with preoperative BMT in patients undergoing carotid revascularization.

METHODS

We performed a retrospective review of Vascular Quality Initiative patients who underwent carotid endarterectomy or carotid artery stenting between January 2003 and February 2022. Multivariable logistic regression models were used to assess the association of patient sex with preoperative BMT after adjusting for sociodemographic, comorbidity, and disease severity characteristics. In-hospital outcomes were assessed by sex and preoperative BMT status.

RESULTS

Of 214,008 patients who underwent carotid revascularization, 38.7% (n = 82,855) were female and 61.3% (n = 131,153) were male. Overall, 77.2% (n = 63,922) of females were on preoperative BMT, compared with 80.4% (n = 105,375) of males (P < .001). After adjusting for baseline differences, females had 11% lower odds of being on BMT compared with males (adjusted odds ratio, 0.89; 95% confidence interval, 0.86-0.91). Postoperatively, females had 18% lower odds of being prescribed BMT than males (adjusted odds ratio, 0.82; 95% confidence interval, 0.79-0.84). In-hospital stroke (1.20% vs 1.51%), death (0.37% vs 0.66%), and stroke/death (1.46% vs 1.98%) were all significantly lower for patients on BMT (all P < .001).

CONCLUSIONS

There is a significant discrepancy in the proportion of females versus males receiving preoperative BMT for stroke prevention before carotid artery revascularization. In-hospital outcomes are worse in patients without BMT, highlighting the importance of raising awareness and implementing targeted interventions to improve preoperative adherence to stroke prevention guidelines.

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.

Practice patterns surrounding the use of tibial interventions for claudication in the Medicare population

OBJECTIVE

At present, no data are available to support the use of tibial interventions in the treatment of claudication. We characterized the practice patterns surrounding tibial peripheral vascular interventions (PVIs) for patients with claudication in the United States.

METHODS

Using 100% Medicare fee-for-service claims from 2017 to 2019, we conducted a retrospective analysis of all patients who underwent an index PVI for claudication. Patients with any previous PVI, acute limb ischemia, or chronic limb-threatening ischemia in the preceding 12 months were excluded. The primary outcome was the receipt or delivery of tibial revascularization during an index PVI for claudication, defined as tibial PVI with or without concomitant femoropopliteal PVI. Univariable comparisons and multivariable hierarchical logistic regression were used to assess the patient and physician characteristics associated with the use of tibial PVI for claudication.

RESULTS

Of 59,930 Medicare patients who underwent an index PVI for claudication between 2017 and 2019, 16,594 (27.7%) underwent a tibial PVI (isolated tibial PVI, 38.5%; tibial PVI with concomitant femoropopliteal PVI, 61.5%). Of the 1542 physicians included in our analysis, the median physician-level tibial PVI rate was 20.0% (interquartile range, 9.1%-37.5%). Hierarchical logistic regression suggested that patient-level characteristics associated with tibial PVI for claudication included male sex (adjusted odds ratio [aOR], 1.23), increasing age (aOR, 1.30-1.96), Black race (aOR, 1.47), Hispanic ethnicity (aOR, 1.86), diabetes (aOR, 1.36), no history of hypertension (aOR, 1.12), and never-smoking status (aOR, 1.64; P < .05 for all). Physician-level characteristics associated with tibial PVI for claudication included early-career status (aOR, 2.97), practice location in the West (aOR, 1.75), high-volume PVI practice (aOR, 1.87), majority of practice in an ambulatory surgery center or office-based laboratory setting (aOR, 2.37), and physician specialty. The odds of vascular surgeons performing tibial PVI were significantly lower compared with radiologists (aOR, 2.98) and cardiologists (aOR, 1.67; P < .05 for all). The average Medicare reimbursement per patient was dramatically higher for physicians performing high rates of tibial PVI (quartile 4 vs quartile 1-3, $12,023.96 vs $692.31 per patient; P < .001).

CONCLUSIONS

Tibial PVI for claudication was performed more often by nonvascular surgeons in high-volume practices and high-reimbursement settings. Thus, a critical need exists to reevaluate the indications, education, and reimbursement policies surrounding these procedures.

Autologous blood resuscitation for large animals in a research setting using the Hemafuse device: Preliminary data of device use for controlled and real-world hemorrhage

Introduction

New low-cost technologies are needed to salvage lost blood in low-resource settings and large animal laboratories. The Hemafuse device is a simple mechanical device that can recover lost blood during surgery. The aim of this study is to assess the feasibility of this device for resuscitating large animals with controlled and unintended hemorrhage and to provide device considerations for use in this context.

Methods

This study had two experimental components: (1) the Hemafuse device was kept on-shelf and used as needed to assess real-world use for unintended hemorrhage during experiments, and (2) animals underwent a controlled hemorrhage protocol, where four anesthetized swine underwent aortic and external jugular vein catheterization for pressure monitoring. Animals were hemorrhaged into the pelvis, and the Hemafuse device was used to suction the blood through a filter and pushed into a heparinized bag for subsequent retransfusion. Blood samples were collected at baseline, hemorrhage, within the device, and post-retransfusion and laboratory tests were performed.

Results

Animals that underwent controlled hemorrhage had a baseline mean arterial pressure of 83.6 ± 7.8 mmHg, and central venous pressure of 12.8 ± 1.9 mmHg, with expected changes throughout hemorrhage and resuscitation. Following resuscitation, pH was similar to baseline (7.39 ± 0.05 vs. 7.31 ± 0.03, p = 0.24). Lactate increased throughout the experiment with no significant differences after autotransfusion compared to baseline (2.7 ± 0.7 vs. 4.1 ± 1.4 mmol/L, p = 0.37). There were no significant changes in metabolic physiology. Compared to baseline, the hemoglobin (7.8 ± 2.4 vs. 7.3 ± 1.8 g/dL, p = 0.74), hematocrit (23% ± 6.9 vs. 21.3% ± 5.6, p = 0.71), and activated clotting time (268.5 ± 44.5 vs. 193 ± 24.6 s, p = 0.35) were similar after retransfusion. When used for unintended hemorrhage, the animals were resuscitated using the device with a mean time to retransfusion time of 128.7 ± 13.3 s and 100% survival throughout the experiment.

Conclusion

The Hemafuse device is feasible and efficacious for supporting large animal resuscitation. This is preliminary evidence that the device is a low-risk and low-cost off-the-shelf option for resuscitation using autologous blood with no significant effect on physiology post-retransfusion. We recommend that research laboratories consider the Hemafuse device for emergency use, particularly for highly invasive surgical laboratories where banked blood is not readily available.

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.

Class of hemorrhagic shock is associated with progressive diastolic coronary flow reversal and diminished left ventricular function

Introduction: The relationship between coronary artery flow and left ventricular (LV) function during hemorrhagic shock remains unknown. The aim of this study was to quantify coronary artery flow directionality alongside left ventricular function through the four classes of hemorrhage shock. Methods: Following baseline data collection, swine were exsanguinated into cardiac arrest via the femoral artery using a logarithmic bleed, taking each animal through the four classes of hemorrhagic shock based on percent bleed (class I: 15%; class II: 15%-30%; class III: 30%-40%; class IV: >40%). Telemetry data, left ventricular pressure-volume loops, and left anterior descending artery flow tracings over numerous cardiac cycles were collected and analyzed for each animal throughout. Results: Five male swine (mean 72 ± 12 kg) were successfully exsanguinated into cardiac arrest. Mean left ventricular end-diastolic volume, end-diastolic pressure, and stroke work decreased as the hemorrhagic shock class progressed (p < 0.001). The proportion of diastole spent with retrograde coronary flow was also associated with class of hemorrhagic shock (mean 5.6% of diastole in baseline, to 63.9% of diastole in class IV; p < 0.0001), worsening at each class from baseline through class IV. Preload recruitable stroke work (PRSW) decreased significantly in classes II through IV (p < 0.001). Systemic Vascular Resistance (SVR) is associated with class of hemorrhage shock (p < 0.001). Conclusion: With progressive classes of hemorrhagic shock left ventricular function progressively decreased, and the coronary arteries spent a greater proportion of diastole in retrograde flow, with progressively more negative total coronary flow. Preload recruitable stroke work, a load-independent measure of inotropy, also worsened in severe hemorrhagic shock, indicating the mechanism extends beyond the drop in preload and afterload alone.

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.

Drug-Eluting Stents are Associated with Superior Mid-Term Outcomes for the Treatment of Infrainguinal Bypass Graft Stenoses

BACKGROUND

We previously demonstrated that everolimus drug-eluting stents (eDES) have reasonable short-term patency for the treatment of infrainguinal bypass stenoses. The aim of this study is to compare mid-term outcomes of eDES, plain balloon angioplasty (PTA), percutaneous cutting balloon (PCB), and drug-coated balloon (DCB) interventions for failing infrainguinal bypasses.

METHODS

We conducted a retrospective review of patients with infrainguinal bypass stenoses treated by endovascular intervention (August 2010-August 2021). The primary outcome was primary patency (PP). Secondary outcomes were primary-assisted patency (PAP), secondary patency (SP), limb salvage (LS), and mortality. Outcomes were compared by treatment using Kaplan-Meier curves with log-rank tests and Cox proportional hazards models adjusting for baseline differences between groups.

RESULTS

Seventy-two consecutive patients with 152 discrete infrainguinal bypass graft stenoses were identified. Mean age was 65.1 ± 10.6 years, 55.6% were male, and 48.6% were Black. In total, 81.9% of patients were originally treated for chronic limb-threatening ischemia, and 57.2% of distal anastomoses were to tibial or pedal targets. Of 152 lesions, 44.1% (n = 67) were treated with PTA, 17.8% (n = 27) with PCB, 20.4% (n = 31) with DCB, and 17.8% (n = 27) with eDES. Median follow-up was 28.5 months (interquartile range 11.5-51.9). There was no difference in bypass configuration, conduit choice, or stenosis location (proximal anastomosis, mid-bypass, distal anastomosis) between groups. At 24 months postintervention, PP was significantly better for eDES (72.9%, 95% confidence interval [CI] 49.8-85.6), followed by PCB (55.9%, 95% CI 34.2-72.9), PTA (34.4%, 95% CI 21.7-47.4), and DCB (33.6%, 95% CI 14.5-53.9) (P = 0.03). PAP, LS, and mortality did not significantly differ between modalities (P > 0.05). After risk adjustment, eDES was associated with the lowest risk of PP loss (hazard ratio versus PTA 0.15, 95% CI 0.05-0.47).

CONCLUSIONS

eDES is associated with superior 24-month patency rates compared to other endovascular technologies, and should be considered a primary therapy modality for the treatment of infrainguinal bypass graft stenoses.

Characterization of cerebral blood flow during open cardiac massage in swine: Effect of volume status

Introduction: Patients in cardiac arrest treated with resuscitative thoracotomy and open cardiac massage (OCM) have high rates of mortality with poor neurological outcomes. The aim of this study is to quantitate cerebral perfusion during OCM using computed tomography perfusion (CTP) imaging in a swine model of normo- and hypovolemia.

Methods: Anesthetized swine underwent instrumentation with right atrial and aortic pressure catheters. A catheter placed in the ascending aorta was used to administer iodinated contrast and CTP imaging acquired. Cerebral blood flow (CBF; ml/100 g of brain) and time to peak (TTP; s) were measured. Animals were then euthanized by exsanguination (hypovolemic group) or potassium chloride injection (normovolemic group) and subjected to a clamshell thoracotomy, aortic cross clamping, OCM, and repeated CTP. Data pertaining to peak coronary perfusion pressure (pCoPP; mmHg) were collected and % CoPP > 15 mmHg (% CoPP; s) calculated post hoc.

Results: Normovolemic animals (n = 5) achieved superior pCoPP compared to the hypovolemic animals (n = 5) pCoPP (39.3 vs. 12.3, p < 0.001) and % CoPP (14.5 ± 1.9 vs. 30.9 ± 6.5, p < 0.001). CTP acquisition was successful and TTP elongated from spontaneous circulation, normovolemia to hypovolemia (5.7 vs. 10.8 vs. 14.8, p = 0.01). CBF during OCM was similar between hypovolemic and normovolemic groups (7.5 ± 8.1 vs. 4.9 ± 6.0, p = 0.73) which was significantly lower than baseline values (51.9 ± 12.1, p < 0.001).

Conclusion: OCM in normovolemia generates superior coronary hemodynamics compared to hypovolemia. Despite this, neither generates adequate CBF as measured by CTP, compared to baseline. To improve the rate of neurologically intact survivors, novel resuscitative techniques need to be investigated that specifically target cerebral perfusion as existing techniques are inadequate.

Use of Transcarotid Artery Revascularization, Transfemoral Carotid Artery Stenting, and Carotid Endarterectomy in the US From 2015 to 2019

IMPORTANCE

A transcarotid artery revascularization (TCAR) device was approved by the US Food and Drug Administration in 2015 for carotid revascularization in patients at high risk for stroke, cranial nerve injury, or major cardiac event. It is unclear how the introduction of TCAR has changed the use of carotid endarterectomy (CEA) and transfemoral carotid artery stenting (TFCAS).

OBJECTIVE

To quantify the temporal changes in the operative approach to carotid revascularization (CEA vs TFCAS vs TCAR), and to identify patient and disease characteristics commonly associated with each approach.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study obtained data from the Vascular Quality Initiative database from January 1, 2015, to December 31, 2019. Patients with carotid artery stenosis who underwent CEA, TFCAS, or TCAR were included. Data were analyzed from January to April 2022.

EXPOSURES

Month and year of surgery as well as patient risk status.

MAIN OUTCOMES AND MEASURES

Number and proportion of carotid revascularization procedures by operative approach.

RESULTS

A total of 108 676 patients (mean [SD] age 56.6 [12.5] years; 66 684 men [61.4%]) were included in the analysis. The most common operative approach overall was CEA (n = 81 508 [75.0%]), followed by TFCAS (n = 15 578 [14.3%]) and TCAR (n = 11 590 [10.7%]). The number of procedures increased over the study period (16 754 in 2015 vs 27 269 in 2019; P < .001). In 2015, CEA was used in 84.9% of all cases, followed by TFCAS (14.4%) and TCAR (0.8%). In 2019, CEA was used in 64.8% of cases, followed by TCAR (21.9%) and TFCAS (13.3%). The proportional use of CEA decreased by 5.0% (95% CI, -7.4% to -2.6%) per year, and TCAR use increased by 5.3% (95% CI, 2.3%-8.3%) per year. Among patients at high risk, the change was greater: CEA use decreased by 7.8% (95% CI, -11.9% to -3.8%) per year, TFCAS decreased by 4.8% (95% CI, -9.5% to -0.14%) per year, and TCAR increased by 12.6% (95% CI, 7.1%-18.1%) per year. Multinomial logistic regression showed that patient risk status was the most important characteristic associated with TCAR compared with CEA (relative risk ratio, 36.10; 95% CI, 29.24-44.66; P < .001) and TFCAS (relative risk ratio, 14.10; 95% CI, 11.86-16.66; P < .001). Linear regression revealed no association between year of surgery and in-hospital myocardial infarction, stroke, or mortality.

CONCLUSIONS AND RELEVANCE

Results of this study indicate that TCAR has become the dominant carotid revascularization approach, surpassing TFCAS and CEA in patients at high risk for stroke, cranial nerve injury, or cardiovascular events. Patient high-risk status was the main characteristic associated with a stenting approach, highlighting the perceived importance of carotid stenting therapies in this patient population.

Association of carotid revascularization approach with perioperative outcomes based on symptom status and degree of stenosis among octogenarians

OBJECTIVE

Age ≥80 years is known to be an independent risk factor for periprocedural stroke after transfemoral carotid artery stenting (TF-CAS) but not after carotid endarterectomy (CEA). The objective of the present study was to compare the perioperative outcomes for CEA, TF-CAS, and transcarotid artery revascularization (TCAR) among octogenarian patients (aged ≥80 years) overall and stratified by symptom status and degree of stenosis.

METHODS

All patients aged ≥80 years with 50% to 99% carotid artery stenosis who had undergone CEA, TF-CAS, or TCAR in the Vascular Quality Initiative (2005-2020) were included. We compared the perioperative (30-day) incidence of ipsilateral stroke or death for CEA vs TF-CAS vs TCAR using analysis of variance and multivariable logistic regression models. The results were confirmed in a sensitivity analysis stratified by symptom status and degree of stenosis.

RESULTS

Overall, 28,571 carotid revascularization procedures were performed in patients aged ≥80 years: CEA, n = 20,912 (73.2%), TF-CAS, n = 3628 (12.7%), and TCAR, n = 4031 (14.1%). The median age was 83 years (interquartile range, 81.0-86.0 years); 49.8% of the patients were symptomatic (51.9% CEA, 46.2% TF-CAS, 42.4% TCAR); and 60.7% had high-grade stenosis (59.0% CEA, 65.2% TF-CAS, 65.4% TCAR). Perioperative stroke/death occurred most frequently following TF-CAS (6.6%), followed by TCAR (3.1%) and CEA (2.5%; P < .001). After adjusting for baseline differences between groups, the odds ratio (OR) for stroke/death was greater for TF-CAS vs CEA (adjusted OR [aOR], 3.35; 95% confidence interval [CI], 2.65-4.23), followed by TCAR vs CEA (aOR 1.49, 95% CI 1.18-1.87). The risk of perioperative stroke/death remained significantly greater for TF-CAS compared with CEA regardless of symptom status and degree of stenosis (P < .05 for all). In contrast, the risk of stroke/death was higher for TCAR vs CEA for asymptomatic patients (aOR, 2.04; 95% CI, 1.41-2.94) and those with high-grade stenosis (aOR, 1.49; 95% CI, 1.11-2.05) but similar for patients with symptomatic and moderate-grade disease (P > .05 for both). The risk of myocardial infarction was lower with TCAR (aOR, 0.59; 95% CI, 0.40-0.87) and TF-CAS (aOR, 0.56; 95% CI, 0.40-0.87) compared with CEA overall.

CONCLUSIONS

Overall, TCAR and CEA can be safely offered to older adults, in particular, symptomatic patients and those with moderate-grade stenosis. TF-CAS should be avoided in older patients when possible.

Acute pain consult and management is associated with improved mortality in rib fracture patients

INTRODUCTION

Traumatic rib fractures result in significant patient morbidity and mortality, which increases with patient age and number of rib fractures. A dedicated acute pain service (APS) providing expertize in multimodal pain management may reduce these risks and improve outcomes. We aimed to test the hypothesis that protocolized APS consultation decreases mortality and morbidity in traumatic rib fracture patients.

METHODS

This is a retrospective observational, propensity-matched cohort study of adult patients with trauma with rib fractures from 2012 to 2015, at a single, large level 1 trauma center corresponding to introduction and incorporation of APS consultation into the institutional rib fracture pathway. Using electronic medical records and trauma registry data, we identified adult patients presenting with traumatic rib fractures. Patients with hospital length of stay (LOS) ≥2 days were split into two cohorts based on presence of APS consult using 1:1 propensity matching of age, gender, comorbidities and injury severity. The primary outcome was difference in hospital mortality. Secondary outcomes included LOS and pulmonary morbidity.

RESULTS

2486 patients were identified, with a final matched cohort of 621 patients receiving APS consult and 621 control patients. The mortality rate was 1.8% among consult patients and 6.6% among control patients (adjusted OR 0.25, 95% CI 0.13 to 0.50; p=0.001). The average treatment effect of consult on mortality was 4.8% (95% CI 1.2% to 8.5%;. p<0.001). APS consultation was associated with increased intensive care unit (ICU) LOS (1.19 day; 95% CI 0.48 to 1.90; p=0.001) and hospital LOS (1.61 days; 95% CI 0.81 to 2.41 days; p<0.001). No difference in pulmonary complications was observed.

DISCUSSION

An APS consult in rib fracture patients is associated with decreased mortality and no difference in pulmonary complications yet increased ICU and hospital LOS.

Whole Blood Selective Aortic Arch Perfusion for Exsanguination Cardiac Arrest: Assessing Myocardial Tolerance to the Duration of Cardiac Arrest

INTRODUCTION

Selective aortic arch perfusion (SAAP) is an endovascular technique that consists of aortic occlusion with perfusion of the coronary and cerebral circulation. It been shown to facilitate return of spontaneous circulation (ROSC) after exanguination cardiac arrest (ECA), but it is not known how long arrest may last before the myocardium can no longer be durably recovered. The aim of this study is to assess the myocardial tolerance to exsanguination cardiac arrest before successful ROSC with SAAP.

METHODS

Male adult swine (n = 24) were anesthetized, instrumented, and hemorrhaged to arrest. Animals were randomized into three groups: 5, 10, and 15 min of cardiac arrest before resuscitation with SAAP. Following ROSC, animals were observed for 60 min in a critical care environment. Primary outcomes were ROSC, and survival at 1-h post-ROSC.

RESULTS

Shorter cardiac arrest time was associated with higher ROSC rate and better 1-h survival. ROSC was obtained for 100% (8/8) of the 5-min ECA group, 75% (6/8) of the 10-min group, 43% (3/7) of the 15-min group (P = 0.04). One-hour post-ROSC survival was 75%, 50%, and 14% in 5-, 10-, and 15-min groups, respectively (P = 0.02). One-hour survivors in the 5-min group required less norepinephrine (1.31 mg ± 0.83 mg) compared with 10-SAAP (0.76 mg ± 0.24 mg), P = 0.008.

CONCLUSION

Whole blood SAAP can accomplish ROSC at high rates even after 10 min of unsupported cardiac arrest secondary to hemorrhage, with some viability beyond to 15 min. This is promising as a tool for ECA, but requires additional optimization and clinical trials.Animal Use Protocol, IACUC: 0919015.

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.

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.

Abstract 289: Utilization Of Intra-Arterial Contrast For Computed Tomography Aortography In A Swine Model

Background: Intraoperative computed tomography (CT) imaging with endovascular catheter delivery of intra-arterial (IA) contrast could potentially provide higher signal attenuation in directed anatomic locations with lower contrast volumes. We compared image quality and attenuation timing of IA versus IV contrast protocols for abdominal imaging.

Methods: Five anesthetized swine had internal jugular access and ascending aortic pigtails placed percutaneously via the brachial artery. The IV contrast protocol utilized 100 mL of iodinated contrast at 5 mL/sec over 20/sec. The IA protocol delivered 50 mL at 5 mL/sec over 10/sec. A 16-slice CT scanner with a 10 mm detector acquired static serial images at 1 image/second for 45 secs. Region-of-interest markers were used to select the aorta and portal vein to capture arterial and venous attenuation via Hounsfield Units (HU) per second. Attenuation curves were assessed using a Pearson’s correlation. Adequate attenuation was defined as >100 HU a priori and image quality assessed using Contrast-to-Noise Ratio (CNR).

Results: Both contrast protocols achieved adequate image attenuation with an aortic peak of 665 ± 226 (Mean HU ± SD) for IA and 414 ± 141 for IV. IA contrast achieved faster peak aortic attenuation compared to IV contrast [8 vs 20 sec; p<0.001] (Fig 1). Portal values (attenuation and time to peak) were similar for IA vs IV: [146 ± 46 vs 169 ± 39; 34 vs 42 sec; p<0.05]. IA administration achieved a superior CNR in less time compared to IV [10 vs 23 sec; p<0.001]. All curves were modeled using non-linear least squares regression and achieved an R 2 >0.94; p<0.001.

Conclusion: IA contrast achieves adequate opacification and a superior CNR compared to IV contrast, while using a smaller volume for intraoperative directed imaging. The incorporation of intraoperative CT with IA contrast could radically change imaging protocols for endovascular aortic repair.

Transcarotid artery revascularization is associated with similar outcomes to carotid endarterectomy regardless of patient risk status

BACKGROUND

Carotid artery stenting, including both transfemoral carotid artery stenting (TFCAS) and transcarotid artery revascularization (TCAR), reimbursement has been limited to high-risk patients by the Centers for Medicare & Medicaid Services (CMS) since 2005. We aimed to assess the association of CMS high-risk status with perioperative outcomes for carotid endarterectomy (CEA), TFCAS, and TCAR.

METHODS

We performed a retrospective review of all Vascular Quality Initiative (VQI) patients who underwent carotid revascularization between 2015 and 2020. Patients were stratified by whether they met CMS CAS criteria, and univariable and multivariable logistic regression analyses were performed to assess the association of procedure type (CEA, TFCAS, TCAR) with perioperative stroke.

RESULTS

Of 124,531 individuals who underwent carotid revascularization procedures, 91,687 (73.6%) underwent CEA, 17,247 (13.9%) underwent TFCAS, and 15,597 (12.5%) underwent TCAR. Among patients who met CMS CAS criteria (i.e., high-risk patients), the incidence of perioperative stroke was 2.7% for CEA, 3.4% for TFCAS, and 2.4% for TCAR (p<0.001). Among standard-risk patients, the incidence of perioperative stroke was 1.7% for CEA, 2.7% for TFCAS, and 1.8% for TCAR (p<0.001). After adjusting for baseline demographic and clinical characteristics, the odds of perioperative stroke were lower for TCAR vs. CEA in high-risk patients [adjusted odds ratio (aOR) 0.82 (95% CI 0.68, 0.99)] and similar in standard-risk patients [aOR 1.05 (95% CI 0.84, 1.31)]. In contrast, the adjusted odds of perioperative stroke were higher for TFCAS vs. CEA in high-risk patients [aOR 1.23 (95% CI 1.03, 1.46)] and standard-risk patients [aOR 1.60 (95% CI 1.37, 1.86)]. In both populations, TFCAS and TCAR patients had significantly lower odds of MI than CEA patients (both, p<0.001).

CONCLUSIONS

The perioperative risks associated with CEA, TFCAS, and TCAR in high-risk patients support the current Centers for Medicare & Medicaid Services (CMS) criteria, while the risks associated with each revascularization approach in standard-risk patients suggest that distinguishing TCAR from TFCAS may be warranted.

119 Identifying Temporal Patterns in Burn Admissions

Introduction

Temporal variations in trauma admissions, based on the time of day, day of week, and day of year, have been previously demonstrated. These variations, which could inform decision making regarding staffing and resource utilization, have not been evaluated with respect to burn admissions. Very little has been published on predicting temporal distribution stratified by total body surface area (TBSA). We hypothesize that temporal patterns exist in the distribution of burn admissions at all TBSA as it relates to time of day, day of week, and day of year.

Methods

This was a cross-sectional observational study of a single burn center over nearly 5 years, from 7/1/2016-3/31/2021, including both pediatric and adult admissions. We captured and plotted bivariate absolute and relative frequency data from all patients who met inclusion criteria in heat-maps showing time of day versus day of week. Frequency analysis was also performed grouped by TBSA against time of day and relative encounters against day of year.

Results

2657 burn patient encounters were analyzed, averaging 1.53 burns per day. Temporal variations were skewed towards evening admission, primarily between 15:00-0:00 hours (p< 0.001). In figure 1, each block of the heatmap represents a one hour block of one day of the week over the nearly five year study period. The color corresponds to the relative frequency of contacts per hour, where 1 represents the mean number of trauma contacts per hour. Evenings (15:00-0:00) have more burn admissions than the rest of the day or night. Figure 2 shows this temporal trend is seen in burn encounters below 20% TBSA as well as those at or greater than 20% TBSA. Unlike trauma admission distribution, which has been shown to increase on weekend, day to day variation does not conform to weekend or weekday distribution. There is no cyclical yearly trend in burn admissions, suggesting that there is no seasonal variation to burn admissions, though individual holidays were not assessed.

Conclusions

We identify temporal variations in burn admissions, including the peak admission window late in the day. However, there is no predictable variation in weekend vs weekday distribution of burns. Furthermore, there is no cyclical annual variation to guide staffing and resource allocation.

A technical and data analytic approach to pressure-volume loops over numerous cardiac cycles

Cardiac pressure-volume (PV) loop analysis is the reference standard for studying the cardiovascular implications of clinical perturbations (eg, heart failure, aortic occlusion, hypovolemia) and is a benchmark for comparisons with noninvasive alternatives (eg, ultrasound, magnetic resonance imaging). Historically, most PV loop analyses were of individual cardiac cycles for which the options to analyze PV loops using off-the-shelf software were limited, and home-grown analysis software often lacked peer review or code-sharing. Our aim was to describe a start-to-finish implementation of PV loops for determination of hemodynamic parameters in swine, to provide technical advice for vascular access and proceduralization, and to describe data capture, curation, preprocessing, and analysis of raw PV time data. We have provided a novel data analytic method to programmatically analyze raw PV loop data beyond single cardiac cycles and real, raw swine PV loop data and the accompanying MATLAB (MathWorks, Inc, Natick, Mass) code as an example of how to process and analyze raw data directly.

Index Atherectomy Peripheral Vascular Interventions Performed for Claudication are Associated with More Reinterventions than Non-Atherectomy Interventions

OBJECTIVE

Despite limited evidence supporting atherectomy alone over stenting/angioplasty as the index peripheral vascular intervention (PVI), the use of atherectomy has rapidly increased in recent years. We previously identified a wide distribution of atherectomy practice patterns among US physicians. The aim of this study was to investigate the association of index atherectomy with reintervention.

METHODS

100% Medicare fee-for-service claims were used to identify all beneficiaries who underwent elective first-time femoropopliteal peripheral vascular intervention (PVI) for claudication between 1/1/2019-12/31/2019. Subsequent PVI reinterventions were examined through 6/30/2021. Kaplan-Meier curves were used to compare the rate of PVI reinterventions for patients who received index atherectomy vs. non-atherectomy procedures. Reintervention rates were also described for physicians by their overall atherectomy use (by quartile). A hierarchical Cox proportional hazard model was used to evaluate patient and physician-level characteristics associated with reinterventions.

RESULTS

A total of 15,246 patients underwent index PVI for claudication in 2019, of which 59.7% were atherectomy. After a median of 603 days (IQR 77, 784) of follow-up, 41.2% of patients underwent a PVI reintervention, including 48.9% of patients who underwent index atherectomy vs. 29.8% of patients who underwent index non-atherectomy (P<0.001). Patients treated by high physician users of atherectomy (quartile 4) received more reinterventions than patients treated by standard physician users (quartiles 1-3) (56.8% vs. 39.6%, P<0.001). After adjustment, patient factors association with PVI reintervention included receipt of index atherectomy (aHR 1.33, 95% CI 1.21-1.46), Black race (vs. White, aHR 1.18, 95% CI 1.03-1.34), diabetes (aHR 1.13, 95% CI 1.07-1.21), and urban residence (aHR 1.11, 95% CI 1.01-1.22). Physician factors associated with reintervention included male sex (aHR 1.52, 95% CI 1.12-2.04), high-volume PVI practices (aHR 1.23, 95% CI 1.10-1.37), and physicians with high use of index atherectomy (aHR 1.49, 95% CI 1.27-1.74). Vascular surgeons had a lower risk of PVI reintervention than Cardiologists (vs. Vascular, aHR 1.22, 95% CI 1.09-1.38), Radiologists (aHR 1.55, 95% CI 1.31-1.83), and other specialties (aHR 1.59, 95% CI 1.20-2.11). Location of services delivered was not associated with reintervention (P>0.05).

CONCLUSIONS

The use of atherectomy as an index PVI for claudication is associated with higher PVI reintervention rates compared to non-atherectomy procedures. Similarly, high physician users of atherectomy perform more PVI reinterventions than their peers. The appropriateness of using atherectomy for initial treatment of claudication needs critical reevaluation.

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.

Factors Associated With Increased Mortality in Severe Abdominopelvic Injury

BACKGROUND

Associated injuries are thought to increase mortality in patients with severe abdominopelvic trauma. This study aimed to identify clinical factors contributing to increased mortality in patients with severe abdominopelvic trauma, with the hypothesis that a greater number of concomitant injuries would result in increased mortality.

METHODS

This was a retrospective review of the Trauma Quality Improvement Program (TQIP) database of patients ≥ 18 years with severe abdominopelvic trauma defined as having an abdominal Abbreviated Injury Score (AIS) ≥ 3 with pelvic fractures and/or iliac vessel injury (2015-2017). Primary outcome was in-hospital mortality based on concomitant body region injuries. Secondary outcomes included mortality at 6 h, 6 to 24 h, and after 24 h based on concomitant injuries, procedures performed, and transfusion requirements.

RESULTS

A total of 185,257 patients were included in this study. Survivors had more severely injured body regions than non-survivors (4 vs. 3, P < 0.001). Among those who died within 6 h, 28.5% of patients required a thoracic procedure and 43% required laparotomy compared to 6.3% and 22.1% among those who died after 24 h (P < 0.001). Head AIS ≥ 3 was the only body region that significantly contributed to overall mortality (OR 1.26, P < 0.001) along with laparotomy (OR 3.02, P < 0.001), neurosurgical procedures (2.82, P < 0.001) and thoracic procedures (2.28, P < 0.001). Non-survivors who died in < 6 h and 6-24 h had greater pRBC requirements than those who died after 24 h (15.5 and 19.5 vs. 8 units, P < 0.001).

CONCLUSION

Increased number of body regions injured does not contribute to greater mortality. Uncontrolled noncompressible torso hemorrhage rather than the burden of concomitant injuries is the major contributor to the high mortality associated with severe abdominopelvic injury.

A systematic review of sutureless vascular anastomosis technologies

Vascular anastomoses typically involve a handsewn technique requiring significant surgical training, expertise, and time. The aim of our systematic review was to identify and describe sutureless vascular anastomosis techniques. We performed a systematic review of all sutureless vascular anastomosis technologies published in MEDLINE, PubMed, Embase, CINAHL, Cochrane, Web of Science, and Scopus Library databases and a patent review using US Patent and Trade Office Application, US Patent and Trademark Office Patent, Google Patents, Lens, Patent Quality Through Artificial Intelligence, SureChEMBL, and E-Space Net. Data from inclusion studies and patents published between January 1, 1980 and July 15, 2021 were abstracted to describe their category, anastomosis type and configuration, study types, and advantages and disadvantages encountered with each technology. Two hundred eleven original studies and 475 patents describing sutureless vascular anastomosis technologies were identified. In the literature, stents/stent-grafts/grafts (n = 61), lasers (n = 53), and couplers (n = 27) were the predominant device categories. In the patent review, adhesive technologies (n = 103), stents/stent-grafts/grafts (n = 68), and mechanical connectors (n = 61) predominated. The majority of studies involved in vivo animal studies (n = 193); 32.2% (n = 68) of investigations involved human trials; and 17.9% (n = 85) of patent technologies were approved by the US Food and Drug Administration. The main advantages described for sutureless anastomosis technologies included faster procedure time and greater patency rates compared with handsewn anastomoses. The main disadvantages included reduced vessel compliance, stenosis, leakage, and device costs. The appeal of sutureless technology is substantiated by numerous animal trials, but their use in humans remains limited. This may be a reflection of strict regulatory criteria and/or vascular complications associated with currently available technologies.

Artificial intelligence's role in vascular surgery decision-making

Artificial intelligence (AI) is the next great advance informing medical science. Several disciplines, including vascular surgery, use AI-based decision-making tools to improve clinical performance. Although applied widely, AI functions best when confronted with voluminous, accurate data. Consistent, predictable analytic technique selection also challenges researchers. This article contextualizes AI analyses within evidence-based medicine, focusing on "big data" and health services research, as well as discussing opportunities to improve data collection and realize AI's promise.