A novel ergonomic simulator for laparoscopic surgery

Despite the importance of laparoscopic skill development to General Surgery trainees, current laparoscopic simulators are either too expensive or suffer from poor portability or low video quality. Moreover, several trainers without height adjustable platforms and screens do not promote optimal ergonomics. In this paper, we present the design process and initial prototype of a novel ergonomic laparoscopic simulator that addresses these limitations.

Instrument and Supply Variability: An Opportunity to Reduce the Carbon Footprint of the Operating Room

INTRODUCTION

Reducing costs and carbon footprints are important, parallel priorities for the US health-care system. Within surgery, reducing the number of instruments that are sterilized and disposable supplies that are used for each operation may help achieve both goals. We wanted to measure the existing variability in surgical instrument and supply choices and assess whether standardization could have a meaningful cost and environmental impact.

METHODS

We analyzed surgeon preference cards for common general surgery operations at our hospital to measure the number of sterilizable instrument trays and supplies used by each surgeon for each operation. From this data, we calculated supply costs, carbon footprint, and median operative time and studied the variability in each of these metrics.

RESULTS

Among the ten operations studied, variability in sterilizable instrument trays requested on surgeon preference cards ranged from one to eight. Variability in disposable supplies requested ranged from 17 to 45. Variability in open supply costs ranged from $104 to $4184. Variability in carbon footprint ranged from 17 to 708 kg CO2e. If the highest-cost surgeon for each operation switched their preference card to that of the median-cost surgeon, $245,343 in open supply costs and 41,708 kg CO2e could be saved.

CONCLUSIONS

There is significant variability in the instrument and supply choices of surgeons performing common general surgery operations. Standardizing this variability may lead to meaningful cost savings and carbon footprint reduction, especially if scaled across the entire health system.

Evaluation of a novel platform for placement confirmation of enteral feeding tubes in adults

OBJECTIVE

The aim of this study was to validate the ability of a novel, impedance-based platform for nasogastric feeding tube (FT) insertion to correctly predict intragastric FT placement in healthy individuals with and without acid suppression medication.

METHODS

Ten patients underwent successive placement of 8, 10, and 12 French FTs with the final intragastric position predicted using an impedance-based algorithm and verified with an abdominal x-ray. Study procedures were repeated after patients received a proton pump inhibitor (PPI) for 3 d.

RESULTS

Nasogastric FTs with embedded electrodes spaced along the distal 31 cm of the tubes were placed with the final insertion depth determined by an algorithm integrating impedance and other physiologic parameters. Sixty FT (30 pre-PPI and 30 post-PPI) insertions were performed. The algorithm-predicted location was confirmed as intragastric in all insertions by post-placement abdominal x-ray. For all tube sizes and those with and without PPIs, the impedance at electrodes within the esophagus was significantly higher than at electrodes in the stomach (P < 0.01). As a secondary objective to assess the use of gastric aspirate pH to determine location, gastric aspirate could only be obtained in 30% of insertions. The mean gastric pH was 6.9 (SD 0.6) in patients taking PPIs.

CONCLUSIONS

A novel platform for real-time assistance with nasogastric FT placement confirmation correctly determined intragastric FT location as confirmed by abdominal x-ray (standard of care) in all 60 insertions. Gastric pH measurements were difficult to obtain and unreliable for intragastric FT placement confirmation in patients taking acid suppression medication.

Renal Embolization-Induced Uremic Swine Model for Assessment of Next-Generation Implantable Hemodialyzers

Reliable models of renal failure in large animals are critical to the successful translation of the next generation of renal replacement therapies (RRT) into humans. While models exist for the induction of renal failure, none are optimized for the implantation of devices to the retroperitoneal vasculature. We successfully piloted an embolization-to-implantation protocol enabling the first implant of a silicon nanopore membrane hemodialyzer (SNMHD) in a swine renal failure model. Renal arterial embolization is a non-invasive approach to near-total nephrectomy that preserves retroperitoneal anatomy for device implants. Silicon nanopore membranes (SNM) are efficient blood-compatible membranes that enable novel approaches to RRT. Yucatan minipigs underwent staged bilateral renal arterial embolization to induce renal failure, managed by intermittent hemodialysis. A small-scale arteriovenous SNMHD prototype was implanted into the retroperitoneum. Dialysate catheters were tunneled externally for connection to a dialysate recirculation pump. SNMHD clearance was determined by intermittent sampling of recirculating dialysate. Creatinine and urea clearance through the SNMHD were 76-105 mL/min/m2 and 140-165 mL/min/m2, respectively, without albumin leakage. Normalized creatinine and urea clearance measured in the SNMHD may translate to a fully implantable clinical-scale device. This pilot study establishes a path toward therapeutic testing of the clinical-scale SNMHD and other implantable RRT devices.

The Global Limb Anatomic Staging System (GLASS) for CLTI: Improving Inter-Observer Agreement

Objective: The 2020 Global Vascular Guidelines aim at improving decision making in Chronic Limb-Threatening Ischemia (CLTI) by providing a framework for evidence-based revascularization. Herein, the Global Limb Anatomic Staging System (GLASS) serves to estimate the chance of success and patency of arterial pathway revascularization based on the extent and distribution of the atherosclerotic lesions. We report the preliminary feasibility results and observer variability of the GLASS. GLASS is a part of the new global guideline and posed as a promising additional tool for EBR strategies to predict the success of lower extremity arterial revascularization. This study reports on the consistency of GLASS scoring to maximize inter-observer agreement and facilitate its application. Methods: GLASS separately scores the femoropopliteal (FP) and infrapopliteal (IP) segment based on stenosis severity, lesion length and the extent of calcification within the target artery pathway (TAP). In our stepwise approach, we used two angiographic datasets. Each following step was based on the lessons learned from the previous step. The primary outcome was inter-observer agreement measured as Cohen’s Kappa, scored by two (step 1 + 2) and four (step 3) blinded and experienced observers, respectively. Steps 1 (n = 139) and 2 (n = 50) were executed within a dataset of a Dutch interventional RCT in CLTI. Step 3 (n = 100) was performed in randomly selected all-comer CLTI patients from two vascular centers in the United States. Results: In step 1, kappa values were 0.346 (FP) and 0.180 (IP). In step 2, applied in the same dataset, the use of other experienced observers and a provided TAP, resulted in similar low kappa values 0.406 (FP) and 0.089 (IP). Subsequently, in step 3, the formation of an altered stepwise approach using component scoring, such as separate scoring of calcification and adding a ruler to the images resulted in kappa values increasing to 0.796 (FP) and 0.730 (IP). Conclusion: This retrospective GLASS validation study revealed low inter-observer agreement for unconditioned scoring. A stepwise component scoring provides acceptable agreement and a solid base for further prospective validation studies to investigate how GLASS relates to treatment outcomes.

Contemporary Experience with Paravisceral Aortic Aneurysm (PVAAA) Repair in a Tertiary Center

OBJECTIVES

To describe contemporary outcomes from a single center capable of both complex open and endovascular aortic repair for paravisceral aortic aneurysms (PVAAA).

METHODS

Data on all patients receiving open or endovascular (endo) treatment for aortic aneurysms with proximal extent at or above the renal arteries and distal to the inferior pulmonary ligament (IPL) were reviewed. Coarsened exact matching (CEM) on age, aneurysm type, gender, coronary artery disease (CAD), previous aortic surgery and symptomatic status created balanced cohorts for outcomes comparisons.

RESULTS

Between October, 2006 and February, 2018, 194 patients were treated for juxtarenal (40%), pararenal (21%), paravisceral (6%) and Type 4 thoracoabdominal (34%) aortic aneurysms with open (81, 42%) or endo (113, 58%) at a single tertiary center. Endo repairs included renal coverage with a bifurcated graft (2%), unilateral (13%) or bilateral (4%) renal snorkels, Z-fen (15%), multi-branched graft (IDE protocol; 62%) and unique complex configurations (4%). On multivariable analysis, patients selected for open surgery were more likely to be symptomatic, whereas older patients, female patients and those with Type 4 TAAA extent were more often selected for endovascular treatment. Matching based on the significant independent covariates reduced the open and endovascular groups by one-third. Survival at 30 days was 97% for endo and 94% for open repair, 98% for both subgroups when excluding symptomatic cases, and was not different between the matched groups (98% vs 89%; P=0.23). Hospital and ICU stays were longer in open patients (8 vs. 10 days, 2 vs. 4, both P≤0.001). Post-op CVA, MI, lower extremity ischemia, surgical site infections and reoperation were not different between matched groups (all p>0.05), while pulmonary and intestinal complications, as well as grade 1/2 renal dysfunction by RIFLE criteria, were more common after open repair (all P<0.05). Spinal cord ischemia was significantly more frequent in the unmatched Endo group (11% vs. 1%, P=0.02), but this difference was not significant after matching. Composite major aortic complications was no different between treatment groups (unmatched P=0.91, matched P=0.87). Endo treatment resulted in patients more frequently discharged to home (84% vs. 66%, P=0.02). Reintervention after 30 days occurred more frequently in the endo group (P=0.002). Estimated survivals at 1 and 5 years for endo and open are 96% vs. 81% and 69% vs. 81% respectively (Log-rank P=0.57).

CONCLUSIONS

Contemporary repair of PVAAA demonstrates safe outcomes with durable survival benefit when patients are well-selected for open or complex endovascular repair. We believe these data have implications for off-label device use in the treatment of PVAAA, and that open repair remains an essential option for younger, good risk patients in experienced centers.

Treatment With a Marine Oil Supplement Alters Lipid Mediators and Leukocyte Phenotype in Healthy Patients and Those With Peripheral Artery Disease

Background

Peripheral artery disease (PAD) is an advanced form of atherosclerosis characterized by chronic inflammation. Resolution of inflammation is a highly coordinated process driven by specialized pro‐resolving lipid mediators endogenously derived from omega‐3 fatty acids. We investigated the impact of a short‐course, oral, enriched marine oil supplement on leukocyte phenotype and biochemical mediators in patients with symptomatic PAD and healthy volunteers.

Methods and Results

This was a prospective, open‐label study of 5‐day oral administration of an enriched marine oil supplement, assessing 3 escalating doses in 10 healthy volunteers and 10 patients with PAD. Over the course of the study, there was a significant increase in the plasma level of several lipid mediator families, total specialized pro‐resolving lipid mediators, and specialized pro‐resolving lipid mediator:prostaglandin ratio. Supplementation was associated with an increase in phagocytic activity of peripheral blood monocytes and neutrophils. Circulating monocyte phenotyping demonstrated reduced expression of multiple proinflammatory markers (cluster of differentiation 18, 163, 54, and 36, and chemokine receptor 2). Similarly, transcriptional profiling of monocyte‐derived macrophages displayed polarization toward a reparative phenotype postsupplementation. The most notable cellular and biochemical changes over the study occurred in patients with PAD. There were strong correlations between integrated biochemical measures of lipid mediators (specialized pro‐resolving lipid mediators:prostaglandin ratio) and phenotypic changes in circulating leukocytes in both healthy individuals and patients with PAD.

Conclusions

These data suggest that short‐term enriched marine oil supplementation dramatically remodels downstream lipid mediator pathways and induces a less inflammatory and more pro‐resolution phenotype in circulating leukocytes and monocyte‐derived macrophages. Further studies are required to determine the potential clinical relevance of these findings in patients with PAD.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02719665.

Abstract 262: Circulating Exosomes from PAD Patients Modulate Vascular Repair and Inflammation

Objectives: Peripheral arterial disease (PAD) is a chronic disease characterized by inflammation. Recent work suggests that circulating exosomes may contribute to vascular injury and remodeling. We hypothesize that exosomes from PAD subjects negatively modulate vascular repair via miRNA and bioactive lipid mediators (LM).

Methods: Exosomes (particle size 30-100nm) were isolated from plasma of healthy (n=6) and PAD (n=6) subjects. Exosome miRNA was isolated and assessed by qPCR. Targeted metabolo-lipidomics was performed by liquid-chromatography-tandem mass spectrometry. VSMC and EC migration were assessed via scratch assay. Monocyte-derived macrophage gene expression after exposure to exosomes was assessed via RT-qPCR.

Results: Compared to healthy subjects, exosomes from PAD subjects contained lower levels of pro-angiogenic miR-126 and miR-210 (25.2±6.4 vs 8.3±1.7, p<0.05 and 0.29±0.07 vs 0.08±0.02, p<0.05, respectively). Exosomes contained arachidonic acid, eicosapentaenoic acid and docosapentanoic acid, as well as both pro-inflammatory and pro-resolving bioactive LMs and their pathway markers, including prostaglandins, leukotrienes, lipoxins, resolvins (D- and E-series) and maresins. By principle component analysis, exosome LM profiles differed significantly between healthy and PAD subjects. Exosomes from PAD subjects increased VSMC migration (1.5±.09-fold vs 1.0±.09-fold wound closure, p<0.005) and decreased EC migration (1.5±.04-fold vs. 1.8±.06-fold wound closure, p<0.005) compared to healthy controls. Both PAD and healthy exosomes increased MDM expression of pro-inflammatory genes TNF-α and MCP-1.

Conclusion: Plasma-derived exosomes from PAD patients contain an altered profile of vascular-active miRNA and LMs and confer effects on VSMCs and ECs that may impair vessel remodeling. We describe the first known evidence that plasma exosomes contain pro-resolving LMs. Collectively these data suggest that circulating exosome-based signaling may modulate vascular inflammation and repair in PAD patients.

Local versus global mechanical effects of intramural swelling in carotid arteries

Glycosaminoglycans (GAGs) are increasingly thought to play important roles in arterial mechanics and mechanobiology. We recently suggested that these highly negatively charged molecules, well known for their important contributions to cartilage mechanics, can pressurize intralamellar units in elastic arteries via a localized swelling process and thereby impact both smooth muscle mechanosensing and structural integrity. In this paper, we report osmotic loading experiments on murine common carotid arteries that revealed different degrees and extents of transmural swelling. Overall geometry changed significantly with exposure to hypo-osmotic solutions, as expected, yet mean pressure-outer diameter behaviors remained largely the same. Histological analyses revealed further that the swelling was not always distributed uniformly despite being confined primarily to the media. This unexpected finding guided a theoretical study of effects of different distributions of swelling on the wall stress. Results suggested that intramural swelling can introduce highly localized changes in the wall mechanics that could induce differential mechanobiological responses across the wall. There is, therefore, a need to focus on local, not global, mechanics when examining issues such as swelling-induced mechanosensing.