The Macromolecular Design of Poly(styrene-isoprene-styrene) (SIS) Copolymers Defines their Performance in Flexible Electrothermal Composite Heaters

Electric cars are desirable for their environmental and economic benefits yet face limitations in range in cold weather due to the increased energy demands for cabin heating. To provide efficient heating for vehicles, flexible composite electrothermal heaters offer a viable solution owing to their lightweight design, efficiency, and adaptability for use within and beyond vehicle interiors. The current study aims to improve electrothermal heater stability and performance by understanding the impact of the polymer structure on composite properties. We explore how the presence and molecular structure of olefinic bonds within the polyisoprene block of styrenic triblock copolymers affect thermal stability and performance. Composite electrothermal heaters were fabricated by dispersing carbon black (CB) as the heating material in three triblock copolymer matrices, poly(styrene-1,4-isoprene-styrene) (1,4-SIS), poly(styrene-3,4-isoprene-styrene) (3,4-SIS), and its hydrogenated version poly(styrene-ethylene-propylene-styrene) (SEPS). The chemical structure and thermal properties of each copolymer were linked to electrothermal performance measurements of composite heaters to establish structure-function relationships. Notably, 3,4-SIS with 28 wt % CB demonstrated the highest thermal and electrical conductivity, resulting in uniform heat distribution. The outcomes unambiguously demonstrate that the olefinic structure of SIS copolymers enhances the electric and thermal conductivity, leading to enhanced electrothermal performance of prototype heaters compared to that of the hydrogenated copolymer.

Subdural evacuation port system and middle meningeal artery embolization for chronic subdural hematoma: a multicenter experience

OBJECTIVE

Middle meningeal artery (MMA) embolization and the Subdural Evacuation Port System (SEPS) are minimally invasive treatment paradigms for chronic subdural hematoma (cSDH). Although SEPS offers acute decompression of local mass effect from a cSDH, MMA embolization has been shown to reduce the rate of cSDH recurrence. In combination, these procedures present a potentially safer strategy to a challenging pathology. The authors present a multi-institutional retrospective case series that assessed the safety, efficacy, and complications of SEPS and MMA embolization for cSDH.

METHODS

A retrospective review was performed of patients who underwent SEPS placement and MMA embolization for cSDH between 2018 and 2021 at three institutions.

RESULTS

One hundred patients with 136 cSDHs and a median age of 73 years underwent both SEPS placement and MMA embolization. Initial Glasgow Coma Scale scores were between 14 and 15 in 81% of patients and between 9 and 13 in 14%. The median initial midline shift (MLS) was 7 mm, with subdural hematoma (SDH) in the left hemisphere (lh) in 30% of patients, right hemisphere (rh) in 34%, and bilateral hemispheres in 36%. Follow-up was available for 86 patients: 93.4% demonstrated decreased MLS, and all patients with lhSDH and rhSDH demonstrated progressive decrease in SDH size. The overall complication rate was 4%, including 1 case of facial palsy and 3 cases of iatrogenic acute SDH. Two subjects (2%) required craniotomy for hematoma evacuation. The rate of good functional outcomes, with modified Rankin Scale (mRS) score < 2, was 89% on final follow-up and the overall mortality rate was 2%. A good mRS score on admission was associated with increased odds of functional improvement at follow-up (p < 0.001).

CONCLUSIONS

SEPS placement with MMA embolization for cSDH can be done safely and effectively reduces cSDH size with minimal perioperative morbidity.

Middle meningeal artery embolization with subdural evacuating port system for primary management of chronic subdural hematomas

Optimal treatment for chronic subdural hematomas remains controversial and perioperative risks and comorbidities may affect management strategies. Minimally invasive procedures are emerging as alternatives to the standard operative treatments. We evaluate our experience with middle meningeal artery (MMA) embolization combined with Subdural Evacuating Port System (SEPS) placement as a first-line treatment for patients with cSDH. A single institution retrospective review was performed of all patients undergoing intervention. Patients were stratified by treatment with MMA embolization and SEPS placement, MMA embolization and surgery, SEPS placement only, and surgery only for cSDH from 2017 to 2020, and cohorts were compared against each other. Patients treated with MMA/SEPS were more likely to be older, be on anticoagulation, have significant comorbidities, have shorter length of stay, and less likely to have symptomatic recurrence compared to SEPS only cohort. Thus, MMA/SEPS appears to be a safe and equally effective minimally invasive treatment for cSDH patients with significant comorbidities who are poor surgical candidates.

Benefits of the Subdural Evacuating Port System (SEPS) Procedure Over Traditional Craniotomy for Subdural Hematoma Evacuation

Background

There remains no consensus on the optimal primary intervention for subdural hematoma (SDH). Although historically favored, craniotomy carries substantial morbidity and incurs significant costs. Contrastingly, the subdural evacuating port system (SEPS) is a minimally invasive bedside procedure. We assessed the benefits of SEPS over traditional craniotomy for SDH evacuation.

Methods

A single-center retrospective cohort study of SDH patients receiving craniotomy or SEPS between 2012 and 2017 was performed. Information regarding demographics, medical history, presentation, surgical outcomes, cost, and complications was collected. Pre- and postoperative hematoma volumes were calculated using 3D image segmentation using Vitrea software. Multivariate regression models were employed to assess the influence of intervention choice.

Results

Of 107 patients, 68 underwent craniotomy and 39 underwent SEPS. There were no differences in age, sex, blood thinner use, platelet count, INR, hematoma lateralization, age, volume, or midline shift at presentation between intervention groups. Although there was no difference in percent residual hematoma volume 24-hour postintervention (44.1% vs 45.1%, P = .894), SEPS was associated with lower hospitalization costs ($108 391 vs $166 318, *P = .002), shorter length of stay (4.0 vs 5.8 days, *P = .0002), and fewer postoperative seizures (2.6% vs 17.7%, *P = .048). Reoperation rate was higher after SEPS overall (33.3% vs 13.2%, *P = .048) but comparable to craniotomy in chronic SDH (12.50% vs 7.69%, P = 1.000).

Conclusion

In this retrospective cohort, SEPS was noninferior to craniotomy at reducing SDH hematoma volume. The SEPS procedure was also associated with decreased length of stay hospitalization costs, and postoperative seizures and demonstrated a comparable recurrence rate to craniotomy for chronic SDH in particular.

Initial Experience with Using a Structured Light 3D Scanner and Image Registration to Plan Bedside Subdural Evacuating Port System Placement

BACKGROUND

Chronic subdural hematoma evacuation can be achieved in select patients through bedside placement of the Subdural Evacuation Port System (SEPS; Medtronic, Inc., Dublin, Ireland). This procedure involves drilling a burr hole at the thickest part of the hematoma. Identifying this location is often difficult, given the variable tilt of available imaging and distant anatomic landmarks. This paper evaluates the feasibility and accuracy of a bedside navigation system that relies on visible light-based 3-dimensional (3D) scanning and image registration to a pre-procedure computed tomography scan. The information provided by this system may increase accuracy of the burr hole location.

METHODS

In Part 1, the accuracy of this system was evaluated using a rigid 3D printed phantom head with implanted fiducials. In Part 2, the navigation system was tested on 3 patients who underwent SEPS placement.

RESULTS

The error in registration of this system was less than 2.5 mm when tested on a rigid 3D printed phantom head. Fiducials located in the posterior aspect of the head were difficult to reliably capture. For the 3 patients who underwent 5 SEPS placements, the distance between anticipated SEPS burr hole location based on registration and actual burr hole location was less than 1cm.

CONCLUSIONS

A bedside cranial navigation system based on 3D scanning and image registration has been introduced. Such a system may increase the success rate of bedside procedures, such as SEPS placement. However, technical challenges such as the ability to scan hair and practical challenges such as minimization of patient movement during scans must be overcome.

First-line management of chronic subdural hematoma with the subdural evacuating port system: Institutional experience and predictors of outcomes

Chronic subdural hematoma (cSDH) is a common condition that disproportionately affects older patients. Given the greater risks of general anesthesia in this population, interest has turned towards less invasive surgical approaches such as the subdural evacuating port system (SEPS; Medtronic, Inc., Minneapolis, MN). There is a relative dearth of information about the outcomes following this procedure. Here, we present our institution's experience with SEPS and analyze factors associated with the outcomes. Using a prospectively maintained institutional database, we retrospectively identified all patients who presented with cSDH and received first line therapy with SEPS. Pre- and post-operative clinical and radiographic data was obtained from the electronic health record. Outcomes included success or failure, Modified Rankin Scale (mRS) at discharge, length of stay (LOS), and discharge disposition. A total of 126 patients met the inclusion criteria (36 females and 90 males; mean age of 71.6 years). None of the pre-procedural clinical or radiographic variables were associated with the likelihood of a successful outcome. Increasing age was associated with non-routine hospital discharge (p = 0.003), and lower presenting GCS was associated with longer hospital stay (p = 0.005). Greater thickness of the cSDH was associated with a lower likelihood of having a favorable outcome (mRS ≥ 3; p = 0.003). SEPS is an effective first-line therapy for cSDH. Variables previously reported to limit the effectiveness of the technique (presence of septations, mixed density collections) were not associated with treatment failure.

Recent Progress of Varicose Vein Treatment Especially about Endovascular Heat Ablation, SEPS and Foam Sclerotherapy

There were three epoch making events in therapy of varicose veins. The first one is that the endovascular heat ablation (EVHA) using diode laser was authorized by the Ministry of Health Labor and Welfare in January 2011. The second one is that Subfascial Endoscopic Perforator Surgery (SEPS) was also authorized in April 2014. All of the therapies which were covered by the national insurance system had been the procedures for superficial veins but the SEPS is procedure for the perforating veins. The third one is that the foam usage of Polidocasklerol was listed formally at the medical package insert in September 2016. Moreover stub avulsion was introduced as figure-related improvement method with a smaller operation wound instead of conventional varicectomy and the other existing therapies are progressing every day. Therefore, by this education seminar, I lecture mainly on the EVHA, SEPS and foam sclerotherapy in varicose vein treatment. Finally I show one case which you should remember. (This is a translation of Jpn J Vasc Surg 2017; 26: 225–230.)

Treatment of chronic subdural hematomas with subdural evacuating port system placement in the intensive care unit: evolution of practice and comparison with bur hole evacuation in the operating room

OBJECTIVE The aims of this study were to evaluate a multiyear experience with subdural evacuating port system (SEPS) placement for chronic subdural hematoma (cSDH) in the intensive care unit at a tertiary neurosurgical center and to compare SEPS placement with bur hole evacuation in the operating room. METHODS All cases of cSDH evacuation were captured over a 7-year period at a tertiary neurosurgical center within an integrated health care delivery system. The authors compared the performance characteristics of SEPS and bur hole placement with respect to recurrence rates, change in recurrence rates over time, complications, length of stay, discharge disposition, and mortality rates. RESULTS A total of 371 SEPS cases and 659 bur hole cases were performed (n = 1030). The use of bedside SEPS placement for cSDH treatment increased over the 7-year period, from 14% to 80% of cases. Reoperation within 6 months was higher for the SEPS (15.6%) than for bur hole drainage (9.1%) across the full 7-year period (p = 0.002). This observed overall difference was due to a higher rate of reoperation during the same hospitalization (7.0% for SEPS vs 3.2% for bur hole; p = 0.008). Over time, as the SEPS procedure became more common and modifications of the SEPS technique were introduced, the rate of in-hospital reoperation after SEPS decreased to 3.3% (p = 0.02 for trend), and the difference between SEPS and bur hole recurrence was no longer significant (p = 0.70). Complications were uncommon and were similar between the groups. CONCLUSIONS Overall performance characteristics of bedside SEPS and bur hole drainage in the operating room were similar. Modifications to the SEPS technique over time were associated with a reduced reoperation rate.

Removable esophageal stents have poor efficacy for the treatment of refractory benign esophageal strictures (RBES)

With the recent availability of removable esophageal stents, endoscopic stenting has been utilized to treat refractory benign esophageal strictures (RBES). The objective of this study was to review the feasibility and effectiveness of removable esophageal stents to treat RBES. Patients who received removable esophageal stents for the treatment of RBES at the institution between 2004-2010 using its stent implantation logs and endoscopic database were retrospectively identified. Patient demographics, stricture etiology and location, stent and procedure characteristics, and clinical outcomes were obtained. Twenty-five patients with a mean age of 70 (72% male) underwent initial stent placement; 24 were successful. Overall clinical success was achieved in five of the 19 patients (26%) ultimately undergoing stent removal. RBES etiologies included anastomotic (13), radiation (5), peptic (3), chemotherapy (1), scleroderma (1), and unknown (2). Alimaxx-E (Merit-Endotek, South Jordan, UT, USA) stents were placed in 20 patients and Polyflex (Boston Scientific, Natick, MA, USA) stents were used in five patients. Immediate complications included failed deployment (1) and chest pain (7). Five patients died prior to stent removal. Stent migration was found in 53% (10/19) of patients who underwent stent removal: nine required additional therapy and one had symptom resolution. Out of the nine patients without stent migration, five required additional therapy and four had symptom resolution. Although placement of removable esophageal stents for RBES is technically feasible, it is frequently complicated by stent migration and chest pain. In addition, few patients achieved long-term stricture resolution after initial stenting. In this study, most patients ultimately required repeated stenting and/or dilations to maintain relief of dysphagia.

Enteral stents: from esophagus to colon

Because of significant advances in endoscopic techniques and the development of high-quality stents, endoscopic enteral stent placement is increasingly being performed for the management of malignant GI obstruction. Palliative stenting is now routinely performed for malignant esophageal, gastric, duodenal, and colon obstruction. In addition to palliative indications, preoperative stenting in the colon may be performed as a bridge to surgery to achieve immediate decompression and convert an emergent surgery into an elective, 1-stage procedure.The realm of enteral stenting has recently expanded to include management of benign conditions such as leaks, fistulas, and benign strictures in the GI tract. Further research is required to study the use of enteral stents in benign conditions and to adequately compare endoscopic stent placement with surgical intervention. Promising new technologies such as biodegradable stents and drug-eluting stents also require further investigation. With continued innovation in endoscopic techniques and stenting devices, the field of enteral stenting is likely to expand further, with an increase in indications and improvement in outcomes.

Placement of a subdural evacuating port system for management of iatrogenic hyperacute subdural hemorrhage following intracranial monitor placement

A 22-year-old man was admitted with a severe traumatic brain injury developed a hyperacute subdural hematoma (SDH) following attempted brain tissue oxygen monitor placement. This patient was successfully treated by placement of a subdural evacuation portal system (SEPS). The patient presented to a Level I trauma center after a severe bike versus auto accident. On admission, he was found to have a Glasgow Coma Scale (GCS) score of 3. The patient had small areas of intraparechymal hemorrhage as well as suspicion for diffuse axonal injury in the midbrain. Based on the patient's GCS score, neurological monitoring was indicated as a part of his intensive care unit treatment, however a SDH occurred during an attempted placement of a brain tissue oxygen monitor. This iatrogenic hyperacute SDH after burr hole monitoring device placement was treated with a SEPS drain. The SEPS drain has been shown to provide complete and/or temporary decompression of liquefied SDH. To our knowledge, this is the first report of using the SEPS to treat iatrogenic SDH associated with an intracranial monitoring device. This technique should be added to the armament of treatment options for a neurosurgeon to treat or temporize a hyperacute SDH with increased intracranial pressure in specific patients.

Subfascial endoscopic perforator surgery using screw-type ports is a very useful component of a comprehensive treatment program for chronic venous insufficiency

BACKGROUND

Subfascial endoscopic perforator surgery (SEPS) with a two-port system utilizing screw-type ports, CO2 insufflation and an ultrasonic coagulation system, is a useful procedure that does not require burdensome apparatus and techniques. SEPS was accepted as a national advanced medical system by the Japanese Ministry of Health, Labor and Welfare in May 2009.

PATIENTS AND METHODS

Forty-one limbs of 35 patients with 10 active ulcers (C6) and 2 healed ulcers (C5) were treated by SEPS between February 2010 and December 2011. Thirty-three limbs had concomitant superficial vein surgery. SEPS alone was performed on 8 limbs, in 6 of which the superficial veins had already been ablated. In 2 limbs, incompetent perforating veins (IPVs) existed under the affected skin, around the scars of past surgery.

RESULTS

All stasis ulcers of the 10 C6 limbs healed between 1 week and 14 months after SEPS (mean 2.9 months), with no ulcer recurrence during the follow-up period (2 to 24 months). IPVs under the scars were easily and safely interrupted by SEPS.

CONCLUSION

SEPS is a very useful component of a comprehensive treatment program for chronic venous insufficiency, especially in patients with venous stasis ulcers and IPVs under the scars of past surgery.

Venous ulcers: new options in treatment: minimally invasive vein surgery

Venous disease has a spectrum of presentations. The most advanced state of chronic venous insufficiency (CVI) managed by wound care specialists being ulceration of the lower extremity. The goal of all treatments for advanced venous disease is to decrease ambulatory venous hypertension. Treatment can be divided into exogenous and endogenous methods. Exogenous methods include those applied externally such as compression, elevation, debridement and wound dressings. Endogenous methods treat the underlying venous pathology either due to venous valvular dysfunction or venous obstruction leading to venous hypertension. Recently, significant advances in endogenous methods have evolved. The development of a new concept, minimally invasive vein surgery (MIVS), has improved upon traditional, open, invasive treatments of venous disease. MIVS techniques are performed percutaneously, with minimal anesthesia, no incisions and rarely require hospital admission. This article summarizes the concept of MIVS, describes each method of MIVS and its complementary role in the management of venous leg ulcers patients.