Planar amorphous silicon carbide microelectrode arrays for chronic recording in rat motor cortex.

Chronic implantation of intracortical microelectrode arrays (MEAs) capable of recording from individual neurons can be used for the development of brain-machine interfaces. However, these devices show reduced recording capabilities under chronic conditions due, at least in part, to the brain's foreign body response (FBR). This creates a need for MEAs that can minimize the FBR to possibly enable long-term recording. A potential approach to reduce the FBR is the use of MEAs with reduced cross-sectional geometries. Here, we fabricated 4-shank amorphous silicon carbide (a-SiC) MEAs and implanted them into the motor cortex of seven female Sprague-Dawley rats. Each a-SiC MEA shank was 8 µm thick by 20 µm wide and had sixteen sputtered iridium oxide film (SIROF) electrodes (4 per shank). A-SiC was chosen as the fabrication base for its high chemical stability, good electrical insulation properties, and amenability to thin film fabrication. Electrochemical analysis and neural recordings were performed weekly for 4 months. MEAs were characterized pre-implantation in buffered saline and in vivo using electrochemical impedance spectroscopy and cyclic voltammetry at 50 mV/s and 50,000 mV/s. Neural recordings were analyzed for single unit activity. At the end of the study, animals were sacrificed for immunohistochemical analysis. We observed statistically significant, but small, increases in 1 and 30 kHz impedance values and 50,000 mV/s charge storage capacity over the 16-week implantation period. Slow sweep 50 mV/s CV and 1 Hz impedance did not significantly change over time. Impedance values increased from 11.6 MΩ to 13.5 MΩ at 1 Hz, 1.2 MΩ-2.9 MΩ at 1 kHz, and 0.11 MΩ-0.13 MΩ at 30 kHz over 16 weeks. The median charge storage capacity of the implanted electrodes at 50 mV/s was 58.1 mC/cm2 on week 1 and 55.9 mC/cm2 on week 16, and at 50,000 mV/s, 4.27 mC/cm2 on week 1 and 5.93 mC/cm2 on week 16. Devices were able to record neural activity from 92% of all active channels at the beginning of the study, At the study endpoint, a-SiC devices were still recording single-unit activity on 51% of electrochemically active electrode channels. In addition, we observed that the signal-to-noise ratio experienced a small decline of -0.19 per week. We also classified observed units as fast and slow repolarizing based on the trough-to-peak time. Although the overall presence of single units declined, fast and slow repolarizing units declined at a similar rate. At recording electrode depth, immunohistochemistry showed minimal tissue response to the a-SiC devices, as indicated by statistically insignificant differences in activated glial cell response between implanted brains slices and contralateral sham slices at 150 µm away from the implant location, as evidenced by GFAP staining. NeuN staining revealed the presence of neuronal cell bodies close to the implantation site, again statistically not different from a contralateral sham slice. These results warrant further investigation of a-SiC MEAs for future long-term implantation neural recording studies.

Reactive Amine Functionalized Microelectrode Arrays Provide Short-Term Benefit but Long-Term Detriment to In Vivo Recording Performance.

Intracortical microelectrode arrays (MEAs) are used for recording neural signals. However, indwelling devices result in chronic neuroinflammation, which leads to decreased recording performance through degradation of the device and surrounding tissue. Coating the MEAs with bioactive molecules is being explored to mitigate neuroinflammation. Such approaches often require an intermediate functionalization step such as (3-aminopropyl)triethoxysilane (APTES), which serves as a linker. However, the standalone effect of this intermediate step has not been previously characterized. Here, we investigated the effect of coating MEAs with APTES by comparing APTES-coated to uncoated controls in vivo and ex vivo. First, we measured water contact angles between silicon uncoated and APTES-coated substrates to verify the hydrophilic characteristics of the APTES coating. Next, we implanted MEAs in the motor cortex (M1) of Sprague-Dawley rats with uncoated or APTES-coated devices. We assessed changes in the electrochemical impedance and neural recording performance over a chronic implantation period of 16 weeks. Additionally, histology and bulk gene expression were analyzed to understand further the reactive tissue changes arising from the coating. Results showed that APTES increased the hydrophilicity of the devices and decreased electrochemical impedance at 1 kHz. APTES coatings proved detrimental to the recording performance, as shown by a constant decay up to 16 weeks postimplantation. Bulk gene analysis showed differential changes in gene expression between groups that were inconclusive with regard to the long-term effect on neuronal tissue. Together, these results suggest that APTES coatings are ultimately detrimental to chronic neural recordings. Furthermore, interpretations of studies using APTES as a functionalization step should consider the potential consequences if the final functionalization step is incomplete.

Costs and Complications Associated with Infected Mesh for Ventral Hernia Repair.

Background: Mesh hernia repair is widely accepted because of the associated reduction in hernia recurrence compared with suture-based repair. Despite initiatives to reduce risk, mesh infection and mesh removal are a significant challenge. In an era of healthcare value, it is essential to understand the global cost of care, including the incidence and cost of complications. The purpose of this study was to identify the outcomes and costs of care of patients who required the removal of infected hernia mesh. Methods: A review of databases from 2006 through June 2018 identified patients who underwent both ventral hernia repair (VHR) and re-operation for infected mesh removal. Patient demographic and operative details for both procedures, including age, Body Mass Index, mesh type, amount of time between procedures, and information regarding interval procedures were obtained. Clinical outcome measures were the length of the hospital stay, hospital re-admission, incision/non-incision complications, and re-operation. Hospital cost data were obtained from the cost accounting system and were combined with the clinical data for a cost and clinical representation of the cases. Results: Thirty-four patients underwent both VHR and removal of infected mesh material over the 12-year time frame and were included in the analyses; the average age at VHR was 48 years, and 16 patients (47%) were female. Following VHR, 21 patients (62%) experienced incision complications within 90 days post-operatively, the complications ranging from superficial surgical site infection (SSI) to evisceration. A mean of 22.65 months passed between procedures. After mesh removal, 16 patients (47%) experienced further incisional complications; and 22 (65%) patients had at least one re-admission. Eighteen patients (53%) required a minimum of one additional related operative procedure after mesh removal. Median hospital costs nearly doubled (p < 0.001) for the mesh removal ($23,841 [interquartile range {IQR} $13,596-$42,148]) compared with the VHR admission ($13,394 [IQR $8,424-$22,161]) not accounting for re-admission costs. A majority experienced hernia recurrence subsequent to mesh removal. Conclusions: Mesh infection after hernia repair is associated with significant morbidity and costs. Hospital re-admission, re-operations, and recurrences are common among these patients, resulting in greater healthcare resource utilization. Development of strategies to prevent mesh infection, identify patients most likely to experience infectious complications, and define best practices for the care of patients with mesh infection are needed.

Implementation of Real-Time Assessment of Patient-Reported Outcomes in a Heart Failure Clinic: A Feasibility Study.

BACKGROUND: Patient-reported outcomes (PROs) quantify, from patients' perspectives, their symptoms, function, and quality of life. Our aim was to determine the feasibility of integrating PRO capture into routine clinical practice at a large heart failure (HF) clinic. METHODS: We examined the practicality of PRO completion at the time of clinic visit, the time required to complete the selected instruments, the completion rate, and the feasibility of immediate PRO scoring and integration of the results into the electronic health record (EHR). We deployed a computer program to capture PROs (Kansas City Cardiomyopathy Questionnaire, Patient-Reported Outcomes Measurement Information System) on a portable computer platform at the time of a clinic visit. An automated algorithm identified patients scheduled for appointments at the HF clinic at registration, provided a portable tablet computer with which to complete the appropriate PRO instruments and then scored and immediately integrated the results in the patient's EHR. RESULTS: In a 12-month period, 862 unique patients completed 1,320 PRO assessments. The mean age of this cohort was 60.1 ± 16.3 years and 66% were male. The average time for PRO assessment was 6.7 minutes and the completion rate among eligible patients was 58%, with 91% of started assessments completed in full. CONCLUSIONS: These preliminary data support the feasibility of serial PRO assessment with real-time integration into the EHR in a large outpatient population of patients with HF. We identified critical steps that should enhance adoption of this approach by clinicians and render PRO results meaningful and actionable in routine clinical care.

Cardiovascular Risk Assessment and Management in Prerenal Transplantation Candidates.

Cardiovascular (CV) assessment in prerenal transplant patients varies by center. Current guidelines recommend stress testing for candidates if ≥ 3 CV risk factors exist. We evaluated the CV assessment and management in 685 patients referred for kidney transplant over a 7-year period. All patients had CV risk factors, and the most common cause of end-stage renal disease was diabetes. Thirty-three percent (n = 229) underwent coronary angiography. The sensitivity of stress testing to detect obstructive coronary artery disease (CAD) was poor (0.26). Patients who had no CAD, nonobstructive CAD, or CAD with intervention had significantly higher event-free survival compared with patients with obstructive CAD without intervention. There were no adverse clinical events (death, myocardial infarction, stroke, revascularization, and graft failure) within 30 days post-transplant in patients who had preoperative angiography (n = 77). Of the transplanted patients who did not have an angiogram (n = 289), there were 8 clinical events (6 myocardial infarctions) in the first 30 days. In conclusion, our results indicate that stress testing and usual risk factors were poor predictors of obstructive CAD and that revascularization may prove beneficial in these patients.

Unplanned readmission after total joint arthroplasty: rates, reasons, and risk factors.

BACKGROUND: There has been a major and alarming increase in readmission rates following total joint arthroplasty. With proposed changes in reimbursement policy, increased rates of unplanned readmission following arthroplasty will penalize providers. In particular, it has been proposed that specific complications--so-called "zero-tolerance" complications--are unacceptable and that their treatment will not qualify for reimbursement. The purpose of this study was to identify the incidence, causes, and risk factors for readmission following total joint arthroplasty. METHODS: An institutional arthroplasty database was utilized to identify those patients undergoing total knee or hip arthroplasty from January 2004 through December 2008. A total of 10,633 admissions for primary arthroplasty (5207 knees and 5426 hips) were identified. The same database was used to identify patients requiring an unplanned readmission within ninety days of discharge. Multivariate logistic regression was utilized to determine the independent predictors of readmission within ninety days. RESULTS: There were 591 unplanned readmissions within ninety days of discharge following 564 (5.3%) of the 10,633 admissions for total joint arthroplasty. The most common cause of readmission was joint-related infection, followed by stiffness. Black race, male sex, discharge to inpatient rehabilitation, increased duration of hospital stay, unilateral replacement, decreased age, decreased distance between home and the hospital, and total knee replacement were independent predictors of readmission within ninety days. CONCLUSIONS: The high incidence of readmissions secondary to potential "zero-tolerance" events suggests that these are not easily preventable complications. In addition, longer hospitalization and discharge to an inpatient continued-care facility increased the risk of readmission.