Feasibility Analysis of Ultrasound-Guided Placement of Tunneled Hemodialysis Catheters.

Introduction: Radiographic fluoroscopy is the current standard for placement of tunneled central venous catheters (CVCs) for hemodialysis. Radiographic fluoroscopy requires structural and personnel infrastructure and exposes the patient to ionizing radiation. Here, we investigate the feasibility of solely ultrasound-guided placement of tunneled central venous dialysis catheters (USCVCs). Methods: We evaluated prospectively collected single-center data regarding safety and catheter function of 134 consecutive patients who underwent USCVC implantation between 2020 and 2021. We used the inset guidewire to visualize the position of the catheter tip. In the case of inadequate visibility by ultrasound, we used intracardiac electrocardiography (ECG) recording or agitated saline. A total of 1844 catheter days were assessed. The optimal CVC position was defined as being within the upper right atrium (URA) and middle to deep right atrium. Results: Of the 134 USCVCs, 87% were placed on the right side. The primary success rate for optimal tip position and catheter function was 98%. Of the USCVCs, 97% were placed solely by ultrasound. Regarding positioning, 6% were in the vena cava superior zone, 70% in the URA and 24% in the middle to deep right atrium, resulting in a rate of 94% with optimal positioning. Effective blood flow averaged 292 ± 39 ml/min. There were no immediate procedure-associated complications. Conclusion: Placement of CVC for hemodialysis solely by ultrasound is an effective alternative to fluoroscopy-assisted placement.

[Treatment response and complications of older patients with ANCA(antineutrophil cytoplasmatic antibody)-associated vasculitis]. / Therapieansprechen und Komplikationen von älteren Patienten mit ANCA(antineutrophile cytoplasmatische Antikörper)-assoziierten Vaskulitiden.

BACKGROUND: ANCA (antineutrophil cytoplasmatic antibody)-associated vasculitis (AAV) mainly affects elderley people but adjusted therapy concepts for this patient group are lacking. AIM: The aim of this study was therefore to analyze differences in course and outcome of patients with AAV with respect to age. MATERIALS AND METHODS: 62 patients were analyzed for treatment response, of whom 53 (85%) experienced adverse events (AE and SAE) that could be evaluated. Older (> 65 yrs.) versus younger (< 65 yrs.) patients were compared. Treatment response was assessed at 6 months, complications were assessed over 18 months. RESULTS: Treatment response was not seen to differ by age groups. In multiple logistic regression, pulmonary involvement (OR = 6,9; CI = 1,7-27,8, p < 0,01) and ΔGFR [ml/min] (OR = 0,93; CI = 0,89-0,97, p < 0,01) were predictors of SAE. 14 patients had more than 1 SAE. Again, pulmonary involvement (28,2% vs. 78,6%, p < 0,01) was a risk factor and older patients (78,6% vs. 43,6%, p = 0,025) were more frequently affected. Patients with multiple SAEs received glucocorticoids of more than 5 mg/d for longer periods of time (171 ± 65 days vs. 120 ± 70 days, p = 0,03). DISCUSSION: No differences were found between older and younger patients with regard to treatment response. Multiple SAEs occurred more frequently in elderly patients. There was a correlation between pulmonary manifestation and duration of glucocorticoid therapy with a complicated course. The most frequent SAEs were infections requiring hospitalisation. CONCLUSION: Therapy for elderly patients should be individualized with the goal of a fast reduction of glucocorticoids. Special monitoring is indicated for elderly patients, especially those with pulmonary involvement.

Charge-Promoted Self-Metalation of Porphyrins on an Oxide Surface.

Metalation and self-metalation reactions of porphyrins on oxide surfaces have recently gained interest. The mechanism of porphyrin self-metalation on oxides is, however, far from being understood. Herein, we show by a combination of results obtained with scanning tunneling microscopy, photoemission spectroscopy, and DFT computations, that the self-metalation of 2H-tetraphenylporphyrin on the surface of ultrathin MgO(001) films is promoted by charge transfer. By tuning the work function of the MgO(001)/Ag(001) substrate, we are able to control the charge and the metalation state of the porphyrin molecules on the surface.

Contrast Reversal in Scanning Tunneling Microscopy and Its Implications for the Topological Classification of SmB6.

SmB6 has recently attracted considerable interest as a candidate for the first strongly correlated topological insulator. Such materials promise entirely new properties such as correlation-enhanced bulk bandgaps or a Fermi surface from spin excitations. Whether SmB6 and its surface states are topological or trivial is still heavily disputed however, and a solution is hindered by major disagreement between angle-resolved photoemission (ARPES) and scanning tunneling microscopy (STM) results. Here, a combined ARPES and STM experiment is conducted. It is discovered that the STM contrast strongly depends on the bias voltage and reverses its sign beyond 1 V. It is shown that the understanding of this contrast reversal is the clue to resolving the discrepancy between ARPES and STM results. In particular, the scanning tunneling spectra reflect a low-energy electronic structure at the surface, which supports a trivial origin of the surface states and the surface metallicity of SmB6 .