[Videoassisted Thoracoscopy with Preserved Spontaneous Breathing - an Anaesthesiological Perspective]. / Videoassistierte Thorakoskopie unter Erhalt der Spontanatmung ­ eine anästhesiologische Perspektive.

INTRODUCTION: Video-assisted thoracoscopic procedures with preserved spontaneous breathing (NI-VATS = conscious video-assisted thoracic surgery) have enjoyed a revival in recent years. However, there have been few reports on proper patient selection, as well as surgical or anaesthesiologic management for these procedures in Germany. Therefore, we present our experience with NI-VATS procedures in the form of a case study and discuss the results with a current survey and the current literature. METHOD: Retrospective evaluation of all NI-VATS procedures at our local institution. RESULTS: From June 2018 to January 2020 n = 17 (9 male and 8 female) patients underwent NI-VATS at our institution. Median age of patients was 68 [61 - 79] years. Fourteen patients suffered from progressive cancer as the underlying disease, leading to thoracic surgery. All patients had a number of comorbidities and were classified according to the ASA categories III (n = 9) or IV (n = 8). Surgical procedures were of short duration (in median 18 [15 - 27] min) and included 82% pleural procedures (pleurectomy, decortication or insertion of pleural drainage). All patients tolerated the surgical procedures under local anaesthesia and conscious sedation very well. Eleven patients could therefore be transferred to the normal ward after surgery, while the remaining patients underwent prolonged and intensified postoperative monitoring. Five of the 17 patients died within the hospital, in median 8 [3.0 - 33.5] days after surgery, in context of the underlying disease. None of the deaths could be associated with the surgical procedures. DISCUSSION: In a well selected patient cohort and with our local experience, NI-VATS is a safe and practicable alternative to standard thoracotomy in general anaesthesia and one-lung ventilation. In our local institution, multimorbid patients with interventions of short duration and reasonable extent underwent successful NI-VATS and emerged as good candidates for this procedure. Careful patient selection and knowledge of the procedure and its side effects present important milestones for successful NI-VATS.

Minimally-invasive parasternal aortic valve replacement-A slow learning curve towards improved outcomes.

BACKGROUND: We report our starting experience with parasternal minimally-invasive aortic valve replacement. METHODS: From 7/14 to 8/18, 192 received classic aortic valve surgery using a 5 cm parasternal incision and percutaneous groin cannulation. Patients were selected based on anatomic feasibility judged by preoperative computed tomography-scan. Except for porcelain aorta, left-sided aortic location, or endocarditic abscess, there were no exclusions. RESULTS: Patients were divided into two groups (first and second half of experience). Demographics were equal. Patients' mean ejection fraction was 59%, with preoperative stroke (12%), severe chronic obstructive pulmonary disorder (11%), and endocarditis (2%). All cases were elective or urgent. The Euroscore II was 3.37 ± 3.31 in the first and 3.68 ± 3.97 in the second group (n.s.). Biological prostheses were implanted in 90%. Operating times in the first group were just under 3 hours, with bypass times of 129 ± 32 minutes and clamp times of 77 ± 20 minutes. In the second group, these times changed only minimally. There were three conversions to sternotomy in the first, but only one in the second group. Similarly, three patients died in the first and one in the second group. There were fewer complications in the second group regarding revision for bleeding (7 vs 1%), stroke (4 vs 0%) dialysis (3 vs 1%), and pericardial effusions (3 vs 1%). The O/E ratio dropped from 0.93 to 0.28. CONCLUSIONS: Parasternal minimally-invasive aortic valve replacement is a feasible technique associated with a slow learning curve but the potential to achieve improved outcomes. Considering the transcatheter alternatives, the relative risk reduction may be worth investigating in future trials.

Pulse compression grating fabrication by diffractive proximity photolithography.

We report about a newly devised throughput-scalable fabrication method for high-quality periodic submicron structures. The process is demonstrated for optical transmission gratings in fused silica with a period of 800 nm (1250 lines/mm) to be used in laser pulse compression. The technology is based on an innovative advancement of i-line proximity photolithography performed in a mask aligner. The aerial image is encoded in a rigorously optimized electron-beam-written three-level phase mask which is illuminated by an adapted multipole configuration of incidence angles. In comparison to conventional proximity lithography, the process enables a significantly higher resolution while maintaining a good depth of focus--in contrast to lithography based on direct Talbot-imaging. Details about the grating fabrication process and characterization of fabricated pulse compression grating wafers are presented. The gratings show a diffraction efficiency of 97% at a wavelength of 1030 nm and a wavefront error comparable to gratings fabricated by electron-beam lithography.

152 W average power Tm-doped fiber CPA system.

A high-power thulium (Tm)-doped fiber chirped-pulse amplification system emitting a record compressed average output power of 152 W and 4 MW peak power is demonstrated. This result is enabled by utilizing Tm-doped photonic crystal fibers with mode-field diameters of 35 µm, which mitigate detrimental nonlinearities, exhibit slope efficiencies of more than 50%, and allow for reaching a pump-power-limited average output power of 241 W. The high-compression efficiency has been achieved by using multilayer dielectric gratings with diffraction efficiencies higher than 98%.

Reflective cavity couplers based on resonant waveguide gratings.

We report on a novel concept for reflective diffractive cavity couplers based on resonant waveguide gratings instead of multilayer coatings. The diffracting or rather beam splitting properties are induced to the subwavelength structures by a periodic parameter modulation of the ridges. Since such a perturbation of the highly reflective system also enhances transmission stacks of two and three reflectors are considered to retrieve transmittivities as low as possible. Our calculations show that transmissions of less than 10(-4) are possible for different configurations based on silicon and silica. The results of first technological tests for the realization of stacked T-shape structures are presented. With a total effective layer thickness not exceeding 1.1 µm the discussed approaches are expected to remarkably reduce the urgent problem of coating thermal noise of conventional components for high-precision metrology.

Optical absorption in degenerately doped semiconductors: Mott transition or Mahan excitons?

Electron doping turns semiconductors conductive even when they have wide fundamental band gaps. The degenerate electron gas in the lowest conduction-band states, e.g., of a transparent conducting oxide, drastically modifies the Coulomb interaction between the electrons and, hence, the optical properties close to the absorption edge. We describe these effects by developing an ab initio technique which captures also the Pauli blocking and the Fermi-edge singularity at the optical-absorption onset, that occur in addition to quasiparticle and excitonic effects. We answer the question whether free carriers induce an excitonic Mott transition or trigger the evolution of Wannier-Mott excitons into Mahan excitons. The prototypical n-type zinc oxide is studied as an example.

Expression of apoptosis-related genes in the organ of Corti, modiolus and stria vascularis of newborn rats.

Cell death in the inner ear tissues is an important mechanism leading to hearing impairment. Here, using microarrays and real-time RT-PCR we analyzed expression of selected apoptosis-related genes in rat's inner ear. We determined the gene expression in tissues freshly isolated from neonatal rats (3-5 days old) and compared it to that of explants cultured for 24 h under normoxic or hypoxic conditions. For the analyses, we used pooled samples of the organ of Corti (OC), modiolus (MOD) and stria vascularis (SV), respectively. We observed region-specific changes in gene expression between the fresh tissues and the normoxic culture. In the OC, expression of the proapoptotic genes caspase-2, caspase-3, caspase-6 and calpain-1 was downregulated. In the MOD, the antioxidative defense SOD-2 and SOD-3 were upregulated. In the SV, caspase-2, caspase-6, calpain-1 and SOD-3 were downregulated and SOD-2 upregulated. We speculate that these changes could reflect survival shift in transcriptome of inner ear explants tissues under in vitro conditions. With the exception of SOD-2, hypoxic culture conditions induced the same changes in gene expression as the normoxic conditions indicating that culture preparation is likely the dominating factor, which modifies the gene expression pattern. We conclude that various culture conditions induce different expression pattern of apoptosis-related genes in the organotypic cochlear cultures, as compared to fresh tissues. This transcriptional pattern may reflect the survival ability of specific tissues and could become a tempting target for a pharmacological intervention in inner ear diseases.