General anesthesia or conscious sedation for thrombectomy in stroke patients: an updated systematic review and meta-analysis

PURPOSE

Endovascular treatment for stroke patients usually requires anesthesia care, with no current consensus on the best anesthetic management strategy. Several randomized controlled trials and meta-analyses have attempted to address this. In 2022, additional evidence from three new trials was published: the GASS trial, the CANVAS II trial, and preliminary results from the AMETIS trial, prompting the execution of this updated systematic review and meta-analysis. The primary objective of this study was to evaluate the effects of general anesthesia and conscious sedation on functional outcomes measured with the modified Rankin scale (mRS) at three months.

METHODS

We performed a systematic review and meta-analysis of randomized controlled trials investigating conscious sedation and general anesthesia in endovascular treatment. The following databases were examined: PubMed, Scopus, Embase, and the Cochrane Database of Randomized Controlled Trials and Systematic Reviews. The Risk of Bias 2 tool was used to assess bias. In addition, trial sequence analysis was performed on the primary outcome to estimate if the cumulative effect is significant enough to be unaffected by further studies.

RESULTS

Nine randomized controlled trials were identified, including 1,342 patients undergoing endovascular treatment for stroke. No significant differences were detected between general anesthesia and conscious sedation with regards to mRS, functional independence (mRS, 0-2), procedure duration, onset to reperfusion, mortality, hospital length of stay, and intensive care unit length of stay. Patients treated under general anesthesia may have more frequent successful reperfusion, though the time from groin to reperfusion was slightly longer. Trial sequential analysis showed that additional trials are unlikely to show marked differences in mean mRS at three months.

CONCLUSIONS

In this updated systematic review and meta-analysis, the choice of anesthetic strategy for endovascular treatment of stroke patients did not significantly impact functional outcome as measured with the mRS at three months. Patients managed with general anesthesia may have more frequent successful reperfusion.

TRIAL REGISTRATION

PROSPERO (CRD42022319368); registered 19 April 2022.

Filament identification in wide-angle high speed imaging of the mega amp spherical tokamak

A new tomographic inversion technique is presented for the identification of plasma filaments in wide-angle visible camera data. The technique works on the assumption that background subtracted images of filaments can be represented as a superposition of uniformly emitting magnetic equilibrium field lines. A large collection of equilibrium magnetic field lines is traced and projected onto the camera field of view and combined to form a geometry matrix describing the coordinate transformation from magnetic field aligned coordinates to image pixel coordinates. Inverting this matrix enables the reprojection of the emission in the camera images onto a field aligned basis, from which filaments are readily identifiable. The inversion is a poorly conditioned problem which is overcome using a least-squares approach with Laplacian regularization. Blobs are identified using the "watershed" algorithm and 2D Gaussians are fitted to get the positions, widths, and amplitudes of the filaments. A synthetic camera diagnostic generating images containing experimentally representative filaments is utilized to rigorously benchmark the accuracy and reliability of the technique. 74% of synthetic filaments above the detection amplitude threshold are successfully detected, with 98.8% of detected filaments being true positives. The accuracy with which filament properties and their probability density functions are recovered is discussed, along with sources of error and methods to minimize them.

Electron cyclotron emission spectra in X- and O-mode polarisation at JET: Martin-Puplett interferometer, absolute calibration, revised uncertainties, inboard/outboard temperature profile, and wall properties

At the tokamak Joint European Torus (JET), the electron cyclotron emission spectra in O-mode and X-mode polarisations are diagnosed simultaneous in absolute terms for several harmonics with two Martin-Puplett interferometers. From the second harmonic range in X-mode polarisation, the electron temperature profile can be deduced for the outboard side (low magnetic field strength) of JET but only for some parts of the inboard side (high magnetic field strength). This spatial restriction can be bypassed, if a cutoff is not present inside the plasma for O-mode waves in the first harmonic range. Then, from this spectral domain, the profile on the entire inboard side is accessible. The profile determination relies on the new absolute and independent calibration for both interferometers. During the calibration procedure, the antenna pattern was investigated as well, and, potentially, an increase in the diagnostic responsivity of about 5% was found for the domain 100-300 GHz. This increase and other uncertainty sources are taken into account in the thorough revision of the uncertainty for the diagnostic absolute calibration. The uncertainty deduced and the convolution inherent for Fourier spectroscopy diagnostics have implications for the temperature profile inferred. Having probed the electron cyclotron emission spectra in orthogonal polarisation directions for the first harmonic range, a condition is derived for the reflection and polarisation-scrambling coefficients of the first wall on the outboard side of JET.

Influence of plasma diagnostics and constraints on the quality of equilibrium reconstructions on Joint European Torus

One of the main approaches to thermonuclear fusion relies on confining high temperature plasmas with properly shaped magnetic fields. The determination of the magnetic topology is, therefore, essential for controlling the experiments and for achieving the required performance. In Tokamaks, the reconstruction of the fields is typically formulated as a free boundary equilibrium problem, described by the Grad-Shafranov equation in toroidal geometry and axisymmetric configurations. Unfortunately, this results in mathematically very ill posed problems and, therefore, the quality of the equilibrium reconstructions depends sensitively on the measurements used as inputs and on the imposed constraints. In this paper, it is shown how the different diagnostics (Magnetics Measurements, Polarimetry and Motional Stark Effect), together with the edge current density and plasma pressure constraints, can have a significant impact on the quality of the equilibrium on JET. Results show that both the Polarimetry and Motional Stark Effect internal diagnostics are crucial in order to obtain reasonable safety factor profiles. The impact of the edge current density constraint is significant when the plasma is in the H-mode of confinement. In this plasma scenario the strike point positions and the plasma last closed flux surface can change even by centimetres, depending on the edge constraints, with a significant impact on the remapping of the equilibrium-dependent diagnostics and of pedestal physics studies. On the other hand and quite counter intuitively, the pressure constraint can severely affect the quality of the magnetic reconstructions in the core. These trends have been verified with several JET discharges and consistent results have been found. An interpretation of these results, as interplay between degrees of freedom and available measurements, is provided. The systematic analysis described in the paper emphasizes the importance of having sufficient diagnostic inputs and of properly validating the results of the codes with independent measurements.

Recent improvements of the JET lithium beam diagnostic

A 60 kV neutral lithium diagnostic beam probes the edge plasma of JET for the measurement of electron density profiles. This paper describes recent enhancements of the diagnostic setup, new procedures for calibration and protection measures for the lithium ion gun during massive gas puffs for disruption mitigation. New light splitting optics allow in parallel beam emission measurements with a new double entrance slit CCD spectrometer (spectrally resolved) and a new interference filter avalanche photodiode camera (fast density and fluctuation studies).