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Abstract Background In patients with subarachnoid hemorrhage (SAH), vasospasm remains one of the major complications. The application of intravenous magnesium sulfate (MgSO4) has been under discussion to prevent cerebral ischemia. Our aim was to examine the impact of early MgSO4 administration on local cerebral microcirculation during microsurgical clipping of SAH-related aneurysms. Methods The non-invasive laser-Doppler spectrophotometry system “Oxygen-to-See (O2C)” was used in 14 consecutive patients (11 female, 3 male, median age 56.5±9.7 yrs) with aneurysmatic SAH. A subdural probe measured capillary venous oxygenation (SO2), relative hemoglobin content (rHb), blood cell velocity (velo) and blood flow (flow) in 7 mm tissue depth. Data samples were recorded as baseline immediately before intraoperative application of MgSO4 10% 50 mg/kg body weight and 10 min thereafter. The continuous MgSO4 infusion rate depended on blood pressure (mean arterial pressure > 60-65 mmHg) and lasted a maximum of 60 min. Results MgSO4 was administered 2.8 (min. 1.6, max. 15.5) hours after onset of symptoms. Median flow increased significantly by 20.8% (5–68%, p = 0.001). Velo increased 4.9% (1–17%), rHb decreased 1.5% (3–34%) and SO2 decreased 9.4% (8–38%) by trend compared to the baseline values. FiO2 correlated positively with velo (rs = 0.712, p = 0.004), whereas arterial HCO3 correlated negatively with SO2 (rs = −0.599, p = 0.024). Of 14 patients, 2 had symptomatic vasospasm. Conclusions Our data suggest an increased cerebral blood flow after early intraoperative administration of MgSO4 in patients with SAH. Using a non-invasive laser-Doppler spectrophotometry system, this technique is feasible for continuous real-time monitoring of cerebral microcirculation. Trial registration DRKS (German Clinical Trial Registry), DRKS00013047 , retrospectively registered on September 21st, 2017.

High brightness electron sources for linac based free-electron lasers (FELs) are being developed at the Photo Injector Test facility at DESY, Zeuthen site (PITZ). Production of electron bunches with extremely small transverse emittance is the focus of the PITZ scientific program. The photoinjector optimization in 2008–2009 for a bunch charge of 1, 0.5, 0.25, and 0.1 nC resulted in measured emittance values which are beyond the requirements of the European XFEL [S. Rimjaem et al., Nucl. Instrum. Methods Phys. Res., Sect. A 671, 62 (2012)NIMAER0168-900210.1016/j.nima.2011.12.101]. Several essential modifications were commissioned in 2010–2011 at PITZ, resulting in further improvement of the photoinjector performance. Significant improvement of the rf gun phase stability is a major contribution in the reduction of the measured transverse emittance. The old TESLA prototype booster was replaced by a new cut disk structure cavity. This allows acceleration of the electron beam to higher energies and supports much higher flexibility for stable booster operation as well as for longer rf pulses which is of vital importance especially for the emittance optimization of low charge bunches. The transverse phase space of the electron beam was optimized at PITZ for bunch charges in the range between 0.02 and 2 nC, where the quality of the beam measurements was preserved by utilizing long pulse train operation. The experimental optimization yielded worldwide unprecedented low normalized emittance beams in the whole charge range studied.