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Background: An unintentional large dose of dexmedetomidine during sedation can lead to increased side effects such as bradycardia and hypotension. We investigated whether the frequency of bradycardia in patients undergoing surgery under spinal anesthesia and sedation with dexmedetomidine was effected if bispectral index (BIS) was used to monitor the sedation. Methodology: Fifty patients between 20 and 60 y of age, who underwent spinal anesthesia, were included in this study. The patients were divided into two groups (control and BIS groups). Patients in the control group were administered a loading dose of 1 μg/kg dexmedetomidine for the first 10 min without BIS monitoring, followed by a maintenance dose of 0.2 μg/kg/h. Patients in the BIS group received a loading dose of 1 μg/kg dexmedetomidine for the first 10 min. The maintenance dose in this group was administered at the discretion of the anesthesiologist to maintain the BIS score between 50 and 70. The baseline heart rate (HR), lowest HR, and the difference between baseline and the lowest HR were calculated. Results: The baseline HR was 74.4 ± 11.0 beats per minute (bpm) and 80.9 ± 16.0 bpm, in the control and BIS groups respectively (p = 0.098). The difference between the baseline and lowest HR in the control and BIS groups was 19.4 ± 7.6 bpm and 25.5 ± 8.8 bpm, respectively (p = 0.011). Low baseline HR was positively correlated with a reduced lowest HR. Conclusions: The frequency of bradycardia during sedation with dexmedetomidine decreased with BIS monitoring. Patients with a low baseline HR were more likely to develop bradycardia during sedation with dexmedetomidine. Therefore, BIS monitoring may be helpful in patients with low baseline HR. Key words: Bispectral index monitor; Dexmedetomidine; heart rate; spinal anesthesia Citation: Kim J, Kim HY, Yun M, Lee J, Kim JD, Kang D. Bispectral index monitoring during sedation with dexmedetomidine in spinal anesthesia prevents bradycardia: a randomized clinical trial. Anaesth. pain intensive care 2021;26(1):14-19 ; DOI: 10.35975/apic.v26i1.1760

Ruthenium (Ru) thin films were grown on thermally-grown SiO2 substrates by plasma enhanced atomic layer deposition (PEALD) using a sequential supply of a new betadiketonate Ru metallorganic precursor, dicarbonyl-bis(5-methyl-2,4-hexanediketonato) Ru(II) (C16H22O6Ru) with a high vapor pressure and NH3 plasma as a reactant at the substrate temperature ranging from 175 and 310 degrees C. A self-limited film growth was confirmed at the deposition temperature of 225 degrees C and the growth rate was 0.063 nm/cycle on the SiO2 substrate with very short number of incubation cycles (approximately 10 cycles). The resistivity of PEALD-Ru films was dependent on the microstructural features characterized by grain size and crystallinity, which could be controlled by varying the deposition temperature. Ru film with the resistivity of -20 μΩ-cm and high density of 11.5 g/cm3 was obtained at the deposition temperature as low as 225 degrees C. It formed polycrystalline structure with hexagonal-close-packed phase that was confirmed by X-ray diffractometry and transmission electronic microscopy analysis. Step coverage of PEALD-Ru film deposited with the optimum condition was good (-75%) at the very small-sized trench (aspect ratio: -4.5 and the top opening size of 25 nm).

Patterned FTO was fabricated via a facile method as an efficient current collector in a photoelectrochemical water splitting system. The photocurrent density of α-Fe2O3 on patterned FTO exhibited a 1.7 times increase relative to α-Fe2O3 on FTO due to the light scattering and rapid transfer of excited electrons.

Dendrimer-stabilized gold nanoparticles (Au-Den) were prepared by a facile solution based method for a highly reliable and robust surface enhanced Raman scattering (SERS) substrate. Au-Den was selectively attached on the surface of reduced graphene oxide (rGO) by noncovalent interactions between the Au capping dendrimer and the graphene surface. Au-Den/rGO exhibits the outstandingly stable and highly magnified Raman signal with an enhancement factor (EF) of 3.9 × 10(7) that enables detection of R6G dyes with concentration as low as 10 nM, retaining 95% of the Raman signal intensity after 1 year. The remarkable stability and enhancement originated not only from a simple combination of the electromagnetic and chemical mechanism of SERS but also from intensified packing density of stable Au-Den on the graphene substrate due to the firm binding between the dendrimer capped metal nanoparticles and the graphene substrate. This method is not limited to the gold nanoparticles and G4 dendrimer used herein, but also can be applied to other dendrimers and metal nanoparticles, which makes the material platform suggested here superior to other SERS substrates.

Ruthenium (Ru) thin films were grown on thermally-grown SiO2 substrates by plasma enhanced atomic layer deposition (PEALD) using a sequential supply of a new betadiketonate Ru metallorganic precursor, dicarbonyl-bis(5-methyl-2,4-hexanediketonato) Ru(II) (C16H22O6Ru) with a high vapor pressure and NH3 plasma as a reactant at the substrate temperature ranging from 175 and 310 degrees C. A self-limited film growth was confirmed at the deposition temperature of 225 degrees C and the growth rate was 0.063 nm/cycle on the SiO2 substrate with very short number of incubation cycles (approximately 10 cycles). The resistivity of PEALD-Ru films was dependent on the microstructural features characterized by grain size and crystallinity, which could be controlled by varying the deposition temperature. Ru film with the resistivity of -20 μΩ-cm and high density of 11.5 g/cm3 was obtained at the deposition temperature as low as 225 degrees C. It formed polycrystalline structure with hexagonal-close-packed phase that was confirmed by X-ray diffractometry and transmission electronic microscopy analysis. Step coverage of PEALD-Ru film deposited with the optimum condition was good (-75%) at the very small-sized trench (aspect ratio: -4.5 and the top opening size of 25 nm).