Effect of dexmedetomidine on perioperative hemodynamics and organ protection in children with congenital heart disease: A randomized controlled trial.

BACKGROUND: This study aimed to investigate the effects of dexmedetomidine (Dex) on hemodynamics and organ protection in congenital heart disease (CHD) children who underwent open-heart surgery under cryogenic cardiopulmonary bypass. METHODS: Ninety children were randomly allocated to group C (0.9% saline 0.2 µg/kg/hour), group D1 (Dex 0.2 µg/kg/hour), and group D2 (Dex 0.4 µg/kg/hour) (n = 30 per group). All participants received fentanyl, propofol and 1% sevoflurane for anesthesia induction. Hemodynamic data were measured from T0 (before the induction) to T7 (30 minutes after extubation). The difference of arterial internal jugular vein bulbar oxygen difference and cerebral oxygen extraction ratio were calculated according to Fick formula. Enzyme-linked immunosorbent assay was performed to detect the serum myocardial, brain and kidney injury markers. The incidence of acute kidney injury (AKI) was calculated by serum creatinine level. Tracheal extubation time, postoperative pain score and emergence agitation score were also recorded. RESULTS: Compared with group C, group D1, and D2 exhibited reduction in hemodynamic parameters, myocardial and brain injury indicators, and tracheal extubation time. There were no significant differences in blood urea nitrogen and neutrophil gelatinase-associated lipocalin or incidence of AKI among the 3 groups. Besides, the incidence of tachycardia, nausea, vomiting and moderate agitation, and the FLACC scale in group D1 and D2 were lower than those in group C. Moreover, Dex 0.4 g/kg/hour could further reduce the dosage of fentanyl and dopamine compared with Dex 0.2 g/kg/hour. CONCLUSIONS: Dex anesthesia can effectively maintain hemodynamic stability and diminish organ injuries in CHD children.

Ultra-Broadband Acoustic Diode in Open Bend Tunnel by Negative Reflective Metasurface.

We theoretically and numerically propose an open bend tunnel with the capability of realizing ultra-broadband unidirectional transmission. The designed tunnel can isolate acoustic wave incidence from opposite directions and substance like the fluids or objects can exchange freely by employing acoustic gradient metasurface. The underlying mechanism is due to apparent negative reflection in ultra-broadband frequency range when the incoming angle impinging on the metasurface is over the critical incidence. The numerical results keep a good agreement with the theoretical analyses. The proposed design could be employed to generate various situations, like broadband noise control, architectural acoustics and ultrasound imaging.

Diamond-Structured Photonic Crystals with Graded Air Spheres Radii.

A diamond-structured photonic crystal (PC) with graded air spheres radii was fabricated successfully by stereolithography (SL) and gel-casting process. The graded radii in photonic crystal were formed by uniting different radii in photonic crystals with a uniform radius together along the Г­Ð¥ direction. The stop band was observed between 26.1 GHz and 34.3 GHz by reflection and transmission measurements in the direction. The result agreed well with the simulation attained by the Finite Integration Technique (FIT). The stop band width was 8.2 GHz and the resulting gap/midgap ratio was 27.2%, which became respectively 141.4% and 161.9% of the perfect PC. The results indicate that the stop band width of the diamond-structured PC can be expanded by graded air spheres radii along the Г­Ð¥ direction, which is beneficial to develop a multi bandpass filter.