机械通气在新生儿麻醉中的应用

目的:评价机械通气在新生儿麻醉应用中的安全性和有效性。方法:47例新生儿手术,在全身麻醉气管插管后,行机械定压模式呼吸通气30 m in,监测通气前后动脉血气值、血氧饱和度(SpO2)、体温、呼气末CO2浓度(PetCO2)、气道压(Paw)、呼吸频率(f)、心电等参数。结果:新生儿手术全身麻醉控制呼吸,根据PetCO2适当调节呼吸参数,采用定压呼吸模式,能够维持动脉血氧分压(PaO2)、动脉血CO2分压(PaCO2)于正常范围。结论:机械通气能安全有效地应用于新生儿手术。     

机械通气患者套囊压力的监测

目的 讨论机械通气患者气管插管导管、气管切开套管的套囊压力和注气量是否合适,提供正确给套囊注气的科学依据.方法 对35例气管插管、气管切开进行机械通气患者的气管套管套囊压力和注气量的实际值和理想值进行准确测量.结果 65％的患者气管套管套囊实际压力和注气量过高,大于理想值.其中套囊实际注气量大于理想注气量2～4ml,套囊压力超过理想压力2～26 cm H2O.结论 临床上大部分气管套管套囊压力和注气量偏高,因此,应对人工气道患者采用专用套囊测压仪指导套囊注气量及控制囊内压,最大限度地避免气道黏膜的损伤.     

Structural design and mechanical behavior of alligator (Alligator mississippiensis) osteoderms

Alligator is a well-adapted living fossil covered with dorsal armor. This dermal shield consists of bony plates, called osteoderms, interconnected by sutures and non-mineralized collagen fibers, providing a dual function of protection and flexibility. Osteoderm features a sandwich structure, combining an inner porous core and an outer dense cortex, to offer enhancements for stiffness and energy absorbance. In this study, we investigated the multi-scale structure and mechanical behaviors of the American alligator (Alligator mississippiensis) osteoderm. Microcomputed tomography was applied to reveal the complex neurovascular network. Through the observation under optical and scanning electron microscopes, the osteoderm was found to consist of woven bone in the dorsal region and lamellar-zonal bone in the ventral region. Nanoindentation and compressive tests were performed to evaluate the mechanical properties of osteoderms. The varying mineral contents and porosity result in a graded mechanical property: a hard and stiff dorsal cortex gradually transform to a more compliant ventral base. Three protective mechanisms optimized for alligator osteoderms were proposed and elucidated.     

Microstructure,mechanical and corrosion properties of Mg–Dy–Gd–Zr alloys for medical applications

In previous investigations, a Mg–10Dy (wt.%) alloy with a good combination of corrosion resistance and cytocompatibility showed great potential for use as a biodegradable implant material. However, the mechanical properties of Mg–10Dy alloy are not satisfactory. In order to allow the tailoring of mechanical properties required for various medical applications, four Mg–10(Dy + Gd)–0.2Zr (wt.%) alloys were investigated with respect to microstructure, mechanical and corrosion properties. With the increase in Gd content, the number of second-phase particles increased in the as-cast alloys, and the age-hardening response increased at 200 °C. The yield strength increased, while the ductility reduced, especially for peak-aged alloys with the addition of Gd. Additionally, with increasing Gd content, the corrosion rate increased in the as-cast condition owing to the galvanic effect, but all the alloys had a similar corrosion rate (～0.5 mm year^?1) in solution-treated and aged condition.     

Evaluating the Benefit of Elevated Acoustic Output in Harmonic Motion Estimation in Ultrasonic Shear Wave Elasticity Imaging

Harmonic imaging techniques have been applied in ultrasonic elasticity imaging to obtain higher-quality tissue motion tracking data. However, harmonic tracking can be signal-to-noise ratio and penetration depth limited during clinical imaging, resulting in decreased yield of successful shear wave speed measurements. A logical approach is to increase the source pressure, but the in situ pressures used in diagnostic ultrasound have been subject to a de facto upper limit based on the Food and Drug Administration guideline for the mechanical index (MI <1.9). A recent American Institute of Ultrasound in Medicine report concluded that an in situ MI up to 4.0 could be warranted without concern for increased risk of cavitation in non-fetal tissues without gas bodies if there were a concurrent clinical benefit. This work evaluates the impact of using an elevated MI in harmonic motion tracking for hepatic shear wave elasticity imaging. The studies indicate that high-MI harmonic tracking increased shear wave speed estimation yield by 27% at a focal depth of 5?cm, with larger yield increase in more difficult-to-image patients. High-MI tracking improved harmonic tracking data quality by increasing the signal-to-noise ratio and decreasing jitter in the tissue motion data. We conclude that there is clinical benefit to use of elevated acoustic output in shear wave tracking, particularly in difficult-to-image patients.