Similar Outer Diameter Research Articles

An Analysis of Driveline Infections with Left Ventricular Assist Devices Utilizing Carbothane versus Pellethane Driveline Sheaths

Purpose Percutaneous driveline infections (DLI) contribute significant morbidity among patients receiving a left ventricular assist device (LVAD). The HeartWare™ HVAD™ System has a thin, flexible, fatigue-resistant driveline, which received FDA approval in mid-2019 to change the outer sheath from a pellethane to a carbothane-based material. Drivelines with carbothane sheaths have a similar outer diameter (4.2 mm) as the pellethane-based drivelines, but have increased flexibility. This enhanced flexibility might allow for improved healing at the skin interface. The DLI infection rate in HVAD Systems with carbothane drivelines in the DT PAS registry will be compared to historical rates from the ENDURANCE Supplemental Trial, which included HVAD Systems with pellethane drivelines. Methods The DT PAS study is the real-world registry of patients receiving the HVAD System as destination therapy in 42 US centers. At the time of presentation, we will have at least 6 months of support data on 184 patients with HVAD implants with a carbothane driveline. Results Descriptive data and rates of driveline infections will be presented, and a comparison with historical data from the HVAD ENDURANCE Supplemental clinical trial will be performed. Baseline parameters of patients currently enrolled in DT PAS includes 71% males with an average age of 58 years, and 16% INTERMACS profile 1. Preliminary data reveals an 8% incidence of driveline infections over a mean time on support of 5 months for all DT PAS patients enrolled (n=212). Data collection and analysis is ongoing. Conclusion This will be the first multicenter clinical evaluation of the driveline infections in HVAD patients receiving the new carbothane drivelines. Final data on driveline infections occurring through 6 months will be available at the time of presentation.

Colloidal plasmonic gold nanoparticles and gold nanorings: shape-dependent generation of singlet oxygen and their performance in enhanced photodynamic cancer therapy.

IntroductionIn recognition of the potentials of gold nanoparticles (Au NPs) in enhanced photodynamic therapy (PDT) for cancer, it is desirable to further understand the shape-dependent surface plasmonic resonance (SPR) properties of various gold nanostructures and evaluate their performances in PDT.Materials and methodsMonodispersed colloidal spherical solid Au NPs were synthesized by UV-assisted reduction using chloroauric acid and sodium citrate, and hollow gold nanorings (Au NRs) with similar outer diameter were synthesized based on sacrificial galvanic replacement method. The enhanced electromagnetic (EM) field distribution and their corresponding efficiency in enhancing singlet oxygen (1O2) generation of both gold nanostructures were investigated based on theoretical simulation and experimental measurements. Their shape-dependent SPR response and resulted cell destruction during cellular PDT in combination with 5-aminolevulinic acid (5-ALA) were further studied under different irradiation conditions.ResultsWith comparable cellular uptake, more elevated formation of 1O2 in 5-ALA-enabled PDT was detected with the presence of Au NRs than that with Au NPs under broadband light irradiation in both cell-free and intracellular conditions. As a result of the unique morphological attributes, exhibiting plasmonic effect of Au NRs was still achievable in the near infrared (NIR) region, which led to an enhanced therapeutic efficacy of PDT under NIR light irradiation.ConclusionShape-dependent SPR response of colloidal Au NPs and Au NRs and their respective effects in promoting PDT efficiency were demonstrated in present study. Our innovative colloidal Au NRs with interior region accessible to surrounding photosensitizers would serve as efficient enhancers of PDT potentially for deep tumor treatment.

Tracheostomy Tube Type and Inner Cannula Selection Impact Pressure and Resistance to Air Flow.

Advancements in tracheostomy tube design now provide clinicians with a range of options to facilitate communication for individuals receiving ventilator assistance through a cuffed tube. Little is known about the impact of these modern design features on resistance to air flow. We undertook a bench model test to measure pressure-flow characteristics and resistance of a range of tubes of similar outer diameter, including those enabling subglottic suction and speech. A constant inspiratory ± expiratory air flow was generated at increasing flows up to 150 L/min through each tube (with or without optional, mandatory, or interchangeable inner cannula). Driving pressures were measured, and resistance was calculated (cm H2O/L/s). Pressures changed with increasing flow (P < .001) and tube type (P < .001), with differing patterns of pressure change according to the type of tube (P < .001) and direction of air flow. The single-lumen reference tube encountered the lowest inspiratory and expiratory pressures compared with all double-lumen tubes (P < .001); placement of an optional inner cannula increased bidirectional tube resistance by a factor of 3. For a tube with interchangeable inner cannulas, the type of cannula altered pressure and resistance differently (P < .001); the speech cannula in particular amplified pressure-flow changes and increased tube resistance by more than a factor of 4. Tracheostomy tube type and inner cannula selection imposed differing pressures and resistance to air flow during inspiration and expiration. These differences may be important when selecting airway equipment or when setting parameters for monitoring, particularly for patients receiving supported ventilation or during the weaning process.

A novel biodegradable device for intestinal lengthening

PurposePrevious studies demonstrated successful mechanical lengthening of rat jejunum using an encapsulated Nitinol spring device over a stabilizing guidewire. We sought to improve the applicability of intestinal lengthening by creating a biodegradable device. MethodsUsing properties of the Nitinol spring device, polycaprolactone (PCL) springs with similar outer diameter and spring constant were created. After in vitro testing in dry and hydrated environments, they were used to lengthen 1-cm isolated segments of rat jejunum in vivo. Retrieved segments were analyzed histologically. ResultsOptimal PCL spring devices had an average spring constant 1.8 ± 0.4 N/m, pitch 1.55 ± 0.85 mm, and band width 0.825 ± 0.016 mm. In vitro testing demonstrated stable spring constants. Jejunal segments were lengthened from 1.0 cm to 2.7 ± 0.4 cm without needing a stabilizing guidewire. Histology demonstrated increased smooth muscle thickness and fewer ganglia compared to controls. Lengthened jejunum was successfully restored into intestinal continuity and demonstrated peristalsis under fluoroscopy. ConclusionsA novel biodegradable spring device was successfully created and used to mechanically lengthen intestinal segments. Use of a biodegradable device may obviate the need for retrieval after lengthening. This improves device applicability and may be useful for the treatment of short bowel syndrome.

Photonic bandgap Bragg fiber sensors for bending/displacement detection

We demonstrate an amplitude-based bending/displacement sensor that uses a plastic photonic bandgap Bragg fiber with one end coated with a silver layer. The reflection intensity of the Bragg fiber is characterized in response to different displacements (or bending curvatures). We note that the Bragg reflector of the fiber acts as an efficient mode stripper for the wavelengths near the edge of the fiber bandgap, which makes the sensor extremely sensitive to bending or displacements at these wavelengths. Besides, by comparison of the Bragg fiber sensor to a sensor based on a standard multimode fiber with similar outer diameter and length, we find that the Bragg fiber sensor is more sensitive to bending due to the presence of a mode stripper in the form of a multilayer reflector. Experimental results show that the minimum detection limit of the Bragg fiber sensor can be as small as 3 μm for displacement sensing.

A comparative analysis of hollow and solid glass fibers

Comparative analyses have been completed on hollow and solid E-type glass fibers. Single fiber tensile tests were performed and correlations have been determined between the geometry and the tensile strength of the fibers. The flexural properties of the solid and the hollow fibers have been determined with deflection tests. The hollow glass fibers showed higher tensile strength and flexural rigidity than the solid glass fibers in the case of similar outer diameter. The hollow fibers were filled with the help of capillary effect, and the filling process was examined as a function of the viscosity and the contact angle between glass and fluids. A relationship has been detected between fiber filling speed and the inner diameter of the fibers, and the filling speed was increased by the lower viscosity and contact angle.

Macroporous anatase titania particle: Aerosol self-assembly fabrication with photocatalytic performance

An anatase titania particle with a honey-comb-like pore structure (200 nm-pore size) and a controllable outer diameter (0.2–1 μm) was successfully prepared using a spray-drying method. As a precursor, an anatase nanoparticle (5 nm) and a polystyrene particle (200 nm) were used as a titania source and a colloidal template, respectively. The outer diameter could be controlled by varying the precursor concentration. The photocatalytic performance of a porous particle was faster than that of a dense particle (with a similar outer diameter).

Preparation and microstructure of hollow mesophase pitch-based carbon fibers

Hollow mesophase pitch fibers with rather thin diameter were successfully prepared by spinning through a C-shaped capillary. Die-swell was found to be the main factor affecting the formation of hollow fiber, and this was controlled by varying the spinning temperature. After carbonization at 1000°C, the hollow fibers possess a relatively small outer diameter of 21 μm and an inner diameter of 6 μm, and show better mechanical properties than solid fibers with similar outer diameter. The higher mechanical properties are attributed to the orientation of mesophase molecules which is related to the shape and dimension of the spinneret. The transverse microstructure of hollow carbon fibers is illustrated by scanning electron microscopy (SEM) observations on fracture sections.

Rigid Ureteroscopes with Fiberoptic Imaging Bundles: Features and Irrigating Capacity

A new ureteroscope design incorporates fiberoptic imaging bundles to replace the rod lens system in a rigid ureteroscope body. These ureteroscopes have evolved along two lines: instruments with a movable eyepiece and those with a small outer diameter (< 10F). The fiberoptic imaging bundles take up less space than the rod lens system. These ureteroscopes thus have a larger working channel than instruments of a similar outer diameter with rod lens imaging systems. Measurement of irrigation rates through a representative sample of these ureteroscopes demonstrated that gravity irrigation was adequate through the empty working channel. However, if an accessory instrument was placed in the working channel, gravity irrigation was insufficient in the smaller models. Manual irrigation was more than adequate under all conditions. The larger models now offer relatively little advantage to counter the decrease in image quality associated with the "honeycomb" fiberoptic image. Nevertheless, the more recent small ureteroscopes allow an adequate irrigant flow while accepting working instruments suitable for a variety of procedures. They thus seem to be ideal for diagnostic ureteroscopy, as they are quick and easy to use, not even requiring ureteral dilation. Furthermore, their small size does not limit their therapeutic applications; on the contrary, it expands them.

Alpha 2-adrenoceptors mediate norepinephrine constriction of porcine pial veins.

The adrenergic innervation and alpha-adrenoceptor agonist-induced constrictions in isolated medium-size pial veins (OD 734 +/- 18 microns) of the pig were investigated. Using in vitro tissue bath techniques, we noted exogenously applied norepinephrine (10(-9) to 10(-5) M) induced venoconstriction with EC50 values of 1.71 x 10(-7) M, where EC50 is the concentration that produced 50% of (non-KCl) agonist-induced maximum constriction. The constriction was mimicked by clonidine but not by phenylephrine and was more effectively blocked by yohimbine than by prazosin. Results from histochemical studies demonstrated that porcine pial veins received a denser plexus of catecholamine fluorescence fibers than do pial arteries with similar outer diameter. These results suggest that norepinephrine-induced pial venoconstriction is mediated predominantly by alpha 2-adrenoceptors and that porcine pial veins have significantly greater sensitivity to the alpha-action of norepinephrine than that reported in pial arteries. These results add further support for adrenergic innervation in pial veins being of importance in regulating cerebral blood volume and intracranial pressure.