Needle Tip Shape Research Articles

Spplaash Study: A Randomized Study to Evaluate the Incidence of Postdural Puncture Headache with the Use of Atraumatic Needles in Hematology

Introduction - Postdural-puncture headache (PDPH) is the most common complication after lumbar puncture, probably due to leakage of cerebrospinal fluid (CSF) from the dural defect into the epidural space. Most cases of PDPH occur within 8 days of a lumbar puncture and may be associated with other symptoms, such as photophobia, nausea or neurological complications. In this context, PDPH is a debilitating condition that significantly impacts quality of life. While several risk factors have been proposed to participate in PDPH etiology, no preventive or therapeutic measures have robustly proven their efficacity . Among PDPH-related risk factors, needle tip shape has been shown to influence the incidence of PDPH, especially in the context of diagnostic LP. The purpose of this study was to assess the incidence of PDPH using conventional (cutting-type) or atraumatic (pencil-point) spinal needles in hematological patients. Methods -This was a randomized, double-blind study of 68 adult patients scheduled for a diagnostic and/or therapeutic lumbar puncture (LP) (SPPLAASH study, NCT03126045). Subjects were randomly assigned to receive one of two needles : 22-gauge cutting (n=36) and 26-gauge atraumatic (n=32). LP and CSF collection were performed in accordance with standardized procedures. The main outcome was the occurrence of severe headache (≥4 out of 10 on the numerical rating scale (NRS)) as measured by interviews for 8 days after LP, repeated until headache resolution. Secondary outcomes included maximum intensity and duration of PDPH as well as procedural failure. Results - The median age at the time of LP was 60 years (Q1-Q3, 46-70) and 40% of patients were women. Demographic and procedural characteristics are summarized in Table 1. No significant difference was statistically observed between the two treatment groups, except for LP indication. The overall rate of severe PDPH was 19.7% (95% CI - 10.9-31.3). Interestingly, the incidence of severe PDPH was statistically reduced from 31.3% (95% CI - 16.9-49.3) in the conventional needle group to 6.5% (95% CI - 0.8-21.4) in the atraumatic group (p=0.011). High body mass index (OR 0.72, 95% - CI 0.57-0.91) and male sex (OR 0.29, 95% CI 0.08-1) were factors associated with a lower risk of PDPH. Means of maximum intensity of PDHP at 8 days were estimated to be 2.3 (sd 3.1) in the conventional needle group and 0.7 (sd 1.31) in the atraumatic group, with a statistically difference when considering median intensities (p=0.032) and number of days with NRS ≥4 (p=0.030). We used Sankey flow diagram to map the trajectories of PDPH intensities during the 8-day follow-up (Figure 1). First attempt LP success, failure rate, mean number of attempts, and the frequency of analgesic prescritions did not statistically differ between the two needle groups. Conclusion - Lumbar puncture is an essential and common procedure in hematologic clinical care and research. Our data indicate that atraumatic needles were associated with a decrease in the incidence of severe PDPH as well as in the duration of PDPH event. Moreover, the use of atraumatic needle was safe and feasible. Given that PDPH has a major impact on quality-of-life already altered by hematological treatments, and that headache might be caused by a differential diagnosis (e.g. cerebral sinus venous thrombosis due to Asparaginase in acute lymphoblastic leukemia), the use of atraumatic needles should be encouraged in this population, which often benefits from multiple LP.

Objective evaluation of the resistance forces of 22-gauge EUS-FNA and fine-needle biopsy needles.

EUS-guided tissue acquisition is routinely performed for the diagnosis of gastrointestinal tract and adjacent organ lesions. Recently, various types of needles have been developed. However, how the shape of the needle tip and echoendoscope tip angle affect puncturability, has not been clarified. The aim of this experimental study was to compare the puncturability of several 22-gauge EUS-FNA and EUS-guided fine-needle biopsy (EUS-FNB) needles, and to evaluate the effects of the needle tip shape and echoendoscope tip angle on tissue puncturability. The following six major FNA and FNB needles were evaluated: SonoTip® ProControl, EZ Shot 3 Plus, Expect™ Standard Handle, SonoTip® TopGain, Acquire™, and SharkCore™. The mean maximum resistance force against needle advancement was evaluated and compared under several conditions using an echoendoscope. The mean maximum resistance force of the needle alone was higher for the FNB needles than for the FNA needles. The mean maximum resistance force of the needle in the echoendoscope with free angle demonstrated that the resistance forces were between 2.10 and 2.34 Newton (N). The mean maximum resistance force increased upon increases in angle of the tip of echoendoscope, particularly in the FNA needles. Among the FNB needles, SharkCore™ had the lowest resistance force (2.23 N). The mean maximum resistance force of the needle alone, the needle in the echoendoscope with free angle, and the needle in the echoendoscope with full-up angle for SonoTip® TopGain were all similar to that of Acquire™. SonoTip® TopGain had similar puncturability to Acquire™ in all tested situations. Regarding the puncturability, SharkCore™ is most suitable for insertion into target lesions, when tight echoendoscope tip angle is necessary.

Modeling of geometry and insertion force of a new lancet medical needle.

Lancet needle is a typical medical treatment device. Its tip consists of two lancet planes and one bevel plane. When the lancet needle is inserted into soft organ tissue, the insertion force may influence the needle cutting direction and treatment effect and increase the pain. One of the main factors affecting this insertion force is the geometry of the needle tip. Based on the research on the shape and processing method of the conventional lancet needle, a new lancet needle tip geometry was obtained by adjusting the relative position of the grinding wheel to the needle. A mathematical model of this new lancet needle was established. The relationship between processing parameters and needle shape was analyzed, and the needle insertion force was predicted. Compared with the conventional lancet needle, the new lancet needle is sharper, and the insertion force on the cutting edge is smaller. However, this change in the grinding position of the needle lancet plane has a great influence on the shape of needle tip near the intersection of the bevel plane and the lancet plane. Some special second bevel angle and rotated angle will cause a large change in the specific force at the intersection place, which is not conducive to reducing the insertion force.

Visualization analysis of relationship between vortex flow and cavitation behavior in diesel nozzle

In diesel engines for passenger cars, the spray and combustion characteristics are one of the important factors for determining the exhaust and engine performances. These characteristics are affected by the internal flow, the film-type and string-type cavitations in the diesel nozzle. Specifically, the string-type cavitation correlates well with the spray cone angle, and the string-type cavitation behavior destabilizes the spray formation and combustion. The string-type cavitation is influenced by the vortex flow in the nozzle sac. Therefore, it is important to clarify the effect of nozzle and needle shapes on the vortex flow for further development of the diesel injector. This study investigates the effect of needle tip shape on a vortex flow, string-type cavitation and the spray characteristics. This was realized by comparison of the three needle shapes which were chosen in order to control the vortex flow in nozzle sac. A real-size transparent nozzle technique was used to investigate the relationship between the vortex flow and cavitation behavior in the diesel nozzle. This technique allows a spray characteristic to be observed concurrently with the inner flow as well. In addition, the visualized vortex flow was analyzed in detail by the micro-particle image velocimetry method and computational fluid dynamics.

Macroscopic and microscopic observations of needle insertion into gels

Needle insertion into soft tissue is one of the most common medical interventions. This study provides macroscopic and microscopic observations of needle-gel interactions. A gelatin mixture is used as a soft-tissue simulant. For the macroscopic studies, system parameters, such as insertion velocity, needle diameter, gel elasticity, needle tip shape (including bevel angle) and insertion motion profile, are varied, while the maximum insertion force and maximum needle deflection are recorded. The needle tip and gel interactions are observed using confocal microscopic images. Observations indicate that increasing the insertion velocity and needle diameter results in larger insertion forces and smaller needle deflections. Varying the needle bevel angle from 8 degrees to 82 degrees results in the insertion force increasing monotonically, while the needle deflection does not. These variations are due to the coupling between gel rupture and tip compression interactions, which are observed during microscopic studies. Increasing the gel elasticity results in larger insertion forces and needle deflections. Varying the tip shapes demonstrates that bevel-tipped needles produce the largest deflection, but insertion force does not vary among the tested tip shapes. Insertion with different motion profiles are performed. Results show that adding I Hz rotational motion during linear insertion decreases the needle deflection. Increasing the rotational motion from I Hz to 5 Hz decreases the insertion force, while the needle deflection remains the same. A high-velocity (250 mm/s and 300 mm/s) tapping during insertion yields no significant decrease in needle deflection and a slight increase in insertion force.

Post-dural Puncture Headache: A Comparison Between Median and Paramedian Approaches in Orthopedic Patients

Background: Post-dural puncture headache (PDPH) is an iatrogenic complication of spinal anesthesia. Reported risk factors for PDPH include sex, age, pregnancy, needle tip shape and size, bevel orientation, approach and others. Little is known regarding the effect of different approaches on the incidence of PDPH. Objectives: In this study we aimed to compare the incidence of PDPH in the case of median and paramedian approaches in patients undergoing spinal anesthesia for orthopedic operations. Patients and Methods: Patients scheduled for orthopedic surgery under spinal anesthesia between 2007 and 2008 were studied in a double-blinded randomized controlled trial. The patients were randomized to receive spinal anesthesia by either a median (n = 75) or paramedian (n = 75) approach through a 25-gauge Crawford needle. No premedication was given, and all patients received 500 mL of normal saline intravenously and 4 mL of 0.5% isobaric Marcaine 30 minutes prior to surgery in both approaches. Results: Fifteen patients (10%) developed PDPH. There was no significant difference in the incidence of PDPH in both groups, with 7 (9.3%) patients in the median approach group versus 8 (10.7%) in the paramedian approach group developing typical PDPH (P = 0.875). However, a significant difference in PDPH incidence (P = 0.041) was observed between females (9; 16.7%) and males (6; 6.3%). Conclusions: There is no difference between median and paramedian approaches with respect to PDPH incidence; the paramedian approach is therefore recommended, especially for older patients with degenerative changes in the spine and intervertebral spaces and those who cannot take the proper position. Moreover, the rate of PDPH was found to be significantly higher in females than in males.

Post-dural Puncture Headache: A Comparison Between Median and Paramedian Approaches in Orthopedic Patients.

Background:Post-dural puncture headache (PDPH) is an iatrogenic complication of spinal anesthesia. Reported risk factors for PDPH include sex, age, pregnancy, needle tip shape and size, bevel orientation, approach and others. Little is known regarding the effect of different approaches on the incidence of PDPH.Objectives:In this study we aimed to compare the incidence of PDPH in the case of median and paramedian approaches in patients undergoing spinal anesthesia for orthopedic operations.Patients and Methods:Patients scheduled for orthopedic surgery under spinal anesthesia between 2007 and 2008 were studied in a double-blinded randomized controlled trial. The patients were randomized to receive spinal anesthesia by either a median (n = 75) or paramedian (n = 75) approach through a 25-gauge Crawford needle. No premedication was given, and all patients received 500 mL of normal saline intravenously and 4 mL of 0.5% isobaric Marcaine 30 minutes prior to surgery in both approaches.Results:Fifteen patients (10%) developed PDPH. There was no significant difference in the incidence of PDPH in both groups, with 7 (9.3%) patients in the median approach group versus 8 (10.7%) in the paramedian approach group developing typical PDPH (P = 0.875). However, a significant difference in PDPH incidence (P = 0.041) was observed between females (9; 16.7%) and males (6; 6.3%).Conclusions:There is no difference between median and paramedian approaches with respect to PDPH incidence; the paramedian approach is therefore recommended, especially for older patients with degenerative changes in the spine and intervertebral spaces and those who cannot take the proper position. Moreover, the rate of PDPH was found to be significantly higher in females than in males.

Needle insertion simulation by arbitrary Lagrangian-Eulerian method.

In this paper, we performed needle insertion simulation considering needle tip shape by Arbitrary Lagrangian-Eulerian (ALE) method. ALE method is suitable for the large deformation and a fracture. To evaluate developed model, we compared the needle deflection between experimental results and simulation results. As a result, errors in each needle between both results were less than 3 mm.

Anatomy and morphology in developing vegetative buds on detached Norway spruce branches in controlled conditions before bud burst

We studied the light and stereomicroscopic structure of developing vegetative buds from a 16-year-old Norway spruce [Picea abies (L.) Karst.] of southern Finnish origin in relation to temperature sum and to externally visible changes in the buds before and during bud burst in forcing conditions. Branches were collected on 17 January and transferred to the greenhouse where they were first subjected to preforcing conditions (darkness, +4 degrees C) for 7 days and then to the forcing conditions (day length 12 h, +20 degrees C). Buds were sampled 20 times between 17 January and 13 February. Air temperature was recorded hourly throughout the study period. The first microscopic change was a temporary increase in the size and number of lipid droplets before the onset of temperature sum (T > or = +5 degrees C) accumulation. From the 4th to the 9th day under the forcing conditions, tracheids started to develop from the base up to the top of the bud. This was closely synchronized with an observed morphological change in the shape of needle tip from rounded to pointed ones. Development from the first visible change in the bud scales on the 12th forcing day to bud burst took 9 days when the temperature sum was 313 d.d. The temperature sums in our experiment overestimated the requirements of temperature sum for bud development phases measured in the field. Bud development could be divided into four structural phases. The first two phases, i.e., morphological changes in the primary needles, occurred without any externally visible changes in the buds. Thus, these phases have a potential for testing and improving the phenological models, which, up to now, have mainly been based on the bud burst observation by the naked eye.

Creation of highly aligned electrospun poly-L-lactic acid fibers for nerve regeneration applications

Aligned, electrospun polymer fibers have shown considerable promise in directing regenerating axons in vitro and in vivo. However, in several studies, final electrospinning parameters are presented for producing aligned fiber scaffolds, and alignment where minimal fiber crossing occurs is not achieved. Highly aligned species are necessary for neural tissue engineering applications to ensure that axonal extension occurs through a regenerating environment efficiently. Axonal outgrowth on fibers that deviate from the natural axis of growth may delay axonal extension from one end of a scaffold to the other. Therefore, producing aligned fiber scaffolds with little fiber crossing is essential. In this study, the contributions of four electrospinning parameters (collection disk rotation speed, needle size, needle tip shape and syringe pump flow rate) were investigated thoroughly with the goal of finding parameters to obtain highly aligned electrospun fibers made from poly-L-lactic acid (PLLA). Using an 8 wt% PLLA solution in chloroform, a collection disk rotation speed of 1000 revolutions per minute (rpm), a 22 gauge, sharp-tip needle and a syringe pump rate of 2 ml h−1 produced highly aligned fiber (1.2–1.6 µm in diameter) scaffolds verified using a fast Fourier transform and a fiber alignment quantification technique. Additionally, the application of an insulating sheath around the needle tip improved the rate of fiber deposition (electrospinning efficiency). Optimized scaffolds were then evaluated in vitro using embryonic stage nine (E9) chick dorsal root ganglia (DRGs) and rat Schwann cells (SCs). To demonstrate the importance of creating highly aligned scaffolds to direct neurite outgrowth, scaffolds were created that contained crossing fibers. Neurites on these scaffolds were directed down the axis of the aligned fibers, but neurites also grew along the crossed fibers. At times, these crossed fibers even stopped further axonal extension. Highly aligned PLLA fibers generated under optimized electrospinning conditions guided neurite and SC growth along the aligned fibers. Schwann cells demonstrated the bipolar phenotype seen along the fibers. Using a novel technique to determine fiber density, an increase in fiber density correlated to an increase in the number of neurites, but average neurite length was not statistically different between the two different fiber densities. Together, this work presents methods by which to produce highly aligned fiber scaffolds efficiently and techniques for assessing neurite outgrowth on different fiber scaffolds, while suggesting that crossing fibers may be detrimental in fostering efficient, directed axonal outgrowth.

A novel approach for the formation of Mg(OH) 2/MgO nanowhiskers on magnesium: Rapid anodization in chloride containing solutions

In the present work we report on the electrochemical formation towards layers of multiscale MgO nanowhiskers by a two step approach. First, metallic magnesium was anodized under “high-voltage”-conditions in chloride containing ethanol/water mixtures. This results within seconds in the formation of dense areas of magnesium hydroxide nanowhiskers on the surface. The individual as-grown whiskers have a needle tip shape, and a length depending on the growth time of up to 20 μm. The whiskers can be transformed to MgO by a thermal annealing process. To gain more insight into this very rapid growth process, the paper describes the influences of the key parameters of the anodization (pH, ion-concentration, electrolyte composition) and the effect of the thermal treatment on the morphology. All steps were characterized using SEM, EDX, XRD and XPS measurements.

Effect of the needle tip shape on fall of force after puncture in epidural anesthesia

Effect of the needle tip shape on fall of force after puncture in epidural anesthesia

Using insulin pen needles up to five times does not affect needle tip shape nor increase pain intensity

Aims: Reusing insulin pen needles could help to reduce the increasing economic burden of diabetes. We tested the hypothesis that reusing insulin pen needles leads to needle tip deformity and increased pain. Methods: Three blinded reviewers assessed 123 electron microscope pictures analyzing needle tip deformity of insulin pen needles used up to four times by diabetic subjects and up to five times by blinded non-diabetic volunteers. The estimated frequency of needle use was correlated to the actual number of needle use. Pain intensity and unpleasantness of each injection were measured by a visual analogue scale and their differences analyzed by Kruskal–Wallis analysis of variance. Results: Unused needles could be differentiated visually from used needles. However, there was no correlation between the actual and guessed number of times a needle was used ( r = 0.07, P = 0.2). Evaluating all 270 injections, neither pain intensity nor unpleasantness increased with repeated injections of the same needles in people with diabetes ( P = 0.1 and 0.96) and in the volunteers ( P = 0.63 and 0.92). Conclusions: Using pen needles four to five times does not lead to progressive needle tip deformity and does not increase pain intensity or unpleasantness, but could increase convenience and lead to substantial financial savings in Europe of around EUR 100 million/year.

A Numerical Analysis of Transonic/Supersonic Flows in the Axisymmetric Main Nozzle of an Air-Jet Loom

This paper reports a numerical analysis of transonic flows in the axisymmetric backward-facing step main nozzle of an air-jet loom. To obtain basic design data for the optimum main nozzle shape of an air-jet loom and to predict transonic/supersonic internal flows, a characteristic-based, upwind flux difference-splitting, compressible Navier-Stokes method is used. Wall static pressure and flow velocity distributions in the nozzle are analyzed by changing air tank pressures and acceleration tube lengths. The flow inside the nozzle experiences double choking, first at the needle tip and then at the acceleration tube exit at air tank pressures near 4 kgf/cm2. The air tank pressure that leads to critical conditions depends on acceleration tube length, i.e., higher air tank pressures for longer acceleration tubes. The air pressure required to bring the acceleration tube exit to sonic conditions is nearly constant regardless of acceleration tube length. The round needle tip shape could lead to less total pressure loss when compared with step shape.

Visual display of the spatial distribution of colloidal particle beams.

Introduction O the past decade microthrust rockets have been developed that employ charged liquid droplet (colloidal) beams sprayed from a hollow needle held at high potential with respect to an aperture in a ground plane. Although it is not difficult to obtain a stable beam current, the spatial distribution of the beam is usually complex and often asymmetric. Since the beam is produced by intense electric fields at the needle tip, factors such as needle tip shape, extractor hole shape, needle alignment, propellant properties, and mass flow rate influence the beam distribution. In turn, the beam shape fundamentally affects microthrust rocket performance, since beam asymmetry causes unwanted side thrust components and results in the actual thrust being less than that calculated from time-of-flight (TOP) data. These problems indicate the desirability of a rapid, reliable method of checking the beam shape whenever any physical or operating parameters are changed. Several approaches have been used to determine beam distribution. Analysis of TOF data for point by point sampling of the beam is the most complete method. However, it is laborious, time consuming, and relies on maintaining perfect beam stability for the duration of the sampling process. A beam current detector with several concentric rings is easier to use but determines only the average current striking a given section and tells little about beam symmetry or alignment. Observation of beam deposition on a surface is a reliable method, but it represents an average over time. None of these methods can illustrate the beam shape during instabilities or transients. In the following sections two detectors that provide continuous visual display of beam distribution are described: a phosphor screen for instantaneous active display of the beam, and a liquid crystal (LC) screen for averaging the beam over time intervals of seconds to minutes. The visual phenomena are compared with TOF data collected by a beam current detector with five concentric rings.