Bending Of Needles Research Articles

A simple insertion technique to reduce the bending of thinbevel-point needles

Objective: Needle insertion is a common component of most diagnostic and therapeutic interventions. Needles with asymmetrically sharpened points such as the bevel point are ubiquitous. Their insertion path is typically curved due to the rudder effect at the point. However, the common planned path is straight, leading to targeting errors. We present a simple technique that may substantially reduce these errors. The method was inspired by practical experience, conceived mathematically, and refined experimentally.Methods: Targeting errors are reduced by flipping the bevel on the opposite side (rotating the needle 180° about its axis), at a certain depth during insertion. The ratio of the flip depth to the full depth of insertion is defined as the flip depth ratio (FDR). Based on a model, FDR is constant 0.3.Results: Experimentally, the ratio depends on the needle diameter, 0.35 for 20Ga and 0.45 for 18Ga needles. Thinner needles should be flipped a little shallower, but never less than 0.3.Conclusion: Practically, a physician may expect to reduce ∼80% of needle deflection errors by simply flipping the needle. The technique may be used by hand or with guidance devices.

A model to predict deflection of bevel-tipped active needle advancing in soft tissue

Active needles are recently being developed to improve steerability and placement accuracy for various medical applications. These active needles can bend during insertion by actuators attached to their bodies. The bending of active needles enables them to be steered away from the critical organs on the way to target and accurately reach target locations previously unachievable with conventional rigid needles. These active needles combined with an asymmetric bevel-tip can further improve their steerability. To optimize the design and to develop accurate path planning and control algorithms, there is a need to develop a tissue–needle interaction model. This work presents an energy-based model that predicts needle deflection of active bevel-tipped needles when inserted into the tissue. This current model was based on an existing energy-based model for bevel-tipped needles, to which work of actuation was included in calculating the system energy. The developed model was validated with needle insertion experiments with a phantom material. The model predicts needle deflection reasonably for higher diameter needles (11.6% error), whereas largest error was observed for the smallest needle diameter (24.7% error).

Polyacrylamide phantom for self-actuating needle–tissue interaction studies

This study presents a polyacrylamide gel as a phantom material for needle insertion studies specifically developed for self-actuating needles to enhance the precise placement of needles in prostate. Bending of these self-actuating needles within tissue is achieved by Nitinol actuators attached to the needle body; however these actuators usually involve heating that can thermally damage the tissue surrounding the needles. Therefore, to develop and access feasibility of these needles, a polyacrylamide gel has been developed that mimics the thermal damage and mechanical properties of prostate tissue. Mechanical properties of the polyacrylamide gel was controlled by varying the concentrations of acrylamide monomer and N,N-methylene-bisacrylamide (BIS) cross-linker, and thermal sensitivity was achieved by adding bovine serum albumin (BSA) protein. Two polyacrylamide gels with different concentrations were developed to mimic the elastic modulus of the tissue. The two phantoms showed different rupture toughness and different deflection of bevel-tip needle. To study the thermal damage, a Nitinol wire was embedded in the phantom and resistively heated. The measured opaque zone (0.40mm) formed around the wire was close to the estimated damage zone (0.43mm) determined using the cumulative equivalent minutes at 43°C.

Iodine-125 thin seeds decrease prostate swelling during transperineal interstitial permanent prostate brachytherapy

Prostate swelling following seed implantation is a well-recognised phenomenon. The purpose of this intervention was to assess whether using thinner seeds reduces post-implant swelling with permanent prostate brachytherapy. Eighteen consecutive patients eligible for prostate seed brachytherapy underwent seed implantation using iodine-125 (I-125) thin seeds. Operative time, dosimetry, prostate swelling and toxicity were assessed and compared with standard I-125 stranded seed controls, sourced from the department's brachytherapy database. A learning curve was noted with the thin seeds in terms of greater bending and deviation of needles from their intended path. This translated into significantly longer total operative time (88 vs 103 minutes; P = 0.009, 95% confidence interval (CI) 4.1-24.3) and time per needle insertion (2.6 vs 3.7 minutes; P < 0.001, 95% CI 0.5-1.3) for the thin seeds. Day 30 prostate volumes were significantly smaller in the thin seed group compared with standard seeds (40.9 cc vs 46.8 cc; P = 0.001, 95% CI 1.5-5.6). The ratio of preoperative transrectal ultrasound to day 30 post-implant CT volume was also smaller in the thin seed group (1.2 ± 0.1 for standard seeds vs 1.1 ± 0.1 for thin seeds). Post-implant dosimetric parameters were comparable for both groups. No significant differences were seen in acute urinary morbidity or quality of life between the two groups. I-125 thin seeds are associated with an initial learning curve, with longer operative time, even for experienced brachytherapists. The significant reduction in day 30 prostate volumes with the thin seeds has useful implications in terms of optimising dose coverage to the prostate in the early period post-implantation, as well as improving the accuracy of post-implant dosimetric assessments.

Mechanical Manipulation of Neurons to Control Axonal Development

Cell manipulations and extension of neuronal axons can be accomplished with calibrated glass micro-fibers capable of measuring and applying forces in the 10-1000 μdyne range. Force measurements are obtained through observation of the Hookean bending of the glass needles, which are calibrated by a direct and empirical method. Equipment requirements and procedures for fabricating, calibrating, treating, and using the needles on cells are fully described. The force regimes previously used and different cell types to which these techniques have been applied demonstrate the flexibility of the methodology and are given as examples for future investigation. The technical advantages are the continuous 'visualization' of the forces produced by the manipulations and the ability to directly intervene in a variety of cellular events. These include direct stimulation and regulation of axonal growth and retraction; as well as detachment and mechanical measurements on any type of cultured cell.

Evaluation of Tip Holed Spinal Needle - A Comparative Study

Background: The performance and post dural puncture headache were assessed in this randomised clinical study. Methods. Total 100 patients of ASA physical status I and II undergoing elective caesarean section were enrolled for the study. Patients in the controlled group Group-A. Patients in the trial group (Group-B). ABSTRACT: Regional block has its own unique place in modem anesthetic practice increasing popularity over 30-40 years has followed better understanding of the technique and acceptance than the incidence of side effects is tow. These depend not only on the correctly performed procedures but the correct design of the needle is also important. The purpose of this clinical study is to evaluate the performance of tip hole spinal needle (25G) in comparison with widely used Quincke spinal needle (25G). Clinical effects, performers satisfaction, side effects and complications were assessed over 100 pts who were decided into group A (Qiuncke gr) &amp; Group B (tip hole gr) undergoing emergency &amp; elective C.S. under spinal anaesthesia. Ease of insertion of the needle, number of attempts for successful insertion, appearance of CSF flow through needle, bending of needle, quality of analgesia, clinical effects &amp; PDPH were assessed. No significant changes in pulce, BP. &amp; SPO2 in 1 minute &amp; 5 minuets were found in pre-operative &amp; per-operative period in Group A &amp; also in Group B. In terms of ease of insertion there was no significant change in Group A (100%) &amp; Group B (90%). It was found that in less than 1 second no CSF fluid appeard in Group A but in Group B, CSF appeard in 30%, in less than 2 seconds, the values among Gr A &amp; Gr B were 4% &amp; 52%, in less than 3 seconds. 50% &amp; 18% respectively. In less than 4 seconds &amp; 5 seconds in Group A 38% &amp; 8% respectively and no CSF fluid appeard in Group B in that period. In Group A 52% cases required 1 attempt, 28% cases 2 attempts, 16% of cases 3 attempts &amp; 4% cases 4 attempts were required. In Group B it was 86%, 14% &amp; no 3rd &amp; 4th attempts required. In terms of bending of needles during insertion, the performance of Group B was better (7% in Group A and no in Group B). The incidence of PDPH was found absolutely nil among the gr B &amp; negligible (2%) in gr A subjects. Journal of BSA, Vol. 18, No. 1 &amp; 2, 2005 p.3-8

Anatomical basis for biophysical differences betweenPinus nigraandP. resinosa(Pinaceae) leaves

Differences in the flexibility of Pinus nigra and P. resinosa leaves can be used to discriminate these two similarly looking pine species from one another. When bent along the longitudinal axis, P. resinosa leaves snap, while P. nigra leaves appear flexible. This useful field test has had no known biophysical or anatomical explanation until now. Analysis of the first order mechanics of bending and buckling of the pine needles was used to elucidate any important anatomical differences between these two species that can account for their different biophysical behaviors when bent. Neither the cross section of the total leaf area nor the inner core area between the two species differed significantly. Differences in the pattern of cell wall thickening and lignification of the endodermal layer of the inner core of the leaves best explain the differences in bending behavior. Thus, subtle variation in anatomy can influence the biophysical properties of naturally occurring structures, which in turn could have important implications for the engineering of manufactured objects.

Use of Curved Needles to Perform Biopsies and Drainages of Inaccessible Targets

Percutaneous image-guided biopsies and fluid drainages are usually feasible with use of standard, mass-produced, straight needles. Occasionally, target lesions are completely surrounded by interposed structures, such as bone, bowel, colon, pancreas, bladder, or blood vessels, so percutaneous access appears impossible. Although the commercial availability of curved needles is very limited, custom bending of needles may allow unconventional access to these well-protected targets. This technique has been used to reach biopsy and drainage targets that would have otherwise required either high-risk transgression of interposed structures or more invasive surgical procedures.

Bending martensite needles in Ni65Al35 investigated by two-dimensional elasticity and high-resolution transmission electron microscopy

The bending and tapering of microtwin needles at the interface between two martensite laminates in ${\mathrm{Ni}}_{65}{\mathrm{Al}}_{35}$ are addressed. A theory is presented, based on the assumption that the microstructure is essentially stress-free; it predicts a linear relationship between the bending and tapering of the needles. The predictions of this theory are compared to experimental data obtained by high-resolution transmission electron microscopy. The agreement between theory and experiment is good, thus bridging the gap between continuum theory and discrete atomic structure, particularly in the region where the bending and tapering are largest.

Formation of miniature sorted patterns by shallow ground freezing: A field experiment

At an experimental site near sea level in Scotland, a miniature sorted net with cell diameters of 56–172 mm and stony borders 4–9 cm deep developed in frost-susceptible regolith over two winters. Pattern formation was evident after only 8 freeze-thaw cycles, during which the minimum surface temperature was −5.3°C and freezing extended to a maximum depth of 16–17 cm. The primary process of pattern development was repeated differential growth of near-surface needle ice, causing upcoming of a cover of coarse debris. During subsequent thaw, bending and melting of ice needles resulted in net migration of upheaved clasts towards dome margins, causing progressive concentration of clasts in stony borders surrounding finer cells. This differentiation of near-surface soil texture appears self-sustaining, promoting preferential growth of ice lenses and thus preferential heave in fine cells. The experiment suggests that miniature frost-sorted patterns are not necessarily diagnostic of present or former periglacial environments, but may develop on unvegetated soil of suitable composition in a wide range of mid- or even low-latitude environments where shallow ground freezing is accompanied by the growth of needle ice. © 1996 John Wiley & Sons, Ltd.

XXX. The influence of the bending of magnetic needles on the apparent magnetic dip

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