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Robert J Webster - One of the best experts on this subject based on the ideXlab platform.
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Debulking From Within: A Robotic Steerable Cannula for Intracerebral Hemorrhage Evacuation
IEEE Transactions on Biomedical Engineering, 2013Co-Authors: Jessica Burgner, Philip J. Swaney, Ray A. Lathrop, Kyle D. Weaver, Robert J WebsterAbstract:New approaches to intracerebral hemorrhage management are motivated by its high incidence and 40% mortality rate. Surgery is sometimes attempted to decompress the brain, although patient outcomes are similar regardless of whether surgery occurs. We hypothesize that surgical decompression is not more effective because current open surgical techniques disrupt healthy brain tissue to access the clot formed by the hemorrhage, offsetting the benefits of surgery. To address this, we propose a less invasive needle-based approach in which the clot is debulked from within using a superelastic, precurved aspiration Cannula that is deployed from a needle. The tip of this aspiration Cannula is controlled by coordinated insertion and retraction of the Cannula and needle, as well as axial rotation of the Cannula. We describe the design of a sterilizable and biocompatible robot that can control the three degrees of freedom of the needle and Cannula. Image guidance is achieved by adapting an approach originally developed for brain biopsy. We provide an optimization method for the selection of the precurvatures of one or more sequentially used aspiration Cannulas to maximize hemorrhage evacuation, based on preoperative medical image data. In vitro experiments demonstrate the feasibility of evacuating 83-92% of hemorrhage volume, depending on the number of tubes and deployment method used.
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Cuffed Inner Cannula and Flexible Outer Cannula Trachesotomy Device: Ensuring a Stable Airway
Journal of Medical Devices-transactions of The Asme, 2010Co-Authors: Sanjay M. Athavale, Todd Dutton, Robert J WebsterAbstract:Tracheostomy tubes (TTs) are used to provide a direct airway to a patient’s trachea when natural respiration is no longer possible. A TT generally includes an elongate outer Cannula as well as a smaller inner Cannula formed so as to have a gradual curve to facilitate insertion into a patient’s trachea. In order seal the airway around the tube, a conventional TT generally has an inflatable cuff attached to the perimeter of the outer Cannula. When inflated, the cuff seals the airway around the Cannula, thereby, requiring air to pass through only the Cannula. In order to retain the distal end of the device in its operative position, the TT generally includes a neck plate or other fixation device, which is attached to the proximal end of the outer Cannula. There are many potential drawbacks with current TTs, which can range in effect from minor irritation to death. Varying sizes of individuals and differences in anatomical dimensions leads to discomfort from TTs that fit poorly. The rigid ends of the outer Cannula often put pressure on the walls of the trachea, which can cause irritation and ulceration. Cuffed inner Cannulas are required to be replaced with uncuffed inner Cannulas as soon as possible, after placement, to avoid pressure necrosis and allow for vocalization. The process of switching TTs may also be very hazardous, especially when treating obese patients. The stoma can easily be lost among layers of fat and skin, as well as the trachea, which all move independently of one another. Losing the stoma may cause suffocation and possibly death. Our novel device is a TT for use with a neck plate having an aperture. The TT comprises an elongate outer Cannula having a lumen and configured to extend through the aperture. An elongate inner Cannula having a lumen and an inflatable cuff and configured to extend through the lumen of the outer Cannula such that the cuff extends beyond a distal end of the outer Cannula and an interlocking mechanism configured to releasably secure a proximal end of the inner Cannula to a proximal end of the outer Cannula. This superior TT has the potential for wide application with a special emphasis on application within the obese population. Such patients experience the most difficulty with current devices. There is no single device in the market today that packages the numerous features of this particular design.
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A model for concentric tube continuum robots under applied wrenches
2010 IEEE International Conference on Robotics and Automation, 2010Co-Authors: Caleb D. Rucker, Bryan A. Jones, Robert J WebsterAbstract:Continuum robots made from telescoping precurved elastic tubes enable base-mounted actuators to specify the curved shapes of robots as thin as standard surgical needles. While free space beam mechanics-based models of the shape of these `active Cannulas' exist, current models cannot account for external forces and torques applied to the Cannula by the environment. In this paper we apply geometrically exact beam theory to solve the statics problem for concentric-tube continuum robots. This yields the equivalent of forward kinematics for an active Cannula with general tube precurvature functions and arbitrarily many tubes, under loading from a general wrench distribution. The model achieves average experimental tip errors of less than 3 mm over the workspace of a prototype active Cannula subject to various tip forces.
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Mechanics of bending, torsion, and variable precurvature in multi-tube active Cannulas
2009 IEEE International Conference on Robotics and Automation, 2009Co-Authors: Caleb D. Rucker, Robert J WebsterAbstract:Active Cannulas are a relatively new continuum robot subclass characterized by their use of preshaped tubes that transmit bending moments as they slide within one another and are axially rotated. Previous (experimentally vetted) mechanics-based models of active Cannula shape assume piecewise constant precurvature of component tubes, and neglect torsion in curved sections of the device. Recently a general, coordinate-free, energy-based framework for active Cannula shape has been formulated that relaxes these requirements and includes all prior models as special cases. However, only the 2-tube, constant-precurvature case has thus far been explored in detail using the framework. In this paper we consider the general case of an arbitrary number of component tubes and precurvatures that vary with arc length, deriving a set of differential equations that capture both bending and torsional effects continuously along the active Cannula backbone.We then show how to solve these differential equations numerically to describe active Cannula shape.
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mechanics of precurved tube continuum robots
IEEE Transactions on Robotics, 2009Co-Authors: Robert J Webster, Joseph M Romano, Noah J CowanAbstract:This paper presents a new class of thin, dexterous continuum robots, which we call active Cannulas due to their potential medical applications. An active Cannula is composed of telescoping, concentric, precurved superelastic tubes that can be axially translated and rotated at the base relative to one another. Active Cannulas derive bending not from tendon wires or other external mechanisms but from elastic tube interaction in the backbone itself, permitting high dexterity and small size, and dexterity improves with miniaturization. They are designed to traverse narrow and winding environments without relying on ldquoguidingrdquo environmental reaction forces. These features seem ideal for a variety of applications where a very thin robot with tentacle-like dexterity is needed. In this paper, we apply beam mechanics to obtain a kinematic model of active Cannula shape and describe design tools that result from the modeling process. After deriving general equations, we apply them to a simple three-link active Cannula. Experimental results illustrate the importance of including torsional effects and the ability of our model to predict energy bifurcation and active Cannula shape.
Joan Webster - One of the best experts on this subject based on the ideXlab platform.
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developing a research base for intravenous peripheral Cannula re sites drip trial a randomised controlled trial of hospital in patients
International Journal of Nursing Studies, 2007Co-Authors: Joan Webster, Sophia Lloyd, Tracey Hopkins, Sonya Osborne, Maria YaxleyAbstract:Abstract Background There is currently no high grade evidence on which to base decisions about the frequency of intravenous Cannula re-sites. Objective To assess the safety of changing peripheral venous Cannulas when clinically indicated. Design Randomised controlled trial. Setting A tertiary referral hospital in Brisbane, Australia. Participants Two hundred and six hospitalised patients from surgical, medical and orthopaedic wards. Interventions Peripheral intravenous Cannulas were re-sited only when complications occurred (intervention group) or every 3 days (control group). Main outcome measures The primary endpoint was any unplanned Cannula removal, the secondary outcome was cost. Results Forty six patients had unplanned removals in the intervention group compared with 41 in the control group [relative risk 1.12, 95% confidence interval 0.81–1.55 ( p =0.286)], a non-significant difference. Total duration of peripheral Cannulation was similar in both groups (mean 123.3h in the intervention group and 125.9h in the control group: P =0.82) but significantly more re-sites occurred in the control group (167 in intervention group, 202 in the control group: p =0.022). Cost of Cannula replacements in the intervention group was AUD$3,183.62 and in the control group AUD$3,837.56 ( p =0.006). Conclusion Re-siting peripheral venous Cannulas when clinically indicated compared with changing them routinely every 3 days does not lead to more complications and reduces costs.
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developing a research base for intravenous peripheral Cannula re sites drip trial a randomised controlled trial of hospital in patients
Faculty of Health, 2007Co-Authors: Joan Webster, Sophia Lloyd, Tracey Hopkins, Sonya Osborne, Maria YaxleyAbstract:Background: There is currently no high grade evidence on which to base decisions about the frequency of intravenous Cannula re-sites Objective: To assess the safety of changing peripheral venous Cannulas when clinically indicated. Design: Randomised controlled trial Setting: A tertiary referral hospital in Brisbane, Australia Participants: 206 hospitalised patients from surgical, medical and orthopaedic wards Interventions: Peripheral intravenous Cannulas were re-sited only when complications occurred (intervention group) or every 3 days (control group). Main outcome measures: The primary endpoint was any unplanned Cannula removal, the secondary outcome was cost. Results: Forty six patients had unplanned removals in the intervention group compared with 41 in the control group [relative risk 1.12, 95% confidence interval 0.81 to 1.55 (p = 0.286)], a non-significant difference. Total duration of peripheral Cannulation was similar in both groups (mean 123.3 hours in the intervention group and 125.9 hours in the control group: P = 0.82) but significantly more re-sites occurred in the control group (167 in intervention group, 202 in the control group: p = 0.022). Cost of Cannula replacements in the intervention group was AUD$3,183.62 and in the control group AUD$3,837.56 (p = 0.006). Conclusion: Re-siting peripheral venous Cannulas when clinically indicated compared with changing them routinely every 3 days does not lead to more complications and reduces costs.
Eisuke Tatsumi - One of the best experts on this subject based on the ideXlab platform.
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development of a novel tissue compatible apical inflow Cannula for an implantable vad
Journal of Heart and Lung Transplantation, 2013Co-Authors: Toshihide Mizuno, Y Takawa, Tomonori Tsukiya, Eisuke TatsumiAbstract:Purpose Clinical application of VAD is a potent therapeutic option for treating the patients with heart failure. However, as the VAD support period prolonged, the incidence of device-related complication, such as wedge thrombus, has been increasing. We already reported on new axial flow blood pump featuring a hydrodynamically levitated impeller with superior mechanical durability and anti-thrombogenesity. However, a measure against device-related complication occurred in the other components was not considered sufficiently. In this study, we developed a novel tissue-compatible polyester velour covered inflow Cannula for preventing the wedge thrombus, and evaluated its performance in a series of animal tests. Methods and Materials Eight calves (BW: 62-99 kg) underwent VAD implantation with our new axial flow blood pump. In the first two animals, a titanium-made inflow Cannula with a smooth surface was used. In the following six animals, the outside of the cylindrical inflow Cannula tip was wrapped with tissue-compatible polyester velour material. Outer diameters of the Cannula tip was 20 mm, respectively, and the length of the Cannula tip was 30 mm. The portion of the velour protruding from the apex was made to be 20 mm in length. Results All animals were sacrificed on 90-92 POD on schedule. At autopsies, first two animals with smooth surface titanium inflow Cannula demonstrated wedge thrombus formation at the Cannula insertion site of the ventricular apex. The granulomatous tissue covered and partially occluded the tip of the inflow Cannula. In contrast, six cases with newly developed Cannula revealed no wedge thrombus formation around the outside of the inflow Cannulas, and the polyester velour was completely enveloped with the neointimal tissue presumably grown from the ventricular endocardium. Conclusions In conclusion, our newly developed tissue-compatible inflow Cannula with polyester velour material successfully reduced the wedge thrombus formation in a series of 3 months animal implantation.
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Neointima-inducing inflow Cannula with titanium mesh for left ventricular assist device
Journal of Artificial Organs, 2011Co-Authors: Yukiko Yamada, Toshihide Mizuno, Tomohiro Nishinaka, Eisuke Tatsumi, Yoshiyuki Taenaka, Kenji YamazakiAbstract:The formation of wedge thrombus is a crucial problem in any left ventricular assist device (LVAD) with a left ventricle apical inflow Cannula. We therefore developed a new titanium mesh wrapped inflow Cannula expecting to induce autologous neointima to avoid such wedge thrombus formation. We performed animal experiments to evaluate the feasibility of this newly developed inflow Cannula with titanium mesh for the induction of autologous neointima. Four calves were implanted with the inflow Cannula as well as an EVAHEART centrifugal pump LVAD (Sun Medical Technology Research Corp., Nagano, Japan) for a duration of about 2 months. The titanium mesh was enveloped with neointimal tissue grown from the ventricular endocardium. There was no thrombus formation in any of the blood pumps or around the outside of the inflow Cannulas. The histological findings showed that the neointimal tissue consisted of a layer of endothelial cells and fibroblasts. The newly developed inflow Cannula using a titanium mesh induces autologous neointima formation, avoiding wedge thrombus formation.
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development and hydrodynamic evaluation of a novel inflow Cannula in a mechanical circulatory support system for bridge to decision
Artificial Organs, 2011Co-Authors: Hirohito Sumikura, Yoshiaki Takewa, Kentaro Ohnuma, Mitsuo Sasagawa, Fumikazu Watanabe, Junichi Ugawa, Tomonori Tsukiya, Koichi Toda, Yoshiyuki Taenaka, Eisuke TatsumiAbstract:: Recent progress in the development of implantable rotary blood pumps realized long-term mechanical circulatory support (MCS) for bridge to transplant, bridge to recovery, or a destination therapy. Meanwhile, a short-term MCS system is becoming necessary for bridge to decision. We developed a novel inflow Cannula for the short-term MCS system, which gives sufficient bypass flow with minimal invasion at insertion, and evaluated its hydrodynamic characteristics. The novel inflow Cannula, named the Lantern Cannula, is made of elastic silicone reinforced with metal wires. The Cannula tip has six slits on the side. This Cannula tip can be extended to the axial direction by using an introducer and can be reduced in diameter, and the Lantern Cannula enables easy insertion into the left ventricle apex with minimal invasion. The sufficient bypass flow rate can be obtained due to low pressure loss. Moreover, this Lantern shape also resists suction complication around the Cannula tip. The pressure loss through the Lantern Cannula was measured using a mock circulation and compared with two commercially available venous Cannulae (Sarns4882, Terumo, Tokyo, Japan and Stockert V122-28, Sorin Group, Tokyo, Japan), which have almost same diameter as the Lantern Cannula. Moreover, the flow patterns around the Cannula tip were numerically analyzed by computational fluid dynamics (CFD). Acute animal experiment was also performed to confirm the practical effectiveness of the Lantern Cannula. The pressure loss of the Lantern Cannula was the lowest compared with those of the commercially available venous Cannulae in in vitro experiment. CFD analysis results demonstrated that the Lantern Cannula has low pressure loss because of wide inflow orifice area and a bell mouth, which were formed via Lantern shape. The highest bypass flow was obtained in the Lantern Cannula because of the low pressure loss under pulsatile condition in in vivo experiments. The Lantern Cannula demonstrated superior hydrodynamic characteristics as the inflow Cannula in terms of pressure loss due to its specially designed Lantern shape.
Maria Yaxley - One of the best experts on this subject based on the ideXlab platform.
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developing a research base for intravenous peripheral Cannula re sites drip trial a randomised controlled trial of hospital in patients
International Journal of Nursing Studies, 2007Co-Authors: Joan Webster, Sophia Lloyd, Tracey Hopkins, Sonya Osborne, Maria YaxleyAbstract:Abstract Background There is currently no high grade evidence on which to base decisions about the frequency of intravenous Cannula re-sites. Objective To assess the safety of changing peripheral venous Cannulas when clinically indicated. Design Randomised controlled trial. Setting A tertiary referral hospital in Brisbane, Australia. Participants Two hundred and six hospitalised patients from surgical, medical and orthopaedic wards. Interventions Peripheral intravenous Cannulas were re-sited only when complications occurred (intervention group) or every 3 days (control group). Main outcome measures The primary endpoint was any unplanned Cannula removal, the secondary outcome was cost. Results Forty six patients had unplanned removals in the intervention group compared with 41 in the control group [relative risk 1.12, 95% confidence interval 0.81–1.55 ( p =0.286)], a non-significant difference. Total duration of peripheral Cannulation was similar in both groups (mean 123.3h in the intervention group and 125.9h in the control group: P =0.82) but significantly more re-sites occurred in the control group (167 in intervention group, 202 in the control group: p =0.022). Cost of Cannula replacements in the intervention group was AUD$3,183.62 and in the control group AUD$3,837.56 ( p =0.006). Conclusion Re-siting peripheral venous Cannulas when clinically indicated compared with changing them routinely every 3 days does not lead to more complications and reduces costs.
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developing a research base for intravenous peripheral Cannula re sites drip trial a randomised controlled trial of hospital in patients
Faculty of Health, 2007Co-Authors: Joan Webster, Sophia Lloyd, Tracey Hopkins, Sonya Osborne, Maria YaxleyAbstract:Background: There is currently no high grade evidence on which to base decisions about the frequency of intravenous Cannula re-sites Objective: To assess the safety of changing peripheral venous Cannulas when clinically indicated. Design: Randomised controlled trial Setting: A tertiary referral hospital in Brisbane, Australia Participants: 206 hospitalised patients from surgical, medical and orthopaedic wards Interventions: Peripheral intravenous Cannulas were re-sited only when complications occurred (intervention group) or every 3 days (control group). Main outcome measures: The primary endpoint was any unplanned Cannula removal, the secondary outcome was cost. Results: Forty six patients had unplanned removals in the intervention group compared with 41 in the control group [relative risk 1.12, 95% confidence interval 0.81 to 1.55 (p = 0.286)], a non-significant difference. Total duration of peripheral Cannulation was similar in both groups (mean 123.3 hours in the intervention group and 125.9 hours in the control group: P = 0.82) but significantly more re-sites occurred in the control group (167 in intervention group, 202 in the control group: p = 0.022). Cost of Cannula replacements in the intervention group was AUD$3,183.62 and in the control group AUD$3,837.56 (p = 0.006). Conclusion: Re-siting peripheral venous Cannulas when clinically indicated compared with changing them routinely every 3 days does not lead to more complications and reduces costs.
Ulrich Steinseifer - One of the best experts on this subject based on the ideXlab platform.
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flow analysis of ventricular assist device inflow and outflow Cannula positioning using a naturally shaped ventricle and aortic branch
Artificial Organs, 2010Co-Authors: Marco Laumen, Shaun D Gregory, Tim A S Kaufmann, Daniel Timms, Peter Schlanstein, Sebastian V Jansen, Kai Chun Wong, Thomas Schmitzrode, Ulrich SteinseiferAbstract:: Tip geometry and placement of rotary blood pump inflow and outflow Cannulae influence the dynamics of flow within the ventricle and aortic branch. Cannulation, therefore, directly influences the potential for thrombus formation and end-organ perfusion during ventricular assist device (VAD) support or cardiopulmonary bypass (CPB). The purpose of this study was to investigate the effect of various inflow/outflow Cannula tip geometries and positions on ventricular and greater vessel flow patterns to evaluate ventricular washout and impact on cerebral perfusion. Transparent models of a dilated cardiomyopathic ventricle and an aortic branch were reconstructed from magnetic resonance imaging data to allow flow measurements using particle image velocimetry (PIV). The contractile function of the failing ventricle was reproduced pneumatically, and supported with a rotary pump. Flow patterns were visualized around VAD inflow Cannulae, with various tip geometries placed in three positions in the ventricle. The outflow Cannula was placed in the subclavian artery and at several positions in the aorta. Flow patterns were measured using PIV and used to validate an aortic flow computational fluid dynamic study. The PIV technique indicated that locating the inflow tip in the left ventricular outflow tract improved complete ventricular washout while the tip geometry had a smaller influence. However, side holes in the inflow Cannula improved washout in all cases. The PIV results confirmed that the positioning and orientation of the outflow Cannula in the aortic branch had a high impact on the flow pattern in the vessels, with a negative blood flow in the right carotid artery observed in some cases. Cannula placement within the ventricle had a high influence on chamber washout. The positioning of the outflow Cannula directly influences the flow through the greater vessels, and may be responsible for the occasional reduction in cerebral perfusion seen in clinical CPB.
