Paul Breedveld

Scopes Too Flexible...and Too Stiff

The article investigates how the difficulties caused by the flexibility of the endoscope shaft could be solved and to provide a categorized overview of designs that potentially provide a solution. The following are discussed: paradoxical problem of flexible endoscopy; NOTES or hybrid endoscopy surgery; design challenges; shaft-guidance: guiding principles; virtual track guidance; physical track guidance; shaft-guidance: rigidity control; material stiffening; structural stiffening; and hybrid stiffening.

Theoretical background and conceptual solution for depth perception and eye-hand coordination problems in laparoscopic surgery

SummaryThe indirect method of observation and manipulation in laparoscopic surgery complicates the surgeons depth perception and impairs his/her eye-hand coordination. Depth perception problems are due to misfits in accommodation and convergence, absence of shadows in endoscopic camera pictures and absence of stereo-vision and movement parallax. Eye-hand coordination problems are caused by the distant location of the monitor and by the fact that the surgeons hand movements are rotated, mirrored and amplified when they appear on the monitor. These effects are very confusing, especially for trainee laparoscopic surgeons and require a long and intensive training period to overcome. This paper gives a theoretical background of the depth perception and eye-hand coordination problems. A technical concept of an endoscope positioning system is described that compensates misorientations by using a flexible 90° endoscope. Movement parallax is achieved using a motorised endoscope positioner controlled by the surge...

Locomotion Through the Intestine by Means of Rolling Stents

Colonoscopy is a standard medical procedure in which a long and flexible endoscope is inserted into the rectum for inspection of the large intestine and for simple interventions. Pushing the endoscope tip from behind via a long and flexible tube leads easily to buckling when the tip comes in contact with sharp curves in the intestinal wall. Buckling is accompanied by painful cramps and makes it difficult to complete the procedure. A way to avoid buckling is not to push the tip from behind, but to use the friction with the intestinal wall to pull the tip forward. This paper describes the state-of-the-art in research on intestinal locomotion methods and presents a new locomotion method based on a rolling donut that is positioned around the endoscope tip. The donut functions like a circular caterpillar and is constructed from three stents that generate high friction with the intestinal wall. The diameter of the donut can be changed and the stents can be driven independently to reduce slip in intestinal curves. The resulting Rolling-Stent Endoscope contains a new steerable mechanism by which the tip can be bent in all directions over a very large angle. The Rolling-Stent Endoscope was applied for a patent and a prototype is under development for evaluation in the intestine of a pig.Copyright

Design of Steerable Endoscopes to Improve the Visual Perception of Depth During Laparoscopic Surgery

Visual feedback during laparoscopic surgery is provided by an endoscope with a camera that is inserted through a small incision in the abdominal wall. The incision restricts the endoscope movements to 4 degrees of freedom (DOF), making it impossible to observe organs from different sides. This paper describes two 6 DOF steerable endoscopes that contain a new spatial parallelogram-mechanism to transform the handgrip movements into movements of the steerable tip. Part of the mechanism is a new kind of spring that combines high torsion stiffness with a low bending stiffness. The endoscopes and the spring have been applied for two international patents.

A state of the art review and categorization of multi-branched instruments for NOTES and SILS

BackgroundSince the advent of Natural Orifice Translumenal Endoscopic Surgery (NOTES) and single incision laparoscopic surgery (SILS), a variety of multitasking platforms have been under development with the objective to allow for bimanual surgical tasks to be performed. These instruments show large differences in construction, enabled degrees of freedom (DOF), and control aspects.MethodsThrough a literature review, the absence of an in-depth analysis and structural comparison of these instruments in the literature is addressed. All the designed and prototyped multitasking platforms are identified and categorized with respect to their actively controlled DOF in their shafts and branches. Additionally, a graphical overview of patents, bench test experiments, and animal and/or human trials performed with each instrument is provided.ResultsThe large range of instruments, various actuation strategies, and different direct and indirect control methods implemented in the instruments show that an optimal instrument configuration has not been found yet. Moreover, several questions remain unanswered with respect to which DOF are essential for bimanual tasks and which control methods are best suited for the control of these DOF.ConclusionsConsidering the complexity of the currently prototyped and tested instruments, future NOTES and SILS instrument development will potentially necessitate a reduction of the available DOF to minimize the control complexity, thereby allowing for single surgeon bimanual task execution.

DragonFlex – Smart Steerable Laparoscopic Instrument

Despite its success, e.g., in prostatectomy, da Vincis steerable grasper EndoWrist from Intuitive Surgical has a complex design prone to steel cable fatigue, potential sterilization issues and high associated costs, all of which insinuate a need for an alternative. The aim of this paper is to demonstrate a design of a structurally simple handheld steerable laparoscopic grasping forceps free from cable fatigue, while attaining sufficient bending stiffness for surgery and improving on EndoWrists maneuverability and dimensions. Having equal joint functionality to EndoWrist, DragonFlexs instrument tip contains only four parts, driven and bound by two cables mechanically fixed in the handle. Two orthogonal planar joints feature an innovative rolling link mechanism allowing the cables to follow circular arc profiles of a diameter 1.5 times larger than the width of the instrument shaft. Besides maximizing the cable lifespan, the rolling link was designed to equalize the force requirements on both cables throughout joint rotation, making the handling fluid and effortless. The smart joint design and stacked instrument construction enable control of seven degrees of freedom by only two cables and seven instrument components in tip, shaft and handgrip altogether. Two DragonFlex prototypes were developed by means of additive manufacturing technology, allowing grasping and omnidirectional steering over ±90 deg, exhibiting promisingly high bending stiffness and featuring extreme simplicity at 5 mm dimensions. DragonFlex concept sheds new light on the possibilities of additive manufacturing of surgical instruments, allowing for a feature-packed design, simple assembly, suitability for disposable use and potential MRI compatibility.

Steerable Laparoscopic Cable-Ring Forceps

Laparoscopic surgery is carried out using long and slender endoscopes and instruments that are inserted through small incisions in the abdominal wall. Current endoscopes and instruments are rigid and have the drawback that their motion is restricted to 4-degrees of freedom (DOF). This paper describes a 6-DOF steerable laparoscopic grasping forceps incorporating a novel and very simple “cable-ring” mechanism consisting out of a ring of cables surrounded by two coil springs. Methods are described to increase stiffness and to improve manual control, resulting in a well-working prototype suitable for commercialization. The paper ends with a discussion on a number of cable-ring variants suitable for challenging new steerable designs in the future.

Review of manual control methods for handheld maneuverable instruments.

Abstract By the introduction of new technologies, surgical procedures have been varying from free access in open surgery towards limited access in minimal access surgery. Improving access to difficult-to-reach anatomic sites, e.g. in neurosurgery or percutaneous interventions, needs advanced maneuverable instrumentation. Advances in maneuverable technology require the development of dedicated methods enabling surgeons to stay in direct, manual control of these complex instruments. This article gives an overview of the state-of-the-art in the development of manual control methods for handheld maneuverable instruments. It categorizes the manual control methods in three levels: a) number of steerable segments, b) number of Degrees Of Freedom (DOF), and c) coupling between control motion of the handle and steering motion of the tip. The literature research was completed by using Web of Science, Scopus and PubMed. The study shows that in controlling single steerable segments, direct as well as indirect control methods have been developed, whereas in controlling multiple steerable segments, a gradual shift can be noticed from parallel and serial control to integrated control. The development of multi-segmented maneuverable instruments is still at an early stage, and an intuitive and effective method to control them has to become a primary focus in the domain of minimal access surgery.

A clearly visible endoscopic instrument shaft on the monitor facilitates hand-eye coordination.

AbstractsBackground: Passing an instrument through a small incision alters the kinematics of the instrument, thus hampering hand–eye coordination. Nevertheless, the incision provides a stable, nearly invariant, point of rotation for instrument movements. Therefore, we set out to evaluate the effects of the altered kinematics on hand–eye coordination. In addition, we assessed the hypothesis that the hand–eye coordination of laparoscopic surgeons incorporates the incision as a point of reference. Methods: Eight surgeons with experience in laparoscopy repeatedly performed a positioning task on a two-dimensional endoscopic manipulation simulator. Task time was measured. In the first experiment, normal endoscopic manipulation was compared to a condition in which the kinematic effects of the incision were compensated for. In the second experiment, the instrument shaft on the monitor was not visible during half of the trials, so that all visual information about the location of the incision was obscured. Results: Task performance improved significantly when the kinematic effects of the incision were compensated for (p = 0.001). Task performance improved when the instrument shaft was clearly visible on the monitor (p <0.05). Conclusions: Compensating for the kinematic effects introduced by the incision improves hand–eye coordination. The results of this study indicate that the incision provides a point of reference for hand–eye coordination during endoscopic manipulation.

Buckling prevention strategies in nature as inspiration for improving percutaneous instruments: a review

A typical mechanical failure mode observed in slender percutaneous instruments, such as needles and guidewires, is buckling. Buckling is observed when the axial compressive force that is required to penetrate certain tissue types exceeds the critical load of the instrument and manifests itself by sudden lateral deflection of the instrument. In nature, several organisms are able to penetrate substrates without buckling while using apparatuses with diameters smaller than those of off-the-shelf available percutaneous needles and guidewires. In this study we reviewed the apparatuses and buckling prevention strategies employed by biological organisms to penetrate substrates such as wood and skin. A subdivision is made between buckling prevention strategies that focus on increasing the critical load of the penetration tool and strategies that focus on decreasing the penetration load of the substrate. In total, 28 buckling prevention strategies were identified and categorized. Most organisms appear to be using a combination of buckling prevention strategies simultaneously. Integration and combination of these biological buckling prevention strategies in percutaneous instruments may contribute to increasing the success rate of percutaneous interventions.