Resectoscope with an easy to use twist mechanism for improved handling

Holger Fritzsche; Axel Boese; Martin Schostak; Michael Friebe

doi:10.1515/cdbme-2016-0084

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Resectoscope with an easy to use twist mechanism for improved handling

Holger Fritzsche , Axel Boese , Martin Schostak and Michael Friebe

Published/Copyright: September 30, 2016

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From the journal Current Directions in Biomedical Engineering Volume 2 Issue 1

Abstract

One of the oldest methods used in minimally invasive surgeries is the transurethral resection. This is an operation technique in which diseased tissue from the bladder or the prostate is removed using a resectoscope through the urethra [Schostak M, Blana A, Hrsg. Alternative operative Therapien in der Uroonkologie. Berlin, Heidelberg, Springer Berlin Heidelberg; 2016]. A resectoscope has a channel for the view of the surgeon, a liquid supply, a working channel and a hand piece which could rotate up to 360 degrees. A RF- electrode on the tip of the resectoscope is used to cut out pathological growths. For diseased tissue which is located in the bladder on the ventral side, a rotation of the resectoscope up to 180 degrees is necessary. This means on the one side tiring of the hands, wrist pain and a change of the position of the operating surgeon. On the other side a reorganization of the connected tubes and cables is necessary. To avoid these problems and integrate additional features a standard resectoscope was adapted with an easy to use twist mechanism. After discussion with experienced urological surgeons a complete new design of the resectoscope with a twist mechanism in combination with a gyro sensor and a reference display was realized.

Keywords: bladder; cancer treatment; prostate; resectoscope; transurethral resection

1 Introduction

The resectoscope is a combined cystoscope and an electrosurgical instrument that allows the resection of prostate tissue, or diseased tissue of the bladder under direct vision by using an electric resection loop. Due to prostate bleeding, the resection is only possible by continuous irrigation [2].

There are a significant number of transurethral interventions. According to the Robert Koch Institute, in the year 2010, about 21,550 men and 7240 women were diagnosed with bladder cancer in Germany [3]. Bladder cancer is the 5^th most common category of cancer for men in Germany. The average age of men diagnosed is approximately 74 years, and for woman 72 years. In addition, approx. 60,000 TUR-P (transurethral resection of the prostate) are performed for benign prostatic hyperplasia [4]. Relevant developments in the area of endoscopic interventions have a market with a nationwide commercial network for sale and trade.

2 Methods

2.1 Identification of clinical need

Based on observed clinical TUR-B procedures (transurethral resection of the bladder) an unmet clinical need in handling optimisation of the resectoscope was identified [5] (Figure 1).

Figure 1

Observation of a TUR-B procedure (KURO, University Hospital Magdeburg).

The surgeon has to re-grab and twists the hand piece to about 180 degrees to reach every section of the bladder. Twisting of the resectoscope brings the surgeon in uncomfortable posture and aggravates the execution of the procedure. Additionally the line of sight on the endoscopic monitor is limited. Due to the movement of the surgeon, the monitor is sometimes hard to see during the procedure. Figure 2 shows a standard resectoscope that has to be rotated.

Figure 2

Standard resectoscope Olympus Surgemaster (A); in different rotation angles, (B) electrode loop downward, (C) electrode loop sideward, (D) electrode loop upward; 1: electrode loop, 2: connector for power supply.

2.2 Definition of the essential functionalities

Figure 3 shows the standard parts of a resectoscope (Surgemaster, Olympus Winter & Ibe GmbH, Hamburg, Germany).

Figure 3

Olympus resectoscope on the left with outer shaft- A22026A (A), inner shaft- A22040 (B) and working element – WA22066A (C); on the right the different electrodes for HF-surgery: resection loop (3), roller (4) and button (5).

The outer shaft enables irrigation of the surgery side. The inner shaft covers the electrode on the working element. The working element carries the hand piece with agitation mechanism. A central pipe allows the access of an endoscope for imaging. Different shapes of resection loops can be combined with the resectoscope.

Beside the standard features like resection, flushing, and the combination with optical imaging, the following additional functionalities were recognized according to the user feedback:

Twist mechanism for improved handling,
Sensing of the loop position for mapping and documentation,
Visualization of the camera image in a user friendly position to overcome line of sight issues.

2.3 Conceptual design

To avoid twisting of the hand and uncomfortable posture an intermediate piece was designed as an adapter interface. This adapter allows a corresponding translation of the movement between 1 and 360 degrees. The challenge in this design is a safe realization of the electrical interface between the moving parts. The adapter interface obviously should be integrated into the standard device. Therefore the connecting dimensions have to be considered.

Mapping the resection areas in the bladder during the procedure can be an advantageous feature for quality insurance. Thus a gyro sensor should be integrated into the new adapter interface. The sensor measures the rotation and the translation of the resection loop. Combined with an external tracking, future mapping of the procedure and staging could become feasible.

To overcome the identified line of sight issue, an additional small monitor is planned. This monitor can be placed in a comfortable position e.g. on the wrist of the surgeon or directly on the endoscope.

2.4 Set up of a first prototype

A standard resectoscope (OES Pro-2, Olympus Winter & Ibe GmbH, Hamburg, Germany) was modified to integrate the described twist mechanism as the basic feature. The parts of the hand piece were manufactured by rapid prototyping. Stainless steel pipes in the dimensions of the original resectoscope are used as carrier for the twist mechanism. Thus the compatibility to established imaging and therapy devices is ensured.

Figure 4 shows the assembly of this first prototype. The acting hand is holding the resectoscope. The translational movement is executed by a grasping movement of the acting hand. For rotation of the loop the other hand has to operate the rotation wheel.

Figure 4

Assembly of the first prototype with twist mechanism; rotational wheel- (A); cable reel- (B); lock mechanism- (C); connector for cable- (D).

2.5 Evaluation with clinical user

The first prototype of the twist mechanism was demonstrated to an experienced clinical user and also tested by himself. The additional rotation was confirmed as useful feature to simplify the intervention. But the operation of the twisting mechanism with the second hand is difficult during the actual therapy. Another important feedback was a critic on the standard hand grip of the resectoscope. The operation by the thumb is tiring for the surgical hand with falling asleep fingers. In additional motion tests for one-hand-handling a complete new concept for the design of a resectoscope based on the design of single use laparoscopic graspers was proposed.

2.6 Redesign of the prototype

A pistol like hand piece with a lever for operating the translational movement of the resection loop was designed. The shape was oriented on established interventional devices. The lever can be moved by two or three fingers of the acting hand. The rotation wheel was integrated directly in the housing of the grip. Thus, an easy operation with the thumb or the forefinger of the same hand is easily possible (Figure 5). The grip provides space for integration of a gyro sensor inside the housing on the shaft of the rotation wheel therefore the rotational movement, back and forth movement could be detected. Electrical conduction of the sensor was carried out directly beside the cable of the connection of the resection loop. For attachment of a miniaturized monitor as a reference display for the sensor data, a plain area on the back of the grip is provided.

Figure 5

Revision of the Prototype with twist mechanism; (A) pistol grip, (B) lever for translational movement, (C) rotation wheel, (D) resection loop.

2.7 Test of the prototype

The manufactured prototype was tested on a porcine sample. An endoscope connected to an endoscopic video processor and light source (Exera III, Olympus) was inserted through the imaging pipe for visualization. The resectoscope was connected to a HF generator (ESG 400, Olympus). The sample was placed on a reusable silicone electrode (Erbe Medizintechnik). The mode coagulation and cut were tested (Figure 6). The twist mechanism could be operated with the thumb for left rotation and the forefinger for right rotation during resection procedure. The translational movement of the electrode is manipulated by the hand lever of the pistol grip.

Figure 6

Test of the prototype on a porcine sample combined with endoscopic imaging.

3 Results

A prototype of the twistable resectoscope was designed and manufactured. The electrical interface was realized by an encapsulated flexible connector. The functionality and handling of the resectoscope was tested in clinical environment on phantoms. To receive feedback from real users, the prototype was demonstrated and discussed with experienced surgeons. For mapping and position detection a gyro sensor was implemented. An external miniature monitor can be attached on the back of the resectoscope easily (Figure 7).

Figure 7

(A) Integration of gyro sensor into the housing; (B) reference display attached to the back end of resectoscope.

4 Discussion

Observation of clinical procedures is an excellent method for generating new ideas for improvement of interventions and devices. The observed clinical needs were addressed by a user integrated design approach. By this, conceptual flaws were detected early in the first design stage. In the second design a user friendly resectoscope with a new twisting mechanism was drafted and manufactured. The proposed and well perceived twist mechanism can now be operated with only one hand. The pistol grip avoids tiring of the hands. Beside the possibility of rotation of the resection loop, a gyro sensor was integrated to measure angulation and movement. In a future development step, that was simulated, it is planned to firmly integrate a small monitor to overcome line of sight issues.

5 Conclusion

The integrated adaption of the resectoscope with a twist mechanism allows a simplified handling of the instrument in combination with the attached cables und tubes. The principle workflow of the procedure has not been changed. The additional small monitor that is in the line of the therapy could further improve the workflow and procedure comfort. With additional gyro sensors and instrument tracking a mapping of the bladder could be obtained for future references and as quality assurance measure.

Author’s Statement

Research funding: Supported by BMBF Germany INKA (03IPT7100X). Conflict of interest: Authors state no conflict of interest. Material and Methods: Informed consent: Informed consent has been obtained from all individuals included in this study. Ethical approval: The research related to human use complies with all the relevant national regulations, institutional policies and was performed in accordance with the tenets of the Helsinki Declaration, and has been approved by the authors’ institutional review board or equivalent committee.

References

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Published Online: 2016-9-30

Published in Print: 2016-9-1

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Articles in the same Issue

https://doi.org/10.1515/cdbme-2016-0084

Keywords for this article

bladder; cancer treatment; prostate; resectoscope; transurethral resection

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