The Design and Development of an Intelligent Atraumatic Laparoscopic Grasper

A key tool in laparoscopic surgery is the grasper, which is the surgeon’s main means of manipulating tissue within the body. However inappropriate use may lead to tissue damage and poor surgical outcomes. This thesis presents a novel approach to the assessment and prevention of tissue damage caused by laparoscopic graspers. The research focusses on establishing typical grasping characteristics used in surgery and thus developing a model of mechanically induced tissue trauma. A review explored the state-of-the-art in devices for measuring surgical grasping, tissue mechanics, and damage quantification to inform the research. An instrumented grasper was developed to characterise typical surgical tasks, enabling the grasping force and jaw displacement to be measured. This device was then used to quantitatively characterise grasper use in an in-vivo porcine model where the device was used to perform organ retraction and manipulation tasks. From this work, the range of forces and the grasping times used in certain tasks were determined and this information was used to guide the rest of the study. The in-vivo investigation highlighted a need for grasping in a controlled environment where the tissue’s mechanical properties could be studied. A grasper test rig was designed and developed to provide automated controlled grasping of ex-vivo tissue. This allowed the mechanical properties of tissue to be determined and analysed for indications of tissue damage. A series of experimental studies were conducted with this system which showed how the mechanical response of tissue varies depending on the applied grasping force characteristics, and how this is indicative of tissue damage through comparison to histological analysis. These data were then used to develop a model which predicts the likelihood and severity of tissue damage during grasping, based on the input conditions of grasping force and time. The model was integrated into the instrumented grasper system to provide a tool which could enable real-time grading and feedback of grasping during surgery, or be used to inform best practice in training scenarios

Optical Fibre-based Force Sensing Needle Driver for Minimally Invasive Surgery

Minimally invasive surgery has been limited from its inception by insufficient haptic feedback to surgeons. The loss of haptic information threatens patients safety and results in longer operation times. To address this problem, various force sensing systems have been developed to provide information about tool–tissue interaction forces. However, the provided results for axial and grasping forces have been inaccurate in most of these studies due to considerable amount of error and uncertainty in their force acquisition method. Furthermore, sterilizability of the sensorized instruments plays a pivotal role in accurate measurement of forces inside a patient\u27s body. Therefore, the objective of this thesis was to develop a sterilizable needle-driver type grasper using fibre Bragg gratings. In order to measure more accurate and reliable tool–tissue interaction forces, optical force sensors were integrated in the grasper jaw to measure axial and grasping forces directly at their exertion point on the tool tip. Two sets of sensor prototypes were developed to prove the feasibility of proposed concept. Implementation of this concept into a needle-driver instrument resulted in the final proposed model of the sensorized laparoscopic instrument. Fibre Bragg gratings were used for measuring forces due to their many advantages for this application such as small size, sterilizability and high sensitivity. Visual force feedback was provided for users based on the acquired real-time force data. Improvement and consideration points related to the current work were identified and potential areas to continue this project in the future are discussed

Haptics in Robot-Assisted Surgery: Challenges and Benefits

Robotic surgery is transforming the current surgical practice, not only by improving the conventional surgical methods but also by introducing innovative robot-enhanced approaches that broaden the capabilities of clinicians. Being mainly of man-machine collaborative type, surgical robots are seen as media that transfer pre- and intra-operative information to the operator and reproduce his/her motion, with appropriate filtering, scaling, or limitation, to physically interact with the patient. The field, however, is far from maturity and, more critically, is still a subject of controversy in medical communities. Limited or absent haptic feedback is reputed to be among reasons that impede further spread of surgical robots. In this paper objectives and challenges of deploying haptic technologies in surgical robotics is discussed and a systematic review is performed on works that have studied the effects of providing haptic information to the users in major branches of robotic surgery. It has been tried to encompass both classical works and the state of the art approaches, aiming at delivering a comprehensive and balanced survey both for researchers starting their work in this field and for the experts

Design of a Hand Held Minimally Invasive Lung Tumour Localization Device

Lung cancer is the leading type of cancer that causes death. If diagnosed, the treatment of choice is surgical resection of the tumour. Traditionally, a surgeon feels for the presence of a tumour in open thoracic surgery. However, a minimally invasive approach is desired. A major problem presented by the minimally invasive approach is the localization of the tumour. This project describes the design, analysis, and experimental validation of a novel minimally invasive instrument for lung tumour localization. The instrument end effector is a two degree of freedom lung tissue palpator. It allows for optimal tissue palpation to increase useful sensor feedback by ensuring sensor contact, and prevents tissue damage by uniformly distributing pressure on the tissue with an upper bound force. Finite element analysis was used extensively to guide the design process. The mechanism is actuated using high strength tungsten cables attached to controlled motors. Heat treatment experiments were undertaken with stainless steel alloy 440C for use in the design, achieving a device factor of safety of 4. This factor of safety is based on a 20 N force on the end effector — the approximate weight of a human lung. The design was prototyped and validation experiments were carried out to assess its articulation and its load carrying capacity. Up to 10 N of force was applied to the prototype. Issues to resolve in the current design include cable extension effects and the existence of joint inflection. The end effector was also designed to allow the inclusion of ultrasound, tactile, and kinaesthetic sensors. It is hypothesized that a plurality of sensors will increase the likelihood of positive tumour localization. These sensors, combined with the presented mechanical design, form the basis for research in robotics-assisted palpation. A proof of concept control system is presented for automated palpation

Development of Sensing Systems for Improving Surgical Grasper Performance

Minimally invasive techniques play a vital and increasing role in modern surgery. In these procedures, surgical graspers are essential in replacing the surgeon’s fingertips as the main manipulator of delicate soft tissues. Current graspers lack haptic feedback, restricting the surgeon to visual feedback. Studies show that this can frequently lead to morbidity or task errors due to inappropriate application of force. Existing research has sought to address these concerns and improve the safety and performance of grasping through the provision of haptic feedback to the surgeon. However, an effective method of grasping task optimisation has not been found. This thesis explores new sensing approaches intended to reduce errors when manipulating soft tissues, and presents a novel tactile sensor designed for deployment in the grasper jaw. The requirements were first established through discussion with clinical partners and a literature review. This resulted in a conceptual approach to use multi-axis tactile sensing within the grasper jaw as a potential novel solution. As a foundation to the research, a study was conducted using instrumented graspers to investigate the characteristics of grasp force employed by surgeons of varying skill levels. The prevention of tissue slip was identified as a key method in the prevention of grasper misuse, preventing both abrasion through slip and crush damage. To detect this phenomena, a novel method was proposed based on an inductive pressure sensing system. To investigate the efficacy of this technique, experimental and computational modelling investigations were conducted. Computational models were used to better understand the transducer mechanisms, to optimise sensor geometry and to evaluate performance in slip detection. Prototype sensors were then fabricated and experimentally evaluated for their ultimate use in slip detection within a surgical grasper. The work concludes by considering future challenges to clinical translation and additional opportunities for this research in different domains

Validation of a Sensorized Instrument-Based Training System for Minimally Invasive Surgery

Minimally invasive surgery training is complicated by the restraints imposed by the surgical environment. A sensorized laparoscopic instrument capable of sensing force in 5 degrees of freedom and position in 6 degrees of freedom was evaluated. Novice and Expert laparoscopists performed a complex minimally invasive surgical task - suturing - using the novel instruments. Their force and position profiles were compared. The novel minimally invasive surgical instrument is construct-valid and capable of detecting differences between novices and experts in a laparoscopic suturing task with respect to force and position. It is also concurrently valid with an existing standard: the Fundamentals of Laparoscopic Skills. Further evaluation is mandated to better understand the ability to predict performance based on force and position as well as the potential for new metrics in minimally invasive surgical education

Evaluation of Haptic Feedback on Bimanually Teleoperated Laparoscopy for Endometriosis Surgery

Robotic minimal invasive surgery is gaining acceptance in surgical care. In contrast with the appreciated 3D vision and enhanced dexterity, haptic feedback is not offered. For this reason robotics is not considered beneficial for delicate interventions such the endometriosis. Overall, haptic feedback remains debatable and yet unproven except for some simple scenarios such as Fundamentals of Laparoscopic Surgery exercises. OBJECTIVE: The present work investigates the benefits of haptic feedback on more complex surgical gestures, manipulating delicate tissue through coordination between multiple instruments. Methods: A new training exercise, “Endometriosis Surgery Exercise” (ESE) has been devised approximating the setting for monocular robotic endometriosis treatment. A bimanual bilateral teleoperation setup was designed for laparoscopic laser surgery. Haptic guidance and haptic feedback are respectively offered to the operator. User experiments have been conducted to i) assess the validity of ESE and to ii) examine possible advantages of haptic technology during execution of bimanual surgery. RESULTS: i) Content and face validity of ESE was established by participating surgeons. Surgeons suggested ESE also as a means to train lasering skills, ii) interaction forces on endometriotic tissue were found to be significantly lower when a bilateral controller is used. Collisions between instruments and the environment were less frequent and so were situations marked as potentially dangerous. CONCLUSION: This study provides some promising results suggesting that haptics may offer a distinct advantage in complex robotic interventions were fragile tissue is manipulated. SIGNIFICANCE: Patients need to know whether it should be incorporated. Improved understanding of the value of haptics is important as current commercial surgical robots are widely used but do not offer haptics

A Sensorized Instrument for Minimally Invasive Surgery for the Measurement of Forces during Training and Surgery: Development and Applications

The reduced access conditions present in Minimally Invasive Surgery (MIS) affect the feel of interaction forces between the instruments and the tissue being treated. This loss of haptic information compromises the safety of the procedure and must be overcome through training. Haptics in MIS is the subject of extensive research, focused on establishing force feedback mechanisms and developing appropriate sensors. This latter task is complicated by the need to place the sensors as close as possible to the instrument tip, as the measurement of forces outside of the patient\u27s body does not represent the true tool--tissue interaction. Many force sensors have been proposed, but none are yet available for surgery. The objectives of this thesis were to develop a set of instruments capable of measuring tool--tissue force information in MIS, and to evaluate the usefulness of force information during surgery and for training and skills assessment. To address these objectives, a set of laparoscopic instruments was developed that can measure instrument position and tool--tissue interaction forces in multiple degrees of freedom. Different design iterations and the work performed towards the development of a sterilizable instrument are presented. Several experiments were performed using these instruments to establish the usefulness of force information in surgery and training. The results showed that the combination of force and position information can be used in the development of realistic tissue models or haptic interfaces specifically designed for MIS. This information is also valuable in order to create tactile maps to assist in the identification of areas of different stiffness. The real-time measurement of forces allows visual force feedback to be presented to the surgeon. When applied to training scenarios, the results show that experience level correlates better with force-based metrics than those currently used in training simulators. The proposed metrics can be automatically computed, are completely objective, and measure important aspects of performance. The primary contribution of this thesis is the design and development of highly versatile instruments capable of measuring force and position during surgery. A second contribution establishes the importance and usefulness of force data during skills assessment, training and surgery