Snake-Like Robots for Minimally Invasive, Single Port, and Intraluminal Surgeries

The surgical paradigm of Minimally Invasive Surgery (MIS) has been a key driver to the adoption of robotic surgical assistance. Progress in the last three decades has led to a gradual transition from manual laparoscopic surgery with rigid instruments to robot-assisted surgery. In the last decade, the increasing demand for new surgical paradigms to enable access into the anatomy without skin incision (intraluminal surgery) or with a single skin incision (Single Port Access surgery - SPA) has led researchers to investigate snake-like flexible surgical devices. In this chapter, we first present an overview of the background, motivation, and taxonomy of MIS and its newer derivatives. Challenges of MIS and its newer derivatives (SPA and intraluminal surgery) are outlined along with the architectures of new snake-like robots meeting these challenges. We also examine the commercial and research surgical platforms developed over the years, to address the specific functional requirements and constraints imposed by operations in confined spaces. The chapter concludes with an evaluation of open problems in surgical robotics for intraluminal and SPA, and a look at future trends in surgical robot design that could potentially address these unmet needs.Comment: 41 pages, 18 figures. Preprint of article published in the Encyclopedia of Medical Robotics 2018, World Scientific Publishing Company www.worldscientific.com/doi/abs/10.1142/9789813232266_000

Physiological effects of apnoeic oxygenation using high-flow nasal oxygen

In anaesthetic practice, the inability to oxygenate and ventilate patients is a much-feared complication with risk for severe hypoxia-induced adverse outcomes. By administrating oxygen in the absence of spontaneous ventilation, apnoeic oxygenation may overcome these challenges by a prolonged time with sufficient oxygenation. However, the concomitant and continuous increase in systemic carbon dioxide has limited its use. Recently, by using high-flow nasal oxygen (HFNO) during apnoea in anaesthetised patients, there seemed to be some carbon dioxide elimination, which has resulted in increased use of apnoeic oxygenation in clinical practice. From these early observations, this thesis has explored an array of aspects of apnoeic oxygenation with high-flow nasal oxygen by describing gaseous exchange, effects on lung volumes and alterations in biomarkers for organ function and oxidative stress in humans, and finally, by studying advanced haemodynamic parameters and the consequences of different oxygen flow rates in an animal model. The alterations of arterial oxygen, carbon dioxide and pH have been investigated by using apnoeic oxygenation with HFNO in subjects during general anaesthesia when laryngeal surgery of approximately 30 min duration was performed. Here, an extension of time with sufficient oxygenation was seen throughout the duration of surgery and a lower carbon dioxide rise compared to older studies of apnoeic oxygenation without high-flow oxygen. Also, an increase of arterial-end tidal carbon dioxide levels over time was noted. Thus, lung volume changes were characterised in subjects randomised to either apnoeic oxygenation with HFNO or mechanical ventilation in patients presenting for laryngeal surgery under general anaesthesia. As determined by electrical impedance tomography, no impedance differences over time or between the groups were seen perioperatively. In the same cohort, biomarkers for oxidative stress and vital organ function were explored to investigate the impact of hyperoxia and the continuously rising hypercapnia during apnoeic oxygenation with HFNO. For both groups, the oxidative stress biomarker MDA increased, and further, a discrete but non-clinically relevant increase in the CNS injury biomarker S100B was described. Finally, an experimental animal model of apnoeic oxygenation using 10 or 70 L/min of oxygen in a cross-over design with continuous central haemodynamic monitoring was used. Anaesthetised pigs were adequately oxygenated for up to 60 min of apnoea, with a carbon dioxide rise of approximately 0.5 kPa/min during both flow rates. Apnoea generated a continuously increasing, almost doubled mean pulmonary artery pressure. Also, cardiac index, heart rate, arterial blood pressure and cardiopulmonary ratio increased. Importantly, apnoea with no supplementary oxygen or flow resulted in a rapid desaturation to SpO2 < 85 % within 2.5 min. In summary, apnoeic oxygenation with HFNO enables oxygenation and partial carbon dioxide elimination, thereby extending safe apnoeic time. Perioperative lung volume changes and alterations in biomarkers for vital organ function do not differ from traditional mechanical ventilation. Experimentally, several central haemodynamic parameters were affected during extreme hypercapnia, primarily pulmonary artery pressure. Different oxygen flow rates generated an equal oxygenation and carbon dioxide rise. These findings add essential knowledge of the physiology and use of apnoeic oxygenation with HFNO

Cable-driven parallel robot for transoral laser phonosurgery

Transoral laser phonosurgery (TLP) is a common surgical procedure in otolaryngology. Currently, two techniques are commonly used: free beam and fibre delivery. For free beam delivery, in combination with laser scanning techniques, accurate laser pattern scanning can be achieved. However, a line-of-sight to the target is required. A suspension laryngoscope is adopted to create a straight working channel for the scanning laser beam, which could introduce lesions to the patient, and the manipulability and ergonomics are poor. For the fibre delivery approach, a flexible fibre is used to transmit the laser beam, and the distal tip of the laser fibre can be manipulated by a flexible robotic tool. The issues related to the limitation of the line-of-sight can be avoided. However, the laser scanning function is currently lost in this approach, and the performance is inferior to that of the laser scanning technique in the free beam approach. A novel cable-driven parallel robot (CDPR), LaryngoTORS, has been developed for TLP. By using a curved laryngeal blade, a straight suspension laryngoscope will not be necessary to use, which is expected to be less traumatic to the patient. Semi-autonomous free path scanning can be executed, and high precision and high repeatability of the free path can be achieved. The performance has been verified in various bench and ex vivo tests. The technical feasibility of the LaryngoTORS robot for TLP was considered and evaluated in this thesis. The LaryngoTORS robot has demonstrated the potential to offer an acceptable and feasible solution to be used in real-world clinical applications of TLP. Furthermore, the LaryngoTORS robot can combine with fibre-based optical biopsy techniques. Experiments of probe-based confocal laser endomicroscopy (pCLE) and hyperspectral fibre-optic sensing were performed. The LaryngoTORS robot demonstrates the potential to be utilised to apply the fibre-based optical biopsy of the larynx.Open Acces