OxVent: Design and evaluation of a rapidly-manufactured Covid-19 ventilator.

BACKGROUND: The manufacturing of any standard mechanical ventilator cannot rapidly be upscaled to several thousand units per week, largely due to supply chain limitations. The aim of this study was to design, verify and perform a pre-clinical evaluation of a mechanical ventilator based on components not required for standard ventilators, and that met the specifications provided by the Medicines and Healthcare Products Regulatory Agency (MHRA) for rapidly-manufactured ventilator systems (RMVS). METHODS: The design utilises closed-loop negative feedback control, with real-time monitoring and alarms. Using a standard test lung, we determined the difference between delivered and target tidal volume (VT) at respiratory rates between 20 and 29 breaths per minute, and the ventilator's ability to deliver consistent VT during continuous operation for >14 days (RMVS specification). Additionally, four anaesthetised domestic pigs (3 male-1 female) were studied before and after lung injury to provide evidence of the ventilator's functionality, and ability to support spontaneous breathing. FINDINGS: Continuous operation lasted 23 days, when the greatest difference between delivered and target VT was 10% at inspiratory flow rates >825 mL/s. In the pre-clinical evaluation, the VT difference was -1 (-90 to 88) mL [mean (LoA)], and positive end-expiratory pressure (PEEP) difference was -2 (-8 to 4) cmH2O. VT delivery being triggered by pressures below PEEP demonstrated spontaneous ventilation support. INTERPRETATION: The mechanical ventilator presented meets the MHRA therapy standards for RMVS and, being based on largely available components, can be manufactured at scale. FUNDING: Work supported by Wellcome/EPSRC Centre for Medical Engineering,King's Together Fund and Oxford University.

Optic Nerve Sheath Fenestration With a Multi-Arm Continuum Robot.

This article presents a medical robotic system for deep orbital interventions, with a focus on Optic Nerve Sheath Fenestration (ONSF). ONSF is a currently invasive ophthalmic surgical approach that can reduce potentially blinding elevated hydrostatic intracranial pressure on the optic disc via an incision on the optic nerve. The prototype is a multi-arm system capable of dexterous manipulation and visualization of the optic nerve area, allowing for a minimally invasive approach. Each arm is an independently controlled concentric tube robot collimated by a bespoke guide that is secured on the eye sclera via sutures. In this article, we consider the robot's end-effector design in order to reach/navigate the optic nerve according to the clinical requirements of ONSF. A prototype of the robot was engineered, and its ability to penetrate the optic nerve was analysed by conducting ex vivo experiments on porcine optic nerves and comparing their stiffness to human ones. The robot was successfully deployed in a custom-made realistic eye phantom. Our simulation studies and experimental results demonstrate that the robot can successfully navigate to the operation site and carry out the intervention.

The i2Snake Robotic Platform for Endoscopic Surgery.

Endoscopic procedures have transformed minimally invasive surgery as they allow the examination and intervention on a patient's anatomy through natural orifices, without the need for external incisions. However, the complexity of anatomical pathways and the limited dexterity of existing instruments, limit such procedures mainly to diagnosis and biopsies. This paper proposes a new robotic platform: the Intuitive imaging sensing navigated and kinematically enhanced ([Formula: see text]) robot that aims to improve the field of endoscopic surgery. The proposed robotic platform includes a snake-like robotic endoscope equipped with a camera, a light-source and two robotic instruments, supported with a robotic arm for global positioning and for insertion of the [Formula: see text] and a master interface for master-slave teleoperation. The proposed robotic platform design focuses on ergonomics and intuitive control. The control workflow was first validated in simulation and then implemented on the robotic platform. The results are consistent with the simulation and show the clear clinical potential of the system. Limitations such as tendon backlash and elongation over time will be further investigated by means of combined hardware and software solutions. In conclusion, the proposed system contributes to the field of endoscopic surgical robots and could allow to perform more complex endoscopic surgical procedures while reducing patient trauma and recovery time.

Artificial neural network EMG classifier for functional hand grasp movements prediction.

Objective To design and implement an electromyography (EMG)-based controller for a hand robotic assistive device, which is able to classify the user's motion intention before the effective kinematic movement execution. Methods Multiple degrees-of-freedom hand grasp movements (i.e. pinching, grasp an object, grasping) were predicted by means of surface EMG signals, recorded from 10 bipolar EMG electrodes arranged in a circular configuration around the forearm 2-3 cm from the elbow. Two cascaded artificial neural networks were then exploited to detect the patient's motion intention from the EMG signal window starting from the electrical activity onset to movement onset (i.e. electromechanical delay). Results The proposed approach was tested on eight healthy control subjects (4 females; age range 25-26 years) and it demonstrated a mean ± SD testing performance of 76% ± 14% for correctly predicting healthy users' motion intention. Two post-stroke patients tested the controller and obtained 79% and 100% of correctly classified movements under testing conditions. Conclusion A task-selection controller was developed to estimate the intended movement from the EMG measured during the electromechanical delay.

Comparative Performance in Single-Port Versus Multiport Minimally Invasive Surgery, and Small Versus Large Operative Working Spaces: A Preclinical Randomized Crossover Trial.

BACKGROUND: Surgical approaches such as transanal endoscopic microsurgery, which utilize small operative working spaces, and are necessarily single-port, are particularly demanding with standard instruments and have not been widely adopted. The aim of this study was to compare simultaneously surgical performance in single-port versus multiport approaches, and small versus large working spaces. METHODS: Ten novice, 4 intermediate, and 1 expert surgeons were recruited from a university hospital. A preclinical randomized crossover study design was implemented, comparing performance under the following conditions: (1) multiport approach and large working space, (2) multiport approach and intermediate working space, (3) single-port approach and large working space, (4) single-port approach and intermediate working space, and (5) single-port approach and small working space. In each case, participants performed a peg transfer and pattern cutting tasks, and each task repetition was scored. RESULTS: Intermediate and expert surgeons performed significantly better than novices in all conditions (P < .05). Performance in single-port surgery was significantly worse than multiport surgery (P < .01). In multiport surgery, there was a nonsignificant trend toward worsened performance in the intermediate versus large working space. In single-port surgery, there was a converse trend; performances in the intermediate and small working spaces were significantly better than in the large working space. CONCLUSIONS: Single-port approaches were significantly more technically challenging than multiport approaches, possibly reflecting loss of instrument triangulation. Surprisingly, in single-port approaches, in which triangulation was no longer a factor, performance in large working spaces was worse than in intermediate and small working spaces.

An affordable, adaptable, and hybrid assistive device for upper-limb neurorehabilitation.

The paper presents a multisensory and multimodal device for neuromuscular rehabilitation of the upper limb, designed to enable enriched rehabilitation treatment in both clinical and home environments. Originating from an existing low-cost, variable-stiffness rehabilitation device, it expands its functionalities by integrating additional modules in order to augment application scenarios and applicable clinical techniques. The newly developed system focuses on the integration of a wearable neuromuscular electrical stimulation system, a virtual rehabilitation scenario, a low-cost unobtrusive sensory system and a patient model for adapting training task parameters. It also monitors the user behavior during each single session and its evolution throughout the entire training period. The result is a modular, integrated and affordable rehabilitation device, enabling a biomechanical, neurological, and physiological-based training of patients, including innovative features currently unavailable within off-the-shelf rehabilitation devices.

Toward Intraoperative Breast Endomicroscopy With a Novel Surface-Scanning Device.

New optical biopsy methods such as confocal endomicroscopy represent a promising tool for breast conserving surgery, allowing real-time assessment of tumor margins. However, it remains difficult to scan over a large surface area because of the small field-of-view. This paper presents a novel robotic instrument to perform automated scanning with a fiber bundle endomicroscope probe to expand the effective imaging area. The device uses a rigid concentric tube scanning mechanism to facilitate large-area mosaicking. It has a compact design with a diameter of 6 mm, incorporating a central channel with a diameter of 3 mm for passing through a fiber bundle probe. A bespoke bearing, an inflated balloon, and a passive linear structure are used to control image rotation and ensure consistent tool-tissue contact. Experimental results show that the device is able to scan a spiral trajectory over a large hemispherical surface. Detailed performance evaluation was performed and the bending angle ranges from -90° to 90° with high repeatability and minimal rotational hysteresis errors. The device has also been validated with breast phantom and ex vivo human breast tissue, demonstrating the potential clinical value of the system.

3D Printed Microfluidic Device with Integrated Biosensors for Online Analysis of Subcutaneous Human Microdialysate.

This work presents the design, fabrication, and characterization of a robust 3D printed microfluidic analysis system that integrates with FDA-approved clinical microdialysis probes for continuous monitoring of human tissue metabolite levels. The microfluidic device incorporates removable needle type integrated biosensors for glucose and lactate, which are optimized for high tissue concentrations, housed in novel 3D printed electrode holders. A soft compressible 3D printed elastomer at the base of the holder ensures a good seal with the microfluidic chip. Optimization of the channel size significantly improves the response time of the sensor. As a proof-of-concept study, our microfluidic device was coupled to lab-built wireless potentiostats and used to monitor real-time subcutaneous glucose and lactate levels in cyclists undergoing a training regime.

Evaluation of a novel flexible snake robot for endoluminal surgery.

BACKGROUND: Endoluminal therapeutic procedures such as endoscopic submucosal dissection are increasingly attractive given the shift in surgical paradigm towards minimally invasive surgery. This novel three-channel articulated robot was developed to overcome the limitations of the flexible endoscope which poses a number of challenges to endoluminal surgery. The device enables enhanced movement in a restricted workspace, with improved range of motion and with the accuracy required for endoluminal surgery. OBJECTIVE: To evaluate a novel flexible robot for therapeutic endoluminal surgery. DESIGN: Bench-top studies. SETTING: Research laboratory. INTERVENTION: Targeting and navigation tasks of the robot were performed to explore the range of motion and retroflexion capabilities. Complex endoluminal tasks such as endoscopic mucosal resection were also simulated. MAIN OUTCOME MEASUREMENTS: Successful completion, accuracy and time to perform the bench-top tasks were the main outcome measures. RESULTS: The robot ranges of movement, retroflexion and navigation capabilities were demonstrated. The device showed significantly greater accuracy of targeting in a retroflexed position compared to a conventional endoscope. LIMITATIONS: Bench-top study and small study sample. CONCLUSIONS: We were able to demonstrate a number of simulated endoscopy tasks such as navigation, targeting, snaring and retroflexion. The improved accuracy of targeting whilst in a difficult configuration is extremely promising and may facilitate endoluminal surgery which has been notoriously challenging with a conventional endoscope.

Robotics in keyhole transcranial endoscope-assisted microsurgery: a critical review of existing systems and proposed specifications for new robotic platforms.

BACKGROUND: Over the past decade, advances in image guidance, endoscopy, and tube-shaft instruments have allowed for the further development of keyhole transcranial endoscope-assisted microsurgery, utilizing smaller craniotomies and minimizing exposure and manipulation of unaffected brain tissue. Although such approaches offer the possibility of shorter operating times, reduced morbidity and mortality, and improved long-term outcomes, the technical skills required to perform such surgery are inevitably greater than for traditional open surgical techniques, and they have not been widely adopted by neurosurgeons. Surgical robotics, which has the ability to improve visualization and increase dexterity, therefore has the potential to enhance surgical performance. OBJECTIVE: To evaluate the role of surgical robots in keyhole transcranial endoscope-assisted microsurgery. METHODS: The technical challenges faced by surgeons utilizing keyhole craniotomies were reviewed, and a thorough appraisal of presently available robotic systems was performed. RESULTS: Surgical robotic systems have the potential to incorporate advances in augmented reality, stereoendoscopy, and jointed-wrist instruments, and therefore to significantly impact the field of keyhole neurosurgery. To date, over 30 robotic systems have been applied to neurosurgical procedures. The vast majority of these robots are best described as supervisory controlled, and are designed for stereotactic or image-guided surgery. Few telesurgical robots are suitable for keyhole neurosurgical approaches, and none are in widespread clinical use in the field. CONCLUSION: New robotic platforms in minimally invasive neurosurgery must possess clear and unambiguous advantages over conventional approaches if they are to achieve significant clinical penetration.

Flexible platforms for natural orifice transluminal and endoluminal surgery.

The flexible endoscope is playing an increasingly pivotal role in minimally invasive transluminal and endoluminal surgery. Whilst the flexible nature of the platform is desirable in order to navigate through the abdominal cavity or through a lumen, there are a number of issues with using the platform for this purpose. The challenges associated with using flexible endoscopes such as a lack of triangulation of instruments and force transmission, which is often inadequate for endoscopic surgery are discussed in this review. As a result of these difficulties, a number of mechanically and robotically driven devices based upon the flexible endoscope are emerging. The design of these devices and potential problems are also reviewed. Finally, future robotic systems which are still in the development and validation stage are briefly discussed. The field of gastroenterology is diverging. The narrowing divide between minimally invasive and endoluminal surgery has led to a surge of innovative and novel devices which may in the future enable precise, seamless and scar less surgery.