The Multi Split Ventilator System: Performance Testing of Respiratory Support Shared by Multiple Patients

Ventilator sharing has been proposed as a method of increasing ventilator capacity during instances of critical shortage. We sought to assess the ability of a regulated, shared ventilator system (Multi Split Ventilator System, MSVS) to individualize support to multiple simulated patients using one ventilator. We employed simulated patients of varying size, compliance, minute ventilation requirement, and PEEP requirement. Performance tests were performed to assess the ability of the QSVS, versus control, to achieve individualized respiratory goals to clinically disparate patients sharing a single ventilator following ARDSNet guidelines. Resilience tests measured the effects of simulated adverse events occurring to one patient on another patient sharing a single ventilator. The QSVS met individual oxygenation and ventilation requirements for multiple simulated patients with a tolerance similar to a single ventilator. Abrupt endotracheal tube occlusion or extubation occurring to one patient resulted in modest, clinically tolerable changes in ventilation parameters for the remaining patients. The QSVS is a regulated, shared ventilator system capable of individualizing ventilatory support to clinically dissimilar simulated patients. It is also resilient to common adverse events. The QSVS represents a feasible option to ventilate multiple patients during a severe ventilator shortage.

Inexpensive Multi-Patient Respiratory Monitoring System for Helmet Ventilation During Covid-19 Pandemic

Helmet continuous positive applied pressure is a form of non-invasive ventilation (NIV) that has been used to provide respiratory support to COVID-19 patients. Helmet NIV is low-cost, readily available, provides viral filters between the patient and clinician, and may reduce the need for invasive ventilation. Its widespread adoption has been limited, however, by the lack of a respiratory monitoring system needed to address known safety vulnerabilities and to monitor patients. To address these safety and clinical needs, we developed an inexpensive respiratory monitoring system based on readily available components suitable for local manufacture. Open-source design and manufacturing documents are provided. The monitoring system comprises flow, pressure and CO2 sensors on the expiratory path of the helmet circuit and a central remote station to monitor up to 20 patients. The system is validated in bench tests, in human-subject tests on healthy volunteers, and in experiments that compare respiratory features obtained at the expiratory path to simultaneous ground-truth measurements from proximal sensors. Measurements of flow and pressure at the expiratory path are shown to deviate at high flow rates, and the tidal volumes reported via the expiratory path are systematically underestimated. Helmet monitoring systems exhibit high-flow rate, non-linear effects from flow and helmet dynamics. These deviations are found to be within a reasonable margin and should, in principle, allow for calibration, correction and deployment of clinically accurate derived quantities.

Evaluation of a Pneumatic Vest to Treat Symptoms of ARDS Caused by COVID-19

Critical care patients who experience symptoms of acute respiratory distress syndrome are commonly placed on mechanical ventilators to increase the oxygen provided to their pulmonary systems and monitor their condition. With the pulmonary inflammation typically accompanying ARDS, patients can experience lower ventilation-perfusion ratios resulting in lower blood oxygenation. In these cases, patients are typically rotated into a prone position to facilitate improved blood flow to portions of the lung that were not previously participating in the gas exchange process. However, proning a patient increases the risk of complications, requires up to seven hospital staff members to carry out, and does not guarantee an improvement in the patient's condition. The low-cost vest presented here was designed to reproduce the effects of proning while also requiring less hospital staff than the proning process. Additionally, the V/Q Vest helps hospital staff predict whether patients would respond well to a proning treatment. A pilot study was conducted on nine patients with ARDS from Coronavirus disease 2019 (COVID-19). The average increase in oxygenation with the V/Q Vest treatment for all patients was 19.7 ± 38.1%. Six of the nine patients responded positively to the V/Q Vest treatment, exhibiting increased oxygenation. The V/Q Vest also helped hospital staff predict that three of the five patients that were proned would experience an increase in oxygenation. An increase in oxygenation resulting from V/Q Vest treatment exceeded that of the proning treatment in two of these five proned patients.

Preoperative Motion Planner for Steerable Needles Using Cost Map Based on Repulsive Field and Empirical Model of Needle Deflection

Needle insertion is a common procedure in percutaneous puncture. A motion planner for a steerable needle that considers the risk level of the path in anatomical environment and the actual deflection of clinical needle is necessary. A novel preoperative motion planner for a steerable needle controlled by robot is proposed. Our method utilizes sampling-based planner to compute candidate path in the reachable region, the path solutions are optimized by calculating the cost of a path based on a cost map. The cost-map, which is built based on repulsive field theory from CT image, encodes the information of the obstacle locations and the criticality of the anatomical environment. The empirical formula that can predict needle trajectory is obtained by insertion experiments. Experiments shown that positioning error in gelatin phantom under the guidance of our planner is less than 1.1mm. Comparing with the straight-line insertion method, the positioning error was reduced by 80%. The results indicate that the motion planner has the potential to provide effective guidance for robot-assisted puncture surgery while enhancing the position precision and patient safety.

Design and Initial Validation of a Multiple Degree-of-Freedom Joint for an Ankle-Foot Orthosis

This paper presents the novel design of a Multi-Degree-Of-Freedom joint (M-DOF) for an Ankle-Foot Orthosis (AFO) that aims to improve upon the commercially available Double Action Joint (DAJ). The M-DOF is designed to maintain the functionality of the DAJ, while increasing dorsiflexion stiffness and introducing inversion/eversion. This increase in range of motion is designed to produce greater engagement from lower limb muscles during gait. The M-DOF was experimentally validated with one able-bodied and one stroke subject. Across walking speeds, the M-DOF AFO minimally affected the able-bodied subject's joint kinematics. The stroke subject's ankle dorsiflexion/plantarflexion and knee flexion were not heavily altered when wearing the M-DOF AFO, compared to the DAJ AFO. The new DOF allowed by the M-DOF AFO increased the inversion/eversion of the ankle by ~3°, without introducing any new compensations compared to their gait with the DAJ AFO.

RestEaze: An Emerging Technology to Characterize Leg Movements During Sleep

Several sleep disorders are characterized by periodic leg movements during sleep including Restless Leg Syndrome, and can indicate disrupted sleep in otherwise healthy individuals. Current technologies to measure periodic leg movements during sleep are limited. Polysomnography and some home sleep tests use surface electromyography to measure electrical activity from the anterior tibilias muscle. Actigraphy uses 3-axis accelerometers to measure movement of the ankle. Electromyography misses periodic leg movements that involve other leg muscles and is obtrusive because of the wires needed to carry the signal. Actigraphy based devices require large amplitude movements of the ankle to detect leg movements (missing the significant number of more subtle leg movements) and can be worn in multiple configurations precluding precision measurement. These limitations have contributed to their lack of adoption as a standard of care for several sleep disorders. In this study, we develop the RestEaze sleep assessment tool as an ankle-worn wearable device that combines capacitive sensors and a 6-axis inertial measurement unit to precisely measure periodic leg movements during sleep. This unique combination of sensors and the form-factor of the device addresses current limitations of periodic leg movements during sleep measurement techniques. Pilot data collected shows high correlation with polysomnography across a heterogeneous participant sample and high usability ratings. RestEaze shows promise in providing ecologically valid, longitudinal measures of leg movements that will be useful for clinicians, researchers, and patients to better understand sleep.

In Vitro Evaluation of a Nasal Interface Used to Improve Delivery from a Portable Oxygen Concentrator

Portable oxygen concentrators (POCs) are widely used to administer long-term oxygen therapy (LTOT) and employ pulsed delivery modes to conserve oxygen. Efficient pulsed delivery requires that POCs are triggered by patient inhalation. Triggering is known to fail for some patients during periods of quite breathing, as occurs during sleep. The present article describes a new nasal interface designed to improve triggering of pulsed oxygen delivery from portable oxygen concentrators (POCs). In vitro experiments incorporating realistic nasal airway replicas and simulated breathing were conducted. The pressure monitored via oxygen supply tubing (the signal pressure) was measured over a range of constant inhalation flow rates with the nasal interface inserted into the nares of the nasal airway replicas, and compared with signal pressures measured for standard and flared nasal cannulas. Triggering efficiency and the fraction of inhaled oxygen (FiO2) were then evaluated for the nasal interface and cannulas used with a commercial POC during simulated tidal breathing through the replicas. Higher signal pressures were achieved for the nasal interface than for nasal cannulas at all flow rates studied. The nasal interface triggered pulsed delivery from the POC in cases where nasal cannulas failed to trigger. FiO2 was significantly higher for successful triggering cases than for failed triggering cases. The nasal interface improved triggering of pulsed oxygen delivery from a POC and presents a simple solution that could be used with commercially-available POCs to reliably supply oxygen during periods of quiet breathing.

Designing and Testing a Closed-loop Magnetically Actuated Laser Scanning System for Tissue Ablation

Biomedical robotic systems continue to hold unlimited potential for surgical procedures. Robotized laser endoscopic tools provide surgeons with increased accuracy in the laser ablation of tissue and tumors. The research here catalogs the design and implementation of a new laser endoscopic tool for tissue ablation. A novel feature of this new device is the inclusion of a feedback loop that measures the position of the laser beam via a photo-detector sensor. The scale of this new device was governed by the dimensions of the photo-detector sensor. The tip of the laser's fiber optic cable is controlled by the torque interaction between permanent magnet rings surrounding the fiber optic and the custom designed solenoid coils. Prior to building the physical test-bed the system was modeled and simulated using COMSOL software. In pre-clinical trials, the physical experimental results showed that the designed prototype laser scanner system accurately track different ablation patterns and gives a consistent output position for the laser beam however, the heat diffusion into the tissue around the desired line of the geometric shape would give wider ablation margins than was desirable.

PEGASOS - A New Linking Mechanism for Modular Osteosynthesis Plates in Minimally Invasive Acetabular Surgery

Background: Recently presented minimally invasive endoscopic surgical techniques demonstrated the feasibility of implanting standard osteosynthesis plates for pelvic fractures. The reconstruction and internal fixation of complex acetabular fractures is still challenging. The goal of this study is to introduce a divisible implant, with a positive-locking in situ linking mechanism for plate osteosynthesis, making it possible to stabilize large and complex acetabular fractures with involvement of the quadrilateral surface. Method: Standard implants were used to recreate a base design. Using computer aided design (CAD), a three-dimensional standard implant was divided into two parts, so they could be re-allocated in situ. A critical objective was to reduce the cross-section of each part (clearance gauge). To connect the separated parts in situ, a new linking mechanism (cone in cone) was created. The new construct also features self-stabilization, self-centering, reinforced positional movement and preloading effects. Results: A linking system for plate osteosynthesis was developed entitled PEGASOS ("Percutaneous Endoscopic Guided Acetabulum-Stabilizing Osteosynthesis System"). Endoscopic implantation and in-situ-linking could be performed in a human cadaver. Therefore, we could demonstrate, that buttressing the quadrilateral surface of the acetabulum could be performed minimally invasive using a divisible suprapectineal buttress plate. Conclusion: We created a linking mechanism to couple two plates in situ. This mechanism enables an extremely strong, positive-locking connection, whereas its geometric shape allows for different relative movements during the locking procedure, with a single screw.

Using Smartphones for Clinical Assessment in Cervical Spondylotic Myelopathy a Feasibility Study

Background Degenerative cervical myelopathy (DCM) is characterized by progressive deterioration in spinal cord function. Its evaluation requires subjective clinical examination with wide inter-observer variability. Objective quantification of spinal cord function remains imprecise, even though validated myelopathy-grading scales have emerged and are now widely used. We created a Smartphone App with the aim of quantifying accurately and reliably spinal cord dysfunction using a 5-minute Test. Methods A patient suffering from DCM was clinically evaluated before surgery, at 3 and 6 months follow-up after surgical decompression of the cervical spinal cord. Standard scores (Nurick grade, mJOA score) were documented at these time points. A 5-minute motor and proprioceptive performance test aided by a smartphone with the N-outcome app was also performed. Results Motor performance in rapid alternating movements and finger tapping improved in correlation with improvements in standard grading scale scores. Clinical improvements were seen in maximum reflex acceleration and in Romberg testing which showed less closed/open eyes variation, suggesting pyramidal and proprioceptive function recovery. Conclusions We demonstrate that using a smartphone app as an adjunct to clinical evaluation of compressive myelopathy is feasible and potentially useful. The results correlate with the results of clinical assessment obtained by standard validated myelopathy scores.