Cardiorespiratory Sensors and Their Implications for Out-of-Hospital Cardiac Arrest Detection: A Systematic Review.

Out-of-hospital cardiac arrest (OHCA) is a major health problem, with a poor survival rate of 2-11%. For the roughly 75% of OHCAs that are unwitnessed, survival is approximately 2-4.4%, as there are no bystanders present to provide life-saving interventions and alert Emergency Medical Services. Sensor technologies may reduce the number of unwitnessed OHCAs through automated detection of OHCA-associated physiological changes. However, no technologies are widely available for OHCA detection. This review identifies research and commercial technologies developed for cardiopulmonary monitoring that may be best suited for use in the context of OHCA, and provides recommendations for technology development, testing, and implementation. We conducted a systematic review of published studies along with a search of grey literature to identify technologies that were able to provide cardiopulmonary monitoring, and could be used to detect OHCA. We searched MEDLINE, EMBASE, Web of Science, and Engineering Village using MeSH keywords. Following inclusion, we summarized trends and findings from included studies. Our searches retrieved 6945 unique publications between January, 1950 and May, 2023. 90 studies met the inclusion criteria. In addition, our grey literature search identified 26 commercial technologies. Among included technologies, 52% utilized electrocardiography (ECG) and 40% utilized photoplethysmography (PPG) sensors. Most wearable devices were multi-modal (59%), utilizing more than one sensor simultaneously. Most included devices were wearable technologies (84%), with chest patches (22%), wrist-worn devices (18%), and garments (14%) being the most prevalent. ECG and PPG sensors are heavily utilized in devices for cardiopulmonary monitoring that could be adapted to OHCA detection. Developers seeking to rapidly develop methods for OHCA detection should focus on using ECG- and/or PPG-based multimodal systems as these are most prevalent in existing devices. However, novel sensor technology development could overcome limitations in existing sensors and could serve as potential additions to or replacements for ECG- and PPG-based devices.

The effect of recognition on survival after out-of-hospital cardiac arrest and implications for biosensor technologies.

BACKGROUND: Biosensor technologies have been proposed as a solution to provide recognition and facilitate earlier responses to unwitnessed out-of-hospital cardiac arrest (OHCA) cases. We sought to estimate the effect of recognition on survival and modelled the potential incremental impact of increased recognition of unwitnessed cases on survival to hospital discharge, to demonstrate the potential benefit of biosensor technologies. METHODS: We included cases from the British Columbia Cardiac Arrest Registry (2019-2020), which includes Emergency Medical Services (EMS)-assessed OHCAs. We excluded cases that would not have benefitted from early recognition (EMS-witnessed, terminal illness, or do-not-resuscitate). Using a mediation analysis, we estimated the relative benefits on survival of a witness recognizing vs. intervening in an OHCA; and estimated the expected additional number of survivors resulting from increasing recognition alone using a bootstrap logistic regression framework. RESULTS: Of 13,655 EMS-assessed cases, 11,412 were included (6314 EMS-treated, 5098 EMS-untreated). Survival to hospital discharge was 191/8879 (2.2%) in unwitnessed cases and 429/2533 (17%) in bystander-witnessed cases. Of the total effect attributable to a bystander witness, recognition accounted for 84% (95% CI: 72, 86) of the benefit. If all previously unwitnessed cases had been bystander witnessed, we would expect 1198 additional survivors. If these cases had been recognized, but no interventions performed, we would expect 912 additional survivors. CONCLUSION: Unwitnessed OHCA account for the majority of OHCAs, yet survival is dismal. Methods to improve recognition, such as with biosensor technologies, may lead to substantial improvements in overall survival.

Evaluation of transcutaneous near-infrared spectroscopy for early detection of cardiac arrest in an animal model.

Sudden cardiac arrest (SCA) is a leading cause of mortality worldwide. The SCA-to-resuscitation interval is a key determinant of patient outcomes, highlighting the clinical need for reliable and timely detection of SCA. Near-infrared spectroscopy (NIRS), a non-invasive optical technique, may have utility for this application. We investigated transcutaneous NIRS as a method to detect pentobarbital-induced changes during cardiac arrest in eight Yucatan miniature pigs. NIRS measurements during cardiac arrest were compared to invasively acquired carotid blood pressure and partial oxygen pressure (PO2) of spinal cord tissues. We observed statistically significant decreases in mean arterial pressure (MAP) 64.68 mmHg ± 13.08, p < 0.0001), spinal cord PO2 (38.16 mmHg ± 20.04, p = 0.0028), and NIRS-derived tissue oxygen saturation (TSI%) (14.50% ± 3.80, p < 0.0001) from baseline to 5 min after pentobarbital administration. Euthanasia-to-first change in hemodynamics for MAP and TSI (%) were similar [MAP (10.43 ± 4.73 s) vs TSI (%) (12.04 ± 1.85 s), p = 0.3714]. No significant difference was detected between NIRS and blood pressure-derived pulse rates during baseline periods (p > 0.99) and following pentobarbital administration (p = 0.97). Transcutaneous NIRS demonstrated the potential to identify rapid hemodynamic changes due to cardiac arrest in periods similar to invasive indices. We conclude that transcutaneous NIRS monitoring may present a novel, non-invasive approach for SCA detection, which warrants further investigation.

Perception of autonomy among people who use wheeled mobility assistive devices: dependence on environment and contextual factors.

PURPOSE: To evaluate and compare the perceived autonomy of people using wheeled mobility assistive devices (WMADs) in five community-based environments. To evaluate how personal, environmental, and assistive device-related factors impact the perceived autonomy of WMAD users. METHOD: A study-specific questionnaire was used to evaluate perceived satisfaction of WMAD users with their autonomy in five environments: the Home Environment, Buildings Outside of the Home Environment, Outdoor Built Environment, Outdoor Natural Environment, and Transportation. For each environment, participants rated their satisfaction with autonomy about 15 personal, environmental, and assistive device-related factors. Qualitative perceptions were also collected with open-ended questions. RESULTS: Participants included 123 full- and part-time community-dwelling WMAD users. Participants' overall satisfaction with autonomy in the Outdoor Natural Environment was statistically significantly lower compared to the other four environments (p < 0.05). In all environments, the top factor respondents were most satisfied with was WMAD ease of use. Their least satisfaction was when negotiating stairs, curbs, or obstacles in the Home, Buildings Outside of the Home, and the Outdoor Built Environments. In the Outdoor Natural Environment, the most dissatisfaction was with manoeuvring on different terrains. Responses to open-ended questions supported the quantitative findings and highlighted the effects of various factors on autonomy (e.g., subject-environment familiarity). CONCLUSIONS: WMAD users reported the greatest restriction to their autonomy in outdoor environments. Different context-specific factors were found to impact autonomy in different environments. Understanding how environment-specific contextual factors contribute to overall perception of autonomy may inform the development of future strategies to overcome identified limitations and challenges.Implications for RehabilitationWheeled mobility assistive device (WMAD) users experienced the highest autonomy in their home environments, specifically, when having access to home modification services.WMAD users had the lowest autonomy in the outdoor natural environment, with manoeuvrability on different terrains being the main predictor of the overall satisfaction with autonomy in this environment.Environment-specific contextual factors with significant impacts on perceived autonomy were identified that can inform the design and development of future WMADs (e.g., distance travelled, safety).

Perceptions of power-assist devices: interviews with manual wheelchair users.

PURPOSE: The study had three main objectives. (1) To investigate the perceived impact of power-assist devices (PADs) on manual wheelchair (MWC) user mobility. (2) To compare perceptions about different types of PADs. (3) To identify preferred features and design characteristics of PADs. METHODS: Semi-structured interviews were conducted with community-dwelling MWC users aged 31 years and older, with at least 2.5 years of experience using an MWC independently (n = 16). Data were thematically analysed using an inductive approach. RESULTS: Two main themes related to participants' perceptions about the effects of PAD use were identified: (1) "Expanding my world", which illustrated the perceived benefits of using PADs (e.g., gaining a sense of autonomy and access to new environments, maintaining physical health) and (2) "Falling short", which described challenges with PADs (e.g., safety, reliability and portability issues). Participants also identified strengths and limitations of different types of PADs that were mainly related to specific user-device and device-environment interactions as well as various functional characteristics. Moreover, participants outlined their priorities for future PAD design, including improving controllability, customizability and affordability of these devices. CONCLUSIONS: Participants' perceptions about PADs varied across different types of devices and in different contexts. However, PADs were generally perceived as enhancing the capabilities of MWCs. Our findings provide insight into the factors that can be considered when selecting a PAD and can inform the development of future PADs that are better equipped to overcome challenges that MWC users frequently encounter.Implications for RehabilitationPower-assist devices (PADs) for manual wheelchairs (MWCs) have the potential to improve the mobility, community participation and well-being of users.Some of the existing PADs have safety and reliability issues that affect their performance and limit their use by MWC users.The three types of PADs (front-mounted attachments, rear-mounted attachments, powered wheels) offer different types of assistance that can benefit users with various capabilities.

High durability of food due to the flow cytometry proved antibacterial and antifouling properties of TiO2 decorated nanocomposite films.

Although polymeric membrane has superior properties, its applications in biomedical and food industrial fields are minimal. Biofouling is a significant concern in the membrane, created from particular interactions between the membrane and untreated water content. This research showed that a careful superhydrophilic modification of polyethersulfone membrane could address those drawbacks that have hindered their utility. Hence, a combination of chemical and physical modification showed far-reaching effects on surface behavior, affecting manifold aspects of its bacterial attachment, protein adsorption resistance, and hydrophilicity. The contact angle measurement results decreased from 30° to 0° in 26 s, and surface free energy increased by 33%, demonstrating the shifting surface wettability behavior toward the Superhydrophilicity. Besides, increasing the average surface roughness on the nanoscale and forming 70-110 nm jagged structures results in a marked reduction in protein adsorption, bacterial adhesion, and biofouling formation, confirmed by the results of Flow cytometry analysis and microtiter plate assay. An improved understanding of antifouling and antibacterial properties will greatly assist in food industries since it can be applied to enhance the durability of food and chemical materials. This is important as it gives us a simple way of improving packing reliability, reducing costs and amounts of undesirable waste products.

Perception of autonomy among people who use wheeled mobility assistive devices: Dependence on the type of wheeled assistive technology.

We evaluated perceived autonomy among users of different types of wheeled mobility assistive devices (WMADs) across five environments and identified the effect on user autonomy due to specific device characteristics. A study-specific questionnaire was used to assess satisfaction with autonomy of WMAD users in the Home, Buildings Outside of the Home, Outdoor Built, Outdoor Natural Environment, and Transportation. For each environment, 15 contextual factors were rated for their impact on participants' autonomy. Our results revealed that manual wheelchair with add-on (MWC+AO) users had higher overall satisfaction with their autonomy compared to other WMAD users. MWC+AO users reported higher satisfaction with autonomy due to their health conditions compared to other WMAD users across all environments. In Outdoor Natural Environments, MWC+AO users had the highest satisfaction with autonomy across all factors except for negotiating hills. When performing activities in Buildings, MWC users with and without add-ons reported higher satisfaction for all factors compared to power wheelchair users, except for maneuverability on different surfaces. Satisfaction with autonomy regarding contextual factors varied among WMAD users, however, MWC+AO(s) appeared to provide a more balanced sense of autonomy across most factors and environments. More in-depth investigations are required to evaluate impacts of add-on use on autonomy.

Offline and Real-Time Implementation of a Terrain Classification Pipeline for Pushrim-Activated Power-Assisted Wheelchairs.

Pushrim-activated power-assisted wheelchairs (PAPAWs) are assistive technologies that provide propulsion assist to wheelchair users and enable access to various indoor and outdoor terrains. Therefore, it is beneficial to use PAPAW controllers that adapt to different terrain conditions. To achieve this objective, terrain classification techniques can be used as an integral part of the control architecture. Previously, the feasibility of using learning-based terrain classification models was investigated for offline applications. In this paper, we examine the effects of three model parameters (i.e., feature characteristics, terrain types, and the length of data segments) on offline and real-time classification accuracy. Our findings revealed that Random Forest classifiers are computationally efficient and can be used effectively for real-time terrain classification. These classifiers have the highest performance accuracy when used with a combination of time- and frequency-domain features. Additionally, we found that increasing the number of data points used for terrain estimation improves the prediction accuracy. Finally, our results revealed that classification accuracy can be improved by considering terrains with similar characteristics under one umbrella group. These findings can contribute to the development of real-time adaptive controllers that enhance PAPAW usability on different terrains.

Comparison of Manual Wheelchair and Pushrim-Activated Power-Assisted Wheelchair Propulsion Characteristics during Common Over-Ground Maneuvers.

Pushrim-activated power-assisted wheels (PAPAWs) are assistive technologies that use force sensor data to provide on-demand propulsion assistance to manual wheelchair users. However, available data about kinetic and kinematic of PAPAW use are mainly limited to experiments performed on a treadmill or using a dynamometer. In this work, we performed experiments to gather kinetics of wheelchair propulsion and kinematics of wheelchair motion for a variety of over-ground wheelchair maneuvers with a manual wheelchair with and without PAPAWs. Our findings revealed that using PAPAWs can significantly reduce the propulsion effort and push frequency. Both linear and angular velocities of the wheelchair were significantly increased when using PAPAWs. Less force and push frequency could potentially reduce risk of chronic upper limb injury. Higher linear velocity could be desirable for various daily life activities; however; the increase in the angular velocity could lead to unintended deviations from a desired path. Future research could investigate PAPAW controllers that amplify the desired intentions of users while mitigating any unwanted behaviours.

Development of A Learning-Based Terrain Classification Framework for Pushrim-Activated Power-Assisted Wheelchairs.

Pushrim-activated power-assisted wheels (PAPAWs) are assistive technologies that provide on-demand torque assistance to wheelchair users. Although the available power can reduce the physical load of wheelchair propulsion, it may also cause maneuverability and controllability issues. Commercially-available PAPAW controllers are insensitive to environmental changes, leading to inefficient and/or unsafe wheelchair movements. In this regard, adaptive velocity/torque control strategies could be employed to improve safety and stability. To investigate this objective, we propose a context-aware sensory framework to recognize terrain conditions. In this paper, we present a learning-based terrain classification framework for PAPAWs. Study participants performed various maneuvers consisting of common daily-life wheelchair propulsion routines on different indoor and outdoor terrains. Relevant features from wheelchair frame-mounted gyroscope and accelerometer measurements were extracted and used to train and test the proposed classifiers. Our findings revealed that a one-stage multi-label classification framework has a higher accuracy performance compared to a two-stage classification pipeline with an indoor-outdoor classification in the first stage. We also found that, on average, outdoor terrains can be classified with higher accuracy (90%) compared to indoor terrains (65%). This framework can be used for real-time terrain classification applications and provide the required information for an adaptive velocity/torque controller design.

Towards the Development of a Learning-Based Intention Classification Framework for Pushrim-Activated Power-Assisted Wheelchairs.

There has been a growth in the design and use of power assist devices for manual wheelchairs (MWCs) to alleviate the physical load of MWC use. A pushrim-activated power-assisted wheel (PAPAW) is an example of a power assist device that replaces the conventional wheel of a MWC. Although the use of PAPAWs provides some benefits to MWC users, it can also cause difficulties in maneuvering the wheelchair. In this research, we examined the characteristics of wheelchair propulsion when using manual and powered wheels. We used the left and right wheels' angular velocity to calculate the linear and angular velocity of the wheelchair. Results of this analysis revealed that the powered wheel's controller is not optimally designed to reflect the intentions of a wheelchair user. To address some of the challenges with coordinating the pushes on PAPAWs, we proposed the design of a user-intention detection framework. We used the kinematic data of MWC experiments and tested six supervised learning algorithms to classify one of four movements: "not moving", "moving straight forward", "turning left", and "turning right". We found that all the classification algorithms determined the type of movement with high accuracy and low computation time. The proposed intention detection framework can be used in the design of learning-based controllers for PAPAWs that take into account the individualized characteristics of wheelchair users. Such a system may improve the experience of PAPAW users.

Studies on Practical Applications of Safe-Fall Control Strategies for Lower Limb Exoskeletons.

Lower limb exoskeletons (LLEs) are susceptible to falls, and users are at risk of head and/or hip injuries. To address concerns regarding the safety of LLE users, optimization techniques were used to study safe-fall control strategies. Simulation results of these studies showed promising performance that leads to head impact avoidance and mitigation of hip impact velocity. The motivation for the current research was to extend the application of previously developed optimization techniques to study more realistic human-LLE fall conditions. We examined a range of feasible fall durations for the human-LLE model and found the optimal fall duration for which the user's safety is maximized. Next, we used a range of coefficients of friction to examine fall strategies on different ground surface conditions. We found that the effectiveness of a safe-fall strategy is higher when falling on less slippery surfaces compared to more slippery ones. The simulation results were implemented in a half-scale physical model of a three-link inverted pendulum, which represented a human-LLE model. Results of our experiments verified that the optimal safe-fall strategy could be implemented in a mechanical test setup. The hip linear velocity at impact was found to have similar values in both the experimental (2.04 m/s) and simulation results (2.09 m/s). Further studies should be conducted with appropriate software and hardware platforms to successfully implement safe-fall strategies in an actual LLE.

Improved cellular response on functionalized polypyrrole interfaces.

Neuroregeneration strategies involve multiple factors to stimulate nerve regeneration. Neural support with chemical and physical cues to optimize neural growth and replacing the lesion neuron and axons are crucial for designing neural scaffolds, which is a promising treatment approach. In this study, polypyrrole polymerization and its functionalization at the interface developed by glycine and gelatin for further optimization of cellular response. Nanofibrous scaffolds were fabricated by electrospinning of polyvinyl alcohol and chitosan solutions. The electrospun scaffolds were polymerized on the surface by pyrrole monomers to form an electroactive interface for further applications in neural tissue engineering. The polymerized polypyrrole showed a positive zeta potential value of 57.5 ± 5.46 mV. The in vitro and in vivo biocompatibility of the glycine and gelatin-functionalized polypyrrole-coated scaffolds were evaluated. No inflammatory cells were observed for the implanted scaffolds. Further, DAPI nucleus staining showed a superior cell attachment on the gelatin-functionalized polypyrrole-coated scaffolds. The topography and tuned positively charged polypyrrole interface with gelatin functionalization is expected to be particularly efficient physical and chemical simultaneous factors for promoting neural cell adhesion.

Dendrimer functionalized magnetic nanoparticles as a promising platform for localized hyperthermia and magnetic resonance imaging diagnosis.

Magnetic iron oxide nanoparticles are a well-explored class of nanomaterials known for their high magnetization and biocompatibility. They have been used in various biomedical applications such as drug delivery, biosensors, hyperthermia, and magnetic resonance imaging (MRI) contrast agent. It is necessary to surface modify the nanoparticles with a biocompatible moiety to prevent their agglomeration and enable them to target to the defined area. Dendrimers have attracted considerable attention due to their small size, monodispersed, well-defined globular shape, and a relative ease incorporation of targeting ligands. In this study, superparamagnetic iron oxide nanoparticles were synthesized via a coprecipitation method. The magnetic nanoparticles (MNPs) had been modified with (3-aminopropyl) triethoxysilane, and then polyamidoamine functionalized MNPs had been synthesized cycling. Various characterization techniques had been used to reveal the morphology, size, and structure of the nanoparticles such as scanning electron microscopy, transmission electron microscope, X-ray diffraction analysis, and vibrating sample magnetometer, Fourier-transform infrared spectroscopy and zeta potential measurements. In addition, the cytotoxicity property of G3-dendrimer functionalized MNPs were evaluated using 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide assay which confirmed the biocompatibility of the nanocomposites. Dendrimer functionalized MNPs are able to act as contrast agents for MRI and magnetic fluid hyperthermia mediators. A superior heat generation was achieved for the given concentration according to the hyperthermia results. MRI results show that the synthesized nanocomposites are a favorable option for MRI contrast agent. We believe that these dendrimer functionalized MNPs have the potential of integrating therapeutic and diagnostic functions in a single carrier.

Chemometric simultaneous determination of Sofosbuvir and Ledipasvir in pharmaceutical dosage form.

Partial least squares (PLS), different families of continuous wavelet transform (CWT), and first derivative spectrophotometry (DS) techniques were studied for quantification of Sofosbuvir (SFB) and Ledipasvir (LDV) simultaneously without separation step. The components were dissolved in Acetonitrile and the spectral behaviors were evaluated in the range of 200 to 400nm. The ultraviolet (UV) absorbance of LDV exhibits no interferences between 300 and 400nm and it was decided to predict the LDV amount through the classic spectrophotometry (CS) method in this spectral region as well. Data matrix of concentrations and calibrated models were developed, and then by applying a validation set the accuracy and precision of each model were studied. Actual concentrations versus predicted concentrations plotted and good correlation coefficients by each method resulted. Pharmaceutical dosage form was quantified by developed methods and the results were compared with the High Performance Liquid Chromatography (HPLC) reference method. Analysis Of Variance (ANOVA) in 95% confidence level showed no significant differences among methods.

Developing safe fall strategies for lower limb exoskeletons.

One of the main challenges in the use of a powered lower limb exoskeleton (LLE) is to ensure that balance is maintained throughout the operation of the device. Since no control strategy has yet been implemented that prevents falls in the case of a loss of balance, head or other serious injuries may occur during independent use of LLEs in the event of a fall. These safety concerns limit LLEs in the community to supervised use only. Using the backward fall as a model, we used optimization techniques to develop safe fall control strategies in order to avoid head impact and mitigate the impact velocity of the hips. From available human biomechanics data, we first developed an optimization methodology to study falls of healthy people. The results showed similar kinematic and dynamic characteristics to findings of previous studies on real-life human falls. Second, we extended the optimization methodology to include characteristics of a hypothetical LLE and to generate optimal joint trajectories and optimal torque profiles for the fall duration. The results revealed that by applying the optimal fall strategy, the severity of a simulated fall was minimized compared to when the device fell with locked joints (i.e., how currently used exoskeletons fall): head impact was avoided and hip impact velocity was reduced by more than 50%.

Stimulatory effects of gamma irradiation on phytochemical properties, mitotic behaviour, and nutritional composition of sainfoin (Onobrychis viciifolia Scop.).

Sainfoin (Onobrychis viciifolia Scop. Syn. Onobrychis sativa L.) is a bloat-safe forage crop with high levels of tannins, which is renowned for its medicinal qualities in grazing animals. Mutagenesis technique was applied to investigate the influence of gamma irradiation at 30, 60, 90, and 120 Gy on mitotic behavior, in vitro growth factors, phytochemical and nutritional constituents of sainfoin. Although a percentage of plant necrosis and non-growing seed were enhanced by irradiation increment, the germination speed was significantly decreased. It was observed that gamma irradiated seeds had higher value of crude protein and dry matter digestibility compared to control seeds. Toxicity of copper was reduced in sainfoin irradiated seeds at different doses of gamma rays. Anthocyanin content also decreased in inverse proportion to irradiation intensity. Accumulation of phenolic and flavonoid compounds was enhanced by gamma irradiation exposure in leaf cells. HPLC profiles differed in peak areas of the two important alkaloids, Berberine and Sanguinarine, in 120 Gy irradiated seeds compared to control seeds. There were positive correlations between irradiation dose and some abnormality divisions such as laggard chromosome, micronucleus, binucleated cells, chromosome bridge, and cytomixis. In reality, radiocytological evaluation was proven to be essential in deducing the effectiveness of gamma irradiation to induce somaclonal variation in sainfoin.