Implantable Medical Devices Research Articles

Cardinality matching versus propensity score matching for addressing cluster-level residual confounding in implantable medical device and surgical epidemiology: a parametric and plasmode simulation study

BackgroundRapid innovation and new regulations lead to an increased need for post-marketing surveillance of implantable devices. However, complex multi-level confounding related not only to patient-level but also to surgeon or hospital covariates hampers observational studies of risks and benefits. We conducted parametric and plasmode simulations to compare the performance of cardinality matching (CM) vs propensity score matching (PSM) to reduce confounding bias in the presence of cluster-level confounding.MethodsTwo Monte Carlo simulation studies were carried out: 1) Parametric simulations (1,000 iterations) with patients nested in clusters (ratio 10:1, 50:1, 100:1, 200:1, 500:1) and sample size n = 10,000 were conducted with patient and cluster level confounders; 2) Plasmode simulations generated from a cohort of 9981 patients admitted for pancreatectomy between 2015 to 2019 from a US hospital database. CM with 0.1 standardised mean different constraint threshold (SMD) for confounders and PSM were used to balance the confounders for within-cluster and cross-cluster matching. Treatment effects were then estimated using logistic regression as the outcome model on the obtained matched sample.ResultsCM yielded higher sample retention but more bias than PSM for cross-cluster matching in most scenarios. For instance, with ratio of 100:1, sample retention and relative bias were 97.1% and 26.5% for CM, compared to 82.5% and 12.2% for PSM. The results for plasmode simulation were similar.ConclusionsCM offered better sample retention but higher bias in most scenarios compared to PSM. More research is needed to guide the use of CM particularly in constraint setting for confounders for medical device and surgical epidemiology.

New chamber stapes prosthesis: Effect of ionizing radiation on material and functional properties

Abstract New chamber stapes prosthesis (ChSP) is a middle-ear prosthesis intended for use in ear surgery for restoring the patient's middle ear function. As the prosthesis is an implantable medical device, it must be sterilized before use. However, possible alterations in the material and the functional properties following the sterilization process can influence the safety aspects while using the prosthesis. The purpose of this paper was to determine the effects of ionizing radiation (IR) on the physicochemical and biological properties of the new chamber prosthesis by utilizing EPR spectroscopy, mechanical testing, and cytotoxicity studies. Our research shows that the radiation treatment increases the hardness and the elastic modulus of the polymer, decreases the stiffness of the prosthesis membrane, and does not cause chemical changes in the polymers that may result in cytotoxicity. Furthermore, new ChSPs were successfully tested in preclinical in vitro tests. The test results justify the undertaking of further work, including in vivo biocompatibility tests and clinical trials, which would eventually lead to the increased use of the prosthesis in clinical practice.

Implantable Medical Device Security

Implantable medical devices, or IMDs for short, are medical instruments that are placed into the human body through surgery. IMDs are typically used for treating chronic diseases. Currently available IMDs are capable of communicating using wireless channels with other devices, either in close proximity or even connected to the Internet, making IMDs part of the Internet of Medical Things. This capability opens the possibility of developing a wide range of services, like remote patient data control, localization in case of emergency, or telemedicine, which can improve patients’ lifestyle. On the other hand, given the limited resources of such tiny devices, and the access to the Internet, there are numerous security issues to be considered when designing and deploying IMDs and their support infrastructures. In this paper, we highlight security problems related to Internet-connected IMDs, and survey some solutions that have been presented in the literature.

A framework for developing Generic Implant Safety Procedures (GISPs) for scanning patients with medical implants and devices in MRI.

UK guidelines for MR safety recommend that MRI departments refer to the implant manufacturer for advice regarding the MRI safety of scanning patients with an implantable medical device prior to scanning [1]. This process of assuring safety can be time consuming, leading to delays and potential cancellations of a patient's MRI. Furthermore, at times the implant cannot be identified, or the implant manufacturers cannot provide up to date MRI safety information. The purpose of generic implant safety procedures (GISPs) is to define a process for managing patients with certain types of implants where the risk from scanning is low. This process incorporates scope for an evidence-based risk-benefit decision to scan some groups of patients under locally-approved conditions, without seeking to identify the exact make and model of the implant and subsequent assurance of MR safety from the implant manufacturer. This publication provides best practice recommendations from a multi-professional working group for the development of these procedures. It is supported by The Institute of Physics and Engineering in Medicine, The Society of Radiographers, The Royal College of Radiologists, The British institute of Radiology, The British Association of MR Radiographers, The International Society of Magnetic Resonance in Medicine British and Irish Chapter and the NHS Scotland MRI Physics Group.

Biodegradable and Implantable Triboelectric Nanogenerator Improved by β-Lactoglobulin Fibrils-Assisted Flexible PVA Porous Film.

Triboelectric nanogenerators (TENGs) are highly promising as implantable, degradable energy sources and self-powered sensors. However, the degradable triboelectric materials are often limited in terms of contact electrification and mechanical properties. Here, a bio-macromolecule-assisted toughening strategy for PVA aerogel-based triboelectric materials is proposed. By introducing β-lactoglobulin fibrils (BF) into the PVA aerogel network, the material's mechanical properties while preserving its swelling resistance is significantly enhanced. Compared to pure PVA porous film, the BF-PVA porous film exhibits an eightfold increase in fracture strength (from 1.92 to 15.48J) and a fourfold increase in flexibility (from 10.956 to 39.36MPa). Additionally, the electrical output of BF-PVA in triboelectric performance tests increased nearly fivefold (from 45 to 203V). Leveraging these enhanced properties, a biodegradable TENG (bi-TENG) for implantable muscle activity sensing is developed, achieving real-time monitoring of neuromuscular processes. This innovation holds significant potential for advancing implantable medical devices and promoting new applications in bio-integrated electronics.

Polyamino Acid Based Zwitterionic Coating can Inhibit Coagulation and Inflammation Through Anti-Fouling and Restoring Microenvironment.

Protein adhesion and thrombosis formation caused by limited surface properties pose great challenges to biomedical implants. Although various hydrophilic coating or drug release coatings are reported, the single coating cannot cope with cases under the condition of complex physiological environment, which causes the coating effect is limited. In this study, a polyamino acid-derived zwitterionic coating is constructed to eliminate reactive oxygen species (ROS) in the microenvironment. It is demonstrated that the coating has excellent hydrophilicity, stability, and lubricity, and can obviously prevent protein adhesion. At the same time, the coating can eliminate hydrogen peroxide and maintain the stability of the microenvironment. The in vivo and in vitro experiments show that the coating has good biocompatibility, and inhibits thrombus. Amino acid zwitterion coating prevents protein deposition, alleviates the inflammatory process, inhibit of thrombosis, reduces the risk of implantable medical devices, and prolongs their service time. Hence, the work paves a new way to develop amino acid based zwitterionic polymer coating that can reduce the implant complications.

Advancements in Biocompatible Materials for Enhanced Medical Implants

The incessant evolution of implantable medical devices necessitates parallel advancements in biocompatible materials to ensure optimal compatibility with the complex physiological milieu. This research addresses the critical need for improved biocompatible materials by exploring novel compositions and fabrication techniques. The study aims to enhance the performance and longevity of implantable medical devices, mitigating adverse tissue responses and fostering seamless integration within the biological system. Employing advanced material science principles, the investigation seeks to unravel the intricacies of biocompatibility, focusing on cellular response, inflammation, and long-term stability. The outcome promises to propel the field of implantable medical devices by contributing robust materials that transcend current limitations, fostering safer and more efficacious biomedical interventions.

Feasibility of automated surveillance of implantable devices in orthopaedics via clinical data warehouse: the Studio study

BackgroundTotal hip, knee and shoulder arthroplasties (THKSA) are increasing due to expanding demands in ageing population. Material surveillance is important to prevent severe complications involving implantable medical devices (IMD) by taking appropriate preventive measures. Automating the analysis of patient and IMD features could benefit physicians and public health policies, allowing early issue detection and decision support. The study aimed to demonstrate the feasibility of automated cohorting of patients with a first arthroplasty in two hospital data warehouses (HDW) in France.MethodsThe study included adult patients with an arthroplasty between 2010 and 2019 identified by 2 data sources: hospital discharge and pharmacy. Selection was based on the health insurance thesaurus of IMDs in the pharmacy database: 1,523 distinct IMD references for primary THSKA. In the hospital discharge database, 22 distinct procedures for native joint replacement allowing a matching between IMD and surgical procedure of each patient selected. A program to automate information extraction was implemented in the 1st hospital data warehouse using natural language processing (NLP) on pharmacy labels, then it was then applied to the 2nd hospital.ResultsThe e-cohort was built with a first arthroplasty for THKSA performed in 7,587 patients with a mean age of 67.4 years, and a sex ratio of 0.75. The cohort involved 4,113 hip, 2,630 knee and 844 shoulder surgical patients. Obesity, cardio-vascular diseases and hypertension were the most frequent medical conditions.DiscussionThe implementation of an e-cohort for material surveillance will be easily workable over HDWs France wild. Using NLP as no international IMD mapping exists to study IMD, our approach aims to close the gap between conventional epidemiological cohorting tools and bigdata approach.ConclusionThis pilot study demonstrated the feasibility of an e-cohort of orthopaedic devices using clinical data warehouses. The IMD and patient features could be studied with intra-hospital follow-up and will help analysing the infectious and unsealing complications.

Transitioning from 0.5 to 0.9 mT: Protecting against inadvertent activation of magnet mode in active implants.

The "5 gauss line" is a phrase that is likely to be familiar to everyone working with MRI, but what is its significance, how was it defined, and what changes are currently in progress? This review explores the history of 5 gauss (0.5 mT) as a threshold for protecting against inadvertently putting cardiac pacemakers, implantable cardioverter defibrillators, and other active implantable medical devices into a "magnet mode." Additionally, it describes the background to the recent change of this threshold to 9 gauss (0.9 mT) in the International Standard IEC 60601-2-33 edition 4.0 that defines basic safety requirements for MRI. Practical implications of this change and some ongoing and emerging issues are also discussed.

An Arrhenius-Based Simulation Tool for Predicting Aging of Lithium Manganese Dioxide Primary Batteries in Implantable Medical Devices

This article presents a novel aging-coupled predictive thermo-electrical dynamic modeling tool tailored for primary lithium manganese dioxide (Li-MnO2) batteries in active implantable medical devices (AIMDs). The aging mechanisms of rechargeable lithium batteries are well documented using computationally intensive physics-based models, unsuitable for real-time onboard monitoring in AIMDs due to their high demands. There is a critical need for efficient, less demanding modeling tools for accurate battery health monitoring and end-of-life prediction as well as battery safety assessment in these devices. The presented model in this article simulates the battery terminal voltage, remaining capacity, temperature, and aging during active discharge, making it suitable for real-time health monitoring and end-of-life prediction. We incorporate a first-order dynamic for internal resistance growth, influenced by time, temperature, discharge depth, and load current. By adopting Arrhenius-type kinetics and polynomial relationships, this model effectively simulates the combined impact of these variables on battery aging under diverse operational conditions. The simulation handles both the continuous micro-ampere-level demands necessary for device housekeeping and periodic high-rate pulses needed for therapeutic functions, at a constant ambient temperature of 37 °C, mimicking human body conditions. Our findings reveal a gradual, nonlinear increase in internal resistance as the battery ages, rising by an order of magnitude over a period of 5 years. Sensitivity analysis shows that as the battery ages and load current increases, the terminal voltage becomes increasingly sensitive to internal resistance. Specifically, at defibrillation events, the ∂V∂R trajectory dramatically increases from 10−12 to 10−8, indicating a fourth-order-of-magnitude enhancement in sensitivity. A model verification against experimental data shows an R2 value of 0.9506, indicating a high level of accuracy in predicting the Li-MnO2 cell terminal voltage. This modeling tool offers a comprehensive framework for effectively monitoring and optimizing battery life in AIMDs, therefore enhancing patient safety.

Recent Advances in Enzyme‐based Biofuel Cells Using Glucose Fuel: Achieving High Power Output and Enhanced Operational Stability

AbstractAn enzyme‐based biofuel cell (EBFC) is widely regarded as one of the most efficient power sources for bio‐friendly and implantable medical devices, capable of converting electrochemical reactions into electrical currents under physiological conditions. However, despite its potential, the practical and commercial use of EBFCs is limited by their low power output and operational instability. Therefore, significant research efforts have focused on increasing power output and stability by improving electron transfer between enzymes and host electrodes and developing efficient enzyme immobilization techniques. However, most EBFCs produced by current methods still deliver unsatisfactory performance. A promising approach to address these challenges is the use of conductive linkers that promote favorable interfacial interactions between adjacent enzymes and between enzymes and host electrodes. These linkers can facilitate electron transfer and ensure robust enzyme immobilization. In addition, designing the host electrode with a 3D structure and a large surface area can further improve the areal energy performance. This perspective reviews the working principles, types, and electron transfer mechanisms of EBFC electrodes and explores how conductive linkers and 3D host electrodes can enhance the performance of EBFC electrodes. Finally, recent advances in integrating EBFCs into biomedical devices are described.

Long-term patient outcomes from a multidisciplinary cardiac rehabilitation programme with integrated nurse specialist support: A retrospective cohort study

BackgroundCardiac rehabilitation programmes, while demonstrating benefits, face challenges in universal adoption, particularly in New Zealand. This study evaluates the long-term impact of cardiac rehabilitation participation and attendance on survival and readmission rates in the Auckland Health District. ObjectiveTo examine the impact of patient participation in nurse-led lifestyle rehabilitation and physiotherapy exercise rehabilitation on key outcomes, including all-cause mortality, and all-cause, cardiac-specific, and kidney disease readmission rates. DesignRetrospective cohort study. SettingAuckland Health District, New Zealand. Participants3331 patients registered in the Auckland cardiac rehabilitation programme between 2016 and 2020. MethodsData analysis included examining associations between attendance at nurse-led lifestyle and physiotherapy-led exercise sessions and outcomes at 12, 24 months, and 2022 year-end, including all-cause mortality, all-cause readmission, and cardiac-specific readmission rates. Analysis methods included survival analysis, Cox proportional regression, and logistic binary regression, controlling for confounders using propensity score weights and baseline factors. Results1363 (40.9 %) patients attended at least one lifestyle rehabilitation session (average 5.0 ± 2.9 sessions), 1121 (33.7 %) patients attended at least one exercise rehabilitation session (average 6.8 ± 7.4 sessions), and 649 (19.5 %) patients attended at least one lifestyle and one exercise rehabilitation session. Increased likelihood of participation in rehabilitation was explained by ethnicity, while current and historical tobacco use, history of heart failure, receiving an angiogram, PCI, or other treatment such as medical management or implantable devices were associated with lower odds of participation. Participation in rehabilitation (average 7.9 ± 6.1 sessions) was associated with a higher mean survival estimate (7.6 years vs. 6.4 years, p < 0.001) while Cox proportional hazard regression, controlling for baseline factors and propensity score weights showed that a single session of rehabilitation attended had a 2.1 % decreased risk of mortality (hazard ratio = 0.98, 95 % CI: 0.96 to 0.99, p = 0.29). The cumulative hazard ratio for average attendance (7.9 ± 6.1 sessions) was 0.85 (95 % CI: 0.83 to 0.86, p < 0.001) indicating a 15 % decreased risk of mortality during follow-up. 20 % lower kidney disease readmission rates were observed among participants over the next 24 months (p < 0.05). However, no differences in all-cause or cardiac-specific readmission rates were observed. ConclusionsThe study supports the effectiveness of cardiac rehabilitation in improving long-term survival for Auckland Health District patients. The positive impact of nurse-led interventions and integrated support throughout the cardiac rehabilitation process highlights the need for translating this model to other health districts in New Zealand to optimise patient care and outcomes.

Zwitterionic Polymers for Biomedical Applications: Antimicrobial and Antifouling Strategies toward Implantable Medical Devices and Drug Delivery.

Poly(ethylene glycol) (PEG) is extensively utilized in biomedical applications due to its biocompatibility; however, its thermal instability and susceptibility to oxidative degradation significantly constrain its long-term effectiveness. Zwitterionic polymers, characterized by their distinctive structure, enhanced stability, and superior biocompatibility, offer a more advantageous alternative. These polymers exhibit super hydrophilicity, resist nonspecific protein adsorption, and maintain stability in biological environments due to their charge-neutral ionic nature. Zwitterionic polymers enhance anticancer drug delivery by precisely targeting tumor cells and facilitating an efficient drug release. Their inherent antifouling properties and prolonged circulation within the bloodstream render them highly suitable for redox-sensitive drug carriers, thereby augmenting the antitumor efficacy. Moreover, zwitterionic polymers markedly mitigate biofouling in implants, biosensors, and wound dressings, thereby improving both their functionality and their therapeutic outcomes. These advantages arise from the formation of robust hydration layers, which significantly enhance the hemocompatibility and inhibit the adhesion of proteins, platelets, and bacteria. Zwitterionic polymers, including sulfobetaine (SB), phosphorylcholine (PC), and carboxybetaine (CB), are increasingly employed in blood-contacting devices and as effective coating materials for implantable devices. This mini-review paper aims to explore the recent diverse biomedical applications of zwitterionic polymers and highlight their advantageous properties compared with unmodified polymers. We will cover their use in drug delivery systems, tumor targeting nanocarriers, antibiofouling and antibacterial activities in implantable devices, tissue engineering, and diagnostic devices, demonstrating how their unique properties can translate into different applications. Through this exploration, this Perspective will display the potential of zwitterionic polymers as innovative polymer materials in the field of biomedical engineering and beyond.

The Architecture of Immortality Through Neuroengineering

From mobile health and wearables to implantable medical devices and neuroprosthetics, the integration of machines into human biology and cognition is expanding. This paper explores the technological advancements that are pushing the human–machine boundaries further, raising profound questions about identity and existence in digital realms. The development of robots, androids, and AI–human hybrids promises to augment human capabilities beyond current limits. However, alongside these advancements, significant limitations arise: biological, technical, ethical, and legal. This paper further discusses the existential implications of these technological strides. It addresses the philosophical dimensions of mortality, forgiveness, and the significance of death in a world where technological immortality may be within reach. By addressing these questions, the paper seeks to provide a comprehensive analysis of the potential for these advancements to reshape our understanding of existence and the quest for immortality.

ANN modeling for predicting muscle-implanted antenna performance for skin and fat thickness variations at 2.45 GHz

Abstract Implantable antenna is embedded in implantable medical devices to communicate with external world for continuous patient monitoring. The implantable antenna performance may vary with patients due to their different skin and fat thickness owing to their environment, location and concentration of collagen in skin, estrogen and testosterone concentration, age, diseases like obesity, Gottron syndrome etc. Estimation of IMA performance requires a proper description of its dependence on variable skin and fat thickness which is not studied extensively in previous related works. In this article, we have designed a muscle-implanted antenna at 2.45 GHz to examine its performance dependence on variable skin and fat thickness values. In this study, we have designed an artificial neural network (ANN) for prediction of antenna performance parameters at 2.45 GHz for wide range of skin and fat thickness variations. The designed ANN model can predict antenna performance with ∼0.99 % error. Here, accurate dependence analysis of radiation performance of implantable antenna in terms of S 11, realized gain, bandwidth and operating frequency on skin and fat thickness variations is performed which has not been studied yet and use of ANN in this field for accurate prediction is also a novel approach.

Ultrathin, flexible, and high-performance bacterial cellulose/copper nanowires film for broadband electromagnetic interference shielding and photothermal conversion

The swift advancements in wearable electronics, implantable medical devices, fifth-generation mobile communication, unmanned aerial vehicles, and military stealth technology have led to a surge in demand for highly flexible multifunctional films. Consequently, the enhancement of electromagnetic radiation and the requirement for normal operation in extreme environments have posed significant challenges for flexible electromagnetic interference (EMI) shielding films. In this paper, ultra-thin, flexible bacterial cellulose (BC)/copper nanowires (CuNWs) (BCu) films with Janus structure are prepared by the combination of microwave-assisted hydrothermal synthesis and vacuum filtration method, which can be used for broadband EMI shielding and photothermal conversion. BCu films demonstrate exceptional mechanical properties, boasting a tensile strength range from 48.5 to 77.3 MPa, accompanied fracture strain 4.1–5.9 %. When CuNWs mass in Janus film increases to 10 mg, the conductivity of BCu-4 Janus films can reach 4761.90 S cm−1. The ultra-strong EMI shielding effectiveness (SE, above 56.00 dB) is achieved in 6–26.5 GHz for BCu-4 film with an ultra-thin thickness (16 μm). Moreover, the specific EMI SE of BCu-4 is as high as 4294.38 dB mm−1. Furthermore, BCu Janus films exhibit outstanding photothermal conversion performance. A saturation temperature of BCu-4 Janus film reaches as high as 75 °C under irradiation of one sunlight (100 mW cm−2). The facile and collaborative strategy is provided for fabricating ultra-thin, flexible multifunctional Janus films with EMI shielding and photothermal conversion capabilities, addressing EMI problems in modern electronic technology and offering new avenues for applications in various fields.

Preventing Foreign Body Aspiration and Ingestion with a Damp Gauze in Clinics

Implantable medical devices and prostheses are inherently recognized as foreign bodies by the human body [...]

Exploring the Potential of Tunnel Field-Effect Transistors in Biomedical Devices: A Comprehensive Survey

Implantable medical devices have revolutionized healthcare by providing continuous monitoring and therapeutic interventions within the human body. The overall performance of these devices is heavily dependent on the effectiveness and efficiency of integrated electronic components, such as transistors. This survey explores the growing utilization of Tunnel Field-Effect Transistors (TFETs) in implantable devices, shedding light on their advantages and challenges in this specific application domain. TFETs, characterized by their unique tunnelling mechanism, offer several advantages that make them well suited for implantable devices. Their low-power consumption, reduced leakage current, and improved subthreshold swing make them ideal for energy-efficient, long-lasting operation within the constrained power budgets of implantable devices. Furthermore, TFETs exhibit excellent performance at low supply voltages, ensuring minimal tissue damage and heat generation. This survey also addresses the challenges associated with TFETs in implantable devices, including fabrication complexities, variability, and compatibility with existing technologies. It highlights recent advancements in TFET technology that address these concerns, such as improved material choices and manufacturing techniques. As technology continues to advance, TFETs are poised to play a pivotal role in improving the overall efficiency and reliability of life-saving technologies and medical devices. Overall, this survey provides valuable insights into the current state and future prospects of TFETs in implantable devices, guiding researchers and engineers in harnessing their potential for the benefit of healthcare and patient well-being.

Current trends in micro‐supercapacitor devices

AbstractRecently, efforts have been made to design miniaturized energy storage devices according to custom requirements. The application of micro‐electronic equipment has increased significantly in information technology and biotechnology. Microelectromechanical systems, nanoelectromechanical systems, maintenance‐free wireless sensor networks, implantable medical devices, micro‐robots, and integrating energy conversion devices require micropower sources in small dimensions. Conventional supercapacitor devices cannot fulfill such high‐power demand, but miniaturization within the microscale helps enhance the working efficiency due to the shortening of diffusion path length. Micro‐supercapacitors (MSCs) in the micron to centimeter dimension range integrated with circuits and microelectronic components have gained great interest due to their high‐power density, high‐frequency response, and long cycling stability. Research on the design and fabrication of MSCs has progressed enormously. Integrating MSCs with other electronic units helps to achieve a highly efficient self‐powered system. This review presents a critical summary of the recent progress of novel materials for MSCs, fabrication methods, advanced design, and challenges in the MSCs industry.

Synergistic coating of Laponite swollen-layer and heparin composite for enhanced antifouling and antithrombotic performance

When implantable medical devices come into contact with blood, acute thrombosis and inflammation often occur due to the adhesion and denaturation of plasma proteins, ultimately degrading device performance. To address this issue, we developed a gel-like coating with superhydrophilic properties, incorporating a heparin based outer layer designed to minimize foreign body reactions and enhance hemocompatibility. The coating was engineered using a layer-by-layer (LbL) assembly of poly-l-lysine (PLL), laponite (Lap), and heparin (Hep), utilizing electrostatic interactions. The successful formation of stable layers was confirmed by QCM-D analysis. The inner layer, composed of PLL/Lap multilayers, formed a gel-like structure that maintained superhydrophilicity and effectively prevented cell adhesion. The outermost PLL/Hep multilayers significantly suppressed thrombus formation by inhibiting plasma protein and red blood cell adsorption as well as platelet activation. The coating exhibited excellent stability, retaining its superhydrophilic properties and heparin functionality even after 7 days of immersion in DPBS. Additionally, in vitro hemocompatibility and cytocompatibility tests confirmed its non-toxicity and overall biocompatibility. These results highlight the potential application of this coating to various implantable medical devices, providing a robust solution for improving device performance and safety.