Design and Medical Safety of Neuromuscular Incapacitation Devices [Emerging Technologies]

Neuromuscular incapacitation (NMI) devices deliver electric shocks that disrupt muscle functions in order to immediately stop a truly pain-resistant, aggressive, focused, or combat-trained attacker. Improvements made to shock waveforms secure temporary incapacitation by capturing motor nerves and causing clonic muscular contractions. Suspects can recover immediately after cessation of current delivery. This article discusses NMI topics with a focus on TASER devices. Current models of TASER devices known as electronic control devices (ECD), utilize compressed nitrogen to propel toward the subject two small probes at a speed of about 48 m/s. A special-waveform electrical signal is transmitted through trailing wires to where the probes make contact with the body or clothing. This signal directly stimulates pre-endplate motor nerve tissue resulting in an immediate loss of the person's neuromuscular control, with the initial reaction being a gravitational dysreflexia (i.e., fall to the ground) and loss of ability to perform coordinated action for the duration of the pulse. This provides the law enforcement officers with an opportunity to subdue the resisting suspect. This section address aspects related to the design of ECDs and medical safety concerns raised by their use in the field.     

Fast pipelined CORDIC-based adaptive lattice predictor: algorithmsand architecture

The authors present a novel CORDIC-based adaptive algorithm and a pipelined architecture for unnormalised lattice prediction filter. Previously, they have presented a CORDIC-based adaptive lattice filtering (CALF) algorithm for normalised lattice filters which features a sign-sign direct (rotation) angle updating scheme (Hu and Liao, 1992). The authors consider a delayed CALF (DeCALF) algorithm in which the rotation angle is updated based on `delayed' prediction errors. In doing so, they are able to develop a fully pipelined implementation of DeCALF which achieves B-fold throughput rate increase where B is the number of CORDIC iterations (stages). This is accomplished at insignificant hardware overhead and minor parameter tracking performance degradation     

Best of both worlds [Emerging Technologies]

Expanding on the experience gained at 2006 IEEE Engineering in Medicine and Biology Conference (EMBC'06) in New York, the 30th IEEE Annual International Conference of the Engineering in Medicine and Biology Society (EMBS), held on 24 August 2008, hosted the second Industry--Academia Partnership Roundtable. The panel that pioneered the EMBC'06 efforts, with members from academic and industry communities, debated topics related to the following: · reciprocal value that academia and industry can offer in medical device new product development · the basics of starting up your own company · clash of cultures (industry versus academia): what obstacles academicians may face in reaching entrepreneurship? · intellectual property (IP) joint development and sharing between industry and academia · quick tutorial on use of provisional patents. How are patents used by companies?     

Vagus nerve stimulation for the treatment of depression.

Given the debilitating effects of chronic depression and its economic impact on medical care, there is a need for a well-tolerated and effective long-term treatment for patients who do not respond fully to first-line antidepressant therapies such as antidepressant drugs (ADD), psychotherapy and electroconvulsive therapy. This paper discusses a new treatment that can address this need - the vagus nerve stimulation (VNS) therapy system - an implantable device that can electrically pace the vagus nerve. The VNS technology consists of a pulse generator and a lead system. In the VNS system, just like in a cardiac pacemaker, the stimulator resides subcutaneously and sends an electrical pulse to an organ through an implanted electrode. The VNS pulse generator is a programmable bipolar stimulator. The VNS lead system comprises a bipolar electrode pair and a fixation anchor that are wrapped around the left vagus nerve in the neck, near the carotid artery. The clinical safety and effectiveness of the VNS system was assessed. At present, the VNS therapy system can now be used as treatment for chronic or recurrent depression for patients 18 years of age or older who are experiencing a major depressive episode. The system can only be used as adjunctive therapy, which means that patients still need to continue with their ADD medication.     

Scalable Trehalose‐Functionalized Hydrogel Synthesis for High‐Temperature Protection of Enzymes

Herein, a scalable, two‐step synthesis of a trehalose hydrogel for the thermostabilization of enzymes is reported. A reaction between vinylbenzyl chloride and trehalose in base, followed by a redox‐initiated radical polymerization of the resulting mixture, produces the gel in 88% yield. The reaction scale can be increased 100‐fold while maintaining a 76% yield. Additionally, various solvents are investigated for purification, and more sustainable manufacturing solvents are selected. When the three major enzymes utilized in animal feed, phytase, β‐glucanase, and xylanase, are heated to 90 °C in the hydrogel, greater than 98% activity is retained. Lastly, quantitative release of enzyme from the gel within 4 h is demonstrated. The scalable synthesis of the trehalose hydrogel, combined with its ability to stabilize and release a variety of animal feed enzymes, makes this technology promising for use with enzymes important in animal food production.     

Three-dimensional finite element analysis of current density andtemperature distributions during radio-frequency ablation

This study analyzed the influence of electrode geometry, tissue-electrode angle, and blood flow on current density and temperature distribution, lesion size, and power requirements during radio-frequency ablation. The authors used validated three-dimensional finite element models to perform these analyses. They found that the use of an electrically insulating layer over the junction between electrode and catheter body reduced the chances of charring and coagulation. The use of a thermistor at the tip of the ablation electrodes did not affect the current density distribution. For longer electrodes, the lateral current density decreased more slowly with distance from the electrode surface. The authors analyzed the effects of three tissue-electrode angles: 0, 45, and 90°. More power was needed to reach a maximal tissue temperature of 95°C after 120 s when the electrode-tissue angle was 45°. Consequently, the lesions were larger and deeper for a tissue-electrode angle of 45° than for 0 and 90°. The lesion depth, volume, and required power increased with blood flow rate regardless of the tissue-electrode angle. The significant changes in power with the tissue-electrode angle suggest that it is safer and more efficient to ablate using temperature-controlled RF generators. The maximal temperature was reached at locations within the tissue, a fraction of a millimeter away from the electrode surface. These locations did not always coincide with the local current density maxima. The locations of these hottest spots and the difference between their temperature and the temperature read by a sensor placed at the electrode tip changed with blood flow rate and tissue-electrode angle     

Conductive keratoplasty

Less-invasive surgical techniques are being preferred in the treatment of eye conditions such as myopia, hyperopia, and presbyopia. This paper discusses clinical studies of a technique that falls on this category called conductive keratoplasty (CK). The goal of the CK procedure is to produce minor corneal surface changes that result in a decreased local radius of curvature. This procedure uses radiofrequency currents in reshaping the cornea. The patients with hyperopia could, most of the time, notice near vision improvements immediately after the procedure. In most patients, far vision was not significantly affected. Presbyopes also noticed a significant improvement in near vision. Of over 100 patients enrolled in the clinical trial, 98% could see J5 (magazine- and newspaper-sized print) in the eye that was treated. Additionally, 87% of patients could see 20/20 in the distance and also read J3 or phonebook-sized print (significantly smaller than news print). As these results point to a promising future for CK, the procedure is being adopted by an increasing number of opthalmic surgery centers.