Polymer Optical Fiber Sensors in Healthcare Applications: A Comprehensive Review.

Advances in medicine and improvements in life quality has led to an increase in the life expectancy of the general population. An ageing world population have placed demands on the use of assistive technology and, in particular, towards novel healthcare devices and sensors. Besides the electromagnetic field immunity, polymer optical fiber (POF) sensors have additional advantages due to their material features such as high flexibility, lower Young's modulus (enabling high sensitivity for mechanical parameters), higher elastic limits, and impact resistance. Such advantages are well-aligned with the instrumentation requirements of many healthcare devices and in movement analysis. Aiming at these advantages, this review paper presents the state-of-the-art developments of POF sensors for healthcare applications. A plethora of healthcare applications are discussed, which include movement analysis, physiological parameters monitoring, instrumented insoles, as well as instrumentation of healthcare robotic devices such as exoskeletons, smart walkers, actuators, prostheses, and orthosis. This review paper shows the feasibility of using POF sensors in healthcare applications and, due to the aforementioned advantages, it is possible to envisage a further widespread use of such sensors in this research field in the next few years.

Highly Sensitive and Durable Structured Fibre Sensors for Low-Pressure Measurement in Smart Skin.

Precise measurements of low pressure are highly necessary for many applications. This study developed novel structured fibre sensors embedded in silicone, forming smart skin with high sensitivity, high durability, and good immunity to crosstalk for precise measurement of pressure below 10 kPa. The transduction principle is that an applied pressure leads to bending and stretching of silicone and optical fibre over a purposely made groove and induces the axial strain in the gratings. The fabricated sensor showed high pressure sensitivity up to 26.8 pm/kPa and experienced over 1,000,000 cycles compression without obvious variation. A theoretical model of the sensor was presented and verified to have excellent agreement with experimental results. The prototype of smart leg mannequin and wrist pulse measurements indicated that such optical sensors can precisely measure low-pressure and can easily be integrated for smart skins for mapping low pressure on three-dimensional surfaces.

Next-Generation Fiberoptic and Digital Ureteroscopes.

The versatility of ureteroscopy is attributable to tremendous technological innovations over the past decades. This article provides an overview on emerging technologies in the light of past achievements, current limitations, and possible future directions. Instrument size reduction, pressure and temperature control, active suction of stone dust, multiple-axis tip deflection, variable working channel positions, robotics, ergonomics, image quality, enhanced imaging technology, three-dimensional visualization, and the competition between reusable and single-use ureteroscopes are detailed. The twentieth century has opened an exciting path for future discoveries in ureteroscopy.

A new set of eyes: development of a novel microangioscope for neurointerventional surgery.

BACKGROUND: Endovascular technological advances have revolutionized the field of neurovascular surgery and have become the mainstay of treatment for many cerebrovascular pathologies. Digital subtraction angiography (DSA) is the 'gold standard' for visualization of the vasculature and deployment of endovascular devices. Nonetheless, with recent technological advances in optics, angioscopy has emerged as a potentially important adjunct to DSA. Angioscopy can offer direct visualization of the intracranial vasculature, and direct observation and inspection of device deployment. However, previous iterations of this technology have not been sufficiently miniaturized or practical for modern neurointerventional practice. OBJECTIVE: To describe the evolution, development, and design of a microangioscope that offers both high-quality direct visualization and the miniaturization necessary to navigate in the small intracranial vessels and provide examples of its potential applications in the diagnosis and treatment of cerebrovascular pathologies using an in vivo porcine model. METHODS: In this proof-of-concept study we introduce a novel microangioscope, designed from coherent fiber bundle technology. The microangioscope is smaller than any previously described angioscope, at 1.7 F, while maintaining high-resolution images. A porcine model is used to demonstrate the resolution of the images in vivo. RESULTS: Video recordings of the microangioscope show the versatility of the camera mounted on different microcatheters and its ability to navigate external carotid artery branches. The microangioscope is also shown to be able to resolve the subtle differences between red and white thrombi in a porcine model. CONCLUSION: A new microangioscope, based on miniaturized fiber optic technology, offers a potentially revolutionary way to visualize the intracranial vascular space.

Basic Bronchoscopy: Technology, Techniques, and Professional Fees.

Flexible bronchoscopy has evolved over the last few decades, allowing chest physicians to use advanced high-definition scopes to inspect the airways and perform various sampling techniques. Although the techniques of basic bronchoscopic sampling have not changed dramatically, documentation requirements, coding, and billing have become more complex and require a better understanding on the part of the proceduralists and practice administrators. Areas in need of attention include learning about the multiple endoscopy rule, appropriate use of modifiers, and recent changes to the Current Procedural Terminology codes, associated work relative value units for moderate sedation, and therapeutic aspiration of secretions. This article describes basic bronchoscopic procedures and the principles needed for their coding and billing.

Advances in laser technology and fibre-optic delivery systems in lithotripsy.

The flashlamp-pumped, solid-state holmium:yttrium-aluminium-garnet (YAG) laser has been the laser of choice for use in ureteroscopic lithotripsy for the past 20 years. However, although the holmium laser works well on all stone compositions and is cost-effective, this technology still has several fundamental limitations. Newer laser technologies, including the frequency-doubled, double-pulse YAG (FREDDY), erbium:YAG, femtosecond, and thulium fibre lasers, have all been explored as potential alternatives to the holmium:YAG laser for lithotripsy. Each of these laser technologies is associated with technical advantages and disadvantages, and the search continues for the next generation of laser lithotripsy systems that can provide rapid, safe, and efficient stone ablation. New fibre-optic approaches for safer and more efficient delivery of the laser energy inside the urinary tract include the use of smaller-core fibres and fibres that are tapered, spherical, detachable or hollow steel, or have muzzle brake distal fibre-optic tips. These specialty fibres might provide advantages, including improved flexibility for maximal ureteroscope deflection, reduced cross section for increased saline irrigation rates through the working channel of the ureteroscope, reduced stone retropulsion for improved stone ablation efficiency, and reduced fibre degradation and burnback for longer fibre life.

Integration and utilization of modern technologies in nephrolithiasis research.

Nephrolithiasis, or stones, is one of the oldest urological diseases, with descriptions and treatment strategies dating back to ancient times. Despite the enormous number of patients affected by stones, a surprising lack of conceptual understanding of many aspects of this disease still exists. This lack of understanding includes mechanisms of stone formation and retention, the clinical relevance of different stone compositions and that of formation patterns and associated pathological features to the overall course of the condition. Fortunately, a number of new tools are available to assist in answering such questions. New renal endoscopes enable kidney visualization in much higher definition than was previously possible, while micro-CT imaging is the optimal technique for assessment of stone microstructure and mineral composition in a nondestructive fashion. Together, these tools have the potential to provide novel insights into the aetiology of stone formation that might unlock new prevention and treatment strategies, and enable more effective management of patients with nephrolithiasis.

Improvement of the chromatic dispersion tolerance in coherent optical OFDM systems using shifted DFT windows for ultra-long-haul optical transmission systems.

In a high-capacity ultra-long-haul optical coherent orthogonal frequency-division multiplexing (CO-OFDM) system, the dispersion tolerance is determined by the length of cyclic extension (CE). In this paper, we propose a novel scheme to substantially improve the dispersion tolerance of CO-OFDM systems without increasing the CE length. Multiple time-shifted discrete Fourier transform (DFT) windows are exploited at the receiver, each demodulating only a part of the subcarriers. Effectively, the proposed scheme reduces the bandwidth of the OFDM signals under demodulation. Numerical simulations are performed to show the improved dispersion tolerance of the proposed scheme in comparison with the conventional CO-OFDM system. We show that the dispersion tolerance improves by a factor equal to the number of DFT windows. The tradeoff between the improved dispersion tolerance and increased receiver complexity is also presented.

High-coherence semiconductor lasers based on integral high-Q resonators in hybrid Si/III-V platforms.

The semiconductor laser (SCL) is the principal light source powering the worldwide optical fiber network. The ever-increasing demand for data is causing the network to migrate to phase-coherent modulation formats, which place strict requirements on the temporal coherence of the light source that no longer can be met by current SCLs. This failure can be traced directly to the canonical laser design, in which photons are both generated and stored in the same, optically lossy, III-V material. This leads to an excessive and large amount of noisy spontaneous emission commingling with the laser mode, thereby degrading its coherence. High losses also decrease the amount of stored optical energy in the laser cavity, magnifying the effect of each individual spontaneous emission event on the phase of the laser field. Here, we propose a new design paradigm for the SCL. The keys to this paradigm are the deliberate removal of stored optical energy from the lossy III-V material by concentrating it in a passive, low-loss material and the incorporation of a very high-Q resonator as an integral (i.e., not externally coupled) part of the laser cavity. We demonstrate an SCL with a spectral linewidth of 18 kHz in the telecom band around 1.55 µm, achieved using a single-mode silicon resonator with Q of 10(6).

Surfing the spectrum - what is on the horizon?

Diagnostic imaging techniques have evolved with technological advancements - but how far? The objective of this article was to explore the electromagnetic spectrum to find imaging techniques which may deliver diagnostic information of equal, or improved, standing to conventional radiographs and to explore any developments within radiography which may yield improved diagnostic data. A comprehensive literature search was performed using Medline, Web of Knowledge, Science Direct and PubMed Databases. Boolean Operators were used and key-terms included (not exclusively): terahertz, X-ray, ultraviolet, visible, infra-red, magnetic resonance, dental, diagnostic, caries and periodontal. Radiographic techniques are primarily used for diagnostic imaging in dentistry, and continued developments in X-ray imaging include: phase contrast, darkfield and spectral imaging. Other modalities have potential application, for example, terahertz, laser doppler and optical techniques, but require further development. In particular, infra-red imaging has regenerated interest with caries detection in vitro, due to improved quality and accessibility of cameras. Non-ionising imaging techniques, for example, infra-red, are becoming more commensurate with traditional radiographic techniques for caries detection. Nevertheless, X-rays continue to be the leading diagnostic image for dentists, with improved diagnostic potential for lower radiation dose becoming a reality.

Improving flexible ureterorenoscope durability up to 100 procedures.

BACKGROUND AND PURPOSE: Controversy exists in the literature regarding flexible ureterorenoscopy (F-URS) durability, with a variable expected number of uses from a new F-URS. In this study, a tertiary center experience with the use of two consecutive F-URS is reported and suggestions as to how to improve durability further are made. MATERIALS AND METHODS: All F-URS performed in the same tertiary care center between July 2009 and February 2011, with two new instruments Flex-X, were reviewed retrospectively. All renal pathology were included. Ureteral cases were excluded. A 9.5F semirigid ureteroscope was always used at the start for a ureteral optical predilation and to explore the upper urinary tract for possible lithotripsy/laser ablation/biopsy. The F-URS was introduced sequentially to explore the remaining calices. Data pertaining to the procedure were collected. The method of sterilization was complete immersion with Cidex®. RESULTS: The instruments were substituted after 113 and 102 procedures, respectively. The first F-URS was used for a total operative time of 79 hours and 10 minutes while the second one was used for 71 hours and 25 minutes (mean 75 hours and 15 min). Procedure duration was 15 to 175 minutes (mean 58 min). The flexible instruments were used for a mean of 42 minutes per procedure (range 13-153 min). The indications for F-URS were therapeutic in 75.4% and diagnostic in 22.8% of the cases. For lower pole calculi, the stone was relocated in 65.2% and managed with the nonflexed flexible instrument 90% of the time. The most common causes of damage of F-URS were: Deflection mechanism impairment, inner sheath damage, and fiberoptic bundle breaks. CONCLUSIONS: Increased durability of F-URS was from a variety of factors, a key element of which was the method of sterilization, while routine use of the semirigid instrument initially further contributed significantly to increase the number of F-URS procedures, saving overall costs.

Experimental and theoretical evaluation of a fiber-optic approach for optical property measurement in layered epithelial tissue.

Improvements in measurement of epithelial tissue optical properties (OPs) in the ultraviolet and visible (UV-Vis) may lead to enhanced understanding of optical techniques for neoplasia detection. In this study, we investigated an approach based on fiber-optic measurement of reflectance to determine absorption and reduced scattering coefficients (µ(a) and µ(s)') in two-layer turbid media. Neural network inverse models were trained on simulation data for a wide variety of OP combinations (µ(a) = 1-22.5, µ(s)' = 5-42.5 cm(-1)). Experimental measurements of phantoms with top-layer thicknesses (D) ranging from 0.22 to 0.66 mm were performed at three UV-Vis wavelengths. OP estimation accuracy was calculated and compared to theoretical results. Mean prediction errors were strongly correlated with D and ranged widely, from 1.5 to 12.1 cm(-1). Theoretical analyses indicated the potential for improving accuracy with alternate probe geometries. Although numerous challenges remain, this initial experimental study of an unconstrained approach for fiber-optic-based OP determination in two-layer epithelial tissue indicates the potential to provide useful measurements.

Surgical treatment of bronchial carcinoid tumors: a single-center experience.

BACKGROUND: Bronchial carcinoid is an infrequent neoplasm with a neuroendocrine differentiation. Surgical treatment is the gold standard therapy, with procedures varying from sublobar resections to complex lung sparing broncoplastic procedures. This study evaluates the results of surgical treatment of bronchial carcinoids and its prognostic factors. PATIENTS AND METHODS: Retrospective review of 126 consecutive patients who underwent surgical treatment for bronchial carcinoid tumors between December 1974 and July 2007. RESULTS: There were 70 females (55%) and the mean age was 46 years, ranging from 17 to 81 years. Upon clinical presentation, 38 patients (30%) have had recurrent respiratory tract infection, 31 (24%) cough, 16 (12%) chest pain and 25 (20%) were asymptomatic. Preoperative bronchoscopic diagnosis was obtained in 74 cases (58.7%). The procedures performed were: 19 sublobar resections (14,9%), 58 lobectomies (46%), 8 bilobectomies (6.3%), 6 pneumonectomies (4.7%), 2 sleeve segmentectomies (1.5%), 26 sleeve lobectomies (20.6%) and 9 bronchoplastic procedures without lung resection (7.1%). Operative mortality was 1.5% (n = 2) and morbidity was 25.8% (n=32), including 12 respiratory tract infections and 4 reinterventions due to bleeding (3) and pleural empyema (1). Among the 112 patients available for follow-up, the overall survival at 3, 5 and 10 years was 89.2%, 85.5% and 79.8%, respectively. Five and 10-year survival for typical and atypical carcinoids were 91, 89% and 56, 47%, respectively. Overall disease-free survival at 5 years was 91.9% Statistical analysis showed that overall disease-free survival correlated with histology--typical vs. atypical--(p = 0.04) and stage (p = 0.02). CONCLUSION: Surgery provides safe and adequate treatment to bronchial carcinoid tumors. Histology and stage were the main prognostic factors.

Fiber-optic technologies in laser-based therapeutics: threads for a cure.

In the past decade, novel fiber structures and material compositions have led to the introduction of new diagnostic and therapeutic tools. We review the structure, the material composition and the fabrication processes behind these novel fiber systems. Because of their structural flexibility, their compatibility with endoscopic appliances and their efficiency in laser delivery, these fiber systems have greatly extended the reach of a wide range of surgical lasers in minimally invasive procedures. Much research in novel fiber-optics delivery systems has been focused on the accommodation of higher optical powers and the extension to a broader wavelength range. Until recently, CO2 laser surgery, renowned for its precision and efficiency, was limited to open surgeries by the lack of delivery fibers. Hollow-core photonic bandgap fibers are assessed for their ability to transmit CO2 laser at surgical power level and for their applications in a range of clinical areas. Current fiber-delivery technologies for a number of laser surgery modalities and wavelengths are compared.

Airway adjuncts.

Airway management is an essential component of the emergency medicine skill set. Management of the difficult airway may include airway adjuncts, including variants of laryngoscopic blades, supraglottic devices, stylets, and video laryngoscopy. These various airway adjuncts have certain advantages and disadvantages, and factors to be considered include ease of use, cost, maintenance, storage, and portability. Selection of a subset of the numerous products available can aid the clinician in the development of expertise with airway adjunct devices that can be reliably used in urgent situations.

Retrograde intubation.

Airway management in the emergency department is a critical skill that must be mastered by emergency physicians. When rapid-sequence induction with oral-tracheal intubation performed by way of direct laryngoscopy is difficult or impossible due to a variety of circumstances, an alternative method or device must be used for a rescue airway. Retrograde intubation requires little equipment and has few contraindications. This technique is easy to learn and has a high level of skill retention. Familiarity with this technique is a valuable addition to the airway-management armamentarium of emergency physicians caring for ill or injured patients. Variations of the technique have been described, and their use depends on the individual circumstances.

Recent advances in intracoronary imaging techniques: focus on optical coherence tomography.

Optical coherence tomography (OCT) is a new imaging technology that utilizes advanced photonics and fiberoptics to obtain images and tissue characterization on a microscopic scale. The resolution of the current OCT system is 10-20 microm, which is approximately ten-times higher than that of intravascular ultrasound. Compared with conventional imaging modalities, OCT has a superior ability to evaluate vulnerable plaque features, such as plaque rupture, intracoronary thrombus, thin-capped fibroatheroma and macrophages within the fibrous caps. Furthermore, OCT can clearly visualize stent malapposition and tissue protrusion after stenting and neointimal hyperplasia at late follow-up. Although OCT is a specialized research tool, it might provide new insights into the diagnosis and treatment of coronary artery disease.

Potential solutions for confocal imaging of living animals.

The use of confocal and multiphoton microscopy for in vivo studies in animals continues to be an area of exciting technical and commercial development. However the application of these technologies at high resolution, such that molecular and subcellular information is collected, remains an elusive goal. This review discusses the practical and performance limitations and the potential uses of currently available systems. We also highlight the ongoing developments in both miniaturized and bench-mounted systems for single and multiphoton optical sectioning studies in animals and in human clinical trials.