A Photonic crystal fiber with large effective refractive index separation and low dispersion.

A photonic crystal fiber (PCF) structure with a ring-core and 5 well-ordered semiellipse air-holes has been creatively proposed. Through a comparison between the structures with a high refractive index (RI) ring-core and the structure without, it conclude that a PCF with a high RI ring-core can work better. Schott SF57 was elected as the substrate material of ring-core. This paper compares the effects of long-axis and short-axis changes on the PCF and selects the optimal solution. Especially TE0,1 mode's dispersion is maintained between 0 and 3 ps / (nm · km) ranging from 1.45 µm to 1.65 µm. This property can be used to generate a supercontinuum with 200 µm long zero dispersion wavelength (ZDM). In addition, Δneff reaches up to 10-3, which enables the near -degeneracy of the eigenmodes to be almost neglected. The proposed PCF structure will have great application value in the field of optical communications.

Aspiration in the Fiberoptic Endoscopic Evaluation of Swallowing Associated with an Increased Risk of Mortality in a Cohort of Patients Suspected of Oropharyngeal Dysphagia.

There is a general lack of published studies on the risk of mortality due to alterations in the safety of swallowing detected during the fiberoptic endoscopic evaluation of swallowing (FEES). We aimed at assessing the risk of mortality of the detection of aspiration, penetration, and pharyngeal residues by FEES. A cohort of consecutively evaluated patients suspected of experiencing oropharyngeal dysphagia undergoing FEES at a tertiary care university hospital were prospectively followed up on to assess mortality. The FEES findings, comorbidities, and potential confounders were studied as predictors of death using a Cox multivariate regression analysis. A total of 148 patients were included, 85 of whom were male (57.4%). The mean age (± standard deviation) was 52.7 years (± 22.1). The median of the follow-up time was 4.5 years. The most frequent conditions were stroke in 50 patients (33.8%), brain and spine traumas in 27 (18.2%), and neurodegenerative diseases in 19 (12.8%). Variables associated with mortality in bivariate analyses were age > 65 years (p < 0.001), pneumonia (p = 0.046), aspiration of any consistency (p < 0.001), and pharyngeal residues (p = 0.017). Variables independently associated with mortality in the Cox multivariate model were age (> 65 years) [adjusted hazard ratio (HR) 5.76; 95% CI 2.72 to 17.19; p = 0.001] and aspiration (adjusted HR: 3.96; 95% CI 1.82 to 14.64; p = 0.003). Aspiration detected by FEES and an age > 65 years are independent predictors of mortality in patients with oropharyngeal dysphagia.

The Penetration-Aspiration Scale: Adaptation to Open Partial Laryngectomy and Reliability Analysis.

A standard for assessing swallowing function after open partial horizontal laryngectomy (OPHL) is still not established. The variability in the measures used to investigate swallowing functional outcomes after OPHL limits the communication among clinicians and the possibility to compare and combine results from different studies. The study aims to adapt the PAS to the altered anatomy after OPHLs using fiberoptic endoscopic evaluation of swallowing (FEES) and to test its reliability. To adapt the PAS, two landmarks were identified: the entry of the laryngeal vestibule and the neoglottis. Ninety patients who underwent an OPHL were recruited (27 type I, 31 type II and 32 type III). FEES was performed and video-recorded. Two speech and language therapists (SLTs) independently rated each FEES using the PAS adapted for OPHL (OPHL-PAS). FEES recordings were rated for a second time by both SLTs at least 15 days from the first video analysis. Inter- and intra-rater agreement was assessed using unweighted Cohen's kappa. Overall, inter-rater agreement of the OPHL-PAS was k = 0.863, while intra-rater agreement was k = 0.854. Concerning different OPHL types, inter- and intra-rater agreement were k = 0.924 and k = 0.914 for type I, k = 0.865 and k = 0.790 for type II, and k = 0.808 and k = 0.858 for type III, respectively. The OPHL-PAS is a reliable scale to assess the invasion of lower airway during swallowing in patients with OPHL using FEES. The study represents the first attempt to define standard tools to assess swallowing functional outcome in this population.

Effect of Age, Sex, Bolus Volume, and Bolus Consistency on Whiteout Duration in Healthy Subjects During FEES.

One of the major limitations of the fiberoptic endoscopic evaluation of swallowing (FEES) is related to the challenging application of temporal measures. Among them, Whiteout (WO) is due to pharyngeal and tongue base contraction and might be used as an estimation of the pharyngeal phase duration. The aims of this study were to evaluate the inter- and intrarater reliability of WO duration and to appraise the effects of age, sex, volume, and texture of the boluses on this temporal measurement. A total of 30 healthy volunteers were recruited. According to their age, the subjects were grouped into three different age groups. Each of them underwent FEES examination with different textures (liquid, semisolid, and solid) and volumes. FEES examinations were video recorded, processed with the software Daisy Viewer 2.0, which allowed the acquisition of 25 frames per second (s) and analyzed by three different raters in order to collect data on WO duration. A total of 863 swallowing acts were video recorded. Intra- and interrater reliability of WO duration were excellent. Both volume and bolus's texture significantly affected WO duration. In particular, WO duration was significantly shorter for the liquid texture than for the semisolid and solids ones. In addition, male subjects scored significantly higher values of WO duration. Finally, WO duration was significantly higher in seniors. WO duration seems to be a reliable temporal measure during FEES examination. WO duration seems to be affected by several factors such as age, sex, volume, and consistency.

Observers' Agreement on Measurements in Fiberoptic Endoscopic Evaluation of Swallowing.

This study analyzed the effect that dysphagia etiology, different observers, and bolus consistency might have on the level of agreement for measurements in FEES images reached by independent versus consensus panel rating. Sixty patients were included and divided into two groups according to dysphagia etiology: neurological or head and neck oncological. All patients underwent standardized FEES examination using thin and thick liquid consistencies. Two observers scored the same exams, first independently and then in a consensus panel. Four ordinal FEES variables were analyzed. Statistical analysis was performed using a linear weighted kappa coefficient and Bayesian multilevel model. Intra- and interobserver agreement on FEES measurements ranged from 0.76 to 0.93 and from 0.61 to 0.88, respectively. Dysphagia etiology did not influence observers' agreement level. However, bolus consistency resulted in decreased interobserver agreement for all measured FEES variables during thin liquid swallows. When rating on the consensus panel, the observers deviated considerably from the scores they had previously given on the independent rating task. Observer agreement on measurements in FEES exams was influenced by bolus consistency, not by dysphagia etiology. Therefore, observer agreement on FEES measurements should be analyzed by taking bolus consistency into account, as it might affect the interpretation of the outcome. Identifying factors that might influence agreement levels could lead to better understanding of the rating process and assist in developing a more precise measurement scale that would ensure higher levels of observer agreement for measurements in FEES exams.

Fluorescence and reflectance device variability throughout the progression of a phase II clinical trial to detect and screen for cervical neoplasia using a fiber optic probe.

Large phase II trials of fluorescence and reflectance spectroscopy using a fiber optic probe in the screening and diagnostic settings for detecting cervical neoplasia have been conducted. We present accrual and histopathology data, instrumentation, data processing, and the preliminary results of interdevice consistencies throughout the progression of a trial. Patients were recruited for either a screening trial (no history of abnormal Papanicolaou smears) or a diagnostic trial (a history of abnormal Papanicolaou smears). Colposcopy identified normal and abnormal squamous, columnar, and transformation zone areas that were subsequently measured with the fiber probe and biopsied. In the course of the clinical trial, two generations of spectrometers (FastEEM2 and FastEEM3) were designed and utilized as optical instrumentation for in vivo spectroscopic fluorescence and reflectance measurements. Data processing of fluorescence and reflectance data is explained in detail and a preliminary analysis of the variability across each device and probe combination is explored. One thousand patients were recruited in the screening trial and 850 patients were recruited in the diagnostic trial. Three clinical sites attracted a diverse range of patients of different ages, ethnicities, and menopausal status. The fully processed results clearly show that consistencies exist across all device and probe combinations throughout the diagnostic trial. Based on the stratification of the data, the results also show identifiable differences in mean intensity between normal and high-grade tissue diagnosis, pre- and postmenopausal status, and squamous and columnar tissue type. The mean intensity values of stratified data show consistent separation across each of the device and probe combinations. By analyzing trial spectra, we provide more evidence that biographical variables such as menopausal status as well as tissue type and diagnosis significantly affect the data. Understanding these effects will lead to better modeling parameters when analyzing the performance of fluorescence and reflectance spectroscopy.

[Diagnostic correlation between indirect laryngoscopy, fibro-laryngoscopy and microlaryngoscopy with the anatomopathological results]. / Correlación diagnóstica entre la larin-goscopia indirecta, la fibrolaringoscopia y la microlaringoscopia con los resultados anatomopatológicos.

We have studied 265 patients with an organical lesion of the larynx, using three different laryngoscopical methods: Indirect laryngoscopy, fibrolaryngoscopy and microlaryngoscopy. We have compared the correlation between each one and the anatomopatological diagnosis, concluding that microlaryngoscopy has the best correlation, better than the fibrolaryngoscopy and this one better than indirect laryngoscopy.

Liquid light guides versus fiber light guides in clinical near-infrared spectroscopy.

New commercial liquid light guides have an advantage over fiberoptic bundles regarding breakage during clinical handling. We investigate the quality of clinical data collection using liquid versus fiber bundles as receivers. A four-wavelength NIRO-500 near-IR spectrophotometer is used with single-terminal fiber bundles, multiterminal fiber bundles, or a single-terminal liquid light guide as receivers. Repeated 3-min trials are done using a stable phantom, an unstable phantom, and the human forearm. A least-squares linear best-fit line and its root mean square error (RMSE), a measure of signal noise, are derived for each wavelength of each trial. The mean and standard deviations for the RMSEs of the single-terminal fiber optic receiving cable are derived for comparison standards. The liquid light guides have 51 to 174% greater signal noise with RMSEs 2 to 12 standard deviations above the mean of the single-terminal fiber bundle. The multiterminal fiber bundles have 49% less to 32% greater signal noise and had RMSEs within 1 to 4 standard deviations above the mean of the single-terminal fiber bundle. These comparisons suggest fiber optic bundles are preferable for clinical near-IR spectroscopy (NIRS) applications requiring low signal noise.

Optical coherence tomography for in situ monitoring of laser corneal ablation.

OBJECTIVE: To improve the precision of refractive surgery, a new approach for determination of the removed corneal thickness profile in situ with laser ablation by optical coherence tomography (OCT) is developed. STUDY DESIGN/MATERIALS AND METHODS: The traditional method for precision (less than 10 microm) measurements of intraocular distances is based on the use of the reflected component of probing radiation. This component is characterized by a small range of operating angles between a probing beam and a normal to the surface under study. To enhance this range of operating angles we suggest using a light component backscattered from a biological object. This will enable precision measurements over the entire surface of the cornea without any changes in the orientation between a probing beam and the eye, a necessary condition for in situ monitoring of laser refraction correction in the eye. We suggest a specially developed algorithm of OCT signal processing to measure the corneal thickness by the backscattered light component for a single longitudinal scan (A scan). The corneal thickness profile is obtained by a series of such A scans acquired by successively scanning a probing beam along the corneal surface. The thickness profile of removed layer is determined by changes in the corneal thickness profile in the process of ablation. When the cornea is ablated by a beam with a fixed transverse profile, we propose using integral characteristics of the ablated layer profile, for example, the maximum ablation depth, as criteria of changes in refractive power of the eye. The measurement precision by these characteristics is considerably higher than by a single A scan. Since the cornea is a poorly scattering medium, the Fourier filtering is employed to increase reliability and precision of the method. Model experiments on monitoring the ablation process in a lavsan film and ex vivo human cornea are described. Preliminary experiments on in vivo measurements of human corneal thickness are performed. RESULTS: In model experiments the precision of measurement of laser ablation depth by one A scan was 5-20 microm, depending on the signal-to-noise ratio (SNR), whereas the precision of measurement of laser ablation depth as the integral characteristic of the ablated layer profile was 0.3-5 microm. The experimental results showed that at small SNR Fourier filtering might considerably increase reliability and precision of measurements. When SNR is high, the measurement precision does not change. The precision of measurements of the corneal thickness in preliminary in vivo experiments was higher than in ex vivo experiments. This factor is very promising for application of the method suggested herein in refractive surgery.

Interjudge and intrajudge reliabilities in fiberoptic endoscopic evaluation of swallowing (fees) using the penetration-aspiration scale: a replication study.

This study used Fiberoptic Endoscopic Evaluation of Swallowing (FEES(R)) to assess the reliability of the Penetration-Aspiration Scale (PAS) using 79 swallows and four judges in a replication of a study using videofluoroscopy (VFSS). The swallows were diagnosed using FEES, which allowed for comparison between the two techniques. The findings indicated that all categories of the PAS achieved adequate reliability, both on intrajudge and interjudge assessments. Reliabilities, with the exception of Scale Score 7, were higher in this study than in the original study by Rosenbek and associates. Data analysis indicated that judges were more highly consistent on second ratings compared with their original ratings, indicating a learning curve on the PAS. In addition, findings suggested that the FEES was more reliable on assessing penetration than VFSS, but that VFSS was more reliable on the assessment of the various severities of aspiration. The two techniques were equally effective in discriminating between penetration and aspiration. This study found that FEES was just as reliable as VFSS when using the PAS.

Elective tracheal intubation in cervical spine injuries.

Patients presenting for surgical stabilisation of an unstable cervical spine are at risk of sustaining a further iatrogenic spinal cord injury during intubation of the trachea. Controversy exists regarding the optimal anaesthetic technique for securing the airway. We reviewed the techniques employed for intubating the trachea in our hospital over a five year period. Tracheal intubation was achieved using two different techniques: awake fibre-optic intubation with local anaesthesia, and general anaesthesia via the intravenous or inhalational route with neuromuscular blockade. Forty five patients were included. 16 patients demonstrated a pre-operative neurological deficit. Awake fibre-optic intubation was used in 27 cases, general anaesthesia was employed via the intravenous route in 17 cases and the inhalational route in 1 case. Weighted traction was employed in all cases to immobilize the cervical spine during intubation. There was no new neurological sequelae with any of these techniques. Our study suggests that there is no optimal anaesthetic technique for intubating the trachea in patients with cervical spine injuries and it is noteworthy that in line traction was used in every case.

Fiber optic pressure sensor for biomedical applications.

In vivo measurement of blood pressure is critical in many settings, including patient care, medical research, and control of cardiovascular assist and replacement devices. This article describes a pressure sensor based on fiber optic, white light interferometry. An optical interference filter formed between the end face of an optical fiber and the sensing diaphragm selectively reflects a wavelength component. A low cost, thin film optical wedge interferometer placed at the output end detects the wavelength of the reflected signal, which represents a unique cavity length of the interference filter directly related to the diaphragm deflection and, therefore, pressure. Several key features of this sensing scheme include low drift, high accuracy, and insensitivity to light loss factors along the length of the optical fiber. This fiber optic pressure sensor promises significant advances as a medical monitoring tool, a research instrument, and a component of cardiovascular assist and replacement devices. A prototype pressure gauge has been built, and the feasibility of the optical approach verified. Experimental results of the prototype gauge for resolution, repeatability, and drift and a preliminary design for a high resolution, low drift, miniature fiber optic pressure probe are presented herein.

Feasibility of high-volume screening sigmoidoscopy using a flexible fiberoptic endoscope and a disposable sheath system.

OBJECTIVES: Sigmoidoscopy is an effective screening test for colorectal cancer but has yet to have a major impact on mortality because, in part, of inadequate utilization by physicians. To address concerns of inefficient use of time and resources, we examined the feasibility of high volume, single-day flexible sigmoidoscopy (FS) screening sessions using an innovative fiberoptic sigmoidoscope with a disposable sheath system. METHODS: All City of Boston employees over the age of 50 yr (n = 6137) were invited by mail to undergo a screening FS at Boston City Hospital (BCH). Respondents (n = 564) were contacted by phone by the program coordinator on receipt of a prepaid postcard and were scheduled (n = 227) consecutively into 15-min slots on 1 of 6 1/2-day (3-h) weekend sessions. Preregistration was completed at BCH during the week before each session and included enrollment, completion of a brief risk questionnaire, documentation of informed consent, and bowel prep instructions. Procedures were performed by three physician endoscopists rotating among four endoscopy rooms per session. Each room was staffed with a nurse to aid in patient care and a technician to set up equipment. RESULTS: A total of 198 of the 227 (87%) scheduled patients underwent screening FS during the three sessions. Physicians performed a mean of 3.5 procedures per room per hour, or 4.7 procedures per hour overall, with a mean depth of scope insertion of 51 +/- 10 cm and a mean procedure time of 4.7 +/- 3.3 min. Equipment set-up time and patient turnaround time averaged 4.6 +/- 1.7 min and 11.0 +/- 6.0 min, respectively. Polyps were detected in 29 (14.6%) patients, and a Dukes' A cancer was detected in one (0.5%). The only complication was a cardiac arrhythmia. A crude estimate of direct costs approximated $ 75 per examination. CONCLUSION: High volume, single-day FS using the fiberoptic sigmoidoscope with a disposable sheath system offers an effective strategy for enhancing physicians compliance, and possibly patient compliance, with screening sigmoidoscopy through more efficient use of time and resources.

Disposable, sheathed, flexible sigmoidoscopy: a prospective, multicenter, randomized trial. The Disposable Endoscope Study Group.

A new fiberoptic sigmoidoscopic system has been developed that utilizes a disposable sheath to cover and protect all working surfaces of the endoscope from contamination. The reusable part of the endoscope has no air, water, or suction/biopsy channels. These are incorporated in the disposable sheath, which is easily removed after use to provide each patient with a contamination-free endoscope. A prospective, randomized, controlled trial was performed to compare the disposable, sheathed, flexible sigmoidoscope with standard sigmoidoscopes. Clinical evaluations of the new sigmoidoscope system were performed at 15 facilities. Visual analog rating scales were used to record evaluations of endoscope performance and reprocessing by endoscopists and reprocessing personnel. The time to perform procedures, depth of insertion, and total instrument downtime were also recorded. One hundred forty-three procedures (70 standard, 73 sheathed) were performed. No significant difference was found for overall depth of insertion (50 versus 48 cm), although fewer sheathed endoscopes reached to 60 cm than did standard endoscopes (51% versus 30%). The sheathed system had a slightly longer mean procedure time than the standard (5.6 versus 6.7 minutes), but a significantly shortened overall downtime (32.8 vs 8.1 minutes). The standard system was preferred by the endoscopists. Reprocessing personnel preferred the disposable system. The disposable sigmoidoscope system has important advantages of decreased instrument turn-around time and potentially increased staff and patient safety, and future models should be improved to meet physicians' concerns.

Accuracy and reproducibility of the measurement of actively circulating blood volume with an integrated fiberoptic monitoring system.

OBJECTIVE: Bedside monitoring of circulating blood volume has become possible with the introduction of an integrated fiberoptic monitoring system that calculates blood volume from the changes in blood concentration of indocyanine green dye 4 mins after injection. The aim of this investigation was to compare the blood volume estimate of the integrated fiberoptic monitoring system (group 1) with the standard methods of blood volume measurement using Evans blue (group 2), and indocyanine green measured photometrically (group 3). DESIGN: Prospective laboratory study. SETTING: Animal laboratory of a University's institute for experimental surgery. SUBJECTS: Eleven anesthetized, paralyzed, and mechanically ventilated piglets. INTERVENTIONS: A central venous catheter was used for the injection of the indicator dyes (Evans blue and indocyanine green). A fiberoptic thermistor catheter was advanced into the thoracic aorta. The fiberoptic catheter detects indocyanine green by reflection densitometry for the estimation of blood volume of the integrated fiberoptic monitoring system. Samples for the determination of Evans blue and indocyanine green concentrations were drawn from an arterial catheter in the femoral artery over a period of 17 mins after injection. MEASUREMENTS AND MAIN RESULTS: Measurements were performed during normovolemia, hypovolemia (blood withdrawal of < or = 30 mL/kg), and hypervolemia (retransfusion of the withdrawn blood plus an infusion of 10% hydroxyethyl starch [45 mL/kg]). Linear regression, correlation, and bias were calculated for the comparison of the blood volume estimates by the fiberoptic monitoring system (group 1) vs. the total blood volume estimates using Evans blue (group 2) and indocyanine green (group 3): group 1 = 0.82.group 2-26 mL; r2 = 82.71%; r = .91; n = 40; group 1-group 2 +/- 1 SD = -435 +/- 368 mL; group 1 = 0.79.group 3 + 50 mL; r2 = 74.81%; r = .87; n = 28; group 1-group 3 +/- 1 SD = -506 +/- 374 mL. CONCLUSIONS: The results demonstrate that the blood volume estimate of the fiberoptic monitoring system (group 1) correlates closely with the total blood volume measurement using Evans blue (group 2) and indocyanine green (group 3). Trapped indicator in the packed red cell column after centrifugation of the blood samples may account for an overestimation of group 2 and group 3 of approximately 10% to 14%, but there still remains a proportional difference of 10% between group 1 vs. group 2 and vs. group 3. This difference is due to the longer mixing times of group 3 (16 mins) and group 2 (17 mins), during which they are distributed in slowly exchanging blood pools. It seems that the blood volume estimate of the fiberoptic monitoring system (group 1) represents the actively circulating blood volume and may be useful for bedside monitoring.

Long-term ambulatory enterogastric reflux monitoring. Validation of a new fiberoptic technique.

A new technique for the long-term ambulatory detection of enterogastric and nonacid gastroesophageal reflux has been conceived, developed, and validated. It is based on the use of a fiberoptic sensor that utilizes the optical properties of bile. In vitro studies have shown good precision, good stability, sensitivity of 2.5 mumol/liter bilirubin concentration, as well as a useful working range of 2.5-100 mumol/liter bilirubin concentration. In vivo studies have been performed in 29 subjects. Simultaneous gastric aspirations have allowed a comparison of fiberoptic system measurements both with spectrophotometric analysis and bile acid concentrations of corresponding gastric juice samples. Linear correlations were shown between fiberoptic assessment and both spectrophotometric and bile acid concentration findings (P < 0.01). Simultaneous assessment of reflux with the fiberoptic system and cholescintigraphy has shown a 92.9% concordance as regards the presence or absence of reflux. Present results imply that the fiberoptic system is an important tool for the understanding of the clinical relevance of enterogastric and nonacid gastroesophageal reflux.

[The diagnosis of approximal caries--a comparison of clinical, fiber optic and x-ray diagnostic procedures (the diagnosis of approximal caries)]. / Approximale Kariesdiagnostik--Vergleich klinischer, faseroptischer und röntgenographischer Diagnostikverfahren (Approximalkariesdiagnostik).

A comparison of the efficiency of fibre-optic transillumination with clinical and radiographic diagnosis of proximal caries in posterior teeth was carried out on 186 subjects aged 12 to 17 years. The proportion of diagnosed proximal lesions detected by fibre-optic transillumination was two times more often than by clinical examination while the increase in lesion detection by bitewing radiography was more than threefold. Taking radiographic diagnosis as the validating criteria, the sensitivity of clinical examination was 0.30 and of fibre-optic transillumination 0.68 resp. The specificity was 0.99 for both examinations. In patients with low prevalence of proximal caries and good preventive dental care fibre-optic transillumination should be used as an additional method before using of regular radiographic diagnosing of proximal caries.