Fiber Optic Monitoring System Research Articles

Hexcel builds sensors into blade materials

COMPOSITES materials manufacturer Hexcel Corp is to start supplying materials for wind turbine blades complete with fibre optic monitoring systems. This is a short news story only. Visit www.reinforcedplastics.com for the latest plastics industry news.

Effect of Crystalloid Resuscitation and Inhalation Injury on Extravascular Lung Water: Clinical Implications

Arterial thermal dilution with an integrated fiberoptic monitoring system (COLD Z-021; Pulsion Medical Systems; Munich, Germany) allows measurement of extravascular lung water (EVLW) and pulmonary permeability index (PPI). The aim of this study was to evaluate the widespread clinical assumption that early respiratory failure following burn and inhalation injury is due to interstitial fluid accumulation in the lung.Clinical, prospective study.ICU of a university referral center of burn care.Thirty-five severely burned adults (> 20% of body surface area).Resuscitation therapy was guided by the results of hemodynamic monitoring using the intrathoracic blood volume (ITBV) as a cardiac preload indicator. The resuscitation goals included a normalization of preload (ITBV > 850 mL/m(2)) and cardiac index (> 3.5 L/min/m(2)) within 24 h after ICU admission. Fluid loading was implemented to reach these goals.One hundred forty lung water measurements were performed at 0 h, 12 h, 24 h, and 48 h after admission to the ICU. Significant elevation of EVLW and PPI was found in three measurements (2%) at 48 h after ICU admission, and was in one patient associated with inhalation injury. EVLW and PPI were not significantly different between patients with and without inhalation injury. No correlation was found between resuscitation volume and EVLW (r(2) = 0.02) or between the alveolar-arterial oxygen pressure difference and EVLW (r(2) = 0.017). Chest radiograph abnormalities were found in 2 of 22 patients with inhalation injury; these were not associated with increased values of EVLW.Early fluid accumulation in the lung in burned patients is very uncommon, even in the presence of inhalation injury. There is no evidence that thermal injury causes an increase in pulmonary capillary membrane permeability.

Effects of Steam Curing Temperature on Early Prestress Losses in High-Performance Concrete Beams

Accurate prediction of prestress losses is a very important step in the design of a highly stressed high-performance concrete (HPC) girder and can affect the service behavior of the girder, such as deflections, camber, and cracking. Current methods for calculating prestress losses according to AASHTO and the Prestressed Concrete Institute were developed for conventional concrete. Further research is needed to determine if the current empirical equations provide an accurate estimate of prestress losses for an HPC girder. Actual prestress losses in HPC girders need to be measured and compared with the predicted losses by use of these equations. The higher the prestressing force in the girder, the larger the concrete compressive strength that is needed at the time of release of the prestressing strands. To help achieve the higher release strength, the precast plants have been using longer curing times. Many precast plants are using steam curing to increase the curing rate. A better understanding of the effects of this heating on HPC is needed. An optical fiber monitoring system was designed and built into a three-span HPC highway bridge. The Rio Puerco Bridge, located 15 miles west of Albuquerque, New Mexico, is the first bridge to be built with HPC in New Mexico. The bridge has three spans each with a length of 29 to 30 m. It is designed to be simply supported for dead load and continuous for live load. HPC was used for the cast-in-place concrete deck and the prestressed concrete beams. A total of 40 long-gauge (2-m-long) deformation sensors, along with thermocouples, were installed in parallel pairs at the top and bottom flanges of the girders. The embedded sensors measured temperature and deformations at the supports, at the quarter spans, and at midspan. Measurements were collected during beam fabrication (casting of the beams, steam curing, strand release, and storage), bridge construction, and servicing. The data collected were analyzed to calculate the prestress losses in the girders, to compare the losses with the predicted losses by available code methods, and to get a better understanding of the properties and behavior of HPC.

Prone positioning, systemic hemodynamics, hepatic indocyanine green kinetics, and gastric intramucosal energy balance in patients with acute lung injury

To investigate the effects of prone positioning on systemic hemodynamics, intra-abdominal pressure (IAP), plasma disappearance rate of indocyanine green (PDR(ICG)), and gastric intramucosal to arterial PCO2 difference (Pi-aCO2). Prospective randomized study in the intensive care unit of a university hospital. 12 mechanically ventilated, hemodynamically stable patients with acute lung injury. Positioning supine and prone for 3 h in random order. Systemic hemodynamics were determined by transpulmonary double-indicator dilution technique using an integrating fiberoptic monitoring system. The same monitoring system was used to measure PDR(ICG). IAP was measured in the urinary bladder and gastric intramucosal PCO2 was evaluated by automated recirculation gas tonometry. IAP increased from 10 +/-3 in the supine to 13+/-4 mmHg in the prone position. Cardiac index increased from 3.8+/-0.9 (supine) to 4.2+/-0.6 l/m(2) per minute (prone), mean arterial pressure from 75+/-10 (supine) to 81+/-11 mmHg (prone), PaO2/FIO2 from 194+/-66 (supine) to 269+/-68 mmHg (prone), and oxygen delivery from 558+/-122 (supine) to 620+/-74 ml/m(2) per minute (prone). No other parameters, including PDR(ICG) and Pi-aCO2, differed between the two positions. Prone positioning in mechanically ventilated patients with acute lung injury, despite a small increase in IAP, does not negatively affect the hepatic capacity to eliminate ICG and gastric intramucosal energy balance when systemic blood flow and oxygenation are improved.

Accuracy of blood volume measurement using an integrated fiberoptic monitoring system in septic shock

Accuracy of blood volume measurement using an integrated fiberoptic monitoring system in septic shock

Modelisation and simulation of the light collection in the CMS lead tungstate crystals

The ageing of scintillating crystals under radiation leads to a deterioration of their transparency, thus of their effective light yield and their calibration. The link between the transparency variation, as measured by a fibre optic monitoring system, and the calibration variation is not trivial. A model describing the light collection process is proposed. It helps to understand the parameters which govern this correlation, mainly absorption length and light back-reflection or diffusion characteristics. This model describes well the results of numerical qualitative simulations of light collection in lead tungstate crystals. It also explains the differences between calibration and monitoring variations observed in test beam.

Fiber-Reinforced Polymers for Structural Engineering in Canada

Advanced materials, namely fiber-reinforced polymers (FRP), are being targeted as replacements for steel, primarily in new concrete construction and repairs. With support from the federal government and industry, the main efforts in Canada are to educate and train students and practicing engineers in the design and application of FRP and to encourage the construction industry in its use. Research collaborations have realized several FRP field projects that include innovative FRP uses and fiber-optic monitoring and retrieval systems. On-going design code development for bridges and buildings is supporting these efforts.

Multiplexed Bragg grating optical fiber sensors for damage evaluation in highway bridges

A multiplexed Bragg grating optical fiber monitoring system is designed and integrated at the construction stage in an experimental full scale laboratory bridge. The test bridge is a 40 ft span non-composite steel girder concrete deck bridge. The network of sensors is used to measure the strain throughout the bridge, with sensors bonded to the tension steel in the slab and attached to the bottom flange of the girders. Resistive strain gages and Bragg grating sensors are placed side by side to compare results. The strain data are obtained for the pristine structure, then damage is introduced at midspan for an exterior girder. Several levels of damage in the form of cuts in one of the girders are imposed with the final cut resulting in a half depth fracture of the girder. The load path in the structure is obtained using the built in sensor system.

Effect of craniectomy, durotomy, and wound closure on intracranial pressure in healthy cats

Abstract Objectives To establish intracranial pressure (ICP) measurements in healthy cats under isoflurane anesthesia, using a fiberoptic monitoring system; to assess brain lesions associated with such monitoring; and to determine whether decompressive intracranial surgery decreases ICP in healthy cats. Animals 6 healthy cats. Procedure Craniectomy and durotomy were performed, and the effect of these procedures on ICP was determined. ICP was monitored by use of a fiberoptic monitoring system. Gross and microscopic evaluations of brain tissues were performed after data collection. Results ICP decreased significantly after craniotomy and durotomy. After wound closure, ICP remained significantly reduced relative to initial pressures. However, postsurgical pressures were significantly increased, compared with those associated with ICP after durotomy. Gross and histologic abnormalities associated with placement of the ICP monitoring cable included mild focal acute hemorrhage and mechanical cortical disruption. Conclusions Craniectomy and durotomy significantly decreased ICP in healthy cats. ICP increased after wound closure, but remained significantly lower than initial pressures. Clinical Relevance Craniectomy and durotomy may be used to decrease ICP in cats. (Am J Vet Res 1996;57:1659–1661)

Pathologic effects in brain after intracranial pressure monitoring in clinically normal dogs, using a fiberoptic monitoring system

SUMMARY During 2 separate studies, intracranial pressure (icp) was measured in 13 healthy dogs (group A, n = 7; group B, n = 6), using a fiberoptic monitoring system implanted surgically in the right superficial cerebral cortex. Average icp was measured for 15 minutes after a 15-minute post-implantation period of equilibration. Intracranial pressure was measured in group-A dogs at 2.0 and 1.3% end-tidal isoflurane concentrations. Mean ± 1 sd icp in group-A dogs at 2.0 and 1.3% end-tidal isoflurane concentrations was 11 ± 2 and 11 ± 3 mm of Hg, respectively. Dogs of group A were euthanatized immediately after measurements were obtained. Mean icp ± 1 sd in group-B dogs was 11 ± 3 mm of Hg. After monitoring, but prior to euthanasia, group-B dogs underwent callosotomy, and were maintained for 30 days after surgery. The brain was removed from all dogs, formalin fixed, and examined grossly and microscopically for lesions associated with fiberoptic cable implantation. Variable degrees of hemorrhage and mechanical brain damage were seen focally around the catheter site in all brains from group-A dogs, especially when the cable entered through a sulcus. In 1 dog, local vacuolation was seen in the brain immediately adjacent to the tract associated with implantation of the fiberoptic catheter. In all other dogs, the additional cortex was histologically normal. Histologic lesions associated with cable implantation were not observed in group-B dogs.

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

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). Prospective laboratory study. Animal laboratory of a University's institute for experimental surgery. Eleven anesthetized, paralyzed, and mechanically ventilated piglets. 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 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. 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.

Clinical experience with a fiberoptic intracranial pressure monitor

Retrospective clinical experience with our first 46 patients monitored with a fiberoptic intracranial pressure device is described. In 43 of 46 patients, the transducer was introduced into brain parenchyma. A ventriculostomy system was used in 3 of 46 patients. The monitoring system was generally characterized by ease of placement and system maintenance and by technical simplicity. Several problems were encountered, including breakage of system components (12%), erroneous readings requiring transducer repositioning (8.6%), epidural hematoma (3.4%), and infection (1.7%). No infections or hematomas occurred in the 3 cases in which the ventriculostomy system was used. Overall, our experience with the Camino intracranial pressure fiberoptic monitoring system confirms previous reports of its favorable features.

Vibration Monitoring of Small Lightweight Components Using Fiber Optic Sensors

Abstract Measurements of vibration resonant responses of lightweight components are difficult if the sensor's mass is comparable to the mass of the specimen. Fiber optic sensors, which are lightweight, are particularly attractive for this special application. To demonstrate the capability of fiber optic sensors for this unique application, a polarimetric fiber optic vibration monitoring system was developed to measure the resonant response of a capacitor (0.34 g) mounted vertically on a printed circuit board during a laboratory vibration test. A pronounced resonance peak around 1200 Hz was detected; this is in agreement with the first vibrational mode of the capacitor (1260 Hz) predicted by a NASTRAN finite element analysis. This resonance was suppressed by encapsulating the capacitor leads in RTV silicon rubber adhesive.

Laser-fabricated fiber-optic taps

A CO(2)-laser-based laser ablative chemical etching (LACE) technique was used for the rapid (milliseconds) fabrication of micrometer-scale taps in the cladding of multimode silica optical fibers. In the initial experiments the optical-quality surfaces of the etched groove directionally radiate approximately one third of the total tap output. The fraction of the guided optical energy tapped out can be easily and precisely controlled by the laser parameters. The radiation patter from the tap is in reasonably good agrement with initial theoretical calculations. This novel LACE-based tap manufacturing technique permits computer-controlled, rapid, and inexpensive fabrication of the high-quality fiber-optic taps needed for realizing various fiber-optic signal-processing, interconnection, monitoring, and sensor systems.

Measurement of tumor ph during microwave induced experimental and clinical hyperthermia with a fiber optic pH measurement system

The influence of hyperthermia on tissue pH was investigated using a modified version of the fiber optic monitoring system. This newly developed system was tested for use in tissues and found to be suitable for pH measurement during microwave induced hyperthermia. The fiber optic pH probe (0.7 mm diameter) could be easily used in the electromagnetic fields produced by the microwave applicators, whereas only the display unit required some shielding. Tissue pH of experimental and clinical tumors was measured concurrently with local microwave hyperthermia treatment. The mean initial intratumor pH of a rat rhabdomyosarcoma was 7.03 (SD 0.13, n = 19) and the pH of human subcutis was 7.45 (SD 0.02, n = 8). In rat tumor a primary pH decrease was observed during heating which was fully reversed during cooling. The coefficient of temperature dependence was -0.016 pH unit/°C (SD 0.004, n = 12). After approximately 1 hr of heating at 43°C a further pH decrease of 0.1–0.3 unit occurred which was not reversed directly after treatment. Measurements during clinical local microwave hyperthermia treatments after radiotherapy revealed similar changes in pH values, primary as well as secondary. The estimated coefficient of temperature dependence for the reversible pH change, which occurred in subcutis as well as in tumor tissue, was −0.016 pH unit/°C (SD 0.004, n = 12). The fiber optic pH measurement system is expected to be a valuable tool in the thorough investigation of temperature and time related pH changes in tumor during experimental as well as clinical hyperthermia treatment.

Continuously Distributed Fiber Optic Monitoring System for Shipboard Applications

This paper suggests several areas of applicability wherein continuously monitored fiber optic cables of composite construction will improve the sensing ability of locating and reporting the conditions extant on ships of various types. By using continuous fiber cables strategically located throughout the ship that are compositely clad with different coatings to detect temperature, pressure and strain, an optically attenuated profile can be continuously monitored on a cyclical basis to report the specific conditions on a real-time basis. Preliminary bench test results of prototype jacketed fiber optic cable indicate that strains of 0.0004 to 0.003 in./in. can be detected as well as pressure changes of similar sensitivity. Currently, tests are being run to determine temperature sensitivity, and it is expected that comparable results will be achieved. With the development of the systems and improvement in jacketing materials, further refinements and expansion of capabilities are expected.

Photocatalytic dehydrogenation of liquid propan-2-ol by TiO2. Part 2.—Mechanism

The photodehydrogenation of propan-2-ol mediated by TiO2 has been studied. Using basic additives it has been established that the sites responsible for the bulk of the reaction are acidic in nature. A fibre-optic monitoring system has been used to study changes in absorption of radiation by the TiO2 in the presence of N2, O2 and H2O2. It is concluded that the active sites are Ti4+ ions. A mechanism involving O–2 and H2O2 is proposed.

Acute effects of septic shock on plasma and red cell volumes in baboons.

ArticleAcute effects of septic shock on plasma and red cell volumes in baboons.D L Horwitz, T V Ballantine, and C M HermanD L Horwitz, T V Ballantine, and C M HermanPublished Online:01 Sep 1972https://doi.org/10.1152/jappl.1972.33.3.320MoreSectionsPDF (1 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInEmailWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformationCited ByBlood volume measurements using an integrated fiberoptic monitoring system in a porcine septic shock modelCritical Care Medicine, Vol. 34, No. 5Noninvasive assessment of regional albumin extravasation in porcine septic shockJournal of Critical Care, Vol. 2, No. 4Systemic Microvascular Permeability in Septic ShockMetabolism and disposition of ritodrine in a pregnant baboonAmerican Journal of Obstetrics and Gynecology, Vol. 152, No. 8A morphologic study of live Escherichia coli organism shock in baboonsExperimental and Molecular Pathology, Vol. 31, No. 1Accuracy of blood volume estimations in critically I11 children using 125I-labelled albumin and 51Cr-labelled red cellsEuropean Journal of Pediatrics, Vol. 125, No. 2 More from this issue > Volume 33Issue 3September 1972Pages 320-4 https://doi.org/10.1152/jappl.1972.33.3.320PubMed4626786History Published online 1 September 1972 Published in print 1 September 1972 Metrics