The principles of evanescent wave theory were applied to an immunological sensor for detecting the cardiac-specific isoenzyme creatine kinase-MB (CK-MB). The detection of the CK-MB isoenzyme is used in conjunction with the total CK measurement in the diagnosis of acute myocardial infarction. The clinical range for CK-MB is from 2-100 ng/ml. Previous work which utilized the fluorophor, Fluorescein isothiocyanate (FITC), was able to discriminate between 0 and 3 ng/ml CK-MB. Use of the fluorophor B-phycoerythrin (BPE) increased the assay sensitivity to 0.1 ng/ml CK-MB. The data was collected for 15 minutes using an optical launch and collection angle of 25 degree(s). This fiber optic based system is homogeneous and requires no subsequent washing, handling, or processing steps after exposure to the sample.

A fiber-optic sensor for general anesthetics based on the phase transition of phospholipid vesicles has been developed and reported previously. The instrumentation and optics have been designed using two fibers and constructed in a portable configuration to allow multi-site testing. Because the phase transition is highly dependent on the surrounding temperature, it is necessary to obtain a temperature reference signal; use of a single-fiber configuration for both sample and reference permits the addition of a temperature transducer in the optrode without increasing its size. Because of the extreme turbidity of the liposomes, current theory does not predict whether a two-fiber or one-fiber approach will provide superior signal strength. The signal efficiency of the original dual-fiber configuration has been compared to that of a second dual-fiber configuration and a single-fiber system incorporating a fiber-optic coupler. Despite the reduced excitation power reaching the optrode, the single-fiber configuration produces a superior signal intensity. The addition of a custom-made Y-shaped fiber coupler enables switching from a dual-fiber design to the single-fiber optrode design without sacrificing portability.

Pulmonary artery oximetry represents a combination of the technology of reflection spectrophotometry with that of pulmonary artery catheterization. Pulmonary oximeter catheters, first developed in the early 1980's, employ fiberoptic bundles to transmit light at two or three discrete wavelengths to and from the tip of the catheter. The amount of light reflected from red cells surrounding the catheter tip is a function of the hemoglobin saturation. A microprocessor in the oximeter compares reflected light intensities at the different wavelengths and calculates mixed venous hemoglobin saturation. Some of the sources of error in this calculation will be discussed. Mixed venous hemoglobin saturation is a physiological variable which reflects the oxygen supply versus demand balance of the body. By solving the Fick equation for mixed venous saturation (Sv02), we see that it is a function of arterial saturation (5a02), oxygen consumption (V02), hemoglobin (Hb), and cardiac output (C.O.): Sv02 = Sa02 - 100(V02)/(13.8 x Hb x C.O.) Whenever Sv02 changes, the clinician must decide on the basis of other evidence which of these variables is responsible for the change. Processes that will decrease Sv02 include hypoxemia, anemia, and decreased cardiac output. Sv02 will also decrease following any increase in oxygen consumption (V02), which may result from fever, malignant hyperthermia, thyroid storm, exercise or agitation, and shivering. Increases in Sv02 above the normal range of 68% to 77% result from decreased oxygen uptake in relation to cardiac output, for example: sepsis, Paget's disease of bone, cyanide poisoning, hypothermia, or excessive use of inotropes. Continuous Sv02 monitoring can therefore provide an early warning of many pathologic processes, but it is very nonspecific. The physician must use his clinical expertise in conjunction with the other available data to determine the cause of the change in Sv02 values. Sv02 is a global oxygen parameter; that is, it may not detect changes in the oxygen supply-demand balance of specific organs or regions of the body.

Venous occlusion plethysmography is a clinically well-established technique for limb blood flow assessment. In this method, the measurement of volume changes following venous occlusion has been performed with a variety of methods of which the most common is the mercury strain-gauge. Temperature drift and long-term instability are problems associated with this sensor. In addition, environmental protection authorities are prohibiting the use of mercury in sensors beginning in 1993. This paper presents a fiber-optic sensor that can be used as an alternative to the mercury strain-gauge in venous occlusion plethysmography and in other force or displacement sensor applications.

Fiber-optic sensors are very useful in areas that are hostile to conventional sensors. One of these hostile areas is found in the Magnetic Resonance Imaging (MRI) environment. The primary advantage of using fiber-optic sensors in the MRI environment is the elimination of the hazards associated with wire. Currently there are no completely safe and reliable means to monitor the heart rate of a patient being scanned by MRI equipment. Conventional electrocardiograph (EKG) equipment subjects the patient to burn hazards due to RF coupling in the wires that connect the EKG sensor to the EKG monitor. Simple pulse monitoring is important to the patient's health, but the monitoring of movement is also important for sharp high quality images. Although the EKG measures electrical activity of the heart, it does not necessarily provide a true reflection of organ movement associated with the pulse. Because the EKG monitors only electrical activity, it will never be suited to measure a patient's respiration movement during an MR imaging session. The dielectric fiber-optic sensor can be used safely to monitor a patient's heart rate and to trigger the MRI on the ventricular heartbeat. Additionally, future fiber-optic sensor enhancements will provide the ability to detect respiration movement that affects heart position in the chest and to eliminate that detractor from high quality MR images. Sperry Marine has developed a non-metallic all-optical fiber-optic sensor that can be attached to a patient's pulse point for both monitoring the patient and triggering the MRI equipment. Because the sensor and leads are completely dielectric, this fiber-optic sensor presents no danger of electric shock or burns to the patient. Fiber-optic coupler sensors are optically powered by light traveling through a single mode optical fiber which is later split between two output fibers at the coupler. The return light signal travels through the two output fibers and it ultimately monitored by photodiodes. The photodiodes are connected to the inputs of a differential amplifier where the optical signals are converted to conventional electrical signals, which are interpreted by a PC based analog to digital converter. The pulse data from the sensor is displayed in real time on the PC screen and is used to trigger the MRI on the rising edge of the conducted heartbeat. This signal is then used by the MRI equipment to take a series of pulse-gated snapshots. The MR processor uses 128 sets of data which are Fourier transformed to produce the MR images. The MR images produced using the fiber-optic sensor are equivalent to the images obtained when using the EKG function of the MR equipment. The advantage of the fiber-optic sensor is that it is completely safe for the patient.

The detection of blood coagulation is very important in therapeutics and surgery. It is necessary to determine the overall time taken for blood clotting, production rate of thrombin, presence or absence of blood coagulation factors, etc. In this paper a new method for detection of blood coagulation is presented. This method is based on the fiber-optic sensor and allows for the study of different ways of blood clotting (such as blood coagulation and platelets aggregation) separately, thus enhancing the precision of determination. The method for determining the blood coagulation presented possesses high precision in monitoring the process of coagulation. An elaborate mathematical model of the process of blood coagulation has been developed to help the computer handle obtained data.

A small fiber-optic sensor capable of measuring three parameters (temperature, pressure, and flow) is described. This sensor combines three destinct technologies and yet uses a single optical fiber. The temperature measurement is based on the photoluminescent decay time technology used commercially by Luxtron. Pressure is sensed by measuring the intensity of the return signal from a reflector or photoluminescent layer on the outer surface of a compressible dome-shaped optical element formed on the tip of the fiber. The local flow rate measurement is made by an optical heat balance technique similar to that used in more conventional hot wire (or hot film) anemometry. Studies conducted recently indicate that a submillimeter diameter sensor of this type can be built and should be suitable for in-vivo measurements in various applications such as during radio frequency (RF) or microwave heated angioplasty and in a continuous cardiac output monitoring.

The fiber-optic radiometric thermometry of surfaces with non-uniform temperature distribution was analyzed theoretically and optimization of fibers positioning was considered. An infrared fiber-optic multi-channel radiometer was used to monitor and control the temperature of samples in a microwave (MW) heating system. Several heater control algorithms were investigated and the optimal control mode was obtained. Preliminary results of biological tissue warming by microwave heating were obtained. This novel control system is reliable and precise. Such a system should be very useful for medical and industrial applications.

This paper presents the model of fiber optic liquid crystalline (LC) microsensor for monitoring tissue temperature. The LC layer obtained by dispersion of cholesteric liquid crystals in a polymer matrix, are placed in the end of the fiber optic head. Fiber optic bundles of multicomponent optical fibers are divided into three sections coupled to two LEDs and a photodiode. A reflectivity of cholesteric LC layers depends on temperature with high sensitivity. The sensor can detect temperature in a narrow band (about 5 degrees) within the range 35-45 degree(s)C with a high sensitivity up to 0.01 degree in its linear range of operation. Some results of temperature measurements during microwave treatment of tissue also are presented.

This paper describes a novel optical fiber intracranial pressure (ICP) sensor system that uses a reflective fiber optic displacement sensor to measure hydrostatic pressure. A reference reflection from a mirror incorporated into the fiber is used in signal processing to eliminate the effects of power fluctuations, loss in connector, and splices in the fiber. This sensing technique exhibits a high degree of sensitivity and linearity, and is less susceptible to environmental perturbations than current intensity modulating techniques. Experimental results are presented for measurements taken with and without an anti-reflection (AR) coating on the fiber tip facing the sensor mirror. These measurements indicate an improved dynamic range of operation for this sensor.

This paper discusses diffraction of focused laser beams in thin blood-vessels (TBV). A theoretical description of this process is given, model experiments are conducted, and TBV scattering in biological objects in vivo is analyzed. Relations, establishing connection between scattered field and differential characteristics of blood flow in vessels, diameter of which is equal or smaller than those of erythrocytes, are obtained. Analysis of theoretical model correctness is carried out. The paper also describes two modifications of a sensor for analysis of diffuse-scattering biological objects vibrations. The modifications are based on modified homodyne Michelson speckle-interferometer and laser self-excited oscillator with fiber-optical delay line.

The use of ultraviolet lasers in medicine is expected to produce new surgical treatments. Basic experiments of the laser surgery with both KrF and XeCl excimer lasers have been completed. As is well known, visible and infrared beams are able to use ordinary quartz fiber. However, the optical fiber cannot be of use of power UV beam with excimer lasers. Some techniques about UV beams are needed. One of the techniques is the hollow tube with compound metal and polymer. This paper reports on the experimental results. The authors tried to transmit KrF and XeCl excimer laser beams by hollow tube guide. The hollow tube length is 1 meter. The delivery average power was 1.4W(KrF) and 3.8W(XeCl), the delivery energy was 7.0mJ/pulse(KrF) and 38mJ/pulse(XeCl), the peak power was 300kW(KrF) and 2.5MW(XeCl), the transmittance was 35%(KrF) and 49%(XeCl). The emitted beams are focused to ca.0.5mm diameter spot. Maximum peak power density and one pulse energy density of focused beam reached 700W/cm2(KrF), 1.9kW/cm2(XeCl) and 3.5J/pulse cm2(KrF), 19J/pulse cm2(XeCl). From the results, the hollow tube is possible as a UV power beams delivery system.

Plastic hollow fibers were developed and produced in a lab. The fiber structure was investigated by various methods. Correlation between the analysis results and the transmission characteristics was found. The fibers were used in maxillofacial surgery and excellent results of healing were achieved.

Silica-core optical fibers have become a standard vehicle to remotely deliver high-power laser energy from surgical lasers operating between 200 and 2400 nm. The three primary types of silica-core fibers: plastic-clad; hard-clad; and silica-clad; are discussed. The performance advantages of each are addressed and actual general-surgery medical applications are provided.

Optical fibers are required to withstand high stresses associated with bending. These bends often occur during exposure to high-moisture environments in medical applications. Various polymeric coatings were developed to provide fiber protection. Three coatings on silica fibers were evaluated: acrylates, hard fluoropolymers, and polyimides. The evaluation included dynamic strength and static fatigue. In general, all three coatings produced strong fibers, but the acrylate and hard fluoropolymer provided superior protection. Also a strength dependence on fiber size was demonstrated. The polyimide fiber showed the highest static fatigue resistance with hard fluoropolymers outperforming acrylates. However, the poor abrasion resistance and toughness of the polyimide coatings can degrade both the dynamic and the static fatigue properties of the fiber.

For laser surgery, high-power densities of light may be obtained by guiding a beam through the tapered end of a fiber or through a tapered rod. Due to the decreasing cross-sectional area of the taper, the power density increases until the beam refracts out of the taper. Ray-tracing was used to determine the irradiance distribution and power density within and at the tip of laser scalpels made of sapphire in relation to their geometry in air and in water. Computer beam profiles were compared to photographed profiles. The beams were emitted in cones with discrete angles which were related to the number of reflections within the scalpel. For taper angles as small as 5 degrees, the increase in power density exceeded 500x. Assuming the scalpel tip to be hemispherical rather than pointed or flat, the increase was 10-30% smaller due to internal reflection losses. The design of laser scalpels may be adapted to obtain adequate power density for effective tissue cutting together with radial energy leaking to promote coagulation and hemostasis.

Core-clad optical fibers with efficient IR power delivery are essential components in the development of laser ensoscope systems for surgical applications. The fabrication of such clad fibers of high quality is still an unsolved technical problem. We have investigated parameters of the fabrication of core-clad polyscrystalline silver halide optical fibers and found conditions that yield fibers with relatively good transmittance at 10.6 micrometers (about 3 dB/meter loss) and capable of delivering output power densities up to 3 kwatt/cm2 in CW operation. This performance is lower than what we achieved in core-only silver halide fibers, but the advantage of the protection provided by the clad and a subsequent plastic overcoat, make these core-clad fibers useful in a number of CO2 power transmission applications in laser surgery.

A set of all silica step index fibers was produced using PCVD and PMCVD methods. The influence of the fiber production technology and chemical composition of silica core on the transmission characteristics of fibers in the UV range, as well as on the processes of color centers formation, was studied. The experiments were carried out for the excimer laser wavelengths 308 nm (XeCl) and 248 nm (KrF).

New medical applications of IR lasers are possible with flexible cables and catheters for laser power delivery. Optical parameters of fibers for Er; CO- and CO2-lasers along with design of special optical connectors, efficient coupling units, and optics at distal end are reviewed. Applications of cables and catheters for laser therapy and medical diagnostics are analyzed.

Alumina waveguides are bent to specific shapes by high temperature creep. Sapphire waveguides are mechanically bent, and both are plated with metal to form curved small diameter delivery systems for surgical CO2 laser radiation. The optical properties of these bent waveguides are presented as well as potential surgical uses including percutaneous laser discectomy.

This paper surveys the performances of a particular computer assisted digital sub-system for adding digital image processing and analysis capabilities to existing digestive videoendoscopy systems. The main clinical features offered by this system in particular are its compatibility with all existing videoendoscopes and its ability to work interactively with the endoscopist during the examination as well as after.

A technique utilizing laser induced fluorescence has been developed to obtain direct real-time imaging of the coronary artery network for open heart surgery applications. Both excimer pumped dye and cw argon-ion laser radiation transmitted through a fused silica fiber were used as laser sources to irradiate swine, bovine, and human cadaver hearts whose coronary arteries had been injected with strongly fluorescent dyes. The laser induces fluorescence originating from within the coronary arteries and detected by the surgeon's eye, allows the entire coronary network to be directly viewed. A comparison between laser induced fluorescence and the use of direct visual inspection of arteries following injection of the dye Cardio-Green(R) as well as conventional thermal imaging is presented. The limitations imposed on each technique by layers of fat on top of the coronary arteries are also described. The possibility of using these techniques to detect mechanical or laser beam perforations during laser endarterectomy procedures is discussed.

The characteristics of the thin silica based imagefiber have been investigated by evaluating the image thrown on the TV monitor. As a result, it has been found that the picture diameter of the imagefiber and the magnification of the eyepiece strongly relate to the image quality of the total system. On the basis of this result, the image system for the diagnosis of breast lesions with thte thin endoscope of only 0.4 mm diameter has been developed. And we have applied this system to 66 ducts and succeeded in observing 61 ducts (92.4%) and could get some clinical information, which would be useful to the early detection of cancer.

Flexible image guides are manufactured and applicated in endoscopes for a many years. In technological process formed optical fibres are next glued with the aid of an organic glue. It enables the integration of image guide structure. With this method one can obtain optical fibers of 10-20 pm in diameter what gives a esolution of the image guide in order of 25-50 pairs of lines per mm. It is very di!ficult to obtain the resolution above 50 p1/mm in such a way . It requires a very high speeds of winding drum as well as very high accuracy of its rotation and shift (to obtain a small diameter of the fiber - below 20 pm ). Also there are some difficulties with proper protection and gluing of very thin optical fibers. Half-flexible image guides were developed and applicated in endoscopes in the recent years. They are manufactured with quite different method. Initial material is silica preform with graded index profile. From such a preform in the process of succesive thinning it can be obtained high resolution image guide. Its respectively high flexibility (ray of bending about 0.1 m) is coused by application the silica as an initial material and small diameter of pulled image guide. We decided to employ a similar method, which we call mosaic assembling technology, to manufacture a very thin, rigid image guides rods from multicomponent glasses. Possibility of obtaining very high resolutions (about 100 p1/mm) and very small dimensions (below 1mm) of rigid image guides disposed us to try to applicate this type of image guides inultrathin endoscopes.

Percutaneous coronary angioscopy was successfully performed with a steerable, balloon-tipped microangioscope in 36 of 43 patients undergoing percutaneous transluminal coronary angioplasty. The design of the device, technique of performing angioscopy, reasons for failure to image successfully, angioscopy findings, and clinical implications will be discussed.

This paper reports on the application of angioscopic technology to the endoscopy of previously inaccessible body cavities. Necessary instruments including endoscopes, light sources, cameras, video recorders, monitors, and other accessories are described. Practical considerations for effective instrumentation are discussed. An overview of our clinical microendoscopic applications in more than 630 patients is presented.

In this paper, optical fibers are applied to study artificial joints of human beings. The experimental results of strain and optical fibers are very useful for medical design of artificial joints. The stress distributions and the stress concentration factors of the femur of total hip artificial joint which has been used in clinical practice may be significant in the study of Biomechanics and the design of artificial joints.

A new approach for the endoscopic stereotactic laser surgery using open-system endoscopy; i.e., employing a stereotactic guiding tube and fine endoscopes, is described. Accurate resection of deep-seated intra-axial brain lesions was achieved using Nd:Yag and CO2 lasers with efficient hemostasis under CT/MR image guidance. Stereotactic endoscopic laser surgery is considered a promising new method for the treatment of deep-seated brain pathologies for which biopsy or irradiation was the only therapeutic method.

No abstract available.

During last years one uses and develops successfully the diagnostic analysis and therapy of malignant tumors. The basis for this analysis is the special feature of interaction between the laser emission of a certain wavelength and turnortropic exogenous photosensibilizers, which can concentrate in the pathological af— fected. sections and parts of the bbdy. Por diagnosis one usually uses the difference between spectral characteristics of the sensi— bilizer photoluminescence and the luminescence of the surrounding tissies. For therapy one uses the ability of the excited molecules of the sensibilizer to transact the excitation energy to the celli— colou oxygen. This causes the conversion of oxygen molecules from triplet—state to singlet—state of the excited molecule with high chemical activity,thus destructing the malignant cells in the non— thermal way.

For the safe and reproducible application of lasers in medicine, laser fluorescence spectroscopy (LFS) offers a new instrument. NADH, an enzyme of cell energy metabolism, shows a strong fluorescence band at 480 nm. The NADH concentration gives an opportunity for investigation of dysfunctional metabolism of tissue.

The interstitial laser tumor treatment and the local coagulation of malignant tumors with Nd:YAG laser radiation are approved procedures in minimal invasive medicine. The hyperthermic effects in tissue cause irreversible tissue damage. An advanced but simple disposable plastic introducer has been developed which is designed for volume coagulation by inserting a frosted bare fiber. If the desired size of the coagulation is reached, an alert signal to stop the treatment is derived from an on-line monitoring of NADH concentration by laser induced fluorescence measurements.

Abstract not available.

Since no one laser catheter can treat all types of disease, a new family of 'lesion-specific' devices was evaluated with a holmium laser source. Fifty patients (avg. 69 yrs) with lifestyle-limiting peripheral vascular disease and 29 patients (avg. 58 yrs) with symptomatic coronary disease were studied. Average lesion length was 5.3 cm in legs and 1.5 cm in hearts. A 1.5, 2.0, or 2.8 mm, tapered-tip or non-tapered, multifiber catheter (Eclipse, Palo Alto, CA) was advanced over the wire while emitting 300-1200 mj/pulse at 5 Hz. Mean percent stenosis decreased from 89% to 45% after lasing with a mean of 411 pulses in legs and from 86% to 46% with a mean of 158 pulses in hearts. Complications were infrequent. Laser technical success was 80% and overall procedural success was 97%. Conclusion: 1) Specialized laser catheters delivering holmium laser energy are capable of reducing the severity of peripheral and coronary stenoses including balloon angioplasty failures and bypass graft failures; 2) Follow-up studies are in progress to assess long term efficacy.

A 308 nm excimer laser was employed for ablation of human fibrocartilage. Experiments were conducted in vitro. The tissue response was investigated with respect to dosimetry (ablation rate versus radiant exposure) and thermal effect (thermographic analysis). Irradiation was performed via a 600 um fiber, with radiant exposures ranging between 20mj/mm2 and 80mj/mm2, at 20Hz. The ablation rates were found to range from 3um/pulse to 80um/pulse depending on the radiant exposure and/or the applied pressure on the delivery system. Thermographic analysis, during ablation, revealed maximum average temperatures of about 65 degree(s)C. Similar measurements performed, for the purpose of comparison, with a CW Nd:YAG and a CW CO2 laser showed higher values, of the order of 200 degree(s)C.

Using a very well known characteristic of infrared radiation absorbance by human skin versus the length of radiation wave and by application of the newest achievements of radiation detecting techniques and very fast computing techniques - the authors have designed and manufactured the complete computer system for noninvasive diagnosis of blood vessels in legs. As the basic unit in this system, fiber-optic photoplethysmograph was applied. The measurement method used here was very well described by V. Blazek and some other scientists. This article presents photoplethysmograph and all features of the computer system.

Transmission characteristics and luminescence spectra of fused silica fibers under delivery of KrF (wavelength 248 nm) and XeCl (308 nm) laser radiation was studied. Tested fibers were produced by various technologies based on PCVD and PMCVD methods. Multiple-shot transmission at both KrF and XeCl laser wavelengths was shown to be essentially dependent on the method of production and chemical composition of silica core. In particular, in fibers with high OH content the decrease of transmission during irradiation by XeCl laser is almost fully recoverable and restores after stop of irradiation in about 5 minutes. The maximum value of transmission fall depends on laser repetition rate. When irradiating by KrF laser either stable and unstable laser-induced absorption was observed. Additional losses in 'dry' silica fibers with low OH content are stable at both 248 nm and 308 nm wavelengths. The level of these losses can be significantly reduced by additional treatment of preform during production procedure. In order to determine the type of defects responsible for laser-induced absorption in fibers the study of luminescence spectra was carried out. It was shown that the only band varying during laser irradiation is that centered at 650 nm. Basing on the kinetics measurements which showed that the lifetime of this band is about 15 um luminescence was ascribed to non-bridging oxygen hole centers (NBOHC). The data of luminescence study as well as the results of measurements of induced absorption spectra enable to assume that NBHOC is the main type of defects which influences the multiple-shot transmission of fibers at 248 and 308 nm. Based on the information about the behavior of transmission and luminescence characteristics of fibers during KrF and XeCl lasers irradiation, few mechanisms of NBOHC generation from various precursors were suggested. It was shown that in spite of widespreading convinction hydroxyl groups are not the main precursors of non-bridging oxygen in OH-rich fibers as the value of transmission fall does not correlate with OH content. Moreover, the situation with unstable induced losses it quite opposite: the decrease of transmission as well as initial rate of this decrease diminish with the rise of OH content. The analysis of probable mechanisms of UV-induced losses enables a search for the way of improved fiber production technology to provide fibers characterized by high transmission resistance to multiple-shot excimer laser irradiation.

This article presents the results of spectral - luminescence analysis inves- tigatons of fascial transplats healing processes and tissue functional states before and after surgical invention evaluation. Luminescence spectra in UV and visible ranges were used for spectral information receiving. For NADH and flavoprotein ( FP , components luminescence excitation, N2 laser (A 337 nm ) has been used. Lowintensive radiation of HeNe laser was appld in purpose of physical influence on tissues. General results of experimental data were clinicaly applicated.