Biomedical Engineering and Bioengineering Commons^™

Signal Processing Techniques In Heart Rate And Systolic Arterial Blood Pressure Variability Studies, Christopher O'Bara

Theses

Power spectral analysis of heart rate and systolic arterial blood pressure variability provides a window to the activity of the autonomic nervous system. To derive power spectra from raw blood pressure and electrocardiogram signals, many steps of signal processing must be performed. Most popular methods of spectral analysis require evenly spaced samples; therefore interpolation and resampling techniques must be used.

The results of the present study indicate that different interpolation techniques result in spectral distortions that vary depending upon the interpolation methods used as well as physiological parameters such as heart and respiration rate. Different interpolation methods applied to heart …

Effect Of Fiber-Matrix Coupling On The Mechanical Properties Of A Totally Bioabsorbable Composite, Barbaro Jesus Perez

Theses

The mechanical properties of a new class of bioabsorbable polymer-composite based on the amino acid tyrosine and calcium phosphate fibers were studied. The effect of the fiber aspect ratio on the elastic modulus of a discontinuous fiber composite was analyzed using the SMC composite micromechanics computer model. The mechanical stiffness of this polymer was found to be superior to that of poly-p-dioxanone, caprolactone and poly-o-ester.

The fiber surface was modified with methane plasma spray to improve the fiber-matrix coupling. The treated fiber composites had 16-40% higher tensile modulus than the untreated fiber composites. From the flexural test results it is …

Application Of Signal Processing Techniques For Measurement Of Muscle Fiber Conduction Velocity, Satheesh Kumar Swaminathan

Theses

The objectives of this study were to evaluate if muscle fiber conduction velocity (MFCV) could be used as a reliable indicator of fatigue and to characterize the recovery of MFCV after a fatiguing contraction. The decline of MFCV with fatigue was modelled using linear regression and compared with the decline in median frequency (MF). It was found that the percent decline in MF with fatigue was greater than that of MFCV with fatigue and that the decline of MFCV was consistent in all subjects tested. It was thus determined that MFCV could be used as a reliable indicator of fatigue. …

The Morphology Of Uhmwpe Wear Debris Generated By A Hip Joint Simulator, Aaron P. Essner

Theses

The size, quantity and shape of total hip replacement wear debris may identify wear mechanisms as well as play a role in osteolysis. Characterization of wear particles generated from a hip joint simulator was conducted followed by comparison with literature reported in vivo results. The effect of counterface material and lubricant type on particle morphology was assessed. Biomaterial pairs including UHMWPE articulated against CoCr, Alumina and Zirconia were considered. Deionized (D.I.) water and bovine serum were used as lubricants. Particles generated from Alumina/UHMWPE in serum were slightly larger than those for CoCr and Zirconia against UHMWPE in serum. Particle shape …

Laborconsult : An Expert System For Evaluating Fetal Heart Rate And The Progress Of Labor, Wendy Raymond-Fink

Theses

LaborConsult is a rule-based expert system designed to aid the non-expert practitioner in monitoring the progress and fetal tolerance of labor. The expert system obtains from the user the values of the following labor variables: cervical dilatation, fetal station, and the time between and duration of uterine contractions. The rates of cervical dilatation and fetal descent are then calculated and compared to labor standards. Additionally, the consultation assists the user in the analysis of electronic fetal monitor tracings.

The expert system development tool VP-Expert allows the interfacing of the consultation with the spreadsheet Lotus 1-2-3. This enables the creation of …

Development Of A Multi-Lead Trans-Thoracic Impedance Pneumograph For Heart Rate Variability Studies, Curtis Bashford

Theses

In this study, a device that measures respiratory tidal volume and ECG for use in heart rate variability studies, was designed, built and tested. The device developed is a Multi-Lead Trans-Thoracic Impedance Pneumograph, which determines tidal volume on a breath by breath basis, utilizing both hardware and software. It uses standard ECG electrodes which provide increased comfort and inability to the subject over traditional spirometry methods. The device operates similar to traditional bipolar impedance pneumographs except that instead of only one lead (electrode pair), four leads are acquired simultaneously using time-division multiplexing; providing data from different locations and vectors on …

Model Parameter Identification For Rod And Cone Oscillatory Potentials, Kehur Banker

Theses

The use of signal modeling of the oscillatory potential (OP) of the electroretinogram (ERG), in the study of cone-rod interaction is investigated. ERG response data were analyzed for red, orange, blue and white flashes on no background and with red flashes on a blue background (to suppress rod responses). The OP signals were extracted from the ERG by digital bandpass filtering and a signal model was fitted through a simplex algorithm to produce the parameters including "OP envelope-amplitude", latency in terms of "center-time" of the OP-envelope and OP frequency. Amplitude for red flashes with or without a blue background showed …

Wear Of Polyethylene And Hylamer On Cobalt-Chromium : A Knee Simulator Study, Alessandro F. Canonaco

Theses

Two tests were conducted to examine the wear characteristics of tibial bearings used in total knee replacement systems. Each test consisted of six A/P Glide Tibial Bearings each having a conical control arm. The plastic portion of the conical bearings were all made of UHMWPe. Each of these bearing systems was mounted onto a Co-Cr alloy tibial platform and Co-Cr alloy LCS (low contact stress) femoral component . These test samples were mounted onto the New Jersey Mark III Knee Simulator System. The simulator was configured to produce flexion and axial rotation to simulates normal gait. Each test ran at …

Area And Perimeter Measurements Of Cells With Bound Fluorescent Antibodies, Aicha Weiss

Theses

The objective of this research was to geometrically analyze the characteristics of cells, specifically area and perimeter. The images were transferred from HP A900 system to an AVS work station. The images were visualized and manipulated by the AVS which permits the distinction between the cell body, fluorescent object, and background. The intrinsic geometry of the cell was determined by using image processing algorithms written in C. The images were then passed through a threshold filter, thereby yielding a black background and a white cell body. The perimeter calculation was then applied to the black and white images. Two test …

Preoperative Risk Assessment For Cardiac Surgery Using Piecewise Linear Regression Model, Arifa Zafar

Theses

In the present climate of quality assurance policies, rigorous requirements for informed consent, and a constantly changing patient population, a system of preoperative risk assignment for cardiovascular surgery was developed to monitor and evaluate surgical outcomes. The goal of this work is to estimate the preoperative risk associated with cardiac bypass surgery for patients in different risk categories. These risk categories are determined by the Parsonnet model which is based upon studying the severity of illness. The Parsonnet model assigns a risk value to a range of risk factors consisting of patient attributes and disease parameters. The aggregate of these …

Time Domain And Frequency Domain Analysis Of Myoelectric Signals During Muscle Fatigue, Rakesh M. Maniar

Theses

Spectral analysis of the EMG signal is a useful tool for studying the complex phenomena of fatigue. The spectral parameters of mean frequency and median frequency, and the time domain parameter of root mean square have been used to measure localized fatigue.

The normal values of median frequency and its decline with fatigue have not as yet been determined in healthy subjects. This should be done in order to apply spectral analysis for clinical evaluations of abnormal populations. Normal median frequency values and its slope were established in this work for the upper extremity muscles of biceps, triceps and deltoid …

Wear And Friction Of Hylamer And Polyethylene Against Cobalt Chromium A Pin-On-Disc Study, Jerry D'Alessio, Ii

Theses

Understanding friction and wear of biomaterials is essential to the success of any prosthetic joint. A pin-on-disc wear tester is used to find the friction and wear of pins of one material on a coupon of medical grade cobalt chrome. In this experiment six pins of UHMWPe (ultra high molecular weight polyethylene) and six pins of Hylamer® from Du Pont Manufacturing were tested. Four separate runs were made. The tests were performed for ten million cycles, stopping every one to one and a half million cycles for data acquisition. Volumetric wear, wear rate, and coefficients of friction were measured. Both …

Measurement Of The Reaction To Stress And Meditation Using Brain Wave Coherence And Heart Rate Variability, Christopher B. King

Theses

Measurement of physiological parameters associated with the stress response and the relaxation response caused by various forms of meditation can provide valuable information about the reaction of the body to the mind and to the external environment.

This study used two different techniques to evaluate physiological parameters. The first part examined the meditation response by recording the EEG and calculating the coherence between brain waves originating from different parts of the brain. It was found that high levels of coherence in the alpha portion of the EEG frequency band coincided with a restful state associated with the relaxation response. In …

A Pharmacokinetic Model Of The Liver, Samirbhai Rameshbhai Patel

Theses

The liver is the major organ where chemical breakdown of organic and inorganic compounds takes place. A pharmacokinetic heterogeneous model was developed for the local anesthetic and antiarrhythmic drug lidocaine. It was assumed that transport and elimination of lidocaine and its metabolites are linear with concentration. Simulations were done using VisSim software on a 486 based personal computer to obtain concentration profiles for hepatic clearance and for step input of the drug and its metabolites. It was found that the rate of uptake and rate of breakdown were 0.48 min^-1 and 0.49 min^-1 respectively for lidocaine. The results …

Autonomic Nervous System Evaluation Using Time-Frequency Analysis, Sanjay Fernando

Theses

Spectral analysis of heartrate variability (HRV) provided an estimate of the sympathetic and parasympatheticinfluences on heart rate without drugs or other invasive procedures.However, there are many situations where heart rate changed rapidlyover time and the control of those changes was of considerable interest.Time-frequency analysis was utilized to expand the concept of spectralanalysis of HRV to describe changes in vagal tone and sympatho-vagalbalance as a function of time. As a result the assessment of the autonomicnervous system during rapid changes in heart rate was made.

There were three advantagesto calculating vagal tone and sympatho-vagal balance by using timefrequencyanalysis. First, vagal tone …

Characterization Of Sleep Eeg, Seetharamiah Sateesh

Theses

The physiological relationship between the various components of sleep and its variation due to drug administration has been used as one of the primary tools to analyze the performance of drug. A number of studies have been performed in recent years in this direction. Electroencephalogram (EEG) has been characterized with the help of variables ranging from measurements of the duration of different sleep stages to the activities that define the stages themselves. Advances in computer hardware and software have improved the methods of data acquisition and storage. Analysis of long stretch of data has always been a problem considering the …

Cervical Spine Bone Anchoring System Csbas Pullout Testing And Comparisons, Konstantin Caploon

Theses

The purpose of this study is to prove the effectiveness of the newly designed and patented Cervical Spine Bone Anchoring System (CSBAS). It is a posterior fixation device intended to be used with spine bone-plate systems. Its purposes are to substitute for conventional bone screws, significantly decrease the neurological and vascular risks associated with screws, and have comparable bone purchase strength.

Three CSBAS sizes (10mm, 12mm, and 14mm) were compared to four conventional bone screws in six human cadaveric cervical spines (C2-C7). Post-implantation axial pullout tests of each device using an MTS servohydraulic testing machine yielded bone purchase strength.

In …

Correlation Between Tidal Volume Measured By Spirometry And Impedance Pneumography, Krithika Seshadri

Theses

In this study, an alternative method, impedance pneumography was used to measure the respiration volume. The respiration volume was measured both by using a conventional spirometer and an impedance pneumograph, and evaluated quantitatively in 17 subjects using linear and nonlinear regression algorithms.

Data were collected from 17 normal, healthy subjects during rest and paced breathing conditions. A technique was developed to measure tidal volume by impedance pneumography. The respiration volume measured by the spirometer was correlated with the volume measured by the pneumograph. Different electrode positions and postures were included in the study to determine the position and posture which …

Computerized Scoring Of Sleep Stage Data, Subbarao Narayana

Theses

Sleep is a non-uniform biological state which has been subdivided into different stages. The basic criteria behind staging are the amplitude and frequency variations of sleep data. The sleep analysis is carried out by considering the characteristic variation of all three EEG, EOG and EMG signals. The polygraphic recording of nocturnal sleep is a method of research widely used in neurophysiology laboratories, both for the clinical study of sleep and for the evaluation of the therapeutic effectiveness of drugs acting on sleep. The analysis of this method is carried out by an expert individual whose depth of knowledge regarding the …

Derivation Of Respiration From Electrocardiogram During Heart Rate Variability Studies, Lingeng Zhao

Theses

A method was developed to derive the respiration signal from the ECG signal based on the observation that the body-surface ECG is influenced by electrode motion relative to the heart and that fluctuations in the mean cardiac electrical axis accompany respiration. S-Plus programs were developed to calculate the changes in the value of the mean cardiac electrical axis during respiration from a two lead ECG signal and to generate a continuous ECG-derived respiratory signal from the angle information.

Data were taken from 9 healthy subjects during rest, paced breathing and exercise. The respiration was derived from the recorded ECG signals. …

Modeling, Simulation And Hemodynamic Response Analysis Of Arteriovenous Malformation Occlusion, Huijuan Mao

Theses

The cerebral Arteriovenous Malformation system (AVM) or fistula, is a network with large caliber vessels that yields an alternate pathway for blood flow between arteries and veins. Neurosurgical and interventional radiological techniques are the common way to treat AVM patients so that the normal capillary blood flow would be restored. Several patients who underwent this procedure had different degrees of brain swelling and subsequent hemorrhage. To understand this, Blesser et al. developed a simplified model to simulate the effect of AVM occlusion on cerebrovascular pressure and flow. Their model does not include the cerebrovascular regulatory mechanism which is an important …

3-D Reconstruction And Morphological Analysis Of Normal Rectum, Saritha Sundaresan

Theses

There is no documentation of the 3-D dimensions of normal rectum. We present a method for the architectural and volumetric analysis of the rectum which makes use of a computerized 3-D reconstruction and CT scans of cross-sections of the rectum. The technique is simple, fast, yet potentially reliable. An attempt has been made to calculate the volume, area and average diameter of non-distended rectums (normal). Once we can standardize the technique, then we can study dimensions of the rectum in adult males and females. This thesis constitutes a unified presentation of the essential aspects of the method used in this …

Patient, Disease And Surgical Parameters In The Prediction Of Histologic Nodes And Recurrence Of Squamous Cell Carcinoma, Adolfo A. Ferreira

Theses

This research explores the impact of a variety patient, disease and lesion parameters upon the probability of post surgery recurrence of squamous cell carcinoma and the involvement of histologic nodes. It was found that parameters such as number of nodes, Lymph Vascular Space Invasion (LVS), figo stage, growth rate and host response as well as tumor thickness, depth of invasion and lesion size are good predictors. Other parameters such as cell type and condylomas were found to correlate minimally with recurrence and histologic nodes. Surgical parameters such as surgical margin and distance surgical margin were found to have poor correlation …

Time Frequency Analysis Of The Electromyogram During Fatigue, Michelle Rene Davies

Theses

Spectral parameters obtained from the surface EMG signal have been used as indicators of fatigue during a sustained contraction. These same parameters have not been tested with the EMG signals obtained from fine wire electrodes. One such parameter is the median frequency which is known to decline with fatigue. A comparison was done between the median frequencies obtained from the surface EMG and those obtained from the fine wire EMG. The median frequencies from both types of electrodes decreased with time indicating that fine wire electrodes could be used to measure fatigue.

In addition, a new technique, time frequency analysis, …

Reconstruction And Enhancement Of Medical Computed Tomography Images, Manoj K. Pattahil

Theses

The aim of Computed Tomography is to obtain information regarding the nature of the materials occupying precise positions inside the body. But due to errors in the projection data, which arise due to errors in measurement, beam hardening, missing data and noise, the reconstructed image has artifacts which reduces its diagnostic value. Thus the image obtained has to be processed to remove these artifacts and to improve the quality of the image. This is achieved by iterative reconstruction along with different post-reconstruction processing. Iterative reconstruction is done by repeating the process of projecting the image and creating new projection data …

Biomechanical Comparison Of Interosseous And Subperiosteal Flexor Tendon Reattachment, Alisa Beth Olin

Theses

This study was undertaken to biomechanically compare the interosseous and subperiosteal distal flexor tendon reattachment techniques. Twenty New Zealand white rabbits underwent division of the right second and third hind limb profundus flexor tendon distal to the insertion of the superficial flexor. All tendons were repaired using the Kleinnert-Bunnell configuration with a 5-0 nylon tied over a cotton pad on the dorsum of the digit. In half of the animals, the second profundus was reattached into a hole in the middle phalanx and the third profundus was reattached after periosteal stripping of the middle phalanx. The other animals underwent subperiosteal …

Contour Extraction From Hvem Image Of Microvessel Using Active Contour Models, Manping Xiao

Theses

This thesis reports the research results on automatic contour extraction from high voltage electron microscope (HVEM) image of thick cross section montages of small blood vessels. The previous work on this subject, which was based on the conventional edge detection operations combined with edge linking, has proven inadequate to describe the inner structural compartments of microvessels. In this thesis, an active contour model (commonly referred to as "Snakes") has been applied to advance the previous work. Active contour models have proven themselves to be a powerful and flexible paradigm for many problems in image understanding, especially in contour extraction from …

Three Dimensional Diaphragm Simulation Model For The Relationship Of The Tension, Pressure And Shape, Zhangming He

Theses

Weakness of inspiratory muscles is a major cause of respiratory failure. There are many clinical circumstances in which it may occur. The diaphragm is a major respiratory muscle. It has been difficult to quantify its shape, curvature and length.

To solve this question, a three dimensional diaphragm equation was derived on the, assumption that the diaphragm is only attached at its periphery to the rib cage and the abdomen is filled with fluid. Computer programs were developed to fit the equation to the diaphragm contours obtained from plane X rays.

The results indicate that the ratio of transdiaphragmatic pressure to …

In Vitro Testing And Evaluation Of Intraaortic And Extraaortic Balloon Counterpulsation Devices, Joseph V. Izzo

Theses

The primary purpose of this project was to develop an in vitro environment in which the intraaortic and extra-aortic balloon pumps could be tested and evaluated. This was done by modifying a mechanical heart simulator -- the pulse duplicator system -- to accommodate both devices, and developing a software system that could collect and process the data relevant to the operation of the two balloons.

Both counterpulsation techniques were tested in the pulse duplicator where the aortic pressure and flow data were collected. The software system then processes the data to calculate all of the parameters affected by counterpulsation.

While …

Optimization Of Flow In The Collecting Duct During The Concentrating Mode And The Diluting Mode In A Nephron Population Of Two Different Length With The Renin Angiotensin System And Adh Mechanism, Sivakumar Subramanian

Theses

Our present study is to find out how the short and long nephrons are interacting in the human kidney to adjust the flow in the collecting duct to have the maximum flow during the diluting mode and minimum flow during the concentrating mode. The best lengths for the short nephron and long nephron are calculated during the concentrating mode and the diluting mode by using the Newton-Raphson method. If one wants the kidney to perform only the above mentioned functions, a design criteria for an artificial kidney has been proposed. These studies have provided qualitative information regarding the concentrating mechanism …