Biomedical Engineering and Bioengineering Commons^™

Development And Testing Of A Simulated Closed Loop Drug Delivery System For Chf Patients Under Milrinone Administration, Runa Shah

Theses

The purpose of this thesis project is the development and testing of a simulated closed loop drug delivery (CLDD) system that consists of a pharmacokinetic, physiological, and feedback-controlling model. The focus of this study is on the control of milrinone inflision to maintain cardiac output at desired setpoint range for patients suffering from congestive heart failure (CHF). The simulated CLDD system is written in VisSim dynamic simulation language for an IBM-compatible PC.

Milrinone pharmacokinetics are represented by a three compartment model. The physiological model consists of the cardiovascular system model linked to the pharmacodynamic submodel of milrinone. The feedback-controlling model …

A Study Of Factors Affecting Cardiovascular Reactivity, Andrew Gill Ventura

Theses

This pilot study was conducted to determine what affects the cardiovascular reactivity of different people. Variables such as the order of stress-inducing and relaxing activities, performing multiple tasks on different days, personality, familial history of diseases, and general health were investigated as to their effects, if any, on cardiovascular reactivity.

Ten healthy, normal male subjects, aged 18 - 33 years, volunteered to be subjected to studies on three experimental days, the first one being for gathering information. On the second and third days, the subjects performed the following activities: mental arithmetic, numeric repetition, 10 breaths-per-minute (bpm) paced-breathing, and normal breathing, …

Investigation Of The Relevance Of Heart Rate Variability Changes After Heart Transplantation, Sheeba Arnold

Theses

Heart transplantation has become an established treatment for end-stage heart disease. However, the shortage of donor organs is a major problem and long-term results are limited by allograft rejection. Heart rate variability (HRV) has emerged as a popular noninvasive research tool in cardiology. Analysis of HRV is regarded as a valid technique to assess the sympathovagal balance of the heart. The primary goal of this study was to investigate the relevance of heart rate variability changes after heart transplantation. It was found that spectral analysis of HRV is useful in detecting rejection episodes. Heart transplantation leaves the donor heart denervated. …

Computer Automated Experimentation For The Control And Assessment Of The Classically Conditioned Eyeblink Response, Michael Terrence Bergen

Theses

The use of the classically conditioned eyeblink response, a form of associative learning, is a growing method of experimentation in modem science. This type of associative learning, has many features that make it useful for applications in the study of specific neurological functions. The goal of this project was to design and implement a software system for the automated control and on-line evaluation of a classical conditioning experiment for use with human subjects. A program was developed in the LabVIEW programming environment by National Instruments. Basic hardware components produce acoustic signals, deliver airpuffs, and sense and condition physiological responses. Safety …

Analysis Of Long-Term Heart Rate Variability Using Labview, Daniel Yang

Theses

Long-term heart rate variability measurement is important in understanding the activities of the autonomic nervous system. Many methods and implications of long-terrn HRV were available in the literature. The first two studies focused on two data analysis techniques that were used on a normal subject. The first study focused on the 1/f fluctuations. For this analysis, three 1 1h heart rate variability data sets were collected with the Polar Vantage NV. A LabVIEW program was used to calculate the power spectrum of the heart rate, and then the 1/f line was calculated by taking the log of the power spectrum …

Measurements Of The Effects Of Colored Light On The Body, Lynne Hendrickson

Theses

Colored light is used in movies, restaurants, and other situations to create particular environments. It creates a mood and sets a stage for specific events.

This study used colored light to create relaxation and stress in order to evaluate physiological reactions in the human body. In all four studies of this paper, EEG, EKG, and peripheral blood flow were recorded and observed and in the latter two studies peripheral temperature and conductance were also recorded. An audio stressor was introduced in the first three studies to evaluate the stability of the altered mood of the individuals.

Considerable mood alterations were …

Effect Of Postural Tilt On The Autonomic Nervous System In Gulf War Veterans, Shrenik Dagli

Theses

Time-frequency signal representations characterize signals over a joint time-frequency plane. They combine time-domain and frequency-domain analysis to yield a potentially more revealing picture of the temporal localization of a signal spectrum. Time-frequency distributions (TFDS) of signals map a one-dimensional function of time, x (t), into a two-dimensional function of time and frequency, p(t, f). Most TFDs are "time-varying representations' which are similar conceptually to a musical score with time running along one axis and frequency along the other axis.

Many Gulf War Veterans complained of symptoms like unexplainable tiredness. This condition is known as the Gulf War Syndrome. The purpose …

In Situ Aortic Root In Vitro Testing Of The Stented And Stenless Porcine Aortic Heart Valves, Sean Parker

Theses

Background - The stent, Delrin® support frame, for porcine heart valves has been blamed for reduced durability of these valves due to the additional stress caused by the relative stiffness of the stent. There is a tendency among surgeons to do away with the stent in the aortic position and use porcine stentless valves which are sewn directly in the aortic position after removing diseased valve. These stentless valves are extremely difficult to test and no appropriate holder has been designed for this purpose. New approach for in vitro testing of these valves has been developed at Sheihigh, Inc., Millburn …

Computer Simulation Of Cerebrovascular Responses During Induced Hypotension, John A. Schalago

Theses

The purpose of this project was to develop a computer model of cerebrovascular hemodynamics interacting with a pharmacodynamic drug model to examine the effects of three commonly used anti-hypertensive drugs upon intracranial pressure and cerebral blood flow. The model is used to predict cerebrovascular response during the administration of commonly used anti-hypertensive agents.

The mathematical model of intracranial hemodynamics is a seven compartment constant volume system. A series of resistances relate blood and cerebrospinal fluxes to pressure gradients between compartments. Arterial, venous and tissues compliance are included. Autoregulation is modeled by transmural pressure-dependent arterial-arteriolar resistance. The effects of three drugs …

Role Of Sympathovagal Imbalance In Syncope Using Heart Rate Variability Analysis, Jayadeep Krishnah Unni

Theses

One of the common and challenging problems confronting the physician in clinical practice is recurrent syncope. Despite extensive evaluations, the causes of these cases Of syncope are not found in more than 40% of the patients.

It is thought that most patients who experience unexplained syncope do so because of transient, unpredictable episodes of vasovagally mediated hypotension and bradycardia. It is hypothesized that impaired inhibition of parasympathetic tone during stress accompanies the development of syncope. Head-up tilt table testing reportedly provokes vasovagal episodes effectively in susceptible persons.

This study attempts to explain the role played by the sympathetic and parasympathetic …

Model And Clinical Device Development For Noninvasive Diagnosis Of Low Back Pain And Dysfunction, Ravi Patraju

Theses

Millions of people suffer from acute or chronic low back pain. In order for proper treatment to be administered, a patient must receive an accurate diagnosis. Therefore, it is critical to develop an objective model to measure the motion and any dysfunction of a patient's low back. Only then can a physician effectively implement the correct therapy and measure its effectiveness through follow-up to minimize or eliminate low back pain.

Numerous cadaveric, active and passive studies have been done to understand the mechanics of low back disorders. However, only living human subjects suffer from low back pain and therefore cadaveric …

Analysis Of Multi-Lead Qt Dispersion By Means Of An Algorithm Implemented On Labview, Zafer Sahinoglu

Theses

QT dispersion measurement is significant in diagnostic ECG, and several methods are proposed in the literature to implement QT measurement.

This study consists of two parts: The first part was the development of an algorithm to measure both QT interval and QT dispersion. To check the reliability of the algorithm, 25 single channel ECGs were recorded and their QT intervals were computed. On two subjects, three and four lead ECG data were recorded respectively and their QT dispersions were statistically analyzed. Another part of this study dealt with the effect of the electric dipole of the heart on QT dispersion. …

Measurement Of The Baroreceptor Sensitivity Index (Brsi) In The Frequency Domains, Tanvir Raquib

Theses

Time domain analysis for calculating the Baroreceptor Sensitivity Index (BRSI) did not always provide an accurate result. It also had another limitation in that it could not show the influence of the autonomic nervous system for different subjects. The correlation coefficient is a mechanism that was used to either accept or reject the BRSI values in the time domain but the correlation coefficient values changed drastically depending on how many sample points were selected for the calculation.

On the other hand, frequency domain analysis for the BRSI calculation was relatively easier and provided more accurate information compared to the time …

Development Of A Practical And Effective Technique To Determine The Complete Level Of Autonomic Neural Activity During Stress, Vikki Hazelwood

Theses

Clinical evidence exists to suggest that an individual's level of stress contributes to the state of many physiological and psychological disorders, The autonomic nervous system, by adjusting parasympathetic and sympathetic activity, is attributed with the control over an individual's level of neural stress. Therefore, it is desired to develop a better and quantitative understanding of the stress! autonomic system mechanism.

Previous work has been done to gain a partial understanding of such activity. The primary objective for this study is to complement and advance the previous work by determining whether there is other physiological data which could reveal more about …

Mathematical Model Of Human Sit-To-Stand And Stand-To-Sit Motion Analysis, Jayeshkumar Gandhi

Theses

In designing a device for an amputee, it is important to find those underlying principles which determine the normal human sit-to-stand task. For this purpose we have developed a mathematical model of human sit-to-stand movement, which it is possible to predict the minimum mechanical energy consumption to move from the sit-to-stand position.

To the best of author's knowledge, this thesis represents the first time that the periodic motion of stand-to-sit and sit-to-stand movements have been mathematically modeled by a simple mechanical system. A complex model, such as the one used by Seireg and Arvikar (1973) [1] that contained 31 muscles …

Quantitative Estimation Of Heparin Content On Biological Pericadium Tissue Using In Vitro Anti-Factor Xa Assay, Jean-Claude Simeon

Theses

Shelhigh Inc. (Millburn, NJ) has developed a new heparin binding technique to biological tissues. The technique seems to bind heparin to tissues in a more permanent fashion. Shelhigh's heparinized biological tissues are intended for use in long term implants. This investigation was undertaken to assess whether heparin leaching is prevalent when tissues are quarantine for long shelflife at room temperature, whether tissues maintained thromboresistance properties when in contact with plasma and to estimate heparin content of the tissues.

The study used anti-factor Xa assaying methods: clotting time and chromogenic factor Xa sensitive substrate in order to fulfill the aforementioned objectives. …

Using Heart Variability To Measure The Effects Of Manual Medicine On Autonomic Activity, Michael Zullow

Theses

A pilot study was performed to test the theory that manual medicine techniques known as the CV4 (compression of fourth cerebral ventricle) maneuver and a sacral hold/iliac bridge hold combination increase parasympathetic activity. Manual medicine techniques are widely practiced by Doctors of Osteopathy and Chiropractors to treat physical and mental health problems. Those who have received manual therapy have reported to experience less pain, better mobility, and a greater feeling of relaxation. To help us learn about the effects of manual therapy, autonomic activity was measured scientifically rather than subjectively in this study by monitoring respiration rate and heart rate, …

Electrophysiologic Studies Of Hypothalamic Adenosine-5'-Triphosphate-Sensitive Potassium Channels, Dinora Hernandez

Theses

Of particular interest in this study were the electrical phenomena involving currents from the ATP sensitive K channel in isolated hypothalamic ventromedial nucleus (VMN) neurons. These neurons may play an important role in the glucose-sensing system of the body. Rat VMN neurons were isolated. For neuronal isolation, the proteolytic enzyme pronase was used. However, pronase was too harsh. The use of papain, another proteolytic enzyme, led to better neuronal morphology. The perforated patch clamp technique was used to gain access to the cell's interior. For membrane pore formation, nystatin was used; but seal formation was difficult. Amphotericin was used instead, …

Determination Of Effects Of Stress On Polymeric Ankle-Foot Due To Weight Change: Experimental Stress Analysis, Lin Yu Wang

Theses

Ankle-Foot Orthoses (AFOs) are devices that assist patients who sustained an abnormal motion at the ankle joint of the foot due to traumatic injury and stroke, etc. The objective of this project is to determine the stress patterns in AFOs under different loading conditions such as weights and genders. Thus, the location of failure can be predicted, and a redesign process can be developed. Furthermore, those experimental results will be used to verify the results obtained from the previous Finite Element Analysis (FEA) ^[11,10]. Results from the experiment showed a significant stress change due to load change. This stress …

Renin-Angiotensin System And Its Relationship To Arterial Pressure Regulation, Sami D. Saume

Theses

The renal system is known to participate in the natural regulation of blood pressure. A renal system model that simulates interaction responses of renal output to arterial blood pressure was developed. The major components of this model are glomerular filtration rate, tubular sodium reabsorption, the renin-angiotensin system, Aldosterone secretion, and antidiuretic hormone secretion. The model's differential equations were coded using Vissim 1.2 student version. It was found that, the renal output increased as glomerular filtration rate, Aldosterone concentration, and blood pressure increased. Conversely, increasing antidiuretic hormone concentration lead to decreased renal output.

Additionally, Angiotensin II and Aldosterone concentrations increased as …

Relative Dentifrice Abrasivity On Dentin And Enamel, Laura Marchetti

Theses

The abrasive characteristics of six (6) brands of toothpastes on Enamel and Dentin material were assessed. Human teeth were sliced to expose the dentin surface and then polished using 3 μm and 0.25 μm diamond paste. The outside surface of the tooth (after slicing) was used "as is" for the enamel surface testing. The surface smoothness was evaluated prior to testing using a surface profiler and averaging four (4) to five (5) readings across the surface for each sample.

The tooth slices were then embedded into the acrylic plate surface by routing out an area with a dental drill and …

Determination And Studying Of Stress Distribution In Various Ankle-Foot Orthoses : Experimental Stress Analysis, Rong Feng

Theses

Ankle-Foot Orthosis (AFO) is prescribed to constrain and inhibit abnormal motion such as "drop foot" due to stroke. Most orthoses were hand-made by orthotists according to their own experience. However, some types of AFO were easy to fatigue (out of their functional capabilities) than others due to regular usage. In order to improve the design and usage, quantitative stress analysis of different types of orthoses is needed. The objective of this project is to obtain experimental data which will confirm the results obtained from previous Finite Element Analysis (FEA)^[1]. In addition, the experimental analysis is extended to obtain …

Mechanical Evaluation Of Pedicle Screw Fixation Of The Lumbar Spine, Ding Lu

Theses

Pedicle screw fixation of the lumbar spine has been reported to increase fusion rates A biomechanical evaluation of four different pedicle screw implant systems, (AO. Rogozinski, TSRH and Wiltse). was performed to compare intrinsic device stiffness under conditions of flexion-compression and forty-five degree off-axis flexion-compression The effect on stiffness of the loosening of device members was also studied. Testing was done in load control using an electrohvdrualic testing machine. UHMWPe blocks are used to simulate the vertebra.

Assuming that stiffness is directly proportional to the probability of obtaining fusion. this study allows the ranking of the systems tested in their …

The Relationship Between Thermoregulatory And Haemodynamic Responses Of The Skin To Relaxation And Stress, Paul O. Nketia

Theses

The present study investigated the effects of stress and relaxation on (1) EEG coherence and (2) peripheral blood flow.

EEG coherence of two meditators in two different but adjacent rooms was measured during eyes opened, eyes closed, single meditation and group meditation. The skin temperatures of the subjects together with their room temperatures were also recorded. EEG coherence plots (Cospar) showed a spread out of the alpha band to the beta, theta and occasionally to the delta wave bands during group meditation. The area above the 0.98 coherence threshold in the alpha band was greater during group meditation than during …

Computer Simulation Of Cerebrovascular Circulation : Assessment Of Intracranial Hemodynamics During Induction Of Anesthesia, Steven D. Wolk

Theses

The purpose of this project was to develop a computer model of cerebrovascular hemodynamics interacting with a pharmacokinetic drug model to examine the effects of various stimuli during anesthesia on cerebral blood flow and intracranial pressure.

The mathematical model of intracranial hemodynamics is a seven compartment constant volume system. A series of resistances relate blood and cerebrospinal fluid fluxes to pressure gradients between compartments. Arterial, venous, and tissue compliance are also included. Autoregulation is modeled by transmural pressure dependent arterial-arteriolar resistance. The effect of a drug (thiopental) on cerebrovascular circulation was simulated by a variable arteriolar-capillary resistance. Thiopental concentration, in …

Design Of A Mode Of Delivery For Macrobead Transplantation, Jagdip Desai

Theses

The macrobead is a form of a biohybrid artificial pancreas (BAP), which is being developed to treat type 1 diabetes. A hypothetical human transplant would require 125 rat equivalent macrobeads. For intraperitoneal transplantation a mode of delivery that allows the placement of several hundred macrobeads into a basket or pouch type device is required.

In this study, four commercially available materials were studied as possible candidates for creating a pouch. These materials are polyvinyl chloride acrylic copolymer (PVC), polyethersulfone (PES), polyvinylidenedifluoride (PVDF), and polytetrafluorethylene (PTFE). Tubular pouches of each material were designed. They then underwent in vivo biocompatibility and in-vitro …

Three-Dimensional Stress Analysis Of The Femur With Prosthetic Hip Stem Utilizing Computed Tomography Scans Of The Femur For Geometry And Material Properties, Thomas J. Lavin

Theses

Three-dimensional finite element stress analyses of the femur with prosthesis hip stem were performed for two cases, one male and one female, using ideally bonded cemented titanium prostheses. Computed tomography data files were used to derive the three-dimensional femur geometry and material properties for each cortical bone element. The maximum shear stress (4.7 MPa) in the cement was greater then the maximum tensile stress and occurred at the cement-bone interface. The tensile stresses in the cement were less then the fatigue strength of the cement. The stress patterns were quite similar for the two cases.

A data analysis program was …

The In Vitro Evaluation Of Various Biodegradable Composites Used In Internal Fixation Devices, Hui-Chen Hsieh

Theses

In vitro degradation kinetics and mechanical properties of various composites, comprising a polycarbonate (DTE polymer) reinforced with CaP glass fiber, synthetic ceramic and non-ceramic hydroxyapatite (HA-500,OsteoGen HA) were investigated.

They were soaked in the SBF solution with a constant pH of 7.4 at 37°C for 5 days. The DTE/CaP composite degraded in an acid manner such that a large amount of NaOH was required but with a small decrease in calcium ion concentration. By contrast, the DTE/OsteoGen HA composite required comparable amounts of NaOH, but with a concomitantly large decrease in calcium ion concentration. This showed that the OsteoGen HA …

Development Of A Gel Content Analysis Protocol For Ultra High Molecular Weight Polyethylene, Max Harold Jeanty

Theses

A modified procedure based upon ASTM (D 2765 - 90) to determine the gel content of crosslinked polyethylene plastics was developed. The new procedure was applied to ram extruded Ultra High Molecular Weight (UHMWPE) implant components processed under different manufacturing conditions. This new evaluation tool provides consistent results with greater accuracy and consistency compared to the American Society for the Testing of Materials (ASTM) method. Using the same tool, several relationships between the UHMWPE processing conditions and gel content were established. The amount of gel content is related to the crosslinked material. It has been shown that the more crosslinking …

Modeling Of Cardiovascular System To Simulate Ventricular Septal Defect, Adarsh Kumar Gupta

Theses

The hemodynamics of the ventricular septa] defect is studied using a mathematical modeling technique. A twelve-compartment windkessel model of cardiovascular system is used to study the hemodynamics of the ventricular septal defect. The VSD is incorporated into the model via a parallel flow from the left to right ventricles (left-to-right shunt). The resistance to flow through the shunt is used to characterize the severity of the defect. Changes in the severity of the shunt flow produces changes in the ratio of pulmonary to systemic flow in the circulation. When the pulmonary to systemic flow ratio is more than 2:1, the …