VTechWorks Repository :: Browsing by Author "Muelenaer, Andre A."

Browsing by Author "Muelenaer, Andre A."

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An Acoustic Sensor for Airflow in Pediatric Artificial Airways
Gooty, Vasu; Harris, Charles; Muelenaer, Andre A.; Watson, Brian; Safford, Shawn D. (Elsevier, 2015-01-06)
Pulmonary hyalinizing granuloma (PHG) is a rare benign pulmonary nodular lesion of unknown etiology. We present a case of a 5-year-old boy who was found to have a chest mass while being evaluated for abdominal pain. He underwent a CXR and CT scan that showed popcorn calcifications in the right posterior mediastinum and within the hilum of right lung. These lesions were suspicious for benign calcified lymph nodes and follow-up chest CT after 3.5 months showed no interval changes in the calcified mediastinal masses. Extensive testing ruled out infectious diseases and malignancies. Given the unknown etiology of the lesions, he underwent VATS biopsy that demonstrated a nodular lesion characterized by a peripheral rim of fibrous tissue and central zone of necrosis and calcification, findings consistent with hyalinizing granuloma. PHG is extremely rare in pediatric age group. Although diagnosis of this condition is made by radiological and histopathological findings, it is important to rule out other causes of chest masses. Most of the patients usually have good prognosis with this rare disorder.
Advancing the Global Land Grant Institution: Creating a Virtual Environment to Re-envision Extension and Advance GSS-related Research, Education, and Collaboration
Hall, Ralph P.; Polys, Nicholas F.; Sforza, Peter M.; Eubank, Stephen D.; Lewis, Bryan L.; Krometis, Leigh-Anne H.; Pollyea, Ryan M.; Schoenholtz, Stephen H.; Sridhar, Venkataramana; Crowder, Van; Lipsey, John; Christie, Maria Elisa; Glasson, George E.; Scherer, Hannah H.; Davis, A. Jack; Dunay, Robert J.; King, Nathan T.; Muelenaer, Andre A.; Muelenaer, Penelope; Rist, Cassidy; Wenzel, Sophie (Virginia Tech, 2017-05-15)
The vision for this project has emerged from several years of research, teaching, and service in Africa and holds the potential to internationalize education at Virginia Tech and in our partner institutions in Malawi. The vision is simple, to develop a state-of-the-art, data rich, virtual decision-support and learning environment that enables local-, regional-, and national-level actors in developed and developing regions to make decisions that improve resilience and sustainability. Achieving these objectives will require a system that can combine biogeophysical and sociocultural data in a way that enables actors to understand and leverage these data to enhance decision-making at various levels. The project will begin by focusing on water, agricultural, and health systems in Malawi, and can be expanded over time to include any sector or system in any country. The core ideas are inherently scalable...
Automatic Esophageal Intubation Detection Using Giant Magneto Resistance Sensors
Alson, Bradley Jacob (Virginia Tech, 2015-09-09)
This thesis will cover the principle, design, and construction of an automatic esophageal intubation detector. This device uses a giant magneto recitative sensor to and a magnetized stylet to automatically measure the position of an ET tube in a person's throat. This method is less subjective than currently used methods such as end tidal CO2, as it does not rely on user interpretation of data or physiological state of the patient. The device developed during this project was tested on an anatomical mockup, a porcine airway model, and an intubation training dummy. In all three tests, the device performed well, accurately indicating tracheal intubation when the tube was placed in the trachea. Only one instance of a false positive indication of tracheal intubation was recorded and this occurred in an atypical and avoidable situation. As of now, the device functions in non-obese adult male patients, but plans are in place to increase usability for the entire population.
A Compact Ultrasonic Airflow Sensor for Clinical Monitoring of Pediatric Tracheostomy Patients
Ruscher, Thomas Hall (Virginia Tech, 2013-02-19)
Infants and young children with tracheostomies need better respiratory monitors. Mucus in the tracheostomy tube presents a serious choking hazard. Current devices indirectly detect respiration, often yielding false or delayed alarms. A compact ultrasonic time-of-flight (TOF) airflow sensor capable of attaching directly to the tracheostomy tube has been developed to address this need. The ultrasonic flow sensing principle, also known as transit time ultrasound, is a robust method that correlates the timing of acoustic signals to velocity measurement. The compact prototype developed here can non-invasively measure all airflow into and out of a patient, so that breath interruption can easily be detected. This paper concerns technical design of the sensor, including the transducers, analog/digital electronics, and embedded systems hardware/software integration. Inside the sensor's flow chamber, two piezoelectric transducers sequentially transmit and receive ping-like acoustic pulses propagating upstream and downstream of flow. A microcontroller orchestrates measurement cycles, which consist of the transmission, reception, and signal processing of each acoustic pulse. The velocity and direction of airflow influence transit time of the acoustic signals. Combining TOF measurements with the known geometry of the flow chamber, average air velocity and volumetric flow rate can be calculated. These principles have all been demonstrated successfully by the prototype sensor developed in this research.
The data processing to detect correlated movement of Cerebral Palsy patient in early phase
Pyon, Okmin (Virginia Tech, 2016-02-03)
The early diagnosis of CP (Cerebral Palsy) in infants is important for developing meaningful interventions. One of the major symptoms of the CP is lack of the coordinated movements of a baby. The bilateral coordinated movement (BCM) is that a baby shows in the early development stage. Each limb movement shows various ranges of speed and angle with fluency in a normal infant. When a baby has CP the movements are cramped and more synchronized. A quantitative method is needed to diagnose the BCM. Data is collected from 3-axis accelerometers, which are connected, to each limb of the baby. Signal processing the collected data using short time Fourier transforms, along with the formation of time-dependent transfer functions and the coherence property is the key to the diagnostic approach. Combinations of each limb's movement and their relationship can represent the correlated movement. Data collected from a normal baby is used to develop the technique for identifying the fidgety movement. Time histories and the resulting diagnostic tool are presented to show the regions of the described movement. The evaluation of the transduction approach and the analysis is discussed in detail. The application of the quantitative tool for the early diagnosis of CP offers clinicians the opportunity to provide interventions that may reduce the debilitating impact this condition has on children. Tools such as this can also be used to assess motor development in infants and lead to the identification and early intervention for other conditions.
An Environmental Monitoring Device to Identify Potential Risks for Intraventricular Hemorrhage During Neonatal Transport of Preterm Infants
Guevara, Carlos Ernesto (Virginia Tech, 2011-11-03)
Purpose: To characterize the environment in both ground and aerial ambulances in an effort to identify and quantify the risk factors associated with intraventricular hemorrhage (IVH) in preterm infants, with the goal of developing a device to mitigate this problem. Methods: A small, stand-alone battery operated device was developed to characterize the environment inside neonatal transports. This device included an array of sensors to measure acceleration forces, sound levels, temperature, pressure, and light intensities. Two of the data acquisition devices were used to collect data inside and outside the transport incubator simultaneously for a period of thirty minutes during a test flight in a transport helicopter. Real-time digital signal processing was performed for the sound signals to reduce data. Furthermore batch digital signal processing was performed on an external computer to calculate the vibration spectrograms, occurrence of impulsive forces, and variations in ambient temperature, pressure and luminance. The results were compared between the two devices to determine whether the current transport incubator design is reducing or increasing the suspected risk factors. Results: The vibration levels registered in the transport incubator during flight were five times greater than in the crew cabin in the vertical direction. High vibration levels were registered in the horizontal direction in the transport incubator, which were not registered in the crew cabin. In contrast, vibration in lateral direction was nearly half of that registered in the crew cabin. Sound levels were on average 70 dBA in the transport incubator. Luminance levels reached values up to 6920 Lux. No major changes in temperature and pressure were registered. Conclusions: IVH is a serious consequence of transporting preterm infants from one health care facility to another and occurs in roughly one out of three infants. To address this problem, a transport monitoring device can help characterize the environment in these transports in an effort to design a new state of the art transport incubator to mitigate this problem.
Focused Ultrasound Biofilm Ablation: Investigation of Histotripsy for the Treatment of Catheter-Associated Urinary Tract Infections (CAUTIs)
Childers, Christopher; Edsall, Connor; Gannon, Jessica; Whittington, Abby R.; Muelenaer, Andre A.; Rao, Jayasimha; Vlaisavljevich, Eli (IEEE, 2021-09-01)
Urinary catheters often become contaminated with biofilms, resulting in catheter-associated urinary tract infections (CAUTIs) that adversely affect patient outcomes. Histotripsy is a non-invasive focused ultrasound therapy previously developed for the non-invasive ablation of cancerous tumors and soft tissues. Histotripsy has also previously shown the ability to treat biofilms on glass slides and surgical meshes. Here, we investigate the potential of histotripsy for the treatment of CAUTIs for the first time in vitro. Clinically relevant catheter materials (Tygon, Silicone, and latex catheter mimics) and commonly used clinical catheters were tested to determine the feasibility of producing luminal histotripsy bubble clouds. A Pseudomonas aeruginosa (strain PA14) biofilm model was developed and tested to produce luminal biofilms in an in vitro Tygon catheter mimic. This model was treated with histotripsy to determine the ability to remove a luminal biofilm. Finally, the bactericidal effects of histotripsy were tested by treating PA14 suspended inside the Tygon catheter mimic. Results showed that histotripsy produced precise luminal cavitation within all tested catheter mimics and clinical catheters. Histotripsy treatment of a PA14 biofilm with histotripsy reduced luminal biofilm OD590 signal down to background levels. Further, the treatment of suspended PA14 in LB showed a 3.45±0.11 log10 reduction in CFU/mL after 6 histotripsy scans across the catheter mimics. Overall, the results of this study demonstrate the potential of histotripsy to provide a new modality for removing bacterial biofilms from catheter-based medical devices and suggest that additional work is warranted to investigate histotripsy for the treatment of CAUTIs and other biomaterial-associated infections.
Innovating for Global Health through Community-Based Participatory Research: Design of Mechanical Suction Machines for Rural Health Clinics in Malawi
Taylor, Ashley R. (Virginia Tech, 2016-09-21)
Clinicians in low and middle-income countries (LMIC) face many challenges, including high patient-to-staff ratios, limited resources, and inconsistent access to electricity. This research aimed to improve health outcomes in LMIC through an enlightened understanding of challenges associated with healthcare technology. To understand LMIC barriers to acquiring, maintaining, and repairing medical equipment, a community-based participatory study was conducted at three clinical settings in southern Malawi. Thirty-six clinical staff participated in surveys and focus groups to provide information on medical device challenges. Results from the study emphasize the importance of community-based participatory innovation to improve global health. Many clinical staff expressed frustration regarding inability to prevent patient mortality attributed to equipment failure. Data from the community-based participatory study of medical technology conducted in Malawi revealed key insights for designing for low and middle income countries, and more specifically, for communities in southern Malawi. Specifically, partner communities identified mechanical suction machines as a top priority for design innovation. Working with technical and clinical staff in Malawian communities, a prototype mechanical suction machine was designed and constructed. This work suggests that engineers working in low and middle income countries face a unique sundry of design requirements that require an intimate understanding of the local community, including community leaders, community beliefs and values, and locally available resources. Technology innovation for global health should incorporate community expertise and assets, and health and technical education efforts should be developed to increase working knowledge of medical devices.
InsulPatch: A Slim, Powerless Microfluidic Patch-Pump for Insulin Delivery
Zhang, Shuyu (Virginia Tech, 2021-11-23)
The InsulPatch is a novel integrated patch-pump device used to deliver drugs, especially macromolecular drugs that are difficult to deliver through an oral pathway and that require transdermal delivery. The patch-pump is a promising replacement for conventional syringes and battery-powered pumps because it is slim, powerless, painless, and relatively inexpensive. The majority of this thesis focuses on the fabrication and testing of microfluidic devices for the delivery of insulin, which is a model drug that is widely used and needs to be delivered transdermally. In this thesis, we demonstrate the fabrication of the patch-pump, which includes an insect-mimetic microfluidic pump fabricated using photolithography and replica molding, and a microneedle array fabricated using 3D printing. The microfluidic pump is used to drive the fluid flow powered by pressurized air or the user’s pulse, and the microneedle array is used to inject the fluid through the skin painlessly. Using pressurized air-driven flow testing, we have tested the flow rate across microfluidic pumps of various flow channel widths over a range of physiologically relevant actuation frequencies and pressures. We have found that for the specific channel design we have been using, the flow rate generally positively correlates with the actuation pressure. For devices with wider flow channels, the flow rate generally negatively correlates with the actuation frequency, whereas the flow rate increases and then decreases with increasing actuation frequency for devices with narrower flow channels. This property of these devices is beneficial in insulin delivery because the demand for insulin is generally reduced in vigorous exercise (with elevated heart rate/actuation frequency) and increased in hypertension patients (with elevated blood/actuation pressure). A major future direction of the study is to test a wide range of device designs in a sample of human subjects by attaching the device onto the wrist and measuring the pulse-driven flow across the device. We can further change the channel design parameters of the device so that it will be ideal for insulin delivery. Using the ex vivo flow testing and human subject data, we can further tailor the device design to specific patients using a genetic algorithm-guided optimization based on the heart rate and blood pressure of the patient and the desired flow rate. We will also perform computational modeling using COMSOL Multiphysics to predict the flow across devices of different designs as well as to understand the physics behind the pulse-driven flow. Finally, a 3D-printed insulin reservoir will be incorporated into our patch-pump system for the storage of U-500 insulin.
A new blood pump and oxygenator system for support of infants with neonatal respiratory distress: preliminary in vitro and in vivo evaluation
Muelenaer, Andre A. (Virginia Polytechnic Institute and State University, 1979)
A clinical need exists for a blood oxygenator and pumping system for the support of neonates with respiratory deficiencies. Such systems now available for support of adults are not suitable for neonatal patients. In vitro evaluation of a new blood oxygenator and blood pumping system was performed. The data obtained suggested that this system may be applicable to neonates. In vivo studies with rabbits to further analyze the new system were done. Preliminary data from these studies indicate that the new blood oxygenator and blood pump system may be applicable to supporting neonates with respiratory deficiencies. Suggestions for future development of this system are presented.
Oxygen Therapy in Malawi: Revising Oxygen Concentrator Filtration and Use for Improved function in Low-Resource Hospitals
Cashman, Lauren E. (Virginia Tech, 2017-07-20)
The quality of healthcare in low-resource countries is often limited by the environment, lack of funds, staff availability, electricity availability, and more. In the words of a Malawian physician, medicine can feel like improvisation, wherein one must make due with available resources rather than desired resources. One prevalent problem among low-resource hospitals is the functionality and longevity of medical equipment. A large percentage of all medical equipment in Malawian hospitals is donated, resulting in a wide spectrum of models, necessary spare parts, and functionality. These machines can break quickly due to heavy use prior to donation, missing user and maintenance manuals, and a lack of replacement parts. Thus, finding necessary life-saving equipment in Malawian hospital wards can be a challenge. One such piece of equipment is the oxygen concentrator, necessary for treatment of respiratory disease, use with CPAP machines, and in the administration of surgical anesthesia. This device fills many roles in low-resource hospitals, but in many Malawian hospitals it is the most frequently malfunctioning piece of equipment. A survey administered to medical personnel and maintenance personnel in hospitals in Malawi’s Central and Southern Regions isolated some common causes of oxygen concentrator malfunction. Prominent among these were poor oxygen concentrator ventilation and the lack of consumable replacement parts such as the intake bacterial filter. A stand made from locally-sourced materials was developed to encourage better oxygen concentrator exhaust and raise the device out of dust and cleaning fluids on ward floors. Intake bacterial filter alternatives were researched, designed, constructed, and tested, manufactured from housing materials and filter media available in Malawi or continental Africa. A primary source of difficulty for low-resource hospitals is lack of autonomy, requiring aid from affluent nations to supply equipment and consumable materials. This work suggests that sustainable innovations, such as allowing consumables to be produced in-country, can replace aid with development and create more accessible materials to hospital maintenance personnel. Collaboration with material suppliers and engineers in Malawi can provide sustainable designs and systems to help hospitals access the supplies they need to service oxygen concentrators and other equipment.
Quantification of Motion and Cry Characteristics of NAS Newborns
Austin, Dexter Cyril (Virginia Tech, 2017-09-12)
Neonatal abstinence syndrome (NAS) is a condition caused by in-utero exposure to opioids, and its occurrence is increasing nationwide. NAS patients are newborns who can experience withdrawal symptoms including tremors, poor feeding, and respiratory distress. Presently, the Finnegan Scoring System, a subjective rating scale, is commonly used to judge the patient's condition and determine appropriate treatment methods. This project sought to develop a sensor system that is capable of objectively assessing symptoms of withdrawal, including tremors and high pitched cry. The system developed is composed of five wireless accelerometers, for attachment to a subject's limbs and chest, and an external microphone. The sensor system is targeted toward quantifying limb movements of the subject and recording audio information that includes samples of the subject's cry. The sensor system was used as part of a research study, and data was collected from recruited participants. A total of 29 out of 30 desired participants were enrolled and studied as part of the data collection process. Gathered data was analyzed using MATLAB, with motion data being searched for tremor activity in NAS participants, and cry samples searched for unique characteristics. Results generated indicate that detection of tremors was successful, and that the average fundamental frequency of cry differs between the NAS and non-NAS participants. Future considerations for this project include expanding to measure more symptoms, and system refinement to minimize the number of sensors.
A Sustainable Engineering Solution for Paediatric Dehydration in Low-Resource Clinical Environments
Taylor, Ashley R.; Turovskiy, Jeffrey; Drew, Benjamin; Muelenaer, Andre A.; Redican, Kerry J.; Kochersberger, Kevin B.; Bickford, Lissett R. (Engineers Without Borders Australia, 2016)
Engineering efforts in low resource environments pose a unique set of challenges, requiring an in-depth understanding of local needs, comprehensive mapping of community resources, and extensive collaboration with local expertise. The importance of these principles is demonstrated in this paper by detailing the novel design and field demonstration of an affordable, locally manufactured intravenous fluid regulation device. Collaboration with clinical personnel in Uganda and Malawi guided device design. In-country physicians emphasised the need to regulate volume of intravenous (IV) fluid delivered to a paediatric patient without use of electricity. The proposed device regulates IV fluid delivery within ±20 mL of total prescribed dosage, providing a method of reducing fatalities caused by over-hydration in low resource environments; the feasibility of building the device from local resources was demonstrated by a field research team in Malawi. The device was successfully constructed entirely from local resources for a total cost of $46.21 (USD). Additionally, the device was demonstrated in rural clinics where 89 % of surveyed clinical staff reported that they would use the device to regulate IV fluid delivery. This paper emphasises the importance of collaborating with communities for community-based engineering solutions. Mapping community assets and collaborating with local expertise are crucial to success of engineering efforts. Long-term, community-based efforts are likely to sustainably improve health outcomes and strengthen economies of communities worldwide.
Using Pressure Transducers for Noninvasive Heart and Respiratory Monitoring
Dowden, Matthew Richard Barcroft (Virginia Tech, 2012-07-25)
Detecting heart and respiratory rates is an essential means of providing emergency medical care. Current methods of detecting such signals include the widely used electrocardiography (ECG) method. Other more manual methods of heart and respiratory rate estimation require a practitioner to constantly observe the patient. These methods are time consuming and detract valuable time from emergency medical care. This thesis presents a novel, hands off, heart and respiratory monitor (HARMONI). It uses pressure transducers and medical tubing placed on a person's chest. The tubing is plugged off at one end, and then attached to a pressure transducer at the other end. The transducer sees spikes in voltage whenever the pressure inside the tubing changes. Heart and respiratory rates both cause expansion in the chest, increasing the pressure in the tubing, and causing the transducer to see a change in voltage. The method was first validated, and then tested in a simulated environment. Finally, the device was transformed in to a full system prototype. Human tests were conducted to correlate the signal with that of an industry standard ECG device. This thesis explains how heart and respiratory rates can be derived using signal processing techniques and a simple non-invasive sensor. This device is a rapidly deployable tool that has the potential to save lives specifically in mass casualty situations. It would be a force multiplier, allowing a single responder to monitor multiple casualties, saving time and lives.
Wrist Worn Device to Aid the Elderly to Age in Place
Scott, Latonya Rochelle (Virginia Tech, 2014-10-15)
The elderly population is increasing at a rapid rate each year, and with the increase in the elderly population there is a need for better medical assistance and devices. The greatest problem this demographic is facing is the ability to age in place. More elderly people are being placed in nursing homes, assisted living homes, moving in with relatives due to disabilities or fear of disabilities caused by a life threaten event such as heart disease, stroke, falling/fainting, or uncontrolled glucose levels. Falling is the number one leading cause of deaths, injuries and incapacity in the elderly. Stroke is the 3rd leading cause of death in the U.S; it is the 2nd leading cause worldwide. Rapid change in glucose levels is another leading cause of disabilities and deaths. Heart disease is the 2nd leading cause of death in the elderly. These life threatening events can be prevented and if treated early enough can allow the person to have a full recovery and continue to age in place. A device was proposed that could monitor these four life threatening events: heart disease, stroke, falling/fainting and changes in glucose levels. This device will monitor the user continuously. Research was conducted to see what other products are on the market and how they detect these events and how reliable they are for the user. A literature review was performed to understand what other people are doing to solve the aging in place problem. Using this and needs assessment of the elderly, the system architecture for the wrist worn device was designed along with a testing plan and procedure. More research needs to be done in certain areas to better improve solutions and technology in the area aging in place of the elderly. Before this device can bridge some of the gaps between the current issues and the solution the device will have to be tested for several things such as its ability to differentiate between stimulated falling/fainting and fall like activities such as sitting then lying. The orientation and position will be tested to see if the device can actually tell where the person is located. The device will have to be tested against well-known devices and see if it gives similar precise and accurate readings in real time.

Browsing by Author "Muelenaer, Andre A."

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