7 results for Al-Jumaily, AM, All rights reserved

  • Simulation of Impedance Measurements at Human Forearm Within 1 KHz to 2 MHz

    Anand, G; Lowe, A; Al-Jumaily, AM

    Journal article
    Auckland University of Technology

    This work presents a simulation analysis of the bioimpedance measurements at human forearm. The Ansys® High Frequency Structure Simulator (HFSS) has been used to analyze the electrical response of a section of human forearm with three domains of di-electric behavior- fat, muscle and artery (blood). The impedance values were calculated as the ratio of the output voltage at the electrodes to the applied known current (1mA). A model was developed and was simulated for impedance values obtained within a frequency range of 1 kHz to 2MHz. The measurements were done at three instances of radial artery diameter. The maximum resistance and reactance values were calculated as 445Ω and 178.5Ω, 356Ω and 138Ω, and 368Ω and 144.3Ω for diameters 2.3mm, 2.35mm, and 2.4mm respectively. The set of impedance values obtained followed Cole-plot trend. The results obtained were found to be in excellent agreement with the Cole theory. The set of values obtained at three different diameters reflected the effect of blood flow on impedance values.

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  • Effect of nafion hydration on its actuation characteristics

    Hildesley, M; Al-Jumaily, AM; Paxton, RA; Ramos, MV (2011-11-16)

    Conference item
    Auckland University of Technology

    Traditionally Nafion is actuated while being hydrated along its surface. This paper presents an investigation into the electro-active actuation characteristics of Nafion while being hydrated from one of its edges to avoid direct water contact with the surface. The effectiveness of actuation of electrically excited platinum coated Nafion cantilever past a 12 minute time period without direct hydration is investigated. While cantilever strips were subjected to pressurised water at the fixed end, both coated and uncoated Nafion actuation characteristics were investigated for amplitude and time of response. . The oscillations of coated strips were able to be sustained for more than 24 hours with the techniques used. Although there was a decrease in the amount of deflection over the time period, the results suggest that hydration of the Nafion substrate can be maintained without complete surface contact, and a platinum coated region can perform as an actuator, continuously, for longer periods than previously observed in air.

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  • Nasal air-conditioning during N-CPAP therapy

    White, DE; Al-Jumaily, AM; Bartley, J (2011-12-01)

    Conference item
    Auckland University of Technology

    Over 40% of people who undertake n-CPAP breathing therapy report problems of rhinitis or nasal congestion despite not having these symptoms prior to treatment. Heated humidification is often used to condition inhaled air and to minimise these symptoms by eliminating the need for the airway mucosa to provide or recover heat or moisture during breathing. This research focuses on developing an appropriate mathematical model which describes air-conditioning within the nose during the application of CPAP therapy. The model will incorporate the regulation of airway fluid supply which is partially controlled through epithelial cell stress stimulation induced during tidal breathing. Model outcomes will be the quantification of the effect of air pressures on this regulation. Laws of mass and heat transfer will be used to incorporate data from clinical trials to predict the nasal heating and humidification requirements. This includes: (1) heat and humidification supplement to make up for the dynamic state of mucosa dysfunction encountered during n-CAP therapy (2) maintenance of normal airway fluid volume within the upper airway (3) maintenance of mucociliary clearance (4) prevention of inflammation because of fluid imbalances or thermal injury.

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  • Nasal air-conditioning during breathing therapy

    White, DE; Al-Jumaily, AM; Bartley, J; Somervell, A (2011-12-01)

    Journal article
    Auckland University of Technology

    It has been reported that continuous positive airway pressure therapy introduces negative nasal side-effects including sneezing, itching, nasal dryness, nasal congestion and/or a runny nose. As these symptoms are suggestive of nasal dysfunction, heated humidification is often used to fully saturate and heat the inhaled air to core body temperature. It is expected that this relieves the nasal mucosa from having to supply, or recover, heat and moisture from inspired and expired air. This review summarizes the current in vitro and in vivo knowledge relevant to nasal air-conditioning, and identifies further investigations necessary to improve our understanding the changes that occur during nasal continuous positive airway pressure therapy. Investigations into nasal airway fluid transportation, airflow regulation and heat and fluid supply may lead to a therapy temperature/pressure/humidification algorithm that optimizes these parameters for a prescribed therapy pressure. Optimization could lead to a reduction in titration pressure and improved treatment compliance.

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  • Correlation of nasal morphology to air-conditioning and clearance function

    White, DE; Al-Jumaily, AM; Bartley, J; Lu, J (2011-12-01)

    Journal article
    Auckland University of Technology

    Nasal morphology plays an important functional role in the maintenance of upper airway health. Identification of functional regions, based on morphological attributes, assists in correlating location to primary purpose. The effects of morphological variation on heat and water mass transport in congested and patent nasal airways were investigated by examining nasal cross-sectional MRI images from 8 healthy subjects. This research confirms the previous identification of functional air-conditioning regions within the nose. The first is the anterior region where the morphology prevents over-stressing of tissue heat and fluid supply near the nares. The second is the mid region where low flow velocity favours olfaction and particle deposition. The third is the posterior region which demonstrates an increase in heat and water mass flux coefficients to compensate for rising air humidity and temperature. Factors identified within the congested airway that favour enhanced mucocillary clearance were also identified.

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  • Role of mechanical stress in optimising breathing therapy humidification

    White, DE; Al-Jumaily, AM; Bartley, J (2011-12-01)

    Conference item
    Auckland University of Technology

    During breathing therapy, heated humidification is often used to condition inhaled air and minimise symptoms associated with airway drying. The current treatment paradigm is based on providing the patient with fully humidified air at core body temperatures in an attempt to eliminate the need for the heat or moisture provided or recovered during normal breathing. Although this approach seems to reduce both the occurrence and severity of symptoms, supplementary humidification exposes the airway to additional risks such as excess fluid levels and thermal damage. The ability of the epithelial cells to regulate airway fluid volume during breathing at elevated pressures and the effect supplementary pressure has on the mucociliary transport velocity require an in-depth investigation. The purpose of this study is to quantify the appropriate level of supplementary humidification required for a given pressure augmentation. An appropriate biophysical model, which describes the nose air-conditioning during breathing therapies involving augmented pressures, will be developed. Data from clinical trials, laws of mass and heat transfer will be used to develop the model. The proposed model will incorporate the regulation of airway fluid supply which is partially controlled through the simulation of the epithelial cell stress induced during tidal breathing. This will enable prediction of the optimum heat and humidification supplementation required to make up for the dynamic state of mucosa dysfunction encountered. The physiological benefits in matching supplementary humidification to mucosa state of dysfunction include maintenance of normal airway fluid volume within the upper airway and preservation of healthy mucociliary clearance through prevention of inflammation caused by fluid imbalances or thermal injury.

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  • Nasal morphology and blood flow during augmented air pressure breathing therapies

    White, DE; Al-Jumaily, AM; Bartley, J; Lu, J; Hankin, RKS (2011-12-01)

    Conference item
    Auckland University of Technology

    Air delivered under augmented pressure during breathing therapy normally requires external humidification in order to avoid upper airways dryness and discomfort. Nasal heat and water flux between air and mucosa is dynamically regulated through changes in the erectile tissue volume. This investigation utilizes magnetic resonance imaging to investigate the effects augmented air pressure has on the erectile tissue size and blood flow. Eight healthy participants, aging from 18 to 56 years of mixed gender and ethnicity, undertook head MRI scans during two breathing conditions, ambient and pressurized air. For the latter, each participant experienced one augmented pressure level, ranging from 6 to 15 cmWG in increments of 3 cmWG. This was delivered through a nasal mask using a commercially available continuous positive airway pressure device. Geometrical analysis of images obtained for the region spanning the anterior inferior turbinate to the posterior choanae was undertaken. Results demonstrate a reduction in patent airway volume occurs during breathing at low pressure augmentation whist the congested airway volume remains relatively constant. Increasing pressure results in an opposite response where the congested airway volume increases whilst the patent volume remains unchanged. Only at the highest pressure (15 cmWG) did both patent and congested airways respond in a way consistent with previous observations of tissue compliance (which were based on acoustic rhinometry and modeling). The counter response of the patent airway and independence of reaction between each nasal passage at low to mid pressures is inconsistent with earlier work which detected no differences in morphological response between patent and congested nasal airways. This inter-nasal variation in behavior may be attributed to redistribution in blood occurring within the nasal erectile tissue. Using arterial spin labeling, this research has also qualitatively assessed the changes in nasal blood flow to each side of the nose. Whilst this technique does not indicate total blood volume and hence state of erectile-tissue engorgement, it does identify changes in blood flow occur in both congested and patent airways during pressurized breathing.

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