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  1. Article ; Online: Reconstruction of respiratory physiology based on flow dynamics

    Hiroko KITAOKA

    Journal of Fluid Science and Technology, Vol 13, Iss 4, Pp JFST0023-JFST

    2018  Volume 0023

    Abstract: Since gas exchange in the human lung is mass transports by fluids, respiratory physiology should be based on fluid dynamics. However, current theories of respiratory physiology have been established by regarding the respiratory system as an analogy of ... ...

    Abstract Since gas exchange in the human lung is mass transports by fluids, respiratory physiology should be based on fluid dynamics. However, current theories of respiratory physiology have been established by regarding the respiratory system as an analogy of electric circuit where the airflow is assumed laminar, and led clinicians to wrong ways. In this paper, two representative cases are introduced. One is a popular pulmonary function test and the other is an artificial ventilation method for severe respiratory failure. Maximum forced expiration test is used for diagnosis of expiratory airflow limitation such as emphysema or chronic obstructive pulmonary disease (COPD). Although the cause of expiratory airflow limitation has been believed to be due to small airway obstruction, its true cause is the collapse of the intra-thoracic large airway. The mechanism of high-frequency ventilation (HFV), one of artificial ventilations with tiny tidal volume, has been believed that high frequency oscillation augments gas dispersion and improves gas exchange in spite of tiny tidal volume. However, recent clinical studies have revealed that HFV is useless for acute respiratory distress syndrome (ARDS) in adults. The true gas transport mechanism with tiny tidal volume is asymmetric airflow profile between inspiration and expiration due to the presence of bronchial bifurcations. In both cases, there are several papers published in famous journals more than 25 years ago, which stated the true mechanisms but currently have been seldom refereed. Reconstruction of respiratory physiology is an urgent task both for medical and engineering researchers.
    Keywords pulmonary function test ; maximum forced expiration test ; pulmonary emphysema ; chronic obstructive pulmonary disease ; artificial ventilation ; high-frequency ventilation ; acute respiratory distress syndrome ; Science (General) ; Q1-390 ; Technology ; T
    Subject code 610
    Language English
    Publishing date 2018-11-01T00:00:00Z
    Publisher The Japan Society of Mechanical Engineers
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: What is "functional small airway disease" in inspiratory and expiratory CT images?

    Kitaoka, Hiroko / Kijima, Takashi

    Respiratory investigation

    2020  Volume 59, Issue 1, Page(s) 157–158

    MeSH term(s) Humans ; Pulmonary Disease, Chronic Obstructive ; Tomography, X-Ray Computed/methods
    Language English
    Publishing date 2020-10-11
    Publishing country Netherlands
    Document type Letter
    ZDB-ID 2660821-2
    ISSN 2212-5353 ; 2212-5345
    ISSN (online) 2212-5353
    ISSN 2212-5345
    DOI 10.1016/j.resinv.2020.08.010
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  3. Article ; Online: Static end-tidal expiratory computed tomography visualizes only a static type of expiratory central airway collapse.

    Kitaoka, Hiroko / Takimoto, Takayuki / Kijima, Takashi

    Respiratory investigation

    2021  Volume 60, Issue 1, Page(s) 182–183

    MeSH term(s) Exhalation ; Humans ; Lung ; Tidal Volume ; Tomography, X-Ray Computed
    Language English
    Publishing date 2021-09-10
    Publishing country Netherlands
    Document type Letter
    ZDB-ID 2660821-2
    ISSN 2212-5353 ; 2212-5345
    ISSN (online) 2212-5353
    ISSN 2212-5345
    DOI 10.1016/j.resinv.2021.08.004
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  4. Article ; Online: What Is Tracheobronchomalacia in Obstructive Lung Disease?

    Takimoto, Takayuki / Kitaoka, Hiroko / Kijima, Takashi

    Chest

    2021  Volume 159, Issue 1, Page(s) 442–443

    MeSH term(s) Adrenal Cortex Hormones ; Humans ; Lung Diseases, Obstructive ; Tracheobronchomalacia/diagnosis ; Tracheobronchomalacia/diagnostic imaging
    Chemical Substances Adrenal Cortex Hormones
    Language English
    Publishing date 2021-01-06
    Publishing country United States
    Document type Letter ; Comment
    ZDB-ID 1032552-9
    ISSN 1931-3543 ; 0012-3692
    ISSN (online) 1931-3543
    ISSN 0012-3692
    DOI 10.1016/j.chest.2020.07.085
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  5. Article ; Online: Proposal of selective wedge instillation of pulmonary surfactant for COVID-19 pneumonia based on computational fluid dynamics simulation.

    Kitaoka, Hiroko / Kobayashi, Hisato / Takimoto, Takayuki / Kijima, Takashi

    BMC pulmonary medicine

    2021  Volume 21, Issue 1, Page(s) 62

    Abstract: Background: The most important target cell of SARS-CoV-2 is Type II pneumocyte which produces and secretes pulmonary surfactant (PS) that prevents alveolar collapse. PS instillation therapy is dramatically effective for infant respiratory distress ... ...

    Abstract Background: The most important target cell of SARS-CoV-2 is Type II pneumocyte which produces and secretes pulmonary surfactant (PS) that prevents alveolar collapse. PS instillation therapy is dramatically effective for infant respiratory distress syndrome but has been clinically ineffective for ARDS. Nowadays, ARDS is regarded as non-cardiogenic pulmonary edema with vascular hyper-permeability regardless of direct relation to PS dysfunction. However, there is a possibility that this ineffectiveness of PS instillation for ARDS is caused by insufficient delivery. Then, we performed PS instillation simulation with realistic human airway models by the use of computational fluid dynamics, and investigated how instilled PS would move in the liquid layer covering the airway wall and reach to alveolar regions.
    Methods: Two types of 3D human airway models were prepared: one was from the trachea to the lobular bronchi and the other was from a subsegmental bronchus to respiratory bronchioles. The thickness of the liquid layer covering the airway was assigned as 14 % of the inner radius of the airway segment. The liquid layer was assumed to be replaced by an instilled PS. The flow rate of the instilled PS was assigned a constant value, which was determined by the total amount and instillation time in clinical use. The PS concentration of the liquid layer during instillation was computed by solving the advective-diffusion equation.
    Results: The driving pressure from the trachea to respiratory bronchioles was calculated at 317 cmH
    Conclusions: The simulation study has revealed that selective wedge instillation under bronchoscopic observation should be tried for COVID-19 pneumonia before the onset of ARDS. It will be also useful for preventing secondary lung fibrosis.
    MeSH term(s) Bronchi/physiology ; Bronchioles/physiology ; Bronchoscopy ; COVID-19/drug therapy ; Computer Simulation ; Humans ; Hydrodynamics ; Instillation, Drug ; Pressure ; Pulmonary Surfactants/administration & dosage ; Respiration, Artificial ; SARS-CoV-2 ; Trachea/physiology
    Chemical Substances Pulmonary Surfactants
    Language English
    Publishing date 2021-02-22
    Publishing country England
    Document type Journal Article
    ZDB-ID 2059871-3
    ISSN 1471-2466 ; 1471-2466
    ISSN (online) 1471-2466
    ISSN 1471-2466
    DOI 10.1186/s12890-021-01435-4
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  6. Article ; Online: Frequency and predictors of perioperative psychiatric symptom worsening in patients with schizophrenia spectrum disorders.

    Matsumoto, Yoshihiro / Ayani, Nobutaka / Oya, Nozomu / Kitaoka, Riki / Watanabe, Anri / Yoshii, Hiroko / Kitaura, Yuichi / Inoue, Shinichiro / Narumoto, Jin

    General hospital psychiatry

    2023  Volume 87, Page(s) 148–150

    MeSH term(s) Humans ; Schizophrenia/epidemiology ; Symptom Flare Up ; Mental Disorders/diagnosis ; Psychiatry ; Referral and Consultation
    Language English
    Publishing date 2023-09-30
    Publishing country United States
    Document type Letter
    ZDB-ID 392299-6
    ISSN 1873-7714 ; 0163-8343
    ISSN (online) 1873-7714
    ISSN 0163-8343
    DOI 10.1016/j.genhosppsych.2023.09.011
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    Zs.A 1584: Show issues Location:
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    Jg. 1995 - 2021: Lesesall (1.OG)
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  7. Article ; Online: The origin of frequency dependence of respiratory resistance: an airflow simulation study using a 4D pulmonary lobule model.

    Kitaoka, Hiroko

    Respirology (Carlton, Vic.)

    2011  Volume 16, Issue 3, Page(s) 517–522

    Abstract: Background and objective: The origin of frequency dependence of respiratory resistance has been explained by ventilation inhomogeneity; however, it is unclear which components in the respiratory system generate the frequency dependence. The author ... ...

    Abstract Background and objective: The origin of frequency dependence of respiratory resistance has been explained by ventilation inhomogeneity; however, it is unclear which components in the respiratory system generate the frequency dependence. The author constructed a 4D pulmonary lobule model and analysed relationships between airflow rate, pressure and airway resistance by the use of computational fluid dynamics.
    Methods: The lobule model contained bifurcated bronchioles with two adjacent acini in which deformable inter-acinar septa and alveolar duct walls were designed. Constrictive conditions of respective bronchioles were designed, too. 4D finite element models for computational fluid dynamics were generated and airflow simulations were performed under moving boundary conditions of the arbitrary Lagrangean-Eulerean method. From the simulation results, airway resistances for various conditions were calculated.
    Results: Tissue resistance emerged under the condition of different acinar pressures caused by unequal airway resistances. If the inter-acinar septum was shifted so as to cancel the pressure difference, the acinar pressures were equal in spite of unequal airway resistances, and hence, tissue resistances did not emerge. Therefore, the tissue resistance in the former case is thought to be an index of alveolar pressure inequality (which could be cancelled by mechanical interaction of lung parenchyma), rather than a material property of the tissue itself.
    Conclusions: Inequality of alveolar pressure decreases as the input oscillatory frequency increases. Therefore, frequency dependence of the respiratory resistance should be regarded as a conditional index of the alveolar pressure inequality caused by heterogeneous changes in the intra-pulmonary airway and/or the lung parenchyma.
    MeSH term(s) Airway Resistance/physiology ; Bronchioles/physiology ; Computer Simulation ; Finite Element Analysis ; Humans ; Lung/physiology ; Lung Compliance/physiology ; Models, Biological
    Language English
    Publishing date 2011-04
    Publishing country Australia
    Document type Journal Article
    ZDB-ID 1435849-9
    ISSN 1440-1843 ; 1323-7799
    ISSN (online) 1440-1843
    ISSN 1323-7799
    DOI 10.1111/j.1440-1843.2011.01925.x
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    Zs.A 4957: Show issues Location:
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  8. Article: [The origin of frequency dependence of respiratory resistance: airflow simulation study by the use of a 4D pulmonary lobule model].

    Kitaoka, Hiroko

    Nihon Kokyuki Gakkai zasshi = the journal of the Japanese Respiratory Society

    2011  Volume 49, Issue 9, Page(s) 629–635

    Abstract: Background and objective: The origin of frequency dependence of respiratory resistance has been explained by ventilation inhomogeneity, however it is unclear which components in the respiratory system generate the frequency dependence. The author ... ...

    Abstract Background and objective: The origin of frequency dependence of respiratory resistance has been explained by ventilation inhomogeneity, however it is unclear which components in the respiratory system generate the frequency dependence. The author constructed a 4D pulmonary lobule model and analyzed relationships between airflow rate, pressure and airway resistance by the use of computational fluid dynamics (CFD).
    Methods: The lobule model contained bifurcated bronchioles with two adjacent acini in which deformable inter-acinar septa and alveolar duct walls were designed. Constrictive conditions of respective bronchioles were designed, too. 4D finite element models for CFD were generated and airflow simulations were performed under moving boundary conditions of the arbitrary Lagrangean-Eulerean method. From the simulation results, airway resistances for various conditions were calculated.
    Results: Tissue resistance emerged under the condition of different acinar pressures caused by unequal airway resistances. If the inter-acinar septum was shifted so as to cancel the pressure difference, the acinar pressures were equal in spite of unequal airway resistances, and hence, tissue resistances did not emerge. Therefore, the tissue resistance in the former case is thought to be an index of alveolar pressure inequality (which could be canceled by mechanical interaction of lung parenchyma), rather than a material property of the tissue itself.
    Conclusions: Inequality of alveolar pressure decreases as the input oscillatory frequency increases. Therefore, frequency dependence of the respiratory resistance should be regarded as a conditional index of the alveolar pressure inequality caused by heterogeneous changes in the intra-pulmonary airway and/or the lung parenchyma.
    MeSH term(s) Airway Resistance/physiology ; Bronchioles/physiology ; Humans ; Models, Biological ; Pulmonary Alveoli/physiology ; Pulmonary Ventilation/physiology
    Language Japanese
    Publishing date 2011-09
    Publishing country Japan
    Document type English Abstract ; Journal Article
    ZDB-ID 1456536-5
    ISSN 1345-9538 ; 1343-3490
    ISSN (online) 1345-9538
    ISSN 1343-3490
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    Zs.B 1557: Show issues Location:
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  9. Article ; Online: Aerosol Spread with Use of High-Flow Nasal Cannula: A Computational Fluid Dynamics Analysis

    Kobayashi, Hisato / Takimoto, Takayuki / Kitaoka, Hiroko / Kijima, Takashi

    J Hosp Infect

    Keywords covid19
    Publisher Elsevier; PMC; WHO
    Document type Article ; Online
    Note WHO #Covidence: #597953
    DOI 10.1016/j.jhin.2020.06.010
    Database COVID19

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  10. Article ; Online: Influence of the menstrual cycle on compression-induced pain during mammography: correlation with the thickness and volume of the mammary gland.

    Kitaoka, Hitomi / Kawashima, Hiroko

    Radiological physics and technology

    2017  Volume 11, Issue 1, Page(s) 20–26

    Abstract: In mammography, breast compression is necessary and an important factor influencing image quality. The purpose of this study was to determine the influence of the menstrual cycle on compression-induced pain during mammography and to evaluate the ... ...

    Abstract In mammography, breast compression is necessary and an important factor influencing image quality. The purpose of this study was to determine the influence of the menstrual cycle on compression-induced pain during mammography and to evaluate the association between the thickness and volume of the mammary gland and pain. We examined basal body temperature and categorized the menstrual cycle into five phases. We executed breast compression in the craniocaudal view using a customized compression plate, to which we introduced an opening. We measured the thickness of the mammary gland under compression using echography. Immediately after releasing the compression, we evaluated pain using the visual analogue scale. We performed magnetic resonance imaging (MRI) on the same day and measured the volume of the mammary gland. The thickness of the mammary gland, pain, and the volume of the mammary gland were minimal in the late follicular phase and maximal in the late luteal and early follicular phases. It was shown that the changes in the thickness and volume of the mammary gland during the menstrual cycle accounted for the changes in compression-induced pain. On MRI examination of each breast quadrant, the same changes were observed in areas A and C. In area A, it was shown that both the anatomical characteristics and the increase in volume of the mammary gland were associated with pain. We concluded that the late follicular phase constitutes the optimal timing for mammography.
    MeSH term(s) Adult ; Breast/pathology ; Compressive Strength ; Female ; Humans ; Mammography/methods ; Menstrual Cycle/physiology ; Pain/etiology ; Prognosis ; Young Adult
    Language English
    Publishing date 2017-11-13
    Publishing country Japan
    Document type Journal Article
    ZDB-ID 2433581-2
    ISSN 1865-0341 ; 1865-0333
    ISSN (online) 1865-0341
    ISSN 1865-0333
    DOI 10.1007/s12194-017-0429-y
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